1 @c Copyright (C) 2002 Klar"alvdalens Datakonsult AB
2 @c Copyright (C) 2004, 2005, 2006, 2007 g10 Code GmbH
3 @c This is part of the GnuPG manual.
4 @c For copying conditions, see the file gnupg.texi.
9 @chapter Invoking DIRMNGR
10 @cindex DIRMNGR command options
11 @cindex command options
12 @cindex options, DIRMNGR command
17 \- CRL and OCSP daemon
29 Since version 2.1 of GnuPG, @command{dirmngr} takes care of accessing
30 the OpenPGP keyservers. As with previous versions it is also used as
31 a server for managing and downloading certificate revocation lists
32 (CRLs) for X.509 certificates, downloading X.509 certificates, and
33 providing access to OCSP providers. Dirmngr is invoked internally by
34 @command{gpg}, @command{gpgsm}, or via the @command{gpg-connect-agent}
39 @xref{Option Index},for an index to @command{DIRMNGR}'s commands and
44 * Dirmngr Commands:: List of all commands.
45 * Dirmngr Options:: List of all options.
46 * Dirmngr Configuration:: Configuration files.
47 * Dirmngr Signals:: Use of signals.
48 * Dirmngr Examples:: Some usage examples.
49 * Dirmngr Protocol:: The protocol dirmngr uses.
53 @node Dirmngr Commands
57 Commands are not distinguished from options except for the fact that
58 only one command is allowed.
63 Print the program version and licensing information. Note that you cannot
64 abbreviate this command.
68 Print a usage message summarizing the most useful command-line options.
69 Note that you cannot abbreviate this command.
73 Print a list of all available options and commands. Note that you cannot
74 abbreviate this command.
78 Run in server mode and wait for commands on the @code{stdin}. The
79 default mode is to create a socket and listen for commands there.
80 This is only used for testing.
84 Run in background daemon mode and listen for commands on a socket.
85 This is the way @command{dirmngr} is started on demand by the other
86 GnuPG components. To force starting @command{dirmngr} it is in
87 general best to use @code{gpgconf --launch dirmngr}.
91 Run in the foreground, sending logs to stderr, and listening on file
92 descriptor 3, which must already be bound to a listening socket. This
93 is useful when running under systemd or other similar process
94 supervision schemes. This option is not supported on Windows.
98 List the contents of the CRL cache on @code{stdout}. This is probably
99 only useful for debugging purposes.
101 @item --load-crl @var{file}
103 This command requires a filename as additional argument, and it will
104 make Dirmngr try to import the CRL in @var{file} into it's cache.
105 Note, that this is only possible if Dirmngr is able to retrieve the
106 CA's certificate directly by its own means. In general it is better
107 to use @code{gpgsm}'s @code{--call-dirmngr loadcrl filename} command
108 so that @code{gpgsm} can help dirmngr.
110 @item --fetch-crl @var{url}
112 This command requires an URL as additional argument, and it will make
113 dirmngr try to retrieve and import the CRL from that @var{url} into
114 it's cache. This is mainly useful for debugging purposes. The
115 @command{dirmngr-client} provides the same feature for a running dirmngr.
119 This commands shuts down an running instance of Dirmngr. This command
120 has currently no effect.
124 This command removes all CRLs from Dirmngr's cache. Client requests
125 will thus trigger reading of fresh CRLs.
131 @node Dirmngr Options
132 @section Option Summary
134 Note that all long options with the exception of @option{--options}
135 and @option{--homedir} may also be given in the configuration file
136 after stripping off the two leading dashes.
140 @item --options @var{file}
142 Reads configuration from @var{file} instead of from the default
143 per-user configuration file. The default configuration file is named
144 @file{dirmngr.conf} and expected in the home directory.
146 @item --homedir @var{dir}
148 Set the name of the home directory to @var{dir}. This option is only
149 effective when used on the command line. The default is
150 the directory named @file{.gnupg} directly below the home directory
151 of the user unless the environment variable @code{GNUPGHOME} has been set
152 in which case its value will be used. Many kinds of data are stored within
160 Outputs additional information while running.
161 You can increase the verbosity by giving several
162 verbose commands to @sc{dirmngr}, such as @option{-vv}.
165 @item --log-file @var{file}
167 Append all logging output to @var{file}. This is very helpful in
168 seeing what the agent actually does. Use @file{socket://} to log to
171 @item --debug-level @var{level}
173 Select the debug level for investigating problems. @var{level} may be a
174 numeric value or by a keyword:
178 No debugging at all. A value of less than 1 may be used instead of
181 Some basic debug messages. A value between 1 and 2 may be used
182 instead of the keyword.
184 More verbose debug messages. A value between 3 and 5 may be used
185 instead of the keyword.
187 Even more detailed messages. A value between 6 and 8 may be used
188 instead of the keyword.
190 All of the debug messages you can get. A value greater than 8 may be
191 used instead of the keyword. The creation of hash tracing files is
192 only enabled if the keyword is used.
195 How these messages are mapped to the actual debugging flags is not
196 specified and may change with newer releases of this program. They are
197 however carefully selected to best aid in debugging.
199 @item --debug @var{flags}
201 Set debugging flags. This option is only useful for debugging and its
202 behavior may change with a new release. All flags are or-ed and may
203 be given in C syntax (e.g. 0x0042) or as a comma separated list of
204 flag names. To get a list of all supported flags the single word
209 Same as @code{--debug=0xffffffff}
211 @item --gnutls-debug @var{level}
212 @opindex gnutls-debug
213 Enable debugging of GNUTLS at @var{level}.
215 @item --debug-wait @var{n}
217 When running in server mode, wait @var{n} seconds before entering the
218 actual processing loop and print the pid. This gives time to attach a
221 @item --disable-check-own-socket
222 @opindex disable-check-own-socket
223 On some platforms @command{dirmngr} is able to detect the removal of
224 its socket file and shutdown itself. This option disable this
225 self-test for debugging purposes.
235 Format the info output in daemon mode for use with the standard Bourne
236 shell respective the C-shell. The default is to guess it based on the
237 environment variable @code{SHELL} which is in almost all cases
242 Enabling this option forces loading of expired CRLs; this is only
243 useful for debugging.
247 This option switches Dirmngr and thus GnuPG into ``Tor mode'' to route
248 all network access via Tor (an anonymity network). Certain other
249 features are disabled if this mode is active.
251 @item --standard-resolver
252 @opindex standard-resolver
253 This option forces the use of the system's standard DNS resolver code.
254 This is mainly used for debugging. Note that on Windows a standard
255 resolver is not used and all DNS access will return the error ``Not
256 Implemented'' if this function is used.
258 @item --recursive-resolver
259 @opindex recursive-resolver
260 When possible use a recursive resolver instead of a stub resolver.
262 @item --resolver-timeout @var{n}
263 Set the timeout for the DNS resolver to N seconds. The default are 30
266 @item --allow-version-check
267 @opindex allow-version-check
268 Allow Dirmngr to connect to @code{https://versions.gnupg.org} to get
269 the list of current software versions. On debian-packaged versions,
270 this option does nothing since software updates should be handled by
271 the distribution. See the option @option{--query-swdb} of the command
272 @command{gpgconf} for more details. Note, that regardless of this
273 option a version check can always be triggered using this command:
276 gpg-connect-agent --dirmngr 'loadswdb --force' /bye
280 @item --keyserver @var{name}
282 Use @var{name} as your keyserver. This is the server that @command{gpg}
283 communicates with to receive keys, send keys, and search for
284 keys. The format of the @var{name} is a URI:
285 `scheme:[//]keyservername[:port]' The scheme is the type of keyserver:
286 "hkp" for the HTTP (or compatible) keyservers, "ldap" for the LDAP
287 keyservers, or "mailto" for the Graff email keyserver. Note that your
288 particular installation of GnuPG may have other keyserver types
289 available as well. Keyserver schemes are case-insensitive. After the
290 keyserver name, optional keyserver configuration options may be
291 provided. These are the same as the @option{--keyserver-options} of
292 @command{gpg}, but apply only to this particular keyserver.
294 Most keyservers synchronize with each other, so there is generally no
295 need to send keys to more than one server. The keyserver
296 @code{hkp://keys.gnupg.net} uses round robin DNS to give a different
297 keyserver each time you use it.
299 If exactly two keyservers are configured and only one is a Tor hidden
300 service (.onion), Dirmngr selects the keyserver to use depending on
301 whether Tor is locally running or not. The check for a running Tor is
302 done for each new connection.
304 If no keyserver is explicitly configured, dirmngr will use the
305 built-in default of hkps://hkps.pool.sks-keyservers.net.
307 @item --nameserver @var{ipaddr}
309 In ``Tor mode'' Dirmngr uses a public resolver via Tor to resolve DNS
310 names. If the default public resolver, which is @code{8.8.8.8}, shall
311 not be used a different one can be given using this option. Note that
312 a numerical IP address must be given (IPv6 or IPv4) and that no error
313 checking is done for @var{ipaddr}.
316 @opindex disable-ldap
317 Entirely disables the use of LDAP.
320 @opindex disable-http
321 Entirely disables the use of HTTP.
323 @item --ignore-http-dp
324 @opindex ignore-http-dp
325 When looking for the location of a CRL, the to be tested certificate
326 usually contains so called @dfn{CRL Distribution Point} (DP) entries
327 which are URLs describing the way to access the CRL. The first found DP
328 entry is used. With this option all entries using the @acronym{HTTP}
329 scheme are ignored when looking for a suitable DP.
331 @item --ignore-ldap-dp
332 @opindex ignore-ldap-dp
333 This is similar to @option{--ignore-http-dp} but ignores entries using
334 the @acronym{LDAP} scheme. Both options may be combined resulting in
335 ignoring DPs entirely.
337 @item --ignore-ocsp-service-url
338 @opindex ignore-ocsp-service-url
339 Ignore all OCSP URLs contained in the certificate. The effect is to
340 force the use of the default responder.
342 @item --honor-http-proxy
343 @opindex honor-http-proxy
344 If the environment variable @env{http_proxy} has been set, use its
345 value to access HTTP servers.
347 @item --http-proxy @var{host}[:@var{port}]
350 Use @var{host} and @var{port} to access HTTP servers. The use of this
351 option overrides the environment variable @env{http_proxy} regardless
352 whether @option{--honor-http-proxy} has been set.
355 @item --ldap-proxy @var{host}[:@var{port}]
357 Use @var{host} and @var{port} to connect to LDAP servers. If @var{port}
358 is omitted, port 389 (standard LDAP port) is used. This overrides any
359 specified host and port part in a LDAP URL and will also be used if host
360 and port have been omitted from the URL.
362 @item --only-ldap-proxy
363 @opindex only-ldap-proxy
364 Never use anything else but the LDAP "proxy" as configured with
365 @option{--ldap-proxy}. Usually @command{dirmngr} tries to use other
366 configured LDAP server if the connection using the "proxy" failed.
369 @item --ldapserverlist-file @var{file}
370 @opindex ldapserverlist-file
371 Read the list of LDAP servers to consult for CRLs and certificates from
372 file instead of the default per-user ldap server list file. The default
373 value for @var{file} is @file{dirmngr_ldapservers.conf}.
375 This server list file contains one LDAP server per line in the format
377 @sc{hostname:port:username:password:base_dn}
379 Lines starting with a @samp{#} are comments.
381 Note that as usual all strings entered are expected to be UTF-8 encoded.
382 Obviously this will lead to problems if the password has originally been
383 encoded as Latin-1. There is no other solution here than to put such a
384 password in the binary encoding into the file (i.e. non-ascii characters
385 won't show up readable).@footnote{The @command{gpgconf} tool might be
386 helpful for frontends as it enables editing this configuration file using
387 percent-escaped strings.}
390 @item --ldaptimeout @var{secs}
392 Specify the number of seconds to wait for an LDAP query before timing
393 out. The default is currently 100 seconds. 0 will never timeout.
398 This option makes dirmngr add any servers it discovers when validating
399 certificates against CRLs to the internal list of servers to consult for
400 certificates and CRLs.
402 This option is useful when trying to validate a certificate that has
403 a CRL distribution point that points to a server that is not already
404 listed in the ldapserverlist. Dirmngr will always go to this server and
405 try to download the CRL, but chances are high that the certificate used
406 to sign the CRL is located on the same server. So if dirmngr doesn't add
407 that new server to list, it will often not be able to verify the
408 signature of the CRL unless the @code{--add-servers} option is used.
410 Note: The current version of dirmngr has this option disabled by default.
415 This option enables OCSP support if requested by the client.
417 OCSP requests are rejected by default because they may violate the
418 privacy of the user; for example it is possible to track the time when
419 a user is reading a mail.
422 @item --ocsp-responder @var{url}
423 @opindex ocsp-responder
424 Use @var{url} as the default OCSP Responder if the certificate does
425 not contain information about an assigned responder. Note, that
426 @code{--ocsp-signer} must also be set to a valid certificate.
428 @item --ocsp-signer @var{fpr}|@var{file}
430 Use the certificate with the fingerprint @var{fpr} to check the
431 responses of the default OCSP Responder. Alternatively a filename can be
432 given in which case the response is expected to be signed by one of the
433 certificates described in that file. Any argument which contains a
434 slash, dot or tilde is considered a filename. Usual filename expansion
435 takes place: A tilde at the start followed by a slash is replaced by the
436 content of @env{HOME}, no slash at start describes a relative filename
437 which will be searched at the home directory. To make sure that the
438 @var{file} is searched in the home directory, either prepend the name
439 with "./" or use a name which contains a dot.
441 If a response has been signed by a certificate described by these
442 fingerprints no further check upon the validity of this certificate is
445 The format of the @var{FILE} is a list of SHA-1 fingerprint, one per
446 line with optional colons between the bytes. Empty lines and lines
447 prefix with a hash mark are ignored.
450 @item --ocsp-max-clock-skew @var{n}
451 @opindex ocsp-max-clock-skew
452 The number of seconds a skew between the OCSP responder and them local
453 clock is accepted. Default is 600 (10 minutes).
455 @item --ocsp-max-period @var{n}
456 @opindex ocsp-max-period
457 Seconds a response is at maximum considered valid after the time given
458 in the thisUpdate field. Default is 7776000 (90 days).
460 @item --ocsp-current-period @var{n}
461 @opindex ocsp-current-period
462 The number of seconds an OCSP response is considered valid after the
463 time given in the NEXT_UPDATE datum. Default is 10800 (3 hours).
466 @item --max-replies @var{n}
468 Do not return more that @var{n} items in one query. The default is
471 @item --ignore-cert-extension @var{oid}
472 @opindex ignore-cert-extension
473 Add @var{oid} to the list of ignored certificate extensions. The
474 @var{oid} is expected to be in dotted decimal form, like
475 @code{2.5.29.3}. This option may be used more than once. Critical
476 flagged certificate extensions matching one of the OIDs in the list
477 are treated as if they are actually handled and thus the certificate
478 won't be rejected due to an unknown critical extension. Use this
479 option with care because extensions are usually flagged as critical
482 @item --hkp-cacert @var{file}
483 Use the root certificates in @var{file} for verification of the TLS
484 certificates used with @code{hkps} (keyserver access over TLS). If
485 the file is in PEM format a suffix of @code{.pem} is expected for
486 @var{file}. This option may be given multiple times to add more
487 root certificates. Tilde expansion is supported.
489 If no @code{hkp-cacert} directive is present, dirmngr will make a
490 reasonable choice: if the keyserver in question is the special pool
491 @code{hkps.pool.sks-keyservers.net}, it will use the bundled root
492 certificate for that pool. Otherwise, it will use the system CAs.
498 @c Dirmngr Configuration
501 @node Dirmngr Configuration
502 @section Configuration
504 Dirmngr makes use of several directories when running in daemon mode:
505 There are a few configuration files whih control the operation of
506 dirmngr. By default they may all be found in the current home
507 directory (@pxref{option --homedir}).
512 @efindex dirmngr.conf
513 This is the standard configuration file read by @command{dirmngr} on
514 startup. It may contain any valid long option; the leading two dashes
515 may not be entered and the option may not be abbreviated. This file
516 is also read after a @code{SIGHUP} however not all options will
517 actually have an effect. This default name may be changed on the
518 command line (@pxref{option --options}). You should backup this file.
520 @item /etc/gnupg/trusted-certs
521 This directory should be filled with certificates of Root CAs you
522 are trusting in checking the CRLs and signing OCSP Responses.
524 Usually these are the same certificates you use with the applications
525 making use of dirmngr. It is expected that each of these certificate
526 files contain exactly one @acronym{DER} encoded certificate in a file
527 with the suffix @file{.crt} or @file{.der}. @command{dirmngr} reads
528 those certificates on startup and when given a SIGHUP. Certificates
529 which are not readable or do not make up a proper X.509 certificate
530 are ignored; see the log file for details.
532 Applications using dirmngr (e.g. gpgsm) can request these
533 certificates to complete a trust chain in the same way as with the
534 extra-certs directory (see below).
536 Note that for OCSP responses the certificate specified using the option
537 @option{--ocsp-signer} is always considered valid to sign OCSP requests.
539 @item /etc/gnupg/extra-certs
540 This directory may contain extra certificates which are preloaded
541 into the internal cache on startup. Applications using dirmngr (e.g. gpgsm)
542 can request cached certificates to complete a trust chain.
543 This is convenient in cases you have a couple intermediate CA certificates
544 or certificates usually used to sign OCSP responses.
545 These certificates are first tried before going
546 out to the net to look for them. These certificates must also be
547 @acronym{DER} encoded and suffixed with @file{.crt} or @file{.der}.
549 @item ~/.gnupg/crls.d
550 This directory is used to store cached CRLs. The @file{crls.d}
551 part will be created by dirmngr if it does not exists but you need to
552 make sure that the upper directory exists.
557 To be able to see what's going on you should create the configure file
558 @file{~/gnupg/dirmngr.conf} with at least one line:
561 log-file ~/dirmngr.log
564 To be able to perform OCSP requests you probably want to add the line:
570 To make sure that new options are read and that after the installation
571 of a new GnuPG versions the installed dirmngr is running, you may want
572 to kill an existing dirmngr first:
575 gpgconf --kill dirmngr
578 You may check the log file to see whether all desired root
579 certificates have been loaded correctly.
586 @node Dirmngr Signals
587 @section Use of signals
589 A running @command{dirmngr} may be controlled by signals, i.e. using
590 the @command{kill} command to send a signal to the process.
592 Here is a list of supported signals:
598 This signal flushes all internally cached CRLs as well as any cached
599 certificates. Then the certificate cache is reinitialized as on
600 startup. Options are re-read from the configuration file. Instead of
601 sending this signal it is better to use
603 gpgconf --reload dirmngr
608 Shuts down the process but waits until all current requests are
609 fulfilled. If the process has received 3 of these signals and requests
610 are still pending, a shutdown is forced. You may also use
612 gpgconf --kill dirmngr
614 instead of this signal
618 Shuts down the process immediately.
623 This prints some caching statistics to the log file.
633 @node Dirmngr Examples
636 Here is an example on how to show dirmngr's internal table of OpenPGP
637 keyserver addresses. The output is intended for debugging purposes
638 and not part of a defined API.
641 gpg-connect-agent --dirmngr 'keyserver --hosttable' /bye
644 To inhibit the use of a particular host you have noticed in one of the
645 keyserver pools, you may use
648 gpg-connect-agent --dirmngr 'keyserver --dead pgpkeys.bnd.de' /bye
651 The description of the @code{keyserver} command can be printed using
654 gpg-connect-agent --dirmngr 'help keyserver' /bye
663 @node Dirmngr Protocol
664 @section Dirmngr's Assuan Protocol
666 Assuan is the IPC protocol used to access dirmngr. This is a
667 description of the commands implemented by dirmngr.
670 * Dirmngr LOOKUP:: Look up a certificate via LDAP
671 * Dirmngr ISVALID:: Validate a certificate using a CRL or OCSP.
672 * Dirmngr CHECKCRL:: Validate a certificate using a CRL.
673 * Dirmngr CHECKOCSP:: Validate a certificate using OCSP.
674 * Dirmngr CACHECERT:: Put a certificate into the internal cache.
675 * Dirmngr VALIDATE:: Validate a certificate for debugging.
679 @subsection Return the certificate(s) found
681 Lookup certificate. To allow multiple patterns (which are ORed)
682 quoting is required: Spaces are to be translated into "+" or into
683 "%20"; obviously this requires that the usual escape quoting rules
684 are applied. The server responds with:
687 S: D <DER encoded certificate>
689 S: D <second DER encoded certificate>
694 In this example 2 certificates are returned. The server may return
695 any number of certificates; OK will also be returned when no
696 certificates were found. The dirmngr might return a status line
703 To indicate that the output was truncated to N items due to a
704 limitation of the server or by an arbitrary set limit.
706 The option @option{--url} may be used if instead of a search pattern a
707 complete URL to the certificate is known:
710 C: LOOKUP --url CN%3DWerner%20Koch,o%3DIntevation%20GmbH,c%3DDE?userCertificate
713 If the option @option{--cache-only} is given, no external lookup is done
714 so that only certificates from the cache are returned.
716 With the option @option{--single}, the first and only the first match
717 will be returned. Unless option @option{--cache-only} is also used, no
718 local lookup will be done in this case.
722 @node Dirmngr ISVALID
723 @subsection Validate a certificate using a CRL or OCSP
726 ISVALID [--only-ocsp] [--force-default-responder] @var{certid}|@var{certfpr}
729 Check whether the certificate described by the @var{certid} has been
730 revoked. Due to caching, the Dirmngr is able to answer immediately in
733 The @var{certid} is a hex encoded string consisting of two parts,
734 delimited by a single dot. The first part is the SHA-1 hash of the
735 issuer name and the second part the serial number.
737 Alternatively the certificate's SHA-1 fingerprint @var{certfpr} may be
738 given in which case an OCSP request is done before consulting the CRL.
739 If the option @option{--only-ocsp} is given, no fallback to a CRL check
740 will be used. If the option @option{--force-default-responder} is
741 given, only the default OCSP responder will be used and any other
742 methods of obtaining an OCSP responder URL won't be used.
745 Common return values are:
748 @item GPG_ERR_NO_ERROR (0)
749 This is the positive answer: The certificate is not revoked and we have
750 an up-to-date revocation list for that certificate. If OCSP was used
751 the responder confirmed that the certificate has not been revoked.
753 @item GPG_ERR_CERT_REVOKED
754 This is the negative answer: The certificate has been revoked. Either
755 it is in a CRL and that list is up to date or an OCSP responder informed
756 us that it has been revoked.
758 @item GPG_ERR_NO_CRL_KNOWN
759 No CRL is known for this certificate or the CRL is not valid or out of
762 @item GPG_ERR_NO_DATA
763 The OCSP responder returned an ``unknown'' status. This means that it
764 is not aware of the certificate's status.
766 @item GPG_ERR_NOT_SUPPORTED
767 This is commonly seen if OCSP support has not been enabled in the
771 If DirMngr has not enough information about the given certificate (which
772 is the case for not yet cached certificates), it will will inquire the
776 S: INQUIRE SENDCERT <CertID>
777 C: D <DER encoded certificate>
781 A client should be aware that DirMngr may ask for more than one
784 If Dirmngr has a certificate but the signature of the certificate
785 could not been validated because the root certificate is not known to
786 dirmngr as trusted, it may ask back to see whether the client trusts
787 this the root certificate:
790 S: INQUIRE ISTRUSTED <CertHexfpr>
795 Only this answer will let Dirmngr consider the certificate as valid.
798 @node Dirmngr CHECKCRL
799 @subsection Validate a certificate using a CRL
801 Check whether the certificate with FINGERPRINT (SHA-1 hash of the
802 entire X.509 certificate blob) is valid or not by consulting the CRL
803 responsible for this certificate. If the fingerprint has not been
804 given or the certificate is not known, the function inquires the
808 S: INQUIRE TARGETCERT
809 C: D <DER encoded certificate>
813 Thus the caller is expected to return the certificate for the request
814 (which should match FINGERPRINT) as a binary blob. Processing then
815 takes place without further interaction; in particular dirmngr tries
816 to locate other required certificate by its own mechanism which
817 includes a local certificate store as well as a list of trusted root
821 The return code is 0 for success; i.e. the certificate has not been
822 revoked or one of the usual error codes from libgpg-error.
824 @node Dirmngr CHECKOCSP
825 @subsection Validate a certificate using OCSP
828 CHECKOCSP [--force-default-responder] [@var{fingerprint}]
831 Check whether the certificate with @var{fingerprint} (the SHA-1 hash of
832 the entire X.509 certificate blob) is valid by consulting the appropriate
833 OCSP responder. If the fingerprint has not been given or the
834 certificate is not known by Dirmngr, the function inquires the
838 S: INQUIRE TARGETCERT
839 C: D <DER encoded certificate>
843 Thus the caller is expected to return the certificate for the request
844 (which should match @var{fingerprint}) as a binary blob. Processing
845 then takes place without further interaction; in particular dirmngr
846 tries to locate other required certificates by its own mechanism which
847 includes a local certificate store as well as a list of trusted root
850 If the option @option{--force-default-responder} is given, only the
851 default OCSP responder is used. This option is the per-command variant
852 of the global option @option{--ignore-ocsp-service-url}.
856 The return code is 0 for success; i.e. the certificate has not been
857 revoked or one of the usual error codes from libgpg-error.
859 @node Dirmngr CACHECERT
860 @subsection Put a certificate into the internal cache
862 Put a certificate into the internal cache. This command might be
863 useful if a client knows in advance certificates required for a test and
864 wants to make sure they get added to the internal cache. It is also
865 helpful for debugging. To get the actual certificate, this command
866 immediately inquires it using
869 S: INQUIRE TARGETCERT
870 C: D <DER encoded certificate>
874 Thus the caller is expected to return the certificate for the request
878 The return code is 0 for success; i.e. the certificate has not been
879 successfully cached or one of the usual error codes from libgpg-error.
881 @node Dirmngr VALIDATE
882 @subsection Validate a certificate for debugging
884 Validate a certificate using the certificate validation function used
885 internally by dirmngr. This command is only useful for debugging. To
886 get the actual certificate, this command immediately inquires it using
889 S: INQUIRE TARGETCERT
890 C: D <DER encoded certificate>
894 Thus the caller is expected to return the certificate for the request
901 @command{dirmngr-client}(1)
903 @include see-also-note.texi
906 @c !!! UNDER CONSTRUCTION !!!
909 @c @section Verifying a Certificate
911 @c There are several ways to request services from Dirmngr. Almost all of
912 @c them are done using the Assuan protocol. What we describe here is the
913 @c Assuan command CHECKCRL as used for example by the dirmnr-client tool if
917 @c dirmngr-client foo.crt
920 @c This command will send an Assuan request to an already running Dirmngr
921 @c instance. foo.crt is expected to be a standard X.509 certificate and
922 @c dirmngr will receive the Assuan command
925 @c CHECKCRL @var [{fingerprint}]
928 @c @var{fingerprint} is optional and expected to be the SHA-1 has of the
929 @c DER encoding of the certificate under question. It is to be HEX
930 @c encoded. The rationale for sending the fingerprint is that it allows
931 @c dirmngr to reply immediately if it has already cached such a request. If
932 @c this is not the case and no certificate has been found in dirmngr's
933 @c internal certificate storage, dirmngr will request the certificate using
934 @c the Assuan inquiry
937 @c INQUIRE TARGETCERT
940 @c The caller (in our example dirmngr-client) is then expected to return
941 @c the certificate for the request (which should match @var{fingerprint})
944 @c Dirmngr now passes control to @code{crl_cache_cert_isvalid}. This
945 @c function checks whether a CRL item exists for target certificate. These
946 @c CRL items are kept in a database of already loaded and verified CRLs.
947 @c This mechanism is called the CRL cache. Obviously timestamps are kept
948 @c there with each item to cope with the expiration date of the CRL. The
949 @c possible return values are: @code{0} to indicate that a valid CRL is
950 @c available for the certificate and the certificate itself is not listed
951 @c in this CRL, @code{GPG_ERR_CERT_REVOKED} to indicate that the certificate is
952 @c listed in the CRL or @code{GPG_ERR_NO_CRL_KNOWN} in cases where no CRL or no
953 @c information is available. The first two codes are immediately returned to
954 @c the caller and the processing of this request has been done.
956 @c Only the @code{GPG_ERR_NO_CRL_KNOWN} needs more attention: Dirmngr now
957 @c calls @code{clr_cache_reload_crl} and if this succeeds calls
958 @c @code{crl_cache_cert_isvald) once more. All further errors are
959 @c immediately returned to the caller.
961 @c @code{crl_cache_reload_crl} is the actual heart of the CRL management.
962 @c It locates the corresponding CRL for the target certificate, reads and
963 @c verifies this CRL and stores it in the CRL cache. It works like this:
965 @c * Loop over all crlDPs in the target certificate.
966 @c * If the crlDP is invalid immediately terminate the loop.
967 @c * Loop over all names in the current crlDP.
968 @c * If the URL scheme is unknown or not enabled
969 @c (--ignore-http-dp, --ignore-ldap-dp) continues with
971 @c * @code{crl_fetch} is called to actually retrieve the CRL.
972 @c In case of problems this name is ignore and we continue with
973 @c the next name. Note that @code{crl_fetch} does only return
974 @c a descriptor for the CRL for further reading so does the CRL
975 @c does not yet end up in memory.
976 @c * @code{crl_cache_insert} is called with that descriptor to
977 @c actually read the CRL into the cache. See below for a
978 @c description of this function. If there is any error (e.g. read
979 @c problem, CRL not correctly signed or verification of signature
980 @c not possible), this descriptor is rejected and we continue
981 @c with the next name. If the CRL has been successfully loaded,
982 @c the loop is terminated.
983 @c * If no crlDP has been found in the previous loop use a default CRL.
984 @c Note, that if any crlDP has been found but loading of the CRL failed,
985 @c this condition is not true.
986 @c * Try to load a CRL from all configured servers (ldapservers.conf)
987 @c in turn. The first server returning a CRL is used.
988 @c * @code(crl_cache_insert) is then used to actually insert the CRL
989 @c into the cache. If this failed we give up immediately without
990 @c checking the rest of the servers from the first step.
994 @c The @code{crl_cache_insert} function takes care of reading the bulk of
995 @c the CRL, parsing it and checking the signature. It works like this: A
996 @c new database file is created using a temporary file name. The CRL
997 @c parsing machinery is started and all items of the CRL are put into
998 @c this database file. At the end the issuer certificate of the CRL
999 @c needs to be retrieved. Three cases are to be distinguished:
1001 @c a) An authorityKeyIdentifier with an issuer and serialno exits: The
1002 @c certificate is retrieved using @code{find_cert_bysn}. If
1003 @c the certificate is in the certificate cache, it is directly
1004 @c returned. Then the requester (i.e. the client who requested the
1005 @c CRL check) is asked via the Assuan inquiry ``SENDCERT'' whether
1006 @c he can provide this certificate. If this succeed the returned
1007 @c certificate gets cached and returned. Note, that dirmngr does not
1008 @c verify in any way whether the expected certificate is returned.
1009 @c It is in the interest of the client to return a useful certificate
1010 @c as otherwise the service request will fail due to a bad signature.
1011 @c The last way to get the certificate is by looking it up at
1012 @c external resources. This is done using the @code{ca_cert_fetch}
1013 @c and @code{fetch_next_ksba_cert} and comparing the returned
1014 @c certificate to match the requested issuer and seriano (This is
1015 @c needed because the LDAP layer may return several certificates as
1016 @c LDAP as no standard way to retrieve by serial number).
1018 @c b) An authorityKeyIdentifier with a key ID exists: The certificate is
1019 @c retrieved using @code{find_cert_bysubject}. If the certificate is
1020 @c in the certificate cache, it is directly returned. Then the
1021 @c requester is asked via the Assuan inquiry ``SENDCERT_SKI'' whether
1022 @c he can provide this certificate. If this succeed the returned
1023 @c certificate gets cached and returned. Note, that dirmngr does not
1024 @c verify in any way whether the expected certificate is returned.
1025 @c It is in the interest of the client to return a useful certificate
1026 @c as otherwise the service request will fail due to a bad signature.
1027 @c The last way to get the certificate is by looking it up at
1028 @c external resources. This is done using the @code{ca_cert_fetch}
1029 @c and @code{fetch_next_ksba_cert} and comparing the returned
1030 @c certificate to match the requested subject and key ID.
1032 @c c) No authorityKeyIdentifier exits: The certificate is retrieved
1033 @c using @code{find_cert_bysubject} without the key ID argument. If
1034 @c the certificate is in the certificate cache the first one with a
1035 @c matching subject is is directly returned. Then the requester is
1036 @c asked via the Assuan inquiry ``SENDCERT'' and an exact
1037 @c specification of the subject whether he can
1038 @c provide this certificate. If this succeed the returned
1039 @c certificate gets cached and returned. Note, that dirmngr does not
1040 @c verify in any way whether the expected certificate is returned.
1041 @c It is in the interest of the client to return a useful certificate
1042 @c as otherwise the service request will fail due to a bad signature.
1043 @c The last way to get the certificate is by looking it up at
1044 @c external resources. This is done using the @code{ca_cert_fetch}
1045 @c and @code{fetch_next_ksba_cert} and comparing the returned
1046 @c certificate to match the requested subject; the first certificate
1047 @c with a matching subject is then returned.
1049 @c If no certificate was found, the function returns with the error
1050 @c GPG_ERR_MISSING_CERT. Now the signature is verified. If this fails,
1051 @c the erro is returned. On success the @code{validate_cert_chain} is
1052 @c used to verify that the certificate is actually valid.
1054 @c Here we may encounter a recursive situation:
1055 @c @code{validate_cert_chain} needs to look at other certificates and
1056 @c also at CRLs to check whether these other certificates and well, the
1057 @c CRL issuer certificate itself are not revoked. FIXME: We need to make
1058 @c sure that @code{validate_cert_chain} does not try to lookup the CRL we
1059 @c are currently processing. This would be a catch-22 and may indicate a
1060 @c broken PKI. However, due to overlapping expiring times and imprecise
1061 @c clocks this may actually happen.
1063 @c For historical reasons the Assuan command ISVALID is a bit different
1064 @c to CHECKCRL but this is mainly due to different calling conventions.
1065 @c In the end the same fucntionality is used, albeit hidden by a couple
1066 @c of indirection and argument and result code mangling. It furthere
1067 @c ingetrages OCSP checking depending on options are the way it is
1068 @c called. GPGSM still uses this command but might eventuall switch over
1069 @c to CHECKCRL and CHECKOCSP so that ISVALID can be retired.
1072 @c @section Validating a certificate
1074 @c We describe here how the internal function @code{validate_cert_chain}
1075 @c works. Note that mainly testing purposes this functionality may be
1076 @c called directly using @cmd{dirmngr-client --validate @file{foo.crt}}.
1078 @c The function takes the target certificate and a mode argument as
1079 @c parameters and returns an error code and optionally the closes
1080 @c expiration time of all certificates in the chain.
1082 @c We first check that the certificate may be used for the requested
1083 @c purpose (i.e. OCSP or CRL signing). If this is not the case
1084 @c GPG_ERR_WRONG_KEY_USAGE is returned.
1086 @c The next step is to find the trust anchor (root certificate) and to
1087 @c assemble the chain in memory: Starting with the target certificate,
1088 @c the expiration time is checked against the current date, unknown
1089 @c critical extensions are detected and certificate policies are matched
1090 @c (We only allow 2.289.9.9 but I have no clue about that OID and from
1091 @c where I got it - it does not even seem to be assigned - debug cruft?).
1093 @c Now if this certificate is a self-signed one, we have reached the
1094 @c trust anchor. In this case we check that the signature is good, the
1095 @c certificate is allowed to act as a CA, that it is a trusted one (by
1096 @c checking whether it is has been put into the trusted-certs
1097 @c configuration directory) and finally prepend into to our list
1098 @c representing the certificate chain. This steps ends then.
1100 @c If it is not a self-signed certificate, we check that the chain won't
1101 @c get too long (current limit is 100), if this is the case we terminate
1102 @c with the error GPG_ERR_BAD_CERT_CHAIN.
1104 @c Now the issuer's certificate is looked up: If an
1105 @c authorityKeyIdentifier is available, this one is used to locate the
1106 @c certificate either using issuer and serialnumber or subject DN
1107 @c (i.e. the issuer's DN) and the keyID. The functions
1108 @c @code{find_cert_bysn) and @code{find_cert_bysubject} are used
1109 @c respectively. The have already been described above under the
1110 @c description of @code{crl_cache_insert}. If no certificate was found
1111 @c or with no authorityKeyIdentifier, only the cache is consulted using
1112 @c @code{get_cert_bysubject}. The latter is is done under the assumption
1113 @c that a matching certificate has explicitly been put into the
1114 @c certificate cache. If the issuer's certificate could not be found,
1115 @c the validation terminates with the error code @code{GPG_ERR_MISSING_CERT}.
1117 @c If the issuer's certificate has been found, the signature of the
1118 @c actual certificate is checked and in case this fails the error
1119 @c #code{GPG_ERR_BAD_CERT_CHAIN} is returned. If the signature checks out, the
1120 @c maximum chain length of the issuing certificate is checked as well as
1121 @c the capability of the certificate (i.e. whether he may be used for
1122 @c certificate signing). Then the certificate is prepended to our list
1123 @c representing the certificate chain. Finally the loop is continued now
1124 @c with the issuer's certificate as the current certificate.
1126 @c After the end of the loop and if no error as been encountered
1127 @c (i.e. the certificate chain has been assempled correctly), a check is
1128 @c done whether any certificate expired or a critical policy has not been
1129 @c met. In any of these cases the validation terminates with an
1130 @c appropriate error.
1132 @c Finally the function @code{check_revocations} is called to verify no
1133 @c certificate in the assempled chain has been revoked: This is an
1134 @c recursive process because a CRL has to be checked for each certificate
1135 @c in the chain except for the root certificate, of which we already know
1136 @c that it is trusted and we avoid checking a CRL here due to common
1137 @c setup problems and the assumption that a revoked root certifcate has
1138 @c been removed from the list of trusted certificates.
1143 @c @section Looking up certificates through LDAP.
1145 @c This describes the LDAP layer to retrieve certificates.
1146 @c the functions @code{ca_cert_fetch} and @code{fetch_next_ksba_cert} are
1147 @c used for this. The first one starts a search and the second one is
1148 @c used to retrieve certificate after certificate.