[gnupg2.git] / doc / gpg.texi

@c Copyright (C) 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007,
@c               2008, 2009, 2010 Free Software Foundation, Inc.
@c This is part of the GnuPG manual.
@c For copying conditions, see the file gnupg.texi.

@include defs.inc

@node Invoking GPG
@chapter Invoking GPG
@cindex GPG command options
@cindex command options
@cindex options, GPG command


@c Begin standard stuff
@ifclear gpgtwohack
@manpage gpg.1
@ifset manverb
.B gpg
\- OpenPGP encryption and signing tool
@end ifset

@mansect synopsis
@ifset manverb
.B  gpg
.RB [ \-\-homedir
.IR dir ]
.RB [ \-\-options
.IR file ]
.RI [ options ]
.I command
.RI [ args ]
@end ifset
@end ifclear
@c End standard stuff

@c Begin gpg2 hack stuff
@ifset gpgtwohack
@manpage gpg2.1
@ifset manverb
.B gpg2
\- OpenPGP encryption and signing tool
@end ifset

@mansect synopsis
@ifset manverb
.B  gpg2
.RB [ \-\-homedir
.IR dir ]
.RB [ \-\-options
.IR file ]
.RI [ options ]
.I command
.RI [ args ]
@end ifset
@end ifset
@c End gpg2 hack stuff


@mansect description
@command{@gpgname} is the OpenPGP part of the GNU Privacy Guard (GnuPG). It
is a tool to provide digital encryption and signing services using the
OpenPGP standard. @command{@gpgname} features complete key management and
all the bells and whistles you would expect from a full OpenPGP
implementation.

There are two main versions of GnuPG: GnuPG 1.x and GnuPG 2.x.  GnuPG
2.x supports modern encryption algorithms and thus should be preferred
over GnuPG 1.x.  You only need to use GnuPG 1.x if your platform
doesn't support GnuPG 2.x, or you need support for some features that
GnuPG 2.x has deprecated, e.g., decrypting data created with PGP-2
keys.

@ifclear gpgtwohack
If you are looking for version 1 of GnuPG, you may find that version
installed under the name @command{gpg1}.
@end ifclear
@ifset gpgtwohack
In contrast to the standalone command @command{gpg} from GnuPG 1.x,
the 2.x version is commonly installed under the name
@command{@gpgname}.
@end ifset

@manpause

@xref{Option Index}, for an index to @command{@gpgname}'s commands and options.
@mancont

@menu
* GPG Commands::            List of all commands.
* GPG Options::             List of all options.
* GPG Configuration::       Configuration files.
* GPG Examples::            Some usage examples.

Developer information:
* Unattended Usage of GPG:: Using @command{gpg} from other programs.
@end menu

@c * GPG Protocol::        The protocol the server mode uses.


@c *******************************************
@c ***************            ****************
@c ***************  COMMANDS  ****************
@c ***************            ****************
@c *******************************************
@mansect commands
@node GPG Commands
@section Commands

Commands are not distinguished from options except for the fact that
only one command is allowed.  Generally speaking, irrelevant options
are silently ignored, and may not be checked for correctness.

@command{@gpgname} may be run with no commands. In this case it will
perform a reasonable action depending on the type of file it is given
as input (an encrypted message is decrypted, a signature is verified,
a file containing keys is listed, etc.).


@menu
* General GPG Commands::        Commands not specific to the functionality.
* Operational GPG Commands::    Commands to select the type of operation.
* OpenPGP Key Management::      How to manage your keys.
@end menu


@c *******************************************
@c **********  GENERAL COMMANDS  *************
@c *******************************************
@node General GPG Commands
@subsection Commands not specific to the function

@table @gnupgtabopt
@item --version
@opindex version
Print the program version and licensing information.  Note that you
cannot abbreviate this command.

@item --help
@itemx -h
@opindex help
Print a usage message summarizing the most useful command-line options.
Note that you cannot arbitrarily abbreviate this command
(though you can use its short form @option{-h}).

@item --warranty
@opindex warranty
Print warranty information.

@item --dump-options
@opindex dump-options
Print a list of all available options and commands.  Note that you cannot
abbreviate this command.
@end table


@c *******************************************
@c ********  OPERATIONAL COMMANDS  ***********
@c *******************************************
@node Operational GPG Commands
@subsection Commands to select the type of operation


@table @gnupgtabopt

@item --sign
@itemx -s
@opindex sign
Sign a message. This command may be combined with @option{--encrypt}
(to sign and encrypt a message), @option{--symmetric} (to sign and
symmetrically encrypt a message), or both @option{--encrypt} and
@option{--symmetric} (to sign and encrypt a message that can be
decrypted using a secret key or a passphrase).  The signing key is
chosen by default or can be set explicitly using the
@option{--local-user} and @option{--default-key} options.

@item --clear-sign
@opindex clear-sign
@itemx --clearsign
@opindex clearsign
Make a cleartext signature.  The content in a cleartext signature is
readable without any special software. OpenPGP software is only needed
to verify the signature.  cleartext signatures may modify end-of-line
whitespace for platform independence and are not intended to be
reversible.  The signing key is chosen by default or can be set
explicitly using the @option{--local-user} and @option{--default-key}
options.


@item --detach-sign
@itemx -b
@opindex detach-sign
Make a detached signature.

@item --encrypt
@itemx -e
@opindex encrypt
Encrypt data. This command may be combined with @option{--sign} (to
sign and encrypt a message), @option{--symmetric} (to encrypt a
message that can decrypted using a secret key or a passphrase), or
@option{--sign} and @option{--symmetric} together (for a signed
message that can be decrypted using a secret key or a passphrase).

@item --symmetric
@itemx -c
@opindex symmetric
Encrypt with a symmetric cipher using a passphrase. The default
symmetric cipher used is @value{GPGSYMENCALGO}, but may be chosen with the
@option{--cipher-algo} option. This command may be combined with
@option{--sign} (for a signed and symmetrically encrypted message),
@option{--encrypt} (for a message that may be decrypted via a secret key
or a passphrase), or @option{--sign} and @option{--encrypt} together
(for a signed message that may be decrypted via a secret key or a
passphrase).

@item --store
@opindex store
Store only (make a simple literal data packet).

@item --decrypt
@itemx -d
@opindex decrypt
Decrypt the file given on the command line (or STDIN if no file
is specified) and write it to STDOUT (or the file specified with
@option{--output}). If the decrypted file is signed, the signature is also
verified. This command differs from the default operation, as it never
writes to the filename which is included in the file and it rejects
files that don't begin with an encrypted message.

@item --verify
@opindex verify
Assume that the first argument is a signed file and verify it without
generating any output.  With no arguments, the signature packet is
read from STDIN.  If only one argument is given, the specified file is
expected to include a complete signature.

With more than one argument, the first argument should specify a file
with a detached signature and the remaining files should contain the
signed data. To read the signed data from STDIN, use @samp{-} as the
second filename.  For security reasons, a detached signature will not
read the signed material from STDIN if not explicitly specified.

Note: If the option @option{--batch} is not used, @command{@gpgname}
may assume that a single argument is a file with a detached signature,
and it will try to find a matching data file by stripping certain
suffixes.  Using this historical feature to verify a detached
signature is strongly discouraged; you should always specify the data file
explicitly.

Note: When verifying a cleartext signature, @command{@gpgname} verifies
only what makes up the cleartext signed data and not any extra data
outside of the cleartext signature or the header lines directly following
the dash marker line.  The option @code{--output} may be used to write
out the actual signed data, but there are other pitfalls with this
format as well.  It is suggested to avoid cleartext signatures in
favor of detached signatures.

Note: Sometimes the use of the @command{gpgv} tool is easier than
using the full-fledged @command{gpg} with this option.  @command{gpgv}
is designed to compare signed data against a list of trusted keys and
returns with success only for a good signature.  It has its own manual
page.


@item --multifile
@opindex multifile
This modifies certain other commands to accept multiple files for
processing on the command line or read from STDIN with each filename on
a separate line. This allows for many files to be processed at
once. @option{--multifile} may currently be used along with
@option{--verify}, @option{--encrypt}, and @option{--decrypt}. Note that
@option{--multifile --verify} may not be used with detached signatures.

@item --verify-files
@opindex verify-files
Identical to @option{--multifile --verify}.

@item --encrypt-files
@opindex encrypt-files
Identical to @option{--multifile --encrypt}.

@item --decrypt-files
@opindex decrypt-files
Identical to @option{--multifile --decrypt}.

@item --list-keys
@itemx -k
@itemx --list-public-keys
@opindex list-keys
List the specified keys.  If no keys are specified, then all keys from
the configured public keyrings are listed.

Never use the output of this command in scripts or other programs.
The output is intended only for humans and its format is likely to
change.  The @option{--with-colons} option emits the output in a
stable, machine-parseable format, which is intended for use by scripts
and other programs.

@item --list-secret-keys
@itemx -K
@opindex list-secret-keys
List the specified secret keys.  If no keys are specified, then all
known secret keys are listed.  A @code{#} after the letters @code{sec}
means that the secret key is not usable (for example, if it was
exported using @option{--export-secret-subkeys}).  See also
@option{--list-keys}.

@item --list-signatures
@opindex list-signatures
@itemx --list-sigs
@opindex list-sigs
Same as @option{--list-keys}, but the signatures are listed too.
This command has the same effect as
using @option{--list-keys} with @option{--with-sig-list}.

For each signature listed, there are several flags in between the "sig"
tag and keyid. These flags give additional information about each
signature. From left to right, they are the numbers 1-3 for certificate
check level (see @option{--ask-cert-level}), "L" for a local or
non-exportable signature (see @option{--lsign-key}), "R" for a
nonRevocable signature (see the @option{--edit-key} command "nrsign"),
"P" for a signature that contains a policy URL (see
@option{--cert-policy-url}), "N" for a signature that contains a
notation (see @option{--cert-notation}), "X" for an eXpired signature
(see @option{--ask-cert-expire}), and the numbers 1-9 or "T" for 10 and
above to indicate trust signature levels (see the @option{--edit-key}
command "tsign").

@item --check-signatures
@opindex check-signatures
@itemx --check-sigs
@opindex check-sigs
Same as @option{--list-signatures}, but the signatures are verified.  Note
that for performance reasons the revocation status of a signing key is
not shown.
This command has the same effect as
using @option{--list-keys} with @option{--with-sig-check}.

The status of the verification is indicated by a flag directly following
the "sig" tag (and thus before the flags described above for
@option{--list-signatures}).  A "!" indicates that the signature has been
successfully verified, a "-" denotes a bad signature and a "%" is used
if an error occurred while checking the signature (e.g. a non supported
algorithm).

@item --locate-keys
@opindex locate-keys
Locate the keys given as arguments.  This command basically uses the
same algorithm as used when locating keys for encryption or signing and
may thus be used to see what keys @command{@gpgname} might use.  In
particular external methods as defined by @option{--auto-key-locate} may
be used to locate a key.  Only public keys are listed.

@item --fingerprint
@opindex fingerprint
List all keys (or the specified ones) along with their
fingerprints. This is the same output as @option{--list-keys} but with
the additional output of a line with the fingerprint. May also be
combined with @option{--list-signatures} or @option{--check-signatures}.  If this
command is given twice, the fingerprints of all secondary keys are
listed too.  This command also forces pretty printing of fingerprints
if the keyid format has been set to "none".

@item --list-packets
@opindex list-packets
List only the sequence of packets.  This command is only useful for
debugging.  When used with option @option{--verbose} the actual MPI
values are dumped and not only their lengths.  Note that the output of
this command may change with new releases.


@item --edit-card
@opindex edit-card
@itemx --card-edit
@opindex card-edit
Present a menu to work with a smartcard. The subcommand "help" provides
an overview on available commands. For a detailed description, please
see the Card HOWTO at
https://gnupg.org/documentation/howtos.html#GnuPG-cardHOWTO .

@item --card-status
@opindex card-status
Show the content of the smart card.

@item --change-pin
@opindex change-pin
Present a menu to allow changing the PIN of a smartcard. This
functionality is also available as the subcommand "passwd" with the
@option{--edit-card} command.

@item --delete-keys @code{name}
@itemx --delete-keys @code{name}
Remove key from the public keyring. In batch mode either @option{--yes} is
required or the key must be specified by fingerprint. This is a
safeguard against accidental deletion of multiple keys.

@item --delete-secret-keys @code{name}
@opindex delete-secret-keys
Remove key from the secret keyring. In batch mode the key must be
specified by fingerprint.  The option @option{--yes} can be used to
advice gpg-agent not to request a confirmation.  This extra
pre-caution is done because @command{@gpgname} can't be sure that the
secret key (as controlled by gpg-agent) is only used for the given
OpenPGP public key.


@item --delete-secret-and-public-key @code{name}
@opindex delete-secret-and-public-key
Same as @option{--delete-key}, but if a secret key exists, it will be
removed first. In batch mode the key must be specified by fingerprint.
The option @option{--yes} can be used to advice gpg-agent not to
request a confirmation.

@item --export
@opindex export
Either export all keys from all keyrings (default keyrings and those
registered via option @option{--keyring}), or if at least one name is given,
those of the given name. The exported keys are written to STDOUT or to the
file given with option @option{--output}.  Use together with
@option{--armor} to mail those keys.

@item --send-keys @code{key IDs}
@opindex send-keys
Similar to @option{--export} but sends the keys to a keyserver.
Fingerprints may be used instead of key IDs. Option @option{--keyserver}
must be used to give the name of this keyserver. Don't send your
complete keyring to a keyserver --- select only those keys which are new
or changed by you.  If no key IDs are given, @command{@gpgname} does nothing.

@item --export-secret-keys
@itemx --export-secret-subkeys
@opindex export-secret-keys
@opindex export-secret-subkeys
Same as @option{--export}, but exports the secret keys instead.  The
exported keys are written to STDOUT or to the file given with option
@option{--output}.  This command is often used along with the option
@option{--armor} to allow for easy printing of the key for paper backup;
however the external tool @command{paperkey} does a better job of
creating backups on paper.  Note that exporting a secret key can be a
security risk if the exported keys are sent over an insecure channel.

The second form of the command has the special property to render the
secret part of the primary key useless; this is a GNU extension to
OpenPGP and other implementations can not be expected to successfully
import such a key.  Its intended use is in generating a full key with
an additional signing subkey on a dedicated machine.  This command
then exports the key without the primary key to the main machine.

GnuPG may ask you to enter the passphrase for the key.  This is
required, because the internal protection method of the secret key is
different from the one specified by the OpenPGP protocol.

@item --export-ssh-key
@opindex export-ssh-key
This command is used to export a key in the OpenSSH public key format.
It requires the specification of one key by the usual means and
exports the latest valid subkey which has an authentication capability
to STDOUT or to the file given with option @option{--output}.  That
output can directly be added to ssh's @file{authorized_key} file.

By specifying the key to export using a key ID or a fingerprint
suffixed with an exclamation mark (!), a specific subkey or the
primary key can be exported.  This does not even require that the key
has the authentication capability flag set.

@item --import
@itemx --fast-import
@opindex import
Import/merge keys. This adds the given keys to the
keyring. The fast version is currently just a synonym.

There are a few other options which control how this command works.
Most notable here is the @option{--import-options merge-only} option
which does not insert new keys but does only the merging of new
signatures, user-IDs and subkeys.

@item --receive-keys @code{key IDs}
@opindex receive-keys
@itemx --recv-keys @code{key IDs}
@opindex recv-keys
Import the keys with the given key IDs from a keyserver. Option
@option{--keyserver} must be used to give the name of this keyserver.

@item --refresh-keys
@opindex refresh-keys
Request updates from a keyserver for keys that already exist on the
local keyring. This is useful for updating a key with the latest
signatures, user IDs, etc. Calling this with no arguments will refresh
the entire keyring. Option @option{--keyserver} must be used to give the
name of the keyserver for all keys that do not have preferred keyservers
set (see @option{--keyserver-options honor-keyserver-url}).

@item --search-keys @code{names}
@opindex search-keys
Search the keyserver for the given names. Multiple names given here will
be joined together to create the search string for the keyserver.
Option @option{--keyserver} must be used to give the name of this
keyserver.  Keyservers that support different search methods allow using
the syntax specified in "How to specify a user ID" below. Note that
different keyserver types support different search methods. Currently
only LDAP supports them all.

@item --fetch-keys @code{URIs}
@opindex fetch-keys
Retrieve keys located at the specified URIs. Note that different
installations of GnuPG may support different protocols (HTTP, FTP,
LDAP, etc.).  When using HTTPS the system provided root certificates
are used by this command.

@item --update-trustdb
@opindex update-trustdb
Do trust database maintenance. This command iterates over all keys and
builds the Web of Trust. This is an interactive command because it may
have to ask for the "ownertrust" values for keys. The user has to give
an estimation of how far she trusts the owner of the displayed key to
correctly certify (sign) other keys. GnuPG only asks for the ownertrust
value if it has not yet been assigned to a key. Using the
@option{--edit-key} menu, the assigned value can be changed at any time.

@item --check-trustdb
@opindex check-trustdb
Do trust database maintenance without user interaction. From time to
time the trust database must be updated so that expired keys or
signatures and the resulting changes in the Web of Trust can be
tracked. Normally, GnuPG will calculate when this is required and do it
automatically unless @option{--no-auto-check-trustdb} is set. This
command can be used to force a trust database check at any time. The
processing is identical to that of @option{--update-trustdb} but it
skips keys with a not yet defined "ownertrust".

For use with cron jobs, this command can be used together with
@option{--batch} in which case the trust database check is done only if
a check is needed. To force a run even in batch mode add the option
@option{--yes}.

@anchor{option --export-ownertrust}
@item --export-ownertrust
@opindex export-ownertrust
Send the ownertrust values to STDOUT. This is useful for backup purposes
as these values are the only ones which can't be re-created from a
corrupted trustdb.  Example:
@c man:.RS
@example
  @gpgname{} --export-ownertrust > otrust.txt
@end example
@c man:.RE


@item --import-ownertrust
@opindex import-ownertrust
Update the trustdb with the ownertrust values stored in @code{files} (or
STDIN if not given); existing values will be overwritten.  In case of a
severely damaged trustdb and if you have a recent backup of the
ownertrust values (e.g. in the file @file{otrust.txt}), you may re-create
the trustdb using these commands:
@c man:.RS
@example
  cd ~/.gnupg
  rm trustdb.gpg
  @gpgname{} --import-ownertrust < otrust.txt
@end example
@c man:.RE


@item --rebuild-keydb-caches
@opindex rebuild-keydb-caches
When updating from version 1.0.6 to 1.0.7 this command should be used
to create signature caches in the keyring. It might be handy in other
situations too.

@item --print-md @code{algo}
@itemx --print-mds
@opindex print-md
Print message digest of algorithm ALGO for all given files or STDIN.
With the second form (or a deprecated "*" as algo) digests for all
available algorithms are printed.

@item --gen-random @code{0|1|2} @code{count}
@opindex gen-random
Emit @var{count} random bytes of the given quality level 0, 1 or 2. If
@var{count} is not given or zero, an endless sequence of random bytes
will be emitted.  If used with @option{--armor} the output will be
base64 encoded.  PLEASE, don't use this command unless you know what
you are doing; it may remove precious entropy from the system!

@item --gen-prime @code{mode}  @code{bits}
@opindex gen-prime
Use the source, Luke :-). The output format is still subject to change.


@item --enarmor
@itemx --dearmor
@opindex enarmor
@opindex dearmor
Pack or unpack an arbitrary input into/from an OpenPGP ASCII armor.
This is a GnuPG extension to OpenPGP and in general not very useful.

@item --tofu-policy @code{auto|good|unknown|bad|ask}  @code{key...}
@opindex tofu-policy
Set the TOFU policy for all the bindings associated with the specified
keys.  For more information about the meaning of the policies,
@pxref{trust-model-tofu}.  The keys may be specified either by their
fingerprint (preferred) or their keyid.

@c @item --server
@c @opindex server
@c Run gpg in server mode.  This feature is not yet ready for use and
@c thus not documented.

@end table


@c *******************************************
@c *******  KEY MANGEMENT COMMANDS  **********
@c *******************************************
@node OpenPGP Key Management
@subsection How to manage your keys

This section explains the main commands for key management.

@table @gnupgtabopt

@item --quick-generate-key @code{user-id} [@code{algo} [@code{usage} [@code{expire}]]]
@opindex quick-generate-key
This is a simple command to generate a standard key with one user id.
In contrast to @option{--generate-key} the key is generated directly
without the need to answer a bunch of prompts.  Unless the option
@option{--yes} is given, the key creation will be canceled if the
given user id already exists in the keyring.

If invoked directly on the console without any special options an
answer to a ``Continue?'' style confirmation prompt is required.  In
case the user id already exists in the keyring a second prompt to
force the creation of the key will show up.

If @code{algo} or @code{usage} are given, only the primary key is
created and no prompts are shown.  To specify an expiration date but
still create a primary and subkey use ``default'' or
``future-default'' for @code{algo} and ``default'' for @code{usage}.
For a description of these optional arguments see the command
@code{--quick-add-key}.  The @code{usage} accepts also the value
``cert'' which can be used to create a certification only primary key;
the default is to a create certification and signing key.

The @code{expire} argument can be used to specify an expiration date
for the key.  Several formats are supported; commonly the ISO
YYYY-MM-DD format is used.  The values ``never'', ``none'' can be used
for no expiration date.  Not specifying a value, or using ``-''
results in a key expiring in a reasonable default interval.

If this command is used with @option{--batch},
@option{--pinentry-mode} has been set to @code{loopback}, and one of
the passphrase options (@option{--passphrase},
@option{--passphrase-fd}, or @option{passphrase-file}) is used, the
supplied passphrase is used for the new key and the agent does not ask
for it.  To create a key without any protection @code{--passphrase ''}
may be used.

@item --quick-set-expire @code{fpr} @code{expire}
@opindex quick-set-expire
Directly set the expiration time of the primary key to @code{expire}.
To remove the expiration time @code{0} can be used.


@item --quick-add-key @code{fpr} [@code{algo} [@code{usage} [@code{expire}]]]
@opindex quick-add-key
Directly add a subkey to the key identified by the fingerprint
@code{fpr}.  Without the optional arguments an encryption subkey is
added.  If any of the arguments are given a more specific subkey is
added.

@code{algo} may be any of the supported algorithms or curve names
given in the format as used by key listings.  To use the default
algorithm the string ``default'' or ``-'' can be used.  Supported
algorithms are ``rsa'', ``dsa'', ``elg'', ``ed25519'', ``cv25519'',
and other ECC curves.  For example the string ``rsa'' adds an RSA key
with the default key length; a string ``rsa4096'' requests that the
key length is 4096 bits.  The string ``future-default'' is an alias
for the algorithm which will likely be used as default algorithm in
future versions of gpg.

Depending on the given @code{algo} the subkey may either be an
encryption subkey or a signing subkey.  If an algorithm is capable of
signing and encryption and such a subkey is desired, a @code{usage}
string must be given.  This string is either ``default'' or ``-'' to
keep the default or a comma delimited list of keywords: ``sign'' for a
signing subkey, ``auth'' for an authentication subkey, and ``encr''
for an encryption subkey (``encrypt'' can be used as alias for
``encr'').  The valid combinations depend on the algorithm.

The @code{expire} argument can be used to specify an expiration date
for the subkey.  Several formats are supported; commonly the ISO
YYYY-MM-DD format is used.  The values ``never'', ``none'', or ``-''
can be used for no expiration date.

@item --generate-key
@opindex generate-key
@itemx --gen-key
@opindex gen-key
Generate a new key pair using the current default parameters.  This is
the standard command to create a new key.  In addition to the key a
revocation certificate is created and stored in the
@file{openpgp-revocs.d} directory below the GnuPG home directory.

@item --full-generate-key
@opindex full-generate-key
@itemx --full-gen-key
@opindex full-gen-key
Generate a new key pair with dialogs for all options.  This is an
extended version of @option{--generate-key}.

There is also a feature which allows you to create keys in batch
mode. See the manual section ``Unattended key generation'' on how
to use this.


@item --generate-revocation @code{name}
@opindex generate-revocation
@itemx --gen-revoke @code{name}
@opindex gen-revoke
Generate a revocation certificate for the complete key.  To only revoke
a subkey or a key signature, use the @option{--edit} command.

This command merely creates the revocation certificate so that it can
be used to revoke the key if that is ever needed.  To actually revoke
a key the created revocation certificate needs to be merged with the
key to revoke.  This is done by importing the revocation certificate
using the @option{--import} command.  Then the revoked key needs to be
published, which is best done by sending the key to a keyserver
(command @option{--send-key}) and by exporting (@option{--export}) it
to a file which is then send to frequent communication partners.


@item --generate-designated-revocation @code{name}
@opindex generate-designated-revocation
@itemx --desig-revoke @code{name}
@opindex desig-revoke
Generate a designated revocation certificate for a key. This allows a
user (with the permission of the keyholder) to revoke someone else's
key.


@item --edit-key
@opindex edit-key
Present a menu which enables you to do most of the key management
related tasks.  It expects the specification of a key on the command
line.

@c ******** Begin Edit-key Options **********
@table @asis

  @item uid @code{n}
  @opindex keyedit:uid
  Toggle selection of user ID or photographic user ID with index @code{n}.
  Use @code{*} to select all and @code{0} to deselect all.

  @item key @code{n}
  @opindex keyedit:key
  Toggle selection of subkey with index @code{n} or key ID @code{n}.
  Use @code{*} to select all and @code{0} to deselect all.

  @item sign
  @opindex keyedit:sign
  Make a signature on key of user @code{name}. If the key is not yet
  signed by the default user (or the users given with @option{-u}), the program
  displays the information of the key again, together with its
  fingerprint and asks whether it should be signed. This question is
  repeated for all users specified with
  @option{-u}.

  @item lsign
  @opindex keyedit:lsign
  Same as "sign" but the signature is marked as non-exportable and will
  therefore never be used by others. This may be used to make keys
  valid only in the local environment.

  @item nrsign
  @opindex keyedit:nrsign
  Same as "sign" but the signature is marked as non-revocable and can
  therefore never be revoked.

  @item tsign
  @opindex keyedit:tsign
  Make a trust signature. This is a signature that combines the notions
  of certification (like a regular signature), and trust (like the
  "trust" command). It is generally only useful in distinct communities
  or groups.  For more information please read the sections
  ``Trust Signature'' and ``Regular Expression'' in RFC-4880.
@end table

@c man:.RS
Note that "l" (for local / non-exportable), "nr" (for non-revocable,
and "t" (for trust) may be freely mixed and prefixed to "sign" to
create a signature of any type desired.
@c man:.RE

If the option @option{--only-sign-text-ids} is specified, then any
non-text based user ids (e.g., photo IDs) will not be selected for
signing.

@table @asis

  @item delsig
  @opindex keyedit:delsig
  Delete a signature. Note that it is not possible to retract a signature,
  once it has been send to the public (i.e. to a keyserver).  In that case
  you better use @code{revsig}.

  @item revsig
  @opindex keyedit:revsig
  Revoke a signature. For every signature which has been generated by
  one of the secret keys, GnuPG asks whether a revocation certificate
  should be generated.

  @item check
  @opindex keyedit:check
  Check the signatures on all selected user IDs.  With the extra
  option @code{selfsig} only self-signatures are shown.

  @item adduid
  @opindex keyedit:adduid
  Create an additional user ID.

  @item addphoto
  @opindex keyedit:addphoto
  Create a photographic user ID. This will prompt for a JPEG file that
  will be embedded into the user ID. Note that a very large JPEG will make
  for a very large key. Also note that some programs will display your
  JPEG unchanged (GnuPG), and some programs will scale it to fit in a
  dialog box (PGP).

  @item showphoto
  @opindex keyedit:showphoto
  Display the selected photographic user ID.

  @item deluid
  @opindex keyedit:deluid
  Delete a user ID or photographic user ID.  Note that it is not
  possible to retract a user id, once it has been send to the public
  (i.e. to a keyserver).  In that case you better use @code{revuid}.

  @item revuid
  @opindex keyedit:revuid
  Revoke a user ID or photographic user ID.

  @item primary
  @opindex keyedit:primary
  Flag the current user id as the primary one, removes the primary user
  id flag from all other user ids and sets the timestamp of all affected
  self-signatures one second ahead. Note that setting a photo user ID
  as primary makes it primary over other photo user IDs, and setting a
  regular user ID as primary makes it primary over other regular user
  IDs.

  @item keyserver
  @opindex keyedit:keyserver
  Set a preferred keyserver for the specified user ID(s). This allows
  other users to know where you prefer they get your key from. See
  @option{--keyserver-options honor-keyserver-url} for more on how this
  works.  Setting a value of "none" removes an existing preferred
  keyserver.

  @item notation
  @opindex keyedit:notation
  Set a name=value notation for the specified user ID(s). See
  @option{--cert-notation} for more on how this works. Setting a value of
  "none" removes all notations, setting a notation prefixed with a minus
  sign (-) removes that notation, and setting a notation name (without the
  =value) prefixed with a minus sign removes all notations with that name.

  @item pref
  @opindex keyedit:pref
  List preferences from the selected user ID. This shows the actual
  preferences, without including any implied preferences.

  @item showpref
  @opindex keyedit:showpref
  More verbose preferences listing for the selected user ID. This shows
  the preferences in effect by including the implied preferences of 3DES
  (cipher), SHA-1 (digest), and Uncompressed (compression) if they are
  not already included in the preference list. In addition, the
  preferred keyserver and signature notations (if any) are shown.

  @item setpref @code{string}
  @opindex keyedit:setpref
  Set the list of user ID preferences to @code{string} for all (or just
  the selected) user IDs. Calling setpref with no arguments sets the
  preference list to the default (either built-in or set via
  @option{--default-preference-list}), and calling setpref with "none"
  as the argument sets an empty preference list. Use @command{@gpgname
  --version} to get a list of available algorithms. Note that while you
  can change the preferences on an attribute user ID (aka "photo ID"),
  GnuPG does not select keys via attribute user IDs so these preferences
  will not be used by GnuPG.

  When setting preferences, you should list the algorithms in the order
  which you'd like to see them used by someone else when encrypting a
  message to your key.  If you don't include 3DES, it will be
  automatically added at the end.  Note that there are many factors that
  go into choosing an algorithm (for example, your key may not be the
  only recipient), and so the remote OpenPGP application being used to
  send to you may or may not follow your exact chosen order for a given
  message.  It will, however, only choose an algorithm that is present
  on the preference list of every recipient key.  See also the
  INTEROPERABILITY WITH OTHER OPENPGP PROGRAMS section below.

  @item addkey
  @opindex keyedit:addkey
  Add a subkey to this key.

  @item addcardkey
  @opindex keyedit:addcardkey
  Generate a subkey on a card and add it to this key.

  @item keytocard
  @opindex keyedit:keytocard
  Transfer the selected secret subkey (or the primary key if no subkey
  has been selected) to a smartcard. The secret key in the keyring will
  be replaced by a stub if the key could be stored successfully on the
  card and you use the save command later. Only certain key types may be
  transferred to the card. A sub menu allows you to select on what card
  to store the key. Note that it is not possible to get that key back
  from the card - if the card gets broken your secret key will be lost
  unless you have a backup somewhere.

  @item bkuptocard @code{file}
  @opindex keyedit:bkuptocard
  Restore the given file to a card. This command may be used to restore a
  backup key (as generated during card initialization) to a new card. In
  almost all cases this will be the encryption key. You should use this
  command only with the corresponding public key and make sure that the
  file given as argument is indeed the backup to restore. You should then
  select 2 to restore as encryption key.  You will first be asked to enter
  the passphrase of the backup key and then for the Admin PIN of the card.

  @item delkey
  @opindex keyedit:delkey
  Remove a subkey (secondary key). Note that it is not possible to retract
  a subkey, once it has been send to the public (i.e. to a keyserver).  In
  that case you better use @code{revkey}.  Also note that this only
  deletes the public part of a key.

  @item revkey
  @opindex keyedit:revkey
  Revoke a subkey.

  @item expire
  @opindex keyedit:expire
  Change the key or subkey expiration time. If a subkey is selected, the
  expiration time of this subkey will be changed. With no selection, the
  key expiration of the primary key is changed.

  @item trust
  @opindex keyedit:trust
  Change the owner trust value for the key. This updates the trust-db
  immediately and no save is required.

  @item disable
  @itemx enable
  @opindex keyedit:disable
  @opindex keyedit:enable
  Disable or enable an entire key. A disabled key can not normally be
  used for encryption.

  @item addrevoker
  @opindex keyedit:addrevoker
  Add a designated revoker to the key. This takes one optional argument:
  "sensitive". If a designated revoker is marked as sensitive, it will
  not be exported by default (see export-options).

  @item passwd
  @opindex keyedit:passwd
  Change the passphrase of the secret key.

  @item toggle
  @opindex keyedit:toggle
  This is dummy command which exists only for backward compatibility.

  @item clean
  @opindex keyedit:clean
  Compact (by removing all signatures except the selfsig) any user ID
  that is no longer usable (e.g. revoked, or expired). Then, remove any
  signatures that are not usable by the trust calculations.
  Specifically, this removes any signature that does not validate, any
  signature that is superseded by a later signature, revoked signatures,
  and signatures issued by keys that are not present on the keyring.

  @item minimize
  @opindex keyedit:minimize
  Make the key as small as possible. This removes all signatures from
  each user ID except for the most recent self-signature.

  @item cross-certify
  @opindex keyedit:cross-certify
  Add cross-certification signatures to signing subkeys that may not
  currently have them. Cross-certification signatures protect against a
  subtle attack against signing subkeys. See
  @option{--require-cross-certification}.  All new keys generated have
  this signature by default, so this command is only useful to bring
  older keys up to date.

  @item save
  @opindex keyedit:save
  Save all changes to the keyrings and quit.

  @item quit
  @opindex keyedit:quit
  Quit the program without updating the
  keyrings.
@end table

@c man:.RS
The listing shows you the key with its secondary keys and all user
ids.  The primary user id is indicated by a dot, and selected keys or
user ids are indicated by an asterisk.  The trust
value is displayed with the primary key: the first is the assigned owner
trust and the second is the calculated trust value. Letters are used for
the values:
@c man:.RE

@table @asis

  @item -
  No ownertrust assigned / not yet calculated.

  @item e
  Trust
  calculation has failed; probably due to an expired key.

  @item q
  Not enough information for calculation.

  @item n
  Never trust this key.

  @item m
  Marginally trusted.

  @item f
  Fully trusted.

  @item u
  Ultimately trusted.

@end table
@c ******** End Edit-key Options **********

@item --sign-key @code{name}
@opindex sign-key
Signs a public key with your secret key. This is a shortcut version of
the subcommand "sign" from @option{--edit}.

@item --lsign-key @code{name}
@opindex lsign-key
Signs a public key with your secret key but marks it as
non-exportable. This is a shortcut version of the subcommand "lsign"
from @option{--edit-key}.

@item --quick-sign-key @code{fpr} [@code{names}]
@itemx --quick-lsign-key @code{fpr} [@code{names}]
@opindex quick-sign-key
@opindex quick-lsign-key
Directly sign a key from the passphrase without any further user
interaction.  The @code{fpr} must be the verified primary fingerprint
of a key in the local keyring. If no @code{names} are given, all
useful user ids are signed; with given [@code{names}] only useful user
ids matching one of theses names are signed.  By default, or if a name
is prefixed with a '*', a case insensitive substring match is used.
If a name is prefixed with a '=' a case sensitive exact match is done.

The command @option{--quick-lsign-key} marks the signatures as
non-exportable.  If such a non-exportable signature already exists the
@option{--quick-sign-key} turns it into a exportable signature.

This command uses reasonable defaults and thus does not provide the
full flexibility of the "sign" subcommand from @option{--edit-key}.
Its intended use is to help unattended key signing by utilizing a list
of verified fingerprints.

@item --quick-add-uid  @var{user-id} @var{new-user-id}
@opindex quick-add-uid
This command adds a new user id to an existing key.  In contrast to
the interactive sub-command @code{adduid} of @option{--edit-key} the
@var{new-user-id} is added verbatim with only leading and trailing
white space removed, it is expected to be UTF-8 encoded, and no checks
on its form are applied.

@item --quick-revoke-uid  @var{user-id} @var{user-id-to-revoke}
@opindex quick-revoke-uid
This command revokes a User ID on an existing key.  It cannot be used
to revoke the last User ID on key (some non-revoked User ID must
remain), with revocation reason ``User ID is no longer valid''.  If
you want to specify a different revocation reason, or to supply
supplementary revocation text, you should use the interactive
sub-command @code{revuid} of @option{--edit-key}.

@item --change-passphrase @var{user_id}
@opindex change-passphrase
@itemx --passwd @var{user_id}
@opindex passwd
Change the passphrase of the secret key belonging to the certificate
specified as @var{user_id}.  This is a shortcut for the sub-command
@code{passwd} of the edit key menu.

@end table


@c *******************************************
@c ***************            ****************
@c ***************  OPTIONS   ****************
@c ***************            ****************
@c *******************************************
@mansect options
@node GPG Options
@section Option Summary

@command{@gpgname} features a bunch of options to control the exact
behaviour and to change the default configuration.

@menu
* GPG Configuration Options::   How to change the configuration.
* GPG Key related Options::     Key related options.
* GPG Input and Output::        Input and Output.
* OpenPGP Options::             OpenPGP protocol specific options.
* Compliance Options::          Compliance options.
* GPG Esoteric Options::        Doing things one usually doesn't want to do.
* Deprecated Options::          Deprecated options.
@end menu

Long options can be put in an options file (default
"~/.gnupg/gpg.conf"). Short option names will not work - for example,
"armor" is a valid option for the options file, while "a" is not. Do not
write the 2 dashes, but simply the name of the option and any required
arguments. Lines with a hash ('#') as the first non-white-space
character are ignored. Commands may be put in this file too, but that is
not generally useful as the command will execute automatically with
every execution of gpg.

Please remember that option parsing stops as soon as a non-option is
encountered, you can explicitly stop parsing by using the special option
@option{--}.

@c *******************************************
@c ********  CONFIGURATION OPTIONS  **********
@c *******************************************
@node GPG Configuration Options
@subsection How to change the configuration

These options are used to change the configuration and are usually found
in the option file.

@table @gnupgtabopt

@item --default-key @var{name}
@opindex default-key
Use @var{name} as the default key to sign with. If this option is not
used, the default key is the first key found in the secret keyring.
Note that @option{-u} or @option{--local-user} overrides this option.
This option may be given multiple times.  In this case, the last key
for which a secret key is available is used.  If there is no secret
key available for any of the specified values, GnuPG will not emit an
error message but continue as if this option wasn't given.

@item --default-recipient @var{name}
@opindex default-recipient
Use @var{name} as default recipient if option @option{--recipient} is
not used and don't ask if this is a valid one. @var{name} must be
non-empty.

@item --default-recipient-self
@opindex default-recipient-self
Use the default key as default recipient if option @option{--recipient} is not
used and don't ask if this is a valid one. The default key is the first
one from the secret keyring or the one set with @option{--default-key}.

@item --no-default-recipient
@opindex no-default-recipient
Reset @option{--default-recipient} and @option{--default-recipient-self}.

@item -v, --verbose
@opindex verbose
Give more information during processing. If used
twice, the input data is listed in detail.

@item --no-verbose
@opindex no-verbose
Reset verbose level to 0.

@item -q, --quiet
@opindex quiet
Try to be as quiet as possible.

@item --batch
@itemx --no-batch
@opindex batch
@opindex no-batch
Use batch mode.  Never ask, do not allow interactive commands.
@option{--no-batch} disables this option.  Note that even with a
filename given on the command line, gpg might still need to read from
STDIN (in particular if gpg figures that the input is a
detached signature and no data file has been specified).  Thus if you
do not want to feed data via STDIN, you should connect STDIN to
g@file{/dev/null}.

It is highly recommended to use this option along with the options
@option{--status-fd} and @option{--with-colons} for any unattended of
@command{gpg}.

@item --no-tty
@opindex no-tty
Make sure that the TTY (terminal) is never used for any output.
This option is needed in some cases because GnuPG sometimes prints
warnings to the TTY even if @option{--batch} is used.

@item --yes
@opindex yes
Assume "yes" on most questions.

@item --no
@opindex no
Assume "no" on most questions.


@item --list-options @code{parameters}
@opindex list-options
This is a space or comma delimited string that gives options used when
listing keys and signatures (that is, @option{--list-keys},
@option{--list-signatures}, @option{--list-public-keys},
@option{--list-secret-keys}, and the @option{--edit-key} functions).
Options can be prepended with a @option{no-} (after the two dashes) to
give the opposite meaning.  The options are:

@table @asis

  @item show-photos
  @opindex list-options:show-photos
  Causes @option{--list-keys}, @option{--list-signatures},
  @option{--list-public-keys}, and @option{--list-secret-keys} to
  display any photo IDs attached to the key.  Defaults to no. See also
  @option{--photo-viewer}.  Does not work with @option{--with-colons}:
  see @option{--attribute-fd} for the appropriate way to get photo data
  for scripts and other frontends.

  @item show-usage
  @opindex list-options:show-usage
  Show usage information for keys and subkeys in the standard key
  listing.  This is a list of letters indicating the allowed usage for a
  key (@code{E}=encryption, @code{S}=signing, @code{C}=certification,
  @code{A}=authentication).  Defaults to yes.

  @item show-policy-urls
  @opindex list-options:show-policy-urls
  Show policy URLs in the @option{--list-signatures} or @option{--check-signatures}
  listings.  Defaults to no.

  @item show-notations
  @itemx show-std-notations
  @itemx show-user-notations
  @opindex list-options:show-notations
  @opindex list-options:show-std-notations
  @opindex list-options:show-user-notations
  Show all, IETF standard, or user-defined signature notations in the
  @option{--list-signatures} or @option{--check-signatures} listings. Defaults to no.

  @item show-keyserver-urls
  @opindex list-options:show-keyserver-urls
  Show any preferred keyserver URL in the @option{--list-signatures} or
  @option{--check-signatures} listings. Defaults to no.

  @item show-uid-validity
  @opindex list-options:show-uid-validity
  Display the calculated validity of user IDs during key listings.
  Defaults to yes.

  @item show-unusable-uids
  @opindex list-options:show-unusable-uids
  Show revoked and expired user IDs in key listings. Defaults to no.

  @item show-unusable-subkeys
  @opindex list-options:show-unusable-subkeys
  Show revoked and expired subkeys in key listings. Defaults to no.

  @item show-keyring
  @opindex list-options:show-keyring
  Display the keyring name at the head of key listings to show which
  keyring a given key resides on. Defaults to no.

  @item show-sig-expire
  @opindex list-options:show-sig-expire
  Show signature expiration dates (if any) during @option{--list-signatures} or
  @option{--check-signatures} listings. Defaults to no.

  @item show-sig-subpackets
  @opindex list-options:show-sig-subpackets
  Include signature subpackets in the key listing. This option can take an
  optional argument list of the subpackets to list. If no argument is
  passed, list all subpackets. Defaults to no. This option is only
  meaningful when using @option{--with-colons} along with
  @option{--list-signatures} or @option{--check-signatures}.

@end table

@item --verify-options @code{parameters}
@opindex verify-options
This is a space or comma delimited string that gives options used when
verifying signatures. Options can be prepended with a `no-' to give
the opposite meaning. The options are:

@table @asis

  @item show-photos
  @opindex verify-options:show-photos
  Display any photo IDs present on the key that issued the signature.
  Defaults to no. See also @option{--photo-viewer}.

  @item show-policy-urls
  @opindex verify-options:show-policy-urls
  Show policy URLs in the signature being verified. Defaults to yes.

  @item show-notations
  @itemx show-std-notations
  @itemx show-user-notations
  @opindex verify-options:show-notations
  @opindex verify-options:show-std-notations
  @opindex verify-options:show-user-notations
  Show all, IETF standard, or user-defined signature notations in the
  signature being verified. Defaults to IETF standard.

  @item show-keyserver-urls
  @opindex verify-options:show-keyserver-urls
  Show any preferred keyserver URL in the signature being verified.
  Defaults to yes.

  @item show-uid-validity
  @opindex verify-options:show-uid-validity
  Display the calculated validity of the user IDs on the key that issued
  the signature. Defaults to yes.

  @item show-unusable-uids
  @opindex verify-options:show-unusable-uids
  Show revoked and expired user IDs during signature verification.
  Defaults to no.

  @item show-primary-uid-only
  @opindex verify-options:show-primary-uid-only
  Show only the primary user ID during signature verification.  That is
  all the AKA lines as well as photo Ids are not shown with the signature
  verification status.

  @item pka-lookups
  @opindex verify-options:pka-lookups
  Enable PKA lookups to verify sender addresses. Note that PKA is based
  on DNS, and so enabling this option may disclose information on when
  and what signatures are verified or to whom data is encrypted. This
  is similar to the "web bug" described for the @option{--auto-key-retrieve}
  option.

  @item pka-trust-increase
  @opindex verify-options:pka-trust-increase
  Raise the trust in a signature to full if the signature passes PKA
  validation. This option is only meaningful if pka-lookups is set.
@end table

@item --enable-large-rsa
@itemx --disable-large-rsa
@opindex enable-large-rsa
@opindex disable-large-rsa
With --generate-key and --batch, enable the creation of RSA secret keys as
large as 8192 bit.  Note: 8192 bit is more than is generally
recommended.  These large keys don't significantly improve security,
but they are more expensive to use, and their signatures and
certifications are larger.  This option is only available if the
binary was build with large-secmem support.

@item --enable-dsa2
@itemx --disable-dsa2
@opindex enable-dsa2
@opindex disable-dsa2
Enable hash truncation for all DSA keys even for old DSA Keys up to
1024 bit.  This is also the default with @option{--openpgp}.  Note
that older versions of GnuPG also required this flag to allow the
generation of DSA larger than 1024 bit.

@item --photo-viewer @code{string}
@opindex photo-viewer
This is the command line that should be run to view a photo ID. "%i"
will be expanded to a filename containing the photo. "%I" does the
same, except the file will not be deleted once the viewer exits.
Other flags are "%k" for the key ID, "%K" for the long key ID, "%f"
for the key fingerprint, "%t" for the extension of the image type
(e.g. "jpg"), "%T" for the MIME type of the image (e.g. "image/jpeg"),
"%v" for the single-character calculated validity of the image being
viewed (e.g. "f"), "%V" for the calculated validity as a string (e.g.
"full"), "%U" for a base32 encoded hash of the user ID,
and "%%" for an actual percent sign. If neither %i or %I are present,
then the photo will be supplied to the viewer on standard input.

The default viewer is "xloadimage -fork -quiet -title 'KeyID 0x%k'
STDIN". Note that if your image viewer program is not secure, then
executing it from GnuPG does not make it secure.

@item --exec-path @code{string}
@opindex exec-path
@efindex PATH
Sets a list of directories to search for photo viewers and keyserver
helpers. If not provided, keyserver helpers use the compiled-in
default directory, and photo viewers use the @code{PATH} environment
variable.
Note, that on W32 system this value is ignored when searching for
keyserver helpers.

@item --keyring @code{file}
@opindex keyring
Add @code{file} to the current list of keyrings. If @code{file} begins
with a tilde and a slash, these are replaced by the $HOME directory. If
the filename does not contain a slash, it is assumed to be in the GnuPG
home directory ("~/.gnupg" if @option{--homedir} or $GNUPGHOME is not
used).

Note that this adds a keyring to the current list. If the intent is to
use the specified keyring alone, use @option{--keyring} along with
@option{--no-default-keyring}.

If the the option @option{--no-keyring} has been used no keyrings will
be used at all.


@item --secret-keyring @code{file}
@opindex secret-keyring
This is an obsolete option and ignored.  All secret keys are stored in
the @file{private-keys-v1.d} directory below the GnuPG home directory.

@item --primary-keyring @code{file}
@opindex primary-keyring
Designate @code{file} as the primary public keyring. This means that
newly imported keys (via @option{--import} or keyserver
@option{--recv-from}) will go to this keyring.

@item --trustdb-name @code{file}
@opindex trustdb-name
Use @code{file} instead of the default trustdb. If @code{file} begins
with a tilde and a slash, these are replaced by the $HOME directory. If
the filename does not contain a slash, it is assumed to be in the GnuPG
home directory (@file{~/.gnupg} if @option{--homedir} or $GNUPGHOME is
not used).

@include opt-homedir.texi


@item --display-charset @code{name}
@opindex display-charset
Set the name of the native character set. This is used to convert
some informational strings like user IDs to the proper UTF-8 encoding.
Note that this has nothing to do with the character set of data to be
encrypted or signed; GnuPG does not recode user-supplied data. If
this option is not used, the default character set is determined from
the current locale. A verbosity level of 3 shows the chosen set.
Valid values for @code{name} are:

@table @asis

  @item iso-8859-1
  @opindex display-charset:iso-8859-1
  This is the Latin 1 set.

  @item iso-8859-2
  @opindex display-charset:iso-8859-2
  The Latin 2 set.

  @item iso-8859-15
  @opindex display-charset:iso-8859-15
  This is currently an alias for
  the Latin 1 set.

  @item koi8-r
  @opindex display-charset:koi8-r
  The usual Russian set (RFC-1489).

  @item utf-8
  @opindex display-charset:utf-8
  Bypass all translations and assume
  that the OS uses native UTF-8 encoding.
@end table

@item --utf8-strings
@itemx --no-utf8-strings
@opindex utf8-strings
Assume that command line arguments are given as UTF-8 strings. The
default (@option{--no-utf8-strings}) is to assume that arguments are
encoded in the character set as specified by
@option{--display-charset}. These options affect all following
arguments. Both options may be used multiple times.

@anchor{gpg-option --options}
@item --options @code{file}
@opindex options
Read options from @code{file} and do not try to read them from the
default options file in the homedir (see @option{--homedir}). This
option is ignored if used in an options file.

@item --no-options
@opindex no-options
Shortcut for @option{--options /dev/null}. This option is detected
before an attempt to open an option file.  Using this option will also
prevent the creation of a @file{~/.gnupg} homedir.

@item -z @code{n}
@itemx --compress-level @code{n}
@itemx --bzip2-compress-level @code{n}
@opindex compress-level
@opindex bzip2-compress-level
Set compression level to @code{n} for the ZIP and ZLIB compression
algorithms. The default is to use the default compression level of zlib
(normally 6). @option{--bzip2-compress-level} sets the compression level
for the BZIP2 compression algorithm (defaulting to 6 as well). This is a
different option from @option{--compress-level} since BZIP2 uses a
significant amount of memory for each additional compression level.
@option{-z} sets both. A value of 0 for @code{n} disables compression.

@item --bzip2-decompress-lowmem
@opindex bzip2-decompress-lowmem
Use a different decompression method for BZIP2 compressed files. This
alternate method uses a bit more than half the memory, but also runs
at half the speed. This is useful under extreme low memory
circumstances when the file was originally compressed at a high
@option{--bzip2-compress-level}.


@item --mangle-dos-filenames
@itemx --no-mangle-dos-filenames
@opindex mangle-dos-filenames
@opindex no-mangle-dos-filenames
Older version of Windows cannot handle filenames with more than one
dot. @option{--mangle-dos-filenames} causes GnuPG to replace (rather
than add to) the extension of an output filename to avoid this
problem. This option is off by default and has no effect on non-Windows
platforms.

@item --ask-cert-level
@itemx --no-ask-cert-level
@opindex ask-cert-level
When making a key signature, prompt for a certification level. If this
option is not specified, the certification level used is set via
@option{--default-cert-level}. See @option{--default-cert-level} for
information on the specific levels and how they are
used. @option{--no-ask-cert-level} disables this option. This option
defaults to no.

@item --default-cert-level @code{n}
@opindex default-cert-level
The default to use for the check level when signing a key.

0 means you make no particular claim as to how carefully you verified
the key.

1 means you believe the key is owned by the person who claims to own
it but you could not, or did not verify the key at all. This is
useful for a "persona" verification, where you sign the key of a
pseudonymous user.

2 means you did casual verification of the key. For example, this
could mean that you verified the key fingerprint and checked the
user ID on the key against a photo ID.

3 means you did extensive verification of the key. For example, this
could mean that you verified the key fingerprint with the owner of the
key in person, and that you checked, by means of a hard to forge
document with a photo ID (such as a passport) that the name of the key
owner matches the name in the user ID on the key, and finally that you
verified (by exchange of email) that the email address on the key
belongs to the key owner.

Note that the examples given above for levels 2 and 3 are just that:
examples. In the end, it is up to you to decide just what "casual"
and "extensive" mean to you.

This option defaults to 0 (no particular claim).

@item --min-cert-level
@opindex min-cert-level
When building the trust database, treat any signatures with a
certification level below this as invalid. Defaults to 2, which
disregards level 1 signatures. Note that level 0 "no particular
claim" signatures are always accepted.

@item --trusted-key @code{long key ID}
@opindex trusted-key
Assume that the specified key (which must be given
as a full 8 byte key ID) is as trustworthy as one of
your own secret keys. This option is useful if you
don't want to keep your secret keys (or one of them)
online but still want to be able to check the validity of a given
recipient's or signator's key.

@item --trust-model @code{pgp|classic|tofu|tofu+pgp|direct|always|auto}
@opindex trust-model
Set what trust model GnuPG should follow. The models are:

@table @asis

  @item pgp
  @opindex trust-mode:pgp
  This is the Web of Trust combined with trust signatures as used in PGP
  5.x and later. This is the default trust model when creating a new
  trust database.

  @item classic
  @opindex trust-mode:classic
  This is the standard Web of Trust as introduced by PGP 2.

  @item tofu
  @opindex trust-mode:tofu
  @anchor{trust-model-tofu}
  TOFU stands for Trust On First Use.  In this trust model, the first
  time a key is seen, it is memorized.  If later another key is seen
  with a user id with the same email address, a warning is displayed
  indicating that there is a conflict and that the key might be a
  forgery and an attempt at a man-in-the-middle attack.

  Because a potential attacker is able to control the email address
  and thereby circumvent the conflict detection algorithm by using an
  email address that is similar in appearance to a trusted email
  address, whenever a message is verified, statistics about the number
  of messages signed with the key are shown.  In this way, a user can
  easily identify attacks using fake keys for regular correspondents.

  When compared with the Web of Trust, TOFU offers significantly
  weaker security guarantees.  In particular, TOFU only helps ensure
  consistency (that is, that the binding between a key and email
  address doesn't change).  A major advantage of TOFU is that it
  requires little maintenance to use correctly.  To use the web of
  trust properly, you need to actively sign keys and mark users as
  trusted introducers.  This is a time-consuming process and anecdotal
  evidence suggests that even security-conscious users rarely take the
  time to do this thoroughly and instead rely on an ad-hoc TOFU
  process.

  In the TOFU model, policies are associated with bindings between
  keys and email addresses (which are extracted from user ids and
  normalized).  There are five policies, which can be set manually
  using the @option{--tofu-policy} option.  The default policy can be
  set using the @option{--tofu-default-policy} option.

  The TOFU policies are: @code{auto}, @code{good}, @code{unknown},
  @code{bad} and @code{ask}.  The @code{auto} policy is used by
  default (unless overridden by @option{--tofu-default-policy}) and
  marks a binding as marginally trusted.  The @code{good},
  @code{unknown} and @code{bad} policies mark a binding as fully
  trusted, as having unknown trust or as having trust never,
  respectively.  The @code{unknown} policy is useful for just using
  TOFU to detect conflicts, but to never assign positive trust to a
  binding.  The final policy, @code{ask} prompts the user to indicate
  the binding's trust.  If batch mode is enabled (or input is
  inappropriate in the context), then the user is not prompted and the
  @code{undefined} trust level is returned.

  @item tofu+pgp
  @opindex trust-mode:tofu+pgp
  This trust model combines TOFU with the Web of Trust.  This is done
  by computing the trust level for each model and then taking the
  maximum trust level where the trust levels are ordered as follows:
  @code{unknown < undefined < marginal < fully < ultimate < expired <
  never}.

  By setting @option{--tofu-default-policy=unknown}, this model can be
  used to implement the web of trust with TOFU's conflict detection
  algorithm, but without its assignment of positive trust values,
  which some security-conscious users don't like.

  @item direct
  @opindex trust-mode:direct
  Key validity is set directly by the user and not calculated via the
  Web of Trust.

  @item always
  @opindex trust-mode:always
  Skip key validation and assume that used keys are always fully
  valid. You generally won't use this unless you are using some
  external validation scheme. This option also suppresses the
  "[uncertain]" tag printed with signature checks when there is no
  evidence that the user ID is bound to the key.  Note that this
  trust model still does not allow the use of expired, revoked, or
  disabled keys.

  @item auto
  @opindex trust-mode:auto
  Select the trust model depending on whatever the internal trust
  database says. This is the default model if such a database already
  exists.
@end table

@item --auto-key-locate @code{parameters}
@itemx --no-auto-key-locate
@opindex auto-key-locate
GnuPG can automatically locate and retrieve keys as needed using this
option. This happens when encrypting to an email address (in the
"user@@example.com" form), and there are no user@@example.com keys on
the local keyring.  This option takes any number of the following
mechanisms, in the order they are to be tried:

@table @asis

  @item cert
  Locate a key using DNS CERT, as specified in RFC-4398.

  @item pka
  Locate a key using DNS PKA.

  @item dane
  Locate a key using DANE, as specified
  in draft-ietf-dane-openpgpkey-05.txt.

  @item wkd
  Locate a key using the Web Key Directory protocol.
  This is an experimental method and semantics may change.

  @item ldap
  Using DNS Service Discovery, check the domain in question for any LDAP
  keyservers to use.  If this fails, attempt to locate the key using the
  PGP Universal method of checking @samp{ldap://keys.(thedomain)}.

  @item keyserver
  Locate a key using whatever keyserver is defined using the
  @option{--keyserver} option.

  @item keyserver-URL
  In addition, a keyserver URL as used in the @option{--keyserver} option
  may be used here to query that particular keyserver.

  @item local
  Locate the key using the local keyrings.  This mechanism allows the user to
  select the order a local key lookup is done.  Thus using
  @samp{--auto-key-locate local} is identical to
  @option{--no-auto-key-locate}.

  @item nodefault
  This flag disables the standard local key lookup, done before any of the
  mechanisms defined by the @option{--auto-key-locate} are tried.  The
  position of this mechanism in the list does not matter.  It is not
  required if @code{local} is also used.

  @item clear
  Clear all defined mechanisms.  This is useful to override
  mechanisms given in a config file.

@end table

@item --auto-key-retrieve
@itemx --no-auto-key-retrieve
@opindex auto-key-retrieve
@opindex no-auto-key-retrieve
This option enables the automatic retrieving of keys from a keyserver
when verifying signatures made by keys that are not on the local
keyring.

If the method "wkd" is included in the list of methods given to
@option{auto-key-locate}, the Signer's User ID is part of the
signature, and the option @option{--disable-signer-uid} is not used,
the "wkd" method may also be used to retrieve a key.

Note that this option makes a "web bug" like behavior possible.
Keyserver or Web Key Directory operators can see which keys you
request, so by sending you a message signed by a brand new key (which
you naturally will not have on your local keyring), the operator can
tell both your IP address and the time when you verified the
signature.

@item --keyid-format @code{none|short|0xshort|long|0xlong}
@opindex keyid-format
Select how to display key IDs.  "none" does not show the key ID at all
but shows the fingerprint in a separate line.  "short" is the
traditional 8-character key ID.  "long" is the more accurate (but less
convenient) 16-character key ID.  Add an "0x" to either to include an
"0x" at the beginning of the key ID, as in 0x99242560.  Note that this
option is ignored if the option @option{--with-colons} is used.

@item --keyserver @code{name}
@opindex keyserver
This option is deprecated - please use the @option{--keyserver} in
@file{dirmngr.conf} instead.

Use @code{name} as your keyserver. This is the server that
@option{--receive-keys}, @option{--send-keys}, and @option{--search-keys}
will communicate with to receive keys from, send keys to, and search for
keys on. The format of the @code{name} is a URI:
`scheme:[//]keyservername[:port]' The scheme is the type of keyserver:
"hkp" for the HTTP (or compatible) keyservers, "ldap" for the LDAP
keyservers, or "mailto" for the Graff email keyserver. Note that your
particular installation of GnuPG may have other keyserver types
available as well. Keyserver schemes are case-insensitive. After the
keyserver name, optional keyserver configuration options may be
provided. These are the same as the global @option{--keyserver-options}
from below, but apply only to this particular keyserver.

Most keyservers synchronize with each other, so there is generally no
need to send keys to more than one server. The keyserver
@code{hkp://keys.gnupg.net} uses round robin DNS to give a different
keyserver each time you use it.

@item --keyserver-options @code{name=value}
@opindex keyserver-options
This is a space or comma delimited string that gives options for the
keyserver. Options can be prefixed with a `no-' to give the opposite
meaning. Valid import-options or export-options may be used here as
well to apply to importing (@option{--recv-key}) or exporting
(@option{--send-key}) a key from a keyserver. While not all options
are available for all keyserver types, some common options are:

@table @asis

  @item include-revoked
  When searching for a key with @option{--search-keys}, include keys that
  are marked on the keyserver as revoked. Note that not all keyservers
  differentiate between revoked and unrevoked keys, and for such
  keyservers this option is meaningless. Note also that most keyservers do
  not have cryptographic verification of key revocations, and so turning
  this option off may result in skipping keys that are incorrectly marked
  as revoked.

  @item include-disabled
  When searching for a key with @option{--search-keys}, include keys that
  are marked on the keyserver as disabled. Note that this option is not
  used with HKP keyservers.

  @item auto-key-retrieve
  This is the same as the option @option{auto-key-retrieve}.

  @item honor-keyserver-url
  When using @option{--refresh-keys}, if the key in question has a preferred
  keyserver URL, then use that preferred keyserver to refresh the key
  from. In addition, if auto-key-retrieve is set, and the signature
  being verified has a preferred keyserver URL, then use that preferred
  keyserver to fetch the key from. Note that this option introduces a
  "web bug": The creator of the key can see when the keys is
  refreshed.  Thus this option is not enabled by default.

  @item honor-pka-record
  If @option{--auto-key-retrieve} is used, and the signature being
  verified has a PKA record, then use the PKA information to fetch
  the key. Defaults to "yes".

  @item include-subkeys
  When receiving a key, include subkeys as potential targets. Note that
  this option is not used with HKP keyservers, as they do not support
  retrieving keys by subkey id.

  @item timeout
  Tell the keyserver helper program how long (in seconds) to try and
  perform a keyserver action before giving up. Note that performing
  multiple actions at the same time uses this timeout value per action.
  For example, when retrieving multiple keys via @option{--receive-keys}, the
  timeout applies separately to each key retrieval, and not to the
  @option{--receive-keys} command as a whole. Defaults to 30 seconds.

  @item http-proxy=@code{value}
  This option is deprecated.
  Set the proxy to use for HTTP and HKP keyservers.
  This overrides any proxy defined in @file{dirmngr.conf}.

  @item verbose
  This option has no more function since GnuPG 2.1.  Use the
  @code{dirmngr} configuration options instead.

  @item debug
  This option has no more function since GnuPG 2.1.  Use the
  @code{dirmngr} configuration options instead.

  @item check-cert
  This option has no more function since GnuPG 2.1.  Use the
  @code{dirmngr} configuration options instead.

  @item ca-cert-file
  This option has no more function since GnuPG 2.1.  Use the
  @code{dirmngr} configuration options instead.

@end table

@item --completes-needed @code{n}
@opindex compliant-needed
Number of completely trusted users to introduce a new
key signer (defaults to 1).

@item --marginals-needed @code{n}
@opindex marginals-needed
Number of marginally trusted users to introduce a new
key signer (defaults to 3)

@item --tofu-default-policy @code{auto|good|unknown|bad|ask}
@opindex tofu-default-policy
The default TOFU policy (defaults to @code{auto}).  For more
information about the meaning of this option, @pxref{trust-model-tofu}.

@item --max-cert-depth @code{n}
@opindex max-cert-depth
Maximum depth of a certification chain (default is 5).

@item --no-sig-cache
@opindex no-sig-cache
Do not cache the verification status of key signatures.
Caching gives a much better performance in key listings. However, if
you suspect that your public keyring is not safe against write
modifications, you can use this option to disable the caching. It
probably does not make sense to disable it because all kind of damage
can be done if someone else has write access to your public keyring.

@item --auto-check-trustdb
@itemx --no-auto-check-trustdb
@opindex auto-check-trustdb
If GnuPG feels that its information about the Web of Trust has to be
updated, it automatically runs the @option{--check-trustdb} command
internally.  This may be a time consuming
process. @option{--no-auto-check-trustdb} disables this option.

@item --use-agent
@itemx --no-use-agent
@opindex use-agent
This is dummy option. @command{@gpgname} always requires the agent.

@item --gpg-agent-info
@opindex gpg-agent-info
This is dummy option. It has no effect when used with @command{@gpgname}.


@item --agent-program @var{file}
@opindex agent-program
Specify an agent program to be used for secret key operations.  The
default value is determined by running @command{gpgconf} with the
option @option{--list-dirs}.  Note that the pipe symbol (@code{|}) is
used for a regression test suite hack and may thus not be used in the
file name.

@item --dirmngr-program @var{file}
@opindex dirmngr-program
Specify a dirmngr program to be used for keyserver access.  The
default value is @file{@value{BINDIR}/dirmngr}.

@item --no-autostart
@opindex no-autostart
Do not start the gpg-agent or the dirmngr if it has not yet been
started and its service is required.  This option is mostly useful on
machines where the connection to gpg-agent has been redirected to
another machines.  If dirmngr is required on the remote machine, it
may be started manually using @command{gpgconf --launch dirmngr}.

@item --lock-once
@opindex lock-once
Lock the databases the first time a lock is requested
and do not release the lock until the process
terminates.

@item --lock-multiple
@opindex lock-multiple
Release the locks every time a lock is no longer
needed. Use this to override a previous @option{--lock-once}
from a config file.

@item --lock-never
@opindex lock-never
Disable locking entirely. This option should be used only in very
special environments, where it can be assured that only one process
is accessing those files. A bootable floppy with a stand-alone
encryption system will probably use this. Improper usage of this
option may lead to data and key corruption.

@item --exit-on-status-write-error
@opindex exit-on-status-write-error
This option will cause write errors on the status FD to immediately
terminate the process. That should in fact be the default but it never
worked this way and thus we need an option to enable this, so that the
change won't break applications which close their end of a status fd
connected pipe too early. Using this option along with
@option{--enable-progress-filter} may be used to cleanly cancel long
running gpg operations.

@item --limit-card-insert-tries @code{n}
@opindex limit-card-insert-tries
With @code{n} greater than 0 the number of prompts asking to insert a
smartcard gets limited to N-1. Thus with a value of 1 gpg won't at
all ask to insert a card if none has been inserted at startup. This
option is useful in the configuration file in case an application does
not know about the smartcard support and waits ad infinitum for an
inserted card.

@item --no-random-seed-file
@opindex no-random-seed-file
GnuPG uses a file to store its internal random pool over invocations.
This makes random generation faster; however sometimes write operations
are not desired. This option can be used to achieve that with the cost of
slower random generation.

@item --no-greeting
@opindex no-greeting
Suppress the initial copyright message.

@item --no-secmem-warning
@opindex no-secmem-warning
Suppress the warning about "using insecure memory".

@item --no-permission-warning
@opindex permission-warning
Suppress the warning about unsafe file and home directory (@option{--homedir})
permissions. Note that the permission checks that GnuPG performs are
not intended to be authoritative, but rather they simply warn about
certain common permission problems. Do not assume that the lack of a
warning means that your system is secure.

Note that the warning for unsafe @option{--homedir} permissions cannot be
suppressed in the gpg.conf file, as this would allow an attacker to
place an unsafe gpg.conf file in place, and use this file to suppress
warnings about itself. The @option{--homedir} permissions warning may only be
suppressed on the command line.

@item --no-mdc-warning
@opindex no-mdc-warning
Suppress the warning about missing MDC integrity protection.

@item --require-secmem
@itemx --no-require-secmem
@opindex require-secmem
Refuse to run if GnuPG cannot get secure memory. Defaults to no
(i.e. run, but give a warning).


@item --require-cross-certification
@itemx --no-require-cross-certification
@opindex require-cross-certification
When verifying a signature made from a subkey, ensure that the cross
certification "back signature" on the subkey is present and valid.  This
protects against a subtle attack against subkeys that can sign.
Defaults to @option{--require-cross-certification} for
@command{@gpgname}.

@item --expert
@itemx --no-expert
@opindex expert
Allow the user to do certain nonsensical or "silly" things like
signing an expired or revoked key, or certain potentially incompatible
things like generating unusual key types. This also disables certain
warning messages about potentially incompatible actions. As the name
implies, this option is for experts only. If you don't fully
understand the implications of what it allows you to do, leave this
off. @option{--no-expert} disables this option.

@end table


@c *******************************************
@c ********  KEY RELATED OPTIONS  ************
@c *******************************************
@node GPG Key related Options
@subsection Key related options

@table @gnupgtabopt

@item --recipient @var{name}
@itemx -r
@opindex recipient
Encrypt for user id @var{name}. If this option or
@option{--hidden-recipient} is not specified, GnuPG asks for the user-id
unless @option{--default-recipient} is given.

@item --hidden-recipient @var{name}
@itemx -R
@opindex hidden-recipient
Encrypt for user ID @var{name}, but hide the key ID of this user's
key. This option helps to hide the receiver of the message and is a
limited countermeasure against traffic analysis. If this option or
@option{--recipient} is not specified, GnuPG asks for the user ID unless
@option{--default-recipient} is given.

@item --recipient-file @var{file}
@itemx -f
@opindex recipient-file
This option is similar to @option{--recipient} except that it
encrypts to a key stored in the given file.  @var{file} must be the
name of a file containing exactly one key.  @command{@gpgname} assumes that
the key in this file is fully valid.

@item --hidden-recipient-file @var{file}
@itemx -F
@opindex hidden-recipient-file
This option is similar to @option{--hidden-recipient} except that it
encrypts to a key stored in the given file.  @var{file} must be the
name of a file containing exactly one key.  @command{@gpgname} assumes that
the key in this file is fully valid.

@item --encrypt-to @code{name}
@opindex encrypt-to
Same as @option{--recipient} but this one is intended for use in the
options file and may be used with your own user-id as an
"encrypt-to-self". These keys are only used when there are other
recipients given either by use of @option{--recipient} or by the asked
user id.  No trust checking is performed for these user ids and even
disabled keys can be used.

@item --hidden-encrypt-to @code{name}
@opindex hidden-encrypt-to
Same as @option{--hidden-recipient} but this one is intended for use in the
options file and may be used with your own user-id as a hidden
"encrypt-to-self". These keys are only used when there are other
recipients given either by use of @option{--recipient} or by the asked user id.
No trust checking is performed for these user ids and even disabled
keys can be used.

@item --no-encrypt-to
@opindex no-encrypt-to
Disable the use of all @option{--encrypt-to} and
@option{--hidden-encrypt-to} keys.

@item --group @code{name=value}
@opindex group
Sets up a named group, which is similar to aliases in email programs.
Any time the group name is a recipient (@option{-r} or
@option{--recipient}), it will be expanded to the values
specified. Multiple groups with the same name are automatically merged
into a single group.

The values are @code{key IDs} or fingerprints, but any key description
is accepted. Note that a value with spaces in it will be treated as
two different values. Note also there is only one level of expansion
--- you cannot make an group that points to another group. When used
from the command line, it may be necessary to quote the argument to
this option to prevent the shell from treating it as multiple
arguments.

@item --ungroup @code{name}
@opindex ungroup
Remove a given entry from the @option{--group} list.

@item --no-groups
@opindex no-groups
Remove all entries from the @option{--group} list.

@item --local-user @var{name}
@itemx -u
@opindex local-user
Use @var{name} as the key to sign with. Note that this option overrides
@option{--default-key}.

@item --sender @var{mbox}
@opindex sender
This option has two purposes.  @var{mbox} must either be a complete
user id with a proper mail address or just a mail address.  When
creating a signature this option tells gpg the user id of a key used
to make a signature if the key was not directly specified by a user
id.  When verifying a signature the @var{mbox} is used to restrict the
information printed by the TOFU code to matching user ids.

@item --try-secret-key @var{name}
@opindex try-secret-key
For hidden recipients GPG needs to know the keys to use for trial
decryption.  The key set with @option{--default-key} is always tried
first, but this is often not sufficient.  This option allows setting more
keys to be used for trial decryption.  Although any valid user-id
specification may be used for @var{name} it makes sense to use at least
the long keyid to avoid ambiguities.  Note that gpg-agent might pop up a
pinentry for a lot keys to do the trial decryption.  If you want to stop
all further trial decryption you may use close-window button instead of
the cancel button.

@item --try-all-secrets
@opindex try-all-secrets
Don't look at the key ID as stored in the message but try all secret
keys in turn to find the right decryption key. This option forces the
behaviour as used by anonymous recipients (created by using
@option{--throw-keyids} or @option{--hidden-recipient}) and might come
handy in case where an encrypted message contains a bogus key ID.

@item --skip-hidden-recipients
@itemx --no-skip-hidden-recipients
@opindex skip-hidden-recipients
@opindex no-skip-hidden-recipients
During decryption skip all anonymous recipients.  This option helps in
the case that people use the hidden recipients feature to hide there
own encrypt-to key from others.  If oneself has many secret keys this
may lead to a major annoyance because all keys are tried in turn to
decrypt something which was not really intended for it.  The drawback
of this option is that it is currently not possible to decrypt a
message which includes real anonymous recipients.


@end table

@c *******************************************
@c ********  INPUT AND OUTPUT  ***************
@c *******************************************
@node GPG Input and Output
@subsection Input and Output

@table @gnupgtabopt

@item --armor
@itemx -a
@opindex armor
Create ASCII armored output.  The default is to create the binary
OpenPGP format.

@item --no-armor
@opindex no-armor
Assume the input data is not in ASCII armored format.

@item --output @var{file}
@itemx -o @var{file}
@opindex output
Write output to @var{file}.  To write to stdout use @code{-} as the
filename.

@item --max-output @code{n}
@opindex max-output
This option sets a limit on the number of bytes that will be generated
when processing a file. Since OpenPGP supports various levels of
compression, it is possible that the plaintext of a given message may be
significantly larger than the original OpenPGP message. While GnuPG
works properly with such messages, there is often a desire to set a
maximum file size that will be generated before processing is forced to
stop by the OS limits. Defaults to 0, which means "no limit".

@item --input-size-hint @var{n}
@opindex input-size-hint
This option can be used to tell GPG the size of the input data in
bytes.  @var{n} must be a positive base-10 number.  This option is
only useful if the input is not taken from a file.  GPG may use this
hint to optimize its buffer allocation strategy.  It is also used by
the @option{--status-fd} line ``PROGRESS'' to provide a value for
``total'' if that is not available by other means.

@item --import-options @code{parameters}
@opindex import-options
This is a space or comma delimited string that gives options for
importing keys. Options can be prepended with a `no-' to give the
opposite meaning. The options are:

@table @asis

  @item import-local-sigs
  Allow importing key signatures marked as "local". This is not
  generally useful unless a shared keyring scheme is being used.
  Defaults to no.

  @item keep-ownertrust
  Normally possible still existing ownertrust values of a key are
  cleared if a key is imported.  This is in general desirable so that
  a formerly deleted key does not automatically gain an ownertrust
  values merely due to import.  On the other hand it is sometimes
  necessary to re-import a trusted set of keys again but keeping
  already assigned ownertrust values.  This can be achieved by using
  this option.

  @item repair-pks-subkey-bug
  During import, attempt to repair the damage caused by the PKS keyserver
  bug (pre version 0.9.6) that mangles keys with multiple subkeys. Note
  that this cannot completely repair the damaged key as some crucial data
  is removed by the keyserver, but it does at least give you back one
  subkey. Defaults to no for regular @option{--import} and to yes for
  keyserver @option{--receive-keys}.

  @item import-show
  Show a listing of the key as imported right before it is stored.
  This can be combined with the option @option{--dry-run} to only look
  at keys.

  @item import-export
  Run the entire import code but instead of storing the key to the
  local keyring write it to the output.  The export options
  @option{export-pka} and @option{export-dane} affect the output.  This
  option can be used to remove all invalid parts from a key without the
  need to store it.

  @item merge-only
  During import, allow key updates to existing keys, but do not allow
  any new keys to be imported. Defaults to no.

  @item import-clean
  After import, compact (remove all signatures except the
  self-signature) any user IDs from the new key that are not usable.
  Then, remove any signatures from the new key that are not usable.
  This includes signatures that were issued by keys that are not present
  on the keyring. This option is the same as running the @option{--edit-key}
  command "clean" after import. Defaults to no.

  @item import-minimal
  Import the smallest key possible. This removes all signatures except
  the most recent self-signature on each user ID. This option is the
  same as running the @option{--edit-key} command "minimize" after import.
  Defaults to no.

  @item restore
  @itemx import-restore
  Import in key restore mode.  This imports all data which is usually
  skipped during import; including all GnuPG specific data.  All other
  contradicting options are overridden.
@end table

@item --import-filter @code{@var{name}=@var{expr}}
@itemx --export-filter @code{@var{name}=@var{expr}}
@opindex import-filter
@opindex export-filter
These options define an import/export filter which are applied to the
imported/exported keyblock right before it will be stored/written.
@var{name} defines the type of filter to use, @var{expr} the
expression to evaluate.  The option can be used several times which
then appends more expression to the same @var{name}.

@noindent
The available filter types are:

@table @asis

  @item keep-uid
  This filter will keep a user id packet and its dependent packets in
  the keyblock if the expression evaluates to true.

  @item drop-subkey
  This filter drops the selected subkeys.
  Currently only implemented for --export-filter.

  @item drop-sig
  This filter drops the selected key signatures on user ids.
  Self-signatures are not considered.
  Currently only implemented for --import-filter.

@end table

For the syntax of the expression see the chapter "FILTER EXPRESSIONS".
The property names for the expressions depend on the actual filter
type and are indicated in the following table.

The available properties are:

@table @asis

  @item uid
  A string with the user id.  (keep-uid)

  @item mbox
  The addr-spec part of a user id with mailbox or the empty string.
  (keep-uid)

  @item key_algo
  A number with the public key algorithm of a key or subkey packet.
  (drop-subkey)

  @item key_created
  @itemx key_created_d
  The first is the timestamp a public key or subkey packet was
  created.  The second is the same but given as an ISO string,
  e.g. "2016-08-17". (drop-subkey)

  @item primary
  Boolean indicating whether the user id is the primary one.  (keep-uid)

  @item secret
  Boolean indicating whether a key or subkey is a secret one.
  drop-subkey)

  @item sig_created
  @itemx sig_created_d
  The first is the timestamp a signature packet was created.  The
  second is the same but given as an ISO string,
  e.g. "2016-08-17". (drop-sig)

  @item sig_algo
  A number with the public key algorithm of a signature packet. (drop-sig)

  @item sig_digest_algo
  A number with the digest algorithm of a signature packet. (drop-sig)

@end table

@item --export-options @code{parameters}
@opindex export-options
This is a space or comma delimited string that gives options for
exporting keys. Options can be prepended with a `no-' to give the
opposite meaning. The options are:

@table @asis

  @item export-local-sigs
  Allow exporting key signatures marked as "local". This is not
  generally useful unless a shared keyring scheme is being used.
  Defaults to no.

  @item export-attributes
  Include attribute user IDs (photo IDs) while exporting. This is
  useful to export keys if they are going to be used by an OpenPGP
  program that does not accept attribute user IDs. Defaults to yes.

  @item export-sensitive-revkeys
  Include designated revoker information that was marked as
  "sensitive". Defaults to no.

  @c Since GnuPG 2.1 gpg-agent manages the secret key and thus the
  @c export-reset-subkey-passwd hack is not anymore justified.  Such use
  @c cases may be implemented using a specialized secret key export
  @c tool.
  @c @item export-reset-subkey-passwd
  @c When using the @option{--export-secret-subkeys} command, this option resets
  @c the passphrases for all exported subkeys to empty. This is useful
  @c when the exported subkey is to be used on an unattended machine where
  @c a passphrase doesn't necessarily make sense. Defaults to no.

  @item backup
  @itemx export-backup
  Export for use as a backup.  The exported data includes all data
  which is needed to restore the key or keys later with GnuPG.  The
  format is basically the OpenPGP format but enhanced with GnuPG
  specific data.  All other contradicting options are overridden.

  @item export-clean
  Compact (remove all signatures from) user IDs on the key being
  exported if the user IDs are not usable. Also, do not export any
  signatures that are not usable. This includes signatures that were
  issued by keys that are not present on the keyring. This option is
  the same as running the @option{--edit-key} command "clean" before export
  except that the local copy of the key is not modified. Defaults to
  no.

  @item export-minimal
  Export the smallest key possible. This removes all signatures except the
  most recent self-signature on each user ID. This option is the same as
  running the @option{--edit-key} command "minimize" before export except
  that the local copy of the key is not modified. Defaults to no.

  @item export-pka
  Instead of outputting the key material output PKA records suitable
  to put into DNS zone files.  An ORIGIN line is printed before each
  record to allow diverting the records to the corresponding zone file.

  @item export-dane
  Instead of outputting the key material output OpenPGP DANE records
  suitable to put into DNS zone files.  An ORIGIN line is printed before
  each record to allow diverting the records to the corresponding zone
  file.

@end table

@item --with-colons
@opindex with-colons
Print key listings delimited by colons. Note that the output will be
encoded in UTF-8 regardless of any @option{--display-charset} setting. This
format is useful when GnuPG is called from scripts and other programs
as it is easily machine parsed. The details of this format are
documented in the file @file{doc/DETAILS}, which is included in the GnuPG
source distribution.

@item --fixed-list-mode
@opindex fixed-list-mode
Do not merge primary user ID and primary key in @option{--with-colon}
listing mode and print all timestamps as seconds since 1970-01-01.
Since GnuPG 2.0.10, this mode is always used and thus this option is
obsolete; it does not harm to use it though.

@item --legacy-list-mode
@opindex legacy-list-mode
Revert to the pre-2.1 public key list mode.  This only affects the
human readable output and not the machine interface
(i.e. @code{--with-colons}).  Note that the legacy format does not
convey suitable information for elliptic curves.

@item --with-fingerprint
@opindex with-fingerprint
Same as the command @option{--fingerprint} but changes only the format
of the output and may be used together with another command.

@item --with-subkey-fingerprint
@opindex with-subkey-fingerprint
If a fingerprint is printed for the primary key, this option forces
printing of the fingerprint for all subkeys.  This could also be
achieved by using the @option{--with-fingerprint} twice but by using
this option along with keyid-format "none" a compact fingerprint is
printed.

@item --with-icao-spelling
@opindex with-icao-spelling
Print the ICAO spelling of the fingerprint in addition to the hex digits.

@item --with-keygrip
@opindex with-keygrip
Include the keygrip in the key listings.  In @code{--with-colons} mode
this is implicitly enable for secret keys.

@item --with-wkd-hash
@opindex with-wkd-hash
Print a Web Key Directory identifier along with each user ID in key
listings.  This is an experimental feature and semantics may change.

@item --with-secret
@opindex with-secret
Include info about the presence of a secret key in public key listings
done with @code{--with-colons}.

@end table

@c *******************************************
@c ********  OPENPGP OPTIONS  ****************
@c *******************************************
@node OpenPGP Options
@subsection OpenPGP protocol specific options

@table @gnupgtabopt

@item -t, --textmode
@itemx --no-textmode
@opindex textmode
Treat input files as text and store them in the OpenPGP canonical text
form with standard "CRLF" line endings. This also sets the necessary
flags to inform the recipient that the encrypted or signed data is text
and may need its line endings converted back to whatever the local
system uses. This option is useful when communicating between two
platforms that have different line ending conventions (UNIX-like to Mac,
Mac to Windows, etc). @option{--no-textmode} disables this option, and
is the default.

@item --force-v3-sigs
@itemx --no-force-v3-sigs
@item --force-v4-certs
@itemx --no-force-v4-certs
These options are obsolete and have no effect since GnuPG 2.1.

@item --force-mdc
@opindex force-mdc
Force the use of encryption with a modification detection code. This
is always used with the newer ciphers (those with a blocksize greater
than 64 bits), or if all of the recipient keys indicate MDC support in
their feature flags.

@item --disable-mdc
@opindex disable-mdc
Disable the use of the modification detection code. Note that by
using this option, the encrypted message becomes vulnerable to a
message modification attack.

@item --disable-signer-uid
@opindex disable-signer-uid
By default the user ID of the signing key is embedded in the data
signature.  As of now this is only done if the signing key has been
specified with @option{local-user} using a mail address.  This
information can be helpful for verifier to locate the key; see
option @option{--auto-key-retrieve}.

@item --personal-cipher-preferences @code{string}
@opindex personal-cipher-preferences
Set the list of personal cipher preferences to @code{string}.  Use
@command{@gpgname --version} to get a list of available algorithms,
and use @code{none} to set no preference at all.  This allows the user
to safely override the algorithm chosen by the recipient key
preferences, as GPG will only select an algorithm that is usable by
all recipients.  The most highly ranked cipher in this list is also
used for the @option{--symmetric} encryption command.

@item --personal-digest-preferences @code{string}
@opindex personal-digest-preferences
Set the list of personal digest preferences to @code{string}.  Use
@command{@gpgname --version} to get a list of available algorithms,
and use @code{none} to set no preference at all.  This allows the user
to safely override the algorithm chosen by the recipient key
preferences, as GPG will only select an algorithm that is usable by
all recipients.  The most highly ranked digest algorithm in this list
is also used when signing without encryption
(e.g. @option{--clear-sign} or @option{--sign}).

@item --personal-compress-preferences @code{string}
@opindex personal-compress-preferences
Set the list of personal compression preferences to @code{string}.
Use @command{@gpgname --version} to get a list of available
algorithms, and use @code{none} to set no preference at all.  This
allows the user to safely override the algorithm chosen by the
recipient key preferences, as GPG will only select an algorithm that
is usable by all recipients.  The most highly ranked compression
algorithm in this list is also used when there are no recipient keys
to consider (e.g. @option{--symmetric}).

@item --s2k-cipher-algo @code{name}
@opindex s2k-cipher-algo
Use @code{name} as the cipher algorithm for symmetric encryption with
a passphrase if @option{--personal-cipher-preferences} and
@option{--cipher-algo} are not given.  The default is @value{GPGSYMENCALGO}.

@item --s2k-digest-algo @code{name}
@opindex s2k-digest-algo
Use @code{name} as the digest algorithm used to mangle the passphrases
for symmetric encryption.  The default is SHA-1.

@item --s2k-mode @code{n}
@opindex s2k-mode
Selects how passphrases for symmetric encryption are mangled. If
@code{n} is 0 a plain passphrase (which is in general not recommended)
will be used, a 1 adds a salt (which should not be used) to the
passphrase and a 3 (the default) iterates the whole process a number
of times (see @option{--s2k-count}).

@item --s2k-count @code{n}
@opindex s2k-count
Specify how many times the passphrases mangling for symmetric
encryption is repeated.  This value may range between 1024 and
65011712 inclusive.  The default is inquired from gpg-agent.  Note
that not all values in the 1024-65011712 range are legal and if an
illegal value is selected, GnuPG will round up to the nearest legal
value.  This option is only meaningful if @option{--s2k-mode} is set
to the default of 3.


@end table

@c ***************************
@c ******* Compliance ********
@c ***************************
@node Compliance Options
@subsection Compliance options

These options control what GnuPG is compliant to. Only one of these
options may be active at a time. Note that the default setting of
this is nearly always the correct one. See the INTEROPERABILITY WITH
OTHER OPENPGP PROGRAMS section below before using one of these
options.

@table @gnupgtabopt

@item --gnupg
@opindex gnupg
Use standard GnuPG behavior. This is essentially OpenPGP behavior
(see @option{--openpgp}), but with some additional workarounds for common
compatibility problems in different versions of PGP. This is the
default option, so it is not generally needed, but it may be useful to
override a different compliance option in the gpg.conf file.

@item --openpgp
@opindex openpgp
Reset all packet, cipher and digest options to strict OpenPGP
behavior. Use this option to reset all previous options like
@option{--s2k-*}, @option{--cipher-algo}, @option{--digest-algo} and
@option{--compress-algo} to OpenPGP compliant values. All PGP
workarounds are disabled.

@item --rfc4880
@opindex rfc4880
Reset all packet, cipher and digest options to strict RFC-4880
behavior. Note that this is currently the same thing as
@option{--openpgp}.

@item --rfc4880bis
@opindex rfc4880bis
Enable experimental features from proposed updates to RFC-4880.  This
option can be used in addition to the other compliance options.
Warning: The behavior may change with any GnuPG release and created
keys or data may not be usable with future GnuPG versions.

@item --rfc2440
@opindex rfc2440
Reset all packet, cipher and digest options to strict RFC-2440
behavior.

@item --pgp6
@opindex pgp6
Set up all options to be as PGP 6 compliant as possible. This
restricts you to the ciphers IDEA (if the IDEA plugin is installed),
3DES, and CAST5, the hashes MD5, SHA1 and RIPEMD160, and the
compression algorithms none and ZIP. This also disables
@option{--throw-keyids}, and making signatures with signing subkeys as PGP 6
does not understand signatures made by signing subkeys.

This option implies @option{--disable-mdc --escape-from-lines}.

@item --pgp7
@opindex pgp7
Set up all options to be as PGP 7 compliant as possible. This is
identical to @option{--pgp6} except that MDCs are not disabled, and the
list of allowable ciphers is expanded to add AES128, AES192, AES256, and
TWOFISH.

@item --pgp8
@opindex pgp8
Set up all options to be as PGP 8 compliant as possible. PGP 8 is a lot
closer to the OpenPGP standard than previous versions of PGP, so all
this does is disable @option{--throw-keyids} and set
@option{--escape-from-lines}.  All algorithms are allowed except for the
SHA224, SHA384, and SHA512 digests.

@item --compliance @var{string}
@opindex compliance
This option can be used instead of one of the options above.  Valid
values for @var{string} are the above option names (without the double
dash) and possibly others as shown when using "help" for @var{value}.

@end table


@c *******************************************
@c ********  ESOTERIC OPTIONS  ***************
@c *******************************************
@node GPG Esoteric Options
@subsection Doing things one usually doesn't want to do

@table @gnupgtabopt

@item -n
@itemx --dry-run
@opindex dry-run
Don't make any changes (this is not completely implemented).

@item --list-only
@opindex list-only
Changes the behaviour of some commands. This is like @option{--dry-run} but
different in some cases. The semantic of this option may be extended in
the future. Currently it only skips the actual decryption pass and
therefore enables a fast listing of the encryption keys.

@item -i
@itemx --interactive
@opindex interactive
Prompt before overwriting any files.

@item --debug-level @var{level}
@opindex debug-level
Select the debug level for investigating problems. @var{level} may be
a numeric value or by a keyword:

@table @code
  @item none
  No debugging at all.  A value of less than 1 may be used instead of
  the keyword.
  @item basic
  Some basic debug messages.  A value between 1 and 2 may be used
  instead of the keyword.
  @item advanced
  More verbose debug messages.  A value between 3 and 5 may be used
  instead of the keyword.
  @item expert
  Even more detailed messages.  A value between 6 and 8 may be used
  instead of the keyword.
  @item guru
  All of the debug messages you can get. A value greater than 8 may be
  used instead of the keyword.  The creation of hash tracing files is
  only enabled if the keyword is used.
@end table

How these messages are mapped to the actual debugging flags is not
specified and may change with newer releases of this program. They are
however carefully selected to best aid in debugging.

@item --debug @var{flags}
@opindex debug
Set debugging flags. All flags are or-ed and @var{flags} may be given
in C syntax (e.g. 0x0042) or as a comma separated list of flag names.
To get a list of all supported flags the single word "help" can be
used.

@item --debug-all
@opindex debug-all
Set all useful debugging flags.

@item --debug-iolbf
@opindex debug-iolbf
Set stdout into line buffered mode.  This option is only honored when
given on the command line.

@item --faked-system-time @var{epoch}
@opindex faked-system-time
This option is only useful for testing; it sets the system time back or
forth to @var{epoch} which is the number of seconds elapsed since the year
1970.  Alternatively @var{epoch} may be given as a full ISO time string
(e.g. "20070924T154812").

If you suffix @var{epoch} with an exclamation mark (!), the system time
will appear to be frozen at the specified time.

@item --enable-progress-filter
@opindex enable-progress-filter
Enable certain PROGRESS status outputs. This option allows frontends
to display a progress indicator while gpg is processing larger files.
There is a slight performance overhead using it.

@item --status-fd @code{n}
@opindex status-fd
Write special status strings to the file descriptor @code{n}.
See the file DETAILS in the documentation for a listing of them.

@item --status-file @code{file}
@opindex status-file
Same as @option{--status-fd}, except the status data is written to file
@code{file}.

@item --logger-fd @code{n}
@opindex logger-fd
Write log output to file descriptor @code{n} and not to STDERR.

@item --log-file @code{file}
@itemx --logger-file @code{file}
@opindex log-file
Same as @option{--logger-fd}, except the logger data is written to
file @code{file}.  Use @file{socket://} to log to socket.

@item --attribute-fd @code{n}
@opindex attribute-fd
Write attribute subpackets to the file descriptor @code{n}. This is most
useful for use with @option{--status-fd}, since the status messages are
needed to separate out the various subpackets from the stream delivered
to the file descriptor.

@item --attribute-file @code{file}
@opindex attribute-file
Same as @option{--attribute-fd}, except the attribute data is written to
file @code{file}.

@item --comment @code{string}
@itemx --no-comments
@opindex comment
Use @code{string} as a comment string in cleartext signatures and ASCII
armored messages or keys (see @option{--armor}). The default behavior is
not to use a comment string. @option{--comment} may be repeated multiple
times to get multiple comment strings. @option{--no-comments} removes
all comments.  It is a good idea to keep the length of a single comment
below 60 characters to avoid problems with mail programs wrapping such
lines.  Note that comment lines, like all other header lines, are not
protected by the signature.

@item --emit-version
@itemx --no-emit-version
@opindex emit-version
Force inclusion of the version string in ASCII armored output.  If
given once only the name of the program and the major number is
emitted, given twice the minor is also emitted, given thrice
the micro is added, and given four times an operating system identification
is also emitted.  @option{--no-emit-version} (default) disables the version
line.

@item --sig-notation @code{name=value}
@itemx --cert-notation @code{name=value}
@itemx -N, --set-notation @code{name=value}
@opindex sig-notation
@opindex cert-notation
@opindex set-notation
Put the name value pair into the signature as notation data.
@code{name} must consist only of printable characters or spaces, and
must contain a '@@' character in the form keyname@@domain.example.com
(substituting the appropriate keyname and domain name, of course).  This
is to help prevent pollution of the IETF reserved notation
namespace. The @option{--expert} flag overrides the '@@'
check. @code{value} may be any printable string; it will be encoded in
UTF-8, so you should check that your @option{--display-charset} is set
correctly. If you prefix @code{name} with an exclamation mark (!), the
notation data will be flagged as critical
(rfc4880:5.2.3.16). @option{--sig-notation} sets a notation for data
signatures. @option{--cert-notation} sets a notation for key signatures
(certifications). @option{--set-notation} sets both.

There are special codes that may be used in notation names. "%k" will
be expanded into the key ID of the key being signed, "%K" into the
long key ID of the key being signed, "%f" into the fingerprint of the
key being signed, "%s" into the key ID of the key making the
signature, "%S" into the long key ID of the key making the signature,
"%g" into the fingerprint of the key making the signature (which might
be a subkey), "%p" into the fingerprint of the primary key of the key
making the signature, "%c" into the signature count from the OpenPGP
smartcard, and "%%" results in a single "%". %k, %K, and %f are only
meaningful when making a key signature (certification), and %c is only
meaningful when using the OpenPGP smartcard.

@item --sig-policy-url @code{string}
@itemx --cert-policy-url @code{string}
@itemx --set-policy-url @code{string}
@opindex sig-policy-url
@opindex cert-policy-url
@opindex set-policy-url
Use @code{string} as a Policy URL for signatures (rfc4880:5.2.3.20).  If
you prefix it with an exclamation mark (!), the policy URL packet will
be flagged as critical. @option{--sig-policy-url} sets a policy url for
data signatures. @option{--cert-policy-url} sets a policy url for key
signatures (certifications). @option{--set-policy-url} sets both.

The same %-expandos used for notation data are available here as well.

@item --sig-keyserver-url @code{string}
@opindex sig-keyserver-url
Use @code{string} as a preferred keyserver URL for data signatures. If
you prefix it with an exclamation mark (!), the keyserver URL packet
will be flagged as critical.

The same %-expandos used for notation data are available here as well.

@item --set-filename @code{string}
@opindex set-filename
Use @code{string} as the filename which is stored inside messages.
This overrides the default, which is to use the actual filename of the
file being encrypted.  Using the empty string for @code{string}
effectively removes the filename from the output.

@item --for-your-eyes-only
@itemx --no-for-your-eyes-only
@opindex for-your-eyes-only
Set the `for your eyes only' flag in the message. This causes GnuPG to
refuse to save the file unless the @option{--output} option is given,
and PGP to use a "secure viewer" with a claimed Tempest-resistant font
to display the message. This option overrides @option{--set-filename}.
@option{--no-for-your-eyes-only} disables this option.

@item --use-embedded-filename
@itemx --no-use-embedded-filename
@opindex use-embedded-filename
Try to create a file with a name as embedded in the data. This can be
a dangerous option as it enables overwriting files. Defaults to no.

@item --cipher-algo @code{name}
@opindex cipher-algo
Use @code{name} as cipher algorithm. Running the program with the
command @option{--version} yields a list of supported algorithms. If
this is not used the cipher algorithm is selected from the preferences
stored with the key. In general, you do not want to use this option as
it allows you to violate the OpenPGP standard.
@option{--personal-cipher-preferences} is the safe way to accomplish the
same thing.

@item --digest-algo @code{name}
@opindex digest-algo
Use @code{name} as the message digest algorithm. Running the program
with the command @option{--version} yields a list of supported algorithms. In
general, you do not want to use this option as it allows you to
violate the OpenPGP standard. @option{--personal-digest-preferences} is the
safe way to accomplish the same thing.

@item --compress-algo @code{name}
@opindex compress-algo
Use compression algorithm @code{name}. "zlib" is RFC-1950 ZLIB
compression. "zip" is RFC-1951 ZIP compression which is used by PGP.
"bzip2" is a more modern compression scheme that can compress some
things better than zip or zlib, but at the cost of more memory used
during compression and decompression. "uncompressed" or "none"
disables compression. If this option is not used, the default
behavior is to examine the recipient key preferences to see which
algorithms the recipient supports. If all else fails, ZIP is used for
maximum compatibility.

ZLIB may give better compression results than ZIP, as the compression
window size is not limited to 8k. BZIP2 may give even better
compression results than that, but will use a significantly larger
amount of memory while compressing and decompressing. This may be
significant in low memory situations. Note, however, that PGP (all
versions) only supports ZIP compression. Using any algorithm other
than ZIP or "none" will make the message unreadable with PGP. In
general, you do not want to use this option as it allows you to
violate the OpenPGP standard. @option{--personal-compress-preferences} is the
safe way to accomplish the same thing.

@item --cert-digest-algo @code{name}
@opindex cert-digest-algo
Use @code{name} as the message digest algorithm used when signing a
key. Running the program with the command @option{--version} yields a
list of supported algorithms. Be aware that if you choose an algorithm
that GnuPG supports but other OpenPGP implementations do not, then some
users will not be able to use the key signatures you make, or quite
possibly your entire key.

@item --disable-cipher-algo @code{name}
@opindex disable-cipher-algo
Never allow the use of @code{name} as cipher algorithm.
The given name will not be checked so that a later loaded algorithm
will still get disabled.

@item --disable-pubkey-algo @code{name}
@opindex disable-pubkey-algo
Never allow the use of @code{name} as public key algorithm.
The given name will not be checked so that a later loaded algorithm
will still get disabled.

@item --throw-keyids
@itemx --no-throw-keyids
@opindex throw-keyids
Do not put the recipient key IDs into encrypted messages. This helps to
hide the receivers of the message and is a limited countermeasure
against traffic analysis.@footnote{Using a little social engineering
anyone who is able to decrypt the message can check whether one of the
other recipients is the one he suspects.}  On the receiving side, it may
slow down the decryption process because all available secret keys must
be tried.  @option{--no-throw-keyids} disables this option. This option
is essentially the same as using @option{--hidden-recipient} for all
recipients.

@item --not-dash-escaped
@opindex not-dash-escaped
This option changes the behavior of cleartext signatures
so that they can be used for patch files. You should not
send such an armored file via email because all spaces
and line endings are hashed too. You can not use this
option for data which has 5 dashes at the beginning of a
line, patch files don't have this. A special armor header
line tells GnuPG about this cleartext signature option.

@item --escape-from-lines
@itemx --no-escape-from-lines
@opindex escape-from-lines
Because some mailers change lines starting with "From " to ">From " it
is good to handle such lines in a special way when creating cleartext
signatures to prevent the mail system from breaking the signature. Note
that all other PGP versions do it this way too.  Enabled by
default. @option{--no-escape-from-lines} disables this option.

@item --passphrase-repeat @code{n}
@opindex passphrase-repeat
Specify how many times @command{@gpgname} will request a new
passphrase be repeated.  This is useful for helping memorize a
passphrase.  Defaults to 1 repetition.

@item --passphrase-fd @code{n}
@opindex passphrase-fd
Read the passphrase from file descriptor @code{n}. Only the first line
will be read from file descriptor @code{n}. If you use 0 for @code{n},
the passphrase will be read from STDIN. This can only be used if only
one passphrase is supplied.

Note that this passphrase is only used if the option @option{--batch}
has also been given.  This is different from GnuPG version 1.x.

@item --passphrase-file @code{file}
@opindex passphrase-file
Read the passphrase from file @code{file}. Only the first line will
be read from file @code{file}. This can only be used if only one
passphrase is supplied. Obviously, a passphrase stored in a file is
of questionable security if other users can read this file. Don't use
this option if you can avoid it.
Note that this passphrase is only used if the option @option{--batch}
has also been given.  This is different from GnuPG version 1.x.

@item --passphrase @code{string}
@opindex passphrase
Use @code{string} as the passphrase. This can only be used if only one
passphrase is supplied. Obviously, this is of very questionable
security on a multi-user system. Don't use this option if you can
avoid it.
Note that this passphrase is only used if the option @option{--batch}
has also been given.  This is different from GnuPG version 1.x.

@item --pinentry-mode @code{mode}
@opindex pinentry-mode
Set the pinentry mode to @code{mode}.  Allowed values for @code{mode}
are:
@table @asis
  @item default
  Use the default of the agent, which is @code{ask}.
  @item ask
  Force the use of the Pinentry.
  @item cancel
  Emulate use of Pinentry's cancel button.
  @item error
  Return a Pinentry error (``No Pinentry'').
  @item loopback
  Redirect Pinentry queries to the caller.  Note that in contrast to
  Pinentry the user is not prompted again if he enters a bad password.
@end table

@item --command-fd @code{n}
@opindex command-fd
This is a replacement for the deprecated shared-memory IPC mode.
If this option is enabled, user input on questions is not expected
from the TTY but from the given file descriptor. It should be used
together with @option{--status-fd}. See the file doc/DETAILS in the source
distribution for details on how to use it.

@item --command-file @code{file}
@opindex command-file
Same as @option{--command-fd}, except the commands are read out of file
@code{file}

@item --allow-non-selfsigned-uid
@itemx --no-allow-non-selfsigned-uid
@opindex allow-non-selfsigned-uid
Allow the import and use of keys with user IDs which are not
self-signed. This is not recommended, as a non self-signed user ID is
trivial to forge. @option{--no-allow-non-selfsigned-uid} disables.

@item --allow-freeform-uid
@opindex allow-freeform-uid
Disable all checks on the form of the user ID while generating a new
one. This option should only be used in very special environments as
it does not ensure the de-facto standard format of user IDs.

@item --ignore-time-conflict
@opindex ignore-time-conflict
GnuPG normally checks that the timestamps associated with keys and
signatures have plausible values. However, sometimes a signature
seems to be older than the key due to clock problems. This option
makes these checks just a warning. See also @option{--ignore-valid-from} for
timestamp issues on subkeys.

@item --ignore-valid-from
@opindex ignore-valid-from
GnuPG normally does not select and use subkeys created in the future.
This option allows the use of such keys and thus exhibits the
pre-1.0.7 behaviour. You should not use this option unless there
is some clock problem. See also @option{--ignore-time-conflict} for timestamp
issues with signatures.

@item --ignore-crc-error
@opindex ignore-crc-error
The ASCII armor used by OpenPGP is protected by a CRC checksum against
transmission errors. Occasionally the CRC gets mangled somewhere on
the transmission channel but the actual content (which is protected by
the OpenPGP protocol anyway) is still okay. This option allows GnuPG
to ignore CRC errors.

@item --ignore-mdc-error
@opindex ignore-mdc-error
This option changes a MDC integrity protection failure into a warning.
This can be useful if a message is partially corrupt, but it is
necessary to get as much data as possible out of the corrupt message.
However, be aware that a MDC protection failure may also mean that the
message was tampered with intentionally by an attacker.

@item --allow-weak-digest-algos
@opindex allow-weak-digest-algos
Signatures made with known-weak digest algorithms are normally
rejected with an ``invalid digest algorithm'' message.  This option
allows the verification of signatures made with such weak algorithms.
MD5 is the only digest algorithm considered weak by default.  See also
@option{--weak-digest} to reject other digest algorithms.

@item --weak-digest @code{name}
@opindex weak-digest
Treat the specified digest algorithm as weak.  Signatures made over
weak digests algorithms are normally rejected. This option can be
supplied multiple times if multiple algorithms should be considered
weak.  See also @option{--allow-weak-digest-algos} to disable
rejection of weak digests.  MD5 is always considered weak, and does
not need to be listed explicitly.

@item --no-default-keyring
@opindex no-default-keyring
Do not add the default keyrings to the list of keyrings. Note that
GnuPG will not operate without any keyrings, so if you use this option
and do not provide alternate keyrings via @option{--keyring} or
@option{--secret-keyring}, then GnuPG will still use the default public or
secret keyrings.

@item --no-keyring
@opindex no-keyring
Do not add use any keyrings even if specified as options.

@item --skip-verify
@opindex skip-verify
Skip the signature verification step. This may be
used to make the decryption faster if the signature
verification is not needed.

@item --with-key-data
@opindex with-key-data
Print key listings delimited by colons (like @option{--with-colons}) and
print the public key data.

@item --fast-list-mode
@opindex fast-list-mode
Changes the output of the list commands to work faster; this is achieved
by leaving some parts empty. Some applications don't need the user ID
and the trust information given in the listings. By using this options
they can get a faster listing. The exact behaviour of this option may
change in future versions.  If you are missing some information, don't
use this option.

@item --no-literal
@opindex no-literal
This is not for normal use. Use the source to see for what it might be useful.

@item --set-filesize
@opindex set-filesize
This is not for normal use. Use the source to see for what it might be useful.

@item --show-session-key
@opindex show-session-key
Display the session key used for one message. See
@option{--override-session-key} for the counterpart of this option.

We think that Key Escrow is a Bad Thing; however the user should have
the freedom to decide whether to go to prison or to reveal the content
of one specific message without compromising all messages ever
encrypted for one secret key.

You can also use this option if you receive an encrypted message which
is abusive or offensive, to prove to the administrators of the
messaging system that the ciphertext transmitted corresponds to an
inappropriate plaintext so they can take action against the offending
user.

@item --override-session-key @code{string}
@itemx --override-session-key-fd @code{fd}
@opindex override-session-key
Don't use the public key but the session key @code{string} respective
the session key taken from the first line read from file descriptor
@code{fd}.  The format of this string is the same as the one printed
by @option{--show-session-key}. This option is normally not used but
comes handy in case someone forces you to reveal the content of an
encrypted message; using this option you can do this without handing
out the secret key.  Note that using @option{--override-session-key}
may reveal the session key to all local users via the global process
table.

@item --ask-sig-expire
@itemx --no-ask-sig-expire
@opindex ask-sig-expire
When making a data signature, prompt for an expiration time. If this
option is not specified, the expiration time set via
@option{--default-sig-expire} is used. @option{--no-ask-sig-expire}
disables this option.

@item --default-sig-expire
@opindex default-sig-expire
The default expiration time to use for signature expiration. Valid
values are "0" for no expiration, a number followed by the letter d
(for days), w (for weeks), m (for months), or y (for years) (for
example "2m" for two months, or "5y" for five years), or an absolute
date in the form YYYY-MM-DD. Defaults to "0".

@item --ask-cert-expire
@itemx --no-ask-cert-expire
@opindex ask-cert-expire
When making a key signature, prompt for an expiration time. If this
option is not specified, the expiration time set via
@option{--default-cert-expire} is used. @option{--no-ask-cert-expire}
disables this option.

@item --default-cert-expire
@opindex default-cert-expire
The default expiration time to use for key signature expiration.
Valid values are "0" for no expiration, a number followed by the
letter d (for days), w (for weeks), m (for months), or y (for years)
(for example "2m" for two months, or "5y" for five years), or an
absolute date in the form YYYY-MM-DD. Defaults to "0".

@item --default-new-key-algo @var{string}
@opindex default-new-key-algo @var{string}
This option can be used to change the default algorithms for key
generation.  Note that the advanced key generation commands can always
be used to specify a key algorithm directly.  Please consult the
source code to learn the syntax of @var{string}.

@item --allow-secret-key-import
@opindex allow-secret-key-import
This is an obsolete option and is not used anywhere.

@item --allow-multiple-messages
@item --no-allow-multiple-messages
@opindex allow-multiple-messages
Allow processing of multiple OpenPGP messages contained in a single file
or stream.  Some programs that call GPG are not prepared to deal with
multiple messages being processed together, so this option defaults to
no.  Note that versions of GPG prior to 1.4.7 always allowed multiple
messages.

Warning: Do not use this option unless you need it as a temporary
workaround!


@item --enable-special-filenames
@opindex enable-special-filenames
This option enables a mode in which filenames of the form
@file{-&n}, where n is a non-negative decimal number,
refer to the file descriptor n and not to a file with that name.

@item --no-expensive-trust-checks
@opindex no-expensive-trust-checks
Experimental use only.

@item --preserve-permissions
@opindex preserve-permissions
Don't change the permissions of a secret keyring back to user
read/write only. Use this option only if you really know what you are doing.

@item --default-preference-list @code{string}
@opindex default-preference-list
Set the list of default preferences to @code{string}. This preference
list is used for new keys and becomes the default for "setpref" in the
edit menu.

@item --default-keyserver-url @code{name}
@opindex default-keyserver-url
Set the default keyserver URL to @code{name}. This keyserver will be
used as the keyserver URL when writing a new self-signature on a key,
which includes key generation and changing preferences.

@item --list-config
@opindex list-config
Display various internal configuration parameters of GnuPG. This option
is intended for external programs that call GnuPG to perform tasks, and
is thus not generally useful. See the file @file{doc/DETAILS} in the
source distribution for the details of which configuration items may be
listed. @option{--list-config} is only usable with
@option{--with-colons} set.

@item --list-gcrypt-config
@opindex list-gcrypt-config
Display various internal configuration parameters of Libgcrypt.

@item --gpgconf-list
@opindex gpgconf-list
This command is similar to @option{--list-config} but in general only
internally used by the @command{gpgconf} tool.

@item --gpgconf-test
@opindex gpgconf-test
This is more or less dummy action.  However it parses the configuration
file and returns with failure if the configuration file would prevent
@command{@gpgname} from startup.  Thus it may be used to run a syntax check
on the configuration file.

@end table

@c *******************************
@c ******* Deprecated ************
@c *******************************
@node Deprecated Options
@subsection Deprecated options

@table @gnupgtabopt

@item --show-photos
@itemx --no-show-photos
@opindex show-photos
Causes @option{--list-keys}, @option{--list-signatures},
@option{--list-public-keys}, @option{--list-secret-keys}, and verifying
a signature to also display the photo ID attached to the key, if
any. See also @option{--photo-viewer}. These options are deprecated. Use
@option{--list-options [no-]show-photos} and/or @option{--verify-options
[no-]show-photos} instead.

@item --show-keyring
@opindex show-keyring
Display the keyring name at the head of key listings to show which
keyring a given key resides on. This option is deprecated: use
@option{--list-options [no-]show-keyring} instead.

@item --always-trust
@opindex always-trust
Identical to @option{--trust-model always}. This option is deprecated.

@item --show-notation
@itemx --no-show-notation
@opindex show-notation
Show signature notations in the @option{--list-signatures} or @option{--check-signatures} listings
as well as when verifying a signature with a notation in it. These
options are deprecated. Use @option{--list-options [no-]show-notation}
and/or @option{--verify-options [no-]show-notation} instead.

@item --show-policy-url
@itemx --no-show-policy-url
@opindex show-policy-url
Show policy URLs in the @option{--list-signatures} or @option{--check-signatures}
listings as well as when verifying a signature with a policy URL in
it. These options are deprecated. Use @option{--list-options
[no-]show-policy-url} and/or @option{--verify-options
[no-]show-policy-url} instead.


@end table


@c *******************************************
@c ***************            ****************
@c ***************   FILES    ****************
@c ***************            ****************
@c *******************************************
@mansect files
@node GPG Configuration
@section Configuration files

There are a few configuration files to control certain aspects of
@command{@gpgname}'s operation. Unless noted, they are expected in the
current home directory (@pxref{option --homedir}).

@table @file

  @item gpg.conf
  @efindex gpg.conf
  This is the standard configuration file read by @command{@gpgname} on
  startup.  It may contain any valid long option; the leading two dashes
  may not be entered and the option may not be abbreviated.  This default
  name may be changed on the command line (@pxref{gpg-option --options}).
  You should backup this file.

@end table

Note that on larger installations, it is useful to put predefined files
into the directory @file{@value{SYSCONFSKELDIR}} so that
newly created users start up with a working configuration.
For existing users a small
helper script is provided to create these files (@pxref{addgnupghome}).

For internal purposes @command{@gpgname} creates and maintains a few other
files; They all live in in the current home directory (@pxref{option
--homedir}).  Only the @command{@gpgname} program may modify these files.


@table @file
  @item ~/.gnupg
  @efindex ~/.gnupg
  This is the default home directory which is used if neither the
  environment variable @code{GNUPGHOME} nor the option
  @option{--homedir} is given.

  @item ~/.gnupg/pubring.gpg
  @efindex pubring.gpg
  The public keyring.  You should backup this file.

  @item ~/.gnupg/pubring.gpg.lock
  The lock file for the public keyring.

  @item ~/.gnupg/pubring.kbx
  @efindex pubring.kbx
  The public keyring using a different format.  This file is shared
  with @command{gpgsm}.  You should backup this file.

  @item ~/.gnupg/pubring.kbx.lock
  The lock file for @file{pubring.kbx}.

  @item ~/.gnupg/secring.gpg
  @efindex secring.gpg
  A secret keyring as used by GnuPG versions before 2.1.  It is not
  used by GnuPG 2.1 and later.

  @item ~/.gnupg/secring.gpg.lock
  The lock file for the secret keyring.

  @item ~/.gnupg/.gpg-v21-migrated
  @efindex .gpg-v21-migrated
  File indicating that a migration to GnuPG 2.1 has been done.

  @item ~/.gnupg/trustdb.gpg
  @efindex trustdb.gpg
  The trust database.  There is no need to backup this file; it is better
  to backup the ownertrust values (@pxref{option --export-ownertrust}).

  @item ~/.gnupg/trustdb.gpg.lock
  The lock file for the trust database.

  @item ~/.gnupg/random_seed
  @efindex random_seed
  A file used to preserve the state of the internal random pool.

  @item ~/.gnupg/openpgp-revocs.d/
  @efindex openpgp-revocs.d
  This is the directory where gpg stores pre-generated revocation
  certificates.  The file name corresponds to the OpenPGP fingerprint of
  the respective key.  It is suggested to backup those certificates and
  if the primary private key is not stored on the disk to move them to
  an external storage device.  Anyone who can access theses files is
  able to revoke the corresponding key.  You may want to print them out.
  You should backup all files in this directory and take care to keep
  this backup closed away.

  @item @value{DATADIR}/options.skel
  @efindex options.skel
  The skeleton options file.

@end table

Operation is further controlled by a few environment variables:

@table @asis

  @item HOME
  @efindex HOME
  Used to locate the default home directory.

  @item GNUPGHOME
  @efindex GNUPGHOME
  If set directory used instead of "~/.gnupg".

  @item GPG_AGENT_INFO
  This variable is obsolete; it was used by GnuPG versions before 2.1.

  @item PINENTRY_USER_DATA
  @efindex PINENTRY_USER_DATA
  This value is passed via gpg-agent to pinentry.  It is useful to convey
  extra information to a custom pinentry.

  @item COLUMNS
  @itemx LINES
  @efindex COLUMNS
  @efindex LINES
  Used to size some displays to the full size of the screen.

  @item LANGUAGE
  @efindex LANGUAGE
  Apart from its use by GNU, it is used in the W32 version to override the
  language selection done through the Registry.  If used and set to a
  valid and available language name (@var{langid}), the file with the
  translation is loaded from
  @code{@var{gpgdir}/gnupg.nls/@var{langid}.mo}.  Here @var{gpgdir} is the
  directory out of which the gpg binary has been loaded.  If it can't be
  loaded the Registry is tried and as last resort the native Windows
  locale system is used.

@end table


@c *******************************************
@c ***************            ****************
@c ***************  EXAMPLES  ****************
@c ***************            ****************
@c *******************************************
@mansect examples
@node GPG Examples
@section Examples

@table @asis

@item gpg -se -r @code{Bob} @code{file}
sign and encrypt for user Bob

@item gpg --clear-sign @code{file}
make a cleartext signature

@item gpg -sb @code{file}
make a detached signature

@item gpg -u 0x12345678 -sb @code{file}
make a detached signature with the key 0x12345678

@item gpg --list-keys @code{user_ID}
show keys

@item gpg --fingerprint @code{user_ID}
show fingerprint

@item gpg --verify @code{pgpfile}
@itemx gpg --verify @code{sigfile} [@code{datafile}]
Verify the signature of the file but do not output the data unless
requested.  The second form is used for detached signatures, where
@code{sigfile} is the detached signature (either ASCII armored or
binary) and @code{datafile} are the signed data; if this is not given, the name of the
file holding the signed data is constructed by cutting off the
extension (".asc" or ".sig") of @code{sigfile} or by asking the user
for the filename.  If the option @option{--output} is also used the
signed data is written to the file specified by that option; use
@code{-} to write the signed data to stdout.
@end table


@c *******************************************
@c ***************            ****************
@c ***************  USER ID   ****************
@c ***************            ****************
@c *******************************************
@mansect how to specify a user id
@ifset isman
@include specify-user-id.texi
@end ifset

@mansect filter expressions
@chapheading FILTER EXPRESSIONS

The options @option{--import-filter} and @option{--export-filter} use
expressions with this syntax (square brackets indicate an optional
part and curly braces a repetition, white space between the elements
are allowed):

@c man:.RS
@example
  [lc] @{[@{flag@}] PROPNAME op VALUE [lc]@}
@end example
@c man:.RE

The name of a property (@var{PROPNAME}) may only consist of letters,
digits and underscores.  The description for the filter type
describes which properties are defined.  If an undefined property is
used it evaluates to the empty string.  Unless otherwise noted, the
@var{VALUE} must always be given and may not be the empty string.  No
quoting is defined for the value, thus the value may not contain the
strings @code{&&} or @code{||}, which are used as logical connection
operators.  The flag @code{--} can be used to remove this restriction.

Numerical values are computed as long int; standard C notation
applies.  @var{lc} is the logical connection operator; either
@code{&&} for a conjunction or @code{||} for a disjunction.  A
conjunction is assumed at the begin of an expression.  Conjunctions
have higher precedence than disjunctions.  If @var{VALUE} starts with
one of the characters used in any @var{op} a space after the
@var{op} is required.

@noindent
The supported operators (@var{op}) are:

@table @asis

  @item =~
  Substring must match.

  @item  !~
  Substring must not match.

  @item  =
  The full string must match.

  @item  <>
  The full string must not match.

  @item  ==
  The numerical value must match.

  @item  !=
  The numerical value must not match.

  @item  <=
  The numerical value of the field must be LE than the value.

  @item  <
  The numerical value of the field must be LT than the value.

  @item  >
  The numerical value of the field must be GT than the value.

  @item  >=
  The numerical value of the field must be GE than the value.

  @item  -le
  The string value of the field must be less or equal than the value.

  @item  -lt
  The string value of the field must be less than the value.

  @item  -gt
  The string value of the field must be greater than the value.

  @item  -ge
  The string value of the field must be greater or equal than the value.

  @item  -n
  True if value is not empty (no value allowed).

  @item  -z
  True if value is empty (no value allowed).

  @item  -t
  Alias for "PROPNAME != 0" (no value allowed).

  @item  -f
  Alias for "PROPNAME == 0" (no value allowed).

@end table

@noindent
Values for @var{flag} must be space separated.  The supported flags
are:

@table @asis
  @item --
  @var{VALUE} spans to the end of the expression.
  @item -c
  The string match in this part is done case-sensitive.
@end table

The filter options concatenate several specifications for a filter of
the same type.  For example the four options in this example:

@c man:.RS
@example
 --import-option keep-uid="uid =~ Alfa"
 --import-option keep-uid="&& uid !~ Test"
 --import-option keep-uid="|| uid =~ Alpha"
 --import-option keep-uid="uid !~ Test"
@end example
@c man:.RE

@noindent
which is equivalent to

@c man:.RS
@example
 --import-option \
  keep-uid="uid =~ Alfa" && uid !~ Test" || uid =~ Alpha" && "uid !~ Test"
@end example
@c man:.RE

imports only the user ids of a key containing the strings "Alfa"
or "Alpha" but not the string "test".


@mansect return value
@chapheading RETURN VALUE

The program returns 0 if everything was fine, 1 if at least
a signature was bad, and other error codes for fatal errors.

@mansect warnings
@chapheading WARNINGS

Use a *good* password for your user account and a *good* passphrase
to protect your secret key. This passphrase is the weakest part of the
whole system. Programs to do dictionary attacks on your secret keyring
are very easy to write and so you should protect your "~/.gnupg/"
directory very well.

Keep in mind that, if this program is used over a network (telnet), it
is *very* easy to spy out your passphrase!

If you are going to verify detached signatures, make sure that the
program knows about it; either give both filenames on the command line
or use @samp{-} to specify STDIN.

@mansect interoperability
@chapheading INTEROPERABILITY WITH OTHER OPENPGP PROGRAMS

GnuPG tries to be a very flexible implementation of the OpenPGP
standard. In particular, GnuPG implements many of the optional parts
of the standard, such as the SHA-512 hash, and the ZLIB and BZIP2
compression algorithms. It is important to be aware that not all
OpenPGP programs implement these optional algorithms and that by
forcing their use via the @option{--cipher-algo},
@option{--digest-algo}, @option{--cert-digest-algo}, or
@option{--compress-algo} options in GnuPG, it is possible to create a
perfectly valid OpenPGP message, but one that cannot be read by the
intended recipient.

There are dozens of variations of OpenPGP programs available, and each
supports a slightly different subset of these optional algorithms.
For example, until recently, no (unhacked) version of PGP supported
the BLOWFISH cipher algorithm. A message using BLOWFISH simply could
not be read by a PGP user. By default, GnuPG uses the standard
OpenPGP preferences system that will always do the right thing and
create messages that are usable by all recipients, regardless of which
OpenPGP program they use. Only override this safe default if you
really know what you are doing.

If you absolutely must override the safe default, or if the preferences
on a given key are invalid for some reason, you are far better off using
the @option{--pgp6}, @option{--pgp7}, or @option{--pgp8} options. These
options are safe as they do not force any particular algorithms in
violation of OpenPGP, but rather reduce the available algorithms to a
"PGP-safe" list.

@mansect bugs
@chapheading BUGS

On older systems this program should be installed as setuid(root). This
is necessary to lock memory pages. Locking memory pages prevents the
operating system from writing memory pages (which may contain
passphrases or other sensitive material) to disk. If you get no
warning message about insecure memory your operating system supports
locking without being root. The program drops root privileges as soon
as locked memory is allocated.

Note also that some systems (especially laptops) have the ability to
``suspend to disk'' (also known as ``safe sleep'' or ``hibernate'').
This writes all memory to disk before going into a low power or even
powered off mode.  Unless measures are taken in the operating system
to protect the saved memory, passphrases or other sensitive material
may be recoverable from it later.

Before you report a bug you should first search the mailing list
archives for similar problems and second check whether such a bug has
already been reported to our bug tracker at http://bugs.gnupg.org .

@c *******************************************
@c ***************              **************
@c ***************  UNATTENDED  **************
@c ***************              **************
@c *******************************************
@manpause
@node Unattended Usage of GPG
@section Unattended Usage

@command{@gpgname} is often used as a backend engine by other software.  To help
with this a machine interface has been defined to have an unambiguous
way to do this.  The options @option{--status-fd} and @option{--batch}
are almost always required for this.

@menu
* Programmatic use of GnuPG:: Programmatic use of GnuPG
* Ephemeral home directories:: Ephemeral home directories
* The quick key manipulation interface:: The quick key manipulation interface
* Unattended GPG key generation::  Unattended key generation
@end menu


@node Programmatic use of GnuPG
@subsection Programmatic use of GnuPG

Please consider using GPGME instead of calling @command{@gpgname}
directly.  GPGME offers a stable, backend-independent interface for
many cryptographic operations.  It supports OpenPGP and S/MIME, and
also allows interaction with various GnuPG components.

GPGME provides a C-API, and comes with bindings for C++, Qt, and
Python.  Bindings for other languages are available.

@node Ephemeral home directories
@subsection Ephemeral home directories

Sometimes you want to contain effects of some operation, for example
you want to import a key to inspect it, but you do not want this key
to be added to your keyring.  In earlier versions of GnuPG, it was
possible to specify alternate keyring files for both public and secret
keys.  In modern GnuPG versions, however, we changed how secret keys
are stored in order to better protect secret key material, and it was
not possible to preserve this interface.

The preferred way to do this is to use ephemeral home directories.
This technique works across all versions of GnuPG.

Create a temporary directory, create (or copy) a configuration that
meets your needs, make @command{@gpgname} use this directory either
using the environment variable @var{GNUPGHOME}, or the option
@option{--homedir}.  GPGME supports this too on a per-context basis,
by modifying the engine info of contexts.  Now execute whatever
operation you like, import and export key material as necessary.  Once
finished, you can delete the directory.  All GnuPG backend services
that were started will detect this and shut down.

@node The quick key manipulation interface
@subsection The quick key manipulation interface

Recent versions of GnuPG have an interface to manipulate keys without
using the interactive command @option{--edit-key}.  This interface was
added mainly for the benefit of GPGME (please consider using GPGME,
see the manual subsection ``Programmatic use of GnuPG'').  This
interface is described in the subsection ``How to manage your keys''.

@node Unattended GPG key generation
@subsection Unattended key generation

The command @option{--generate-key} may be used along with the option
@option{--batch} for unattended key generation.  This is the most
flexible way of generating keys, but it is also the most complex one.
Consider using the quick key manipulation interface described in the
previous subsection ``The quick key manipulation interface''.

The parameters for the key are either read from stdin or given as a
file on the command line.  The format of the parameter file is as
follows:

@itemize @bullet
  @item Text only, line length is limited to about 1000 characters.
  @item UTF-8 encoding must be used to specify non-ASCII characters.
  @item Empty lines are ignored.
  @item Leading and trailing while space is ignored.
  @item A hash sign as the first non white space character indicates
  a comment line.
  @item Control statements are indicated by a leading percent sign, the
  arguments are separated by white space from the keyword.
  @item Parameters are specified by a keyword, followed by a colon.  Arguments
  are separated by white space.
  @item
  The first parameter must be @samp{Key-Type}; control statements may be
  placed anywhere.
  @item
  The order of the parameters does not matter except for @samp{Key-Type}
  which must be the first parameter.  The parameters are only used for
  the generated keyblock (primary and subkeys); parameters from previous
  sets are not used.  Some syntactically checks may be performed.
  @item
  Key generation takes place when either the end of the parameter file
  is reached, the next @samp{Key-Type} parameter is encountered or at the
  control statement @samp{%commit} is encountered.
@end itemize

@noindent
Control statements:

@table @asis

@item %echo @var{text}
Print @var{text} as diagnostic.

@item %dry-run
Suppress actual key generation (useful for syntax checking).

@item %commit
Perform the key generation.  Note that an implicit commit is done at
the next @asis{Key-Type} parameter.

@item %pubring @var{filename}
Do not write the key to the default or commandline given keyring but
to @var{filename}.  This must be given before the first commit to take
place, duplicate specification of the same filename is ignored, the
last filename before a commit is used.  The filename is used until a
new filename is used (at commit points) and all keys are written to
that file. If a new filename is given, this file is created (and
overwrites an existing one).

See the previous subsection ``Ephemeral home directories'' for a more
robust way to contain side-effects.

@item %secring @var{filename}
This option is a no-op for GnuPG 2.1 and later.

See the previous subsection ``Ephemeral home directories''.

@item %ask-passphrase
@itemx %no-ask-passphrase
This option is a no-op for GnuPG 2.1 and later.

@item %no-protection
Using this option allows the creation of keys without any passphrase
protection.  This option is mainly intended for regression tests.

@item %transient-key
If given the keys are created using a faster and a somewhat less
secure random number generator.  This option may be used for keys
which are only used for a short time and do not require full
cryptographic strength.  It takes only effect if used together with
the control statement @samp{%no-protection}.

@end table

@noindent
General Parameters:

@table @asis

@item Key-Type: @var{algo}
Starts a new parameter block by giving the type of the primary
key. The algorithm must be capable of signing.  This is a required
parameter.  @var{algo} may either be an OpenPGP algorithm number or a
string with the algorithm name.  The special value @samp{default} may
be used for @var{algo} to create the default key type; in this case a
@samp{Key-Usage} shall not be given and @samp{default} also be used
for @samp{Subkey-Type}.

@item Key-Length: @var{nbits}
The requested length of the generated key in bits.  The default is
returned by running the command @samp{@gpgname --gpgconf-list}.

@item Key-Grip: @var{hexstring}
This is optional and used to generate a CSR or certificate for an
already existing key.  Key-Length will be ignored when given.

@item Key-Usage: @var{usage-list}
Space or comma delimited list of key usages.  Allowed values are
@samp{encrypt}, @samp{sign}, and @samp{auth}.  This is used to
generate the key flags.  Please make sure that the algorithm is
capable of this usage.  Note that OpenPGP requires that all primary
keys are capable of certification, so no matter what usage is given
here, the @samp{cert} flag will be on.  If no @samp{Key-Usage} is
specified and the @samp{Key-Type} is not @samp{default}, all allowed
usages for that particular algorithm are used; if it is not given but
@samp{default} is used the usage will be @samp{sign}.

@item Subkey-Type: @var{algo}
This generates a secondary key (subkey).  Currently only one subkey
can be handled.  See also @samp{Key-Type} above.

@item Subkey-Length: @var{nbits}
Length of the secondary key (subkey) in bits.  The default is returned
by running the command @samp{@gpgname --gpgconf-list}.

@item Subkey-Usage: @var{usage-list}
Key usage lists for a subkey; similar to @samp{Key-Usage}.

@item Passphrase: @var{string}
If you want to specify a passphrase for the secret key, enter it here.
Default is to use the Pinentry dialog to ask for a passphrase.

@item Name-Real: @var{name}
@itemx Name-Comment: @var{comment}
@itemx Name-Email: @var{email}
The three parts of a user name.  Remember to use UTF-8 encoding here.
If you don't give any of them, no user ID is created.

@item Expire-Date: @var{iso-date}|(@var{number}[d|w|m|y])
Set the expiration date for the key (and the subkey).  It may either
be entered in ISO date format (e.g. "20000815T145012") or as number of
days, weeks, month or years after the creation date.  The special
notation "seconds=N" is also allowed to specify a number of seconds
since creation.  Without a letter days are assumed.  Note that there
is no check done on the overflow of the type used by OpenPGP for
timestamps.  Thus you better make sure that the given value make
sense.  Although OpenPGP works with time intervals, GnuPG uses an
absolute value internally and thus the last year we can represent is
2105.

@item  Creation-Date: @var{iso-date}
Set the creation date of the key as stored in the key information and
which is also part of the fingerprint calculation.  Either a date like
"1986-04-26" or a full timestamp like "19860426T042640" may be used.
The time is considered to be UTC.  The special notation "seconds=N"
may be used to directly specify a the number of seconds since Epoch
(Unix time).  If it is not given the current time is used.

@item Preferences: @var{string}
Set the cipher, hash, and compression preference values for this key.
This expects the same type of string as the sub-command @samp{setpref}
in the @option{--edit-key} menu.

@item  Revoker: @var{algo}:@var{fpr} [sensitive]
Add a designated revoker to the generated key.  Algo is the public key
algorithm of the designated revoker (i.e. RSA=1, DSA=17, etc.)
@var{fpr} is the fingerprint of the designated revoker.  The optional
@samp{sensitive} flag marks the designated revoker as sensitive
information.  Only v4 keys may be designated revokers.

@item Keyserver: @var{string}
This is an optional parameter that specifies the preferred keyserver
URL for the key.

@item Handle: @var{string}
This is an optional parameter only used with the status lines
KEY_CREATED and KEY_NOT_CREATED.  @var{string} may be up to 100
characters and should not contain spaces.  It is useful for batch key
generation to associate a key parameter block with a status line.

@end table

@noindent
Here is an example on how to create a key in an ephemeral home directory:
@smallexample
$ export GNUPGHOME="$(mktemp -d)"
$ cat >foo <<EOF
     %echo Generating a basic OpenPGP key
     Key-Type: DSA
     Key-Length: 1024
     Subkey-Type: ELG-E
     Subkey-Length: 1024
     Name-Real: Joe Tester
     Name-Comment: with stupid passphrase
     Name-Email: joe@@foo.bar
     Expire-Date: 0
     Passphrase: abc
     # Do a commit here, so that we can later print "done" :-)
     %commit
     %echo done
EOF
$ @gpgname --batch --generate-key foo
 [...]
$ @gpgname --list-secret-keys
/tmp/tmp.0NQxB74PEf/pubring.kbx
-------------------------------
sec   dsa1024 2016-12-16 [SCA]
      768E895903FC1C44045C8CB95EEBDB71E9E849D0
uid           [ultimate] Joe Tester (with stupid passphrase) <joe@@foo.bar>
ssb   elg1024 2016-12-16 [E]
@end smallexample

@noindent
If you want to create a key with the default algorithms you would use
these parameters:
@smallexample
     %echo Generating a default key
     Key-Type: default
     Subkey-Type: default
     Name-Real: Joe Tester
     Name-Comment: with stupid passphrase
     Name-Email: joe@@foo.bar
     Expire-Date: 0
     Passphrase: abc
     # Do a commit here, so that we can later print "done" :-)
     %commit
     %echo done
@end smallexample




@mansect see also
@ifset isman
@command{gpgv}(1),
@command{gpgsm}(1),
@command{gpg-agent}(1)
@end ifset
@include see-also-note.texi