keys/tripe-keys.conf.5.in, server/tripe.8.in: Contemplate more group types.

[tripe] / server / tripe.8.in

diff --git a/server/tripe.8.in b/server/tripe.8.in
index ebbfc7904ce0c009704a198fd068d168d704db33..33f07b5222fdf1804097bb9b6c316088e33a1387 100644 (file)
--- a/server/tripe.8.in
+++ b/server/tripe.8.in
@@ -27,7 +27,7 @@
 .so ../common/defs.man \" @@@PRE@@@
 .
 .\"--------------------------------------------------------------------------
-.TH tripe 8 "10 February 2001" "Straylight/Edgeware" "TrIPE: Trivial IP Encryption"
+.TH tripe 8tripe "10 February 2001" "Straylight/Edgeware" "TrIPE: Trivial IP Encryption"
 .
 .\"--------------------------------------------------------------------------
 .SH "NAME"
@@ -279,48 +279,31 @@ below for the list of options.
 The
 .B tripe
 server uses Diffie\(en\&Hellman key exchange to agree the symmetric keys
-used for bulk data transfer.  Currently
-.B tripe
-can do Diffie\(en\&Hellman in two different kinds of cyclic groups:
-.I "Schnorr groups"
-(denoted
-.BR dh )
-and
-.I "elliptic curve groups"
-(denoted
-.BR ec ).
-.PP
-A Schnorr group is a prime-order subgroup of the multiplicative group of
-a finite field; this is the usual
-.I g\*(ssx\*(se
-mod
-.I p
-kind of Diffie\(en\&Hellman.  An elliptic curve group is a prime-order
-subgroup of the abelian group of
-.BR K -rational
-points on an elliptic curve defined over a finite field
-.BR K .
-.PP
-Given current public knowledge, elliptic curves can provide similar or
-better security to systems based on integer discrete log problems,
-faster, and with less transmitted data.  It's a matter of controversy
-whether this will continue to be the case.  The author uses elliptic
-curves.
+used for bulk data transfer.
 .PP
 The server works out which it should be doing based on the key's
 .B kx-group
-attribute, which should be either
-.B dh
-or
-.BR ec .
+attribute.
 If this attribute isn't present, then the key's type is examined: if
 it's of the form
-.BR tripe\- group
+.BI tripe\- group
 then the
 .I group
 is used.  If no group is specified,
 .B dh
 is used as a fallback.
+The following groups are defined.
+.TP
+.B dh
+.RS
+Use traditional Diffie\(enHellman in a
+.IR "Schnorr group" :
+a prime-order subgroup of the multiplicative group of
+a finite field; this is the usual
+.I g\*(ssx\*(se
+mod
+.I p
+kind of Diffie\(en\&Hellman.
 .PP
 To create usual Schnorr-group keys, say something like
 .VS
@@ -332,6 +315,24 @@ to construct a parameters key; and create the private keys by
 key add \-adh \-pparam \-talice \e
        \-e"now + 1 year" tripe
 .VE
+.RE
+.sv -1
+.TP
+.B ec
+.RS
+Use elliptic curve Diffie\(enHellman.
+An elliptic curve group is a prime-order
+subgroup of the abelian group of
+.BR K -rational
+points on an elliptic curve defined over a finite field
+.BR K .
+.PP
+Given current public knowledge, elliptic curves can provide similar or
+better security to systems based on integer discrete log problems,
+faster, and with less transmitted data.  It's a matter of controversy
+whether this will continue to be the case.  The author uses elliptic
+curves.
+.PP
 To create elliptic curve keys, say something like
 .VS
 key add \-aec\-param \-Cnist-p256 \-eforever \e
@@ -347,6 +348,7 @@ for details); and create the private keys by
 key add \-aec \-pparam \-talice \e
        \-e"now + 1 year" tripe
 .VE
+.RE
 Note that the
 .BR tripe-keys (8)
 program provides a rather more convenient means for generating and
@@ -361,8 +363,14 @@ mode, designed by Bellare, Canetti and Krawczyk).  These can all be
 overridden by setting attributes on your private key, as follows.
 .TP
 .B bulk
-Names the bulk-crypto transform to use.  Currently the only choice is
-.BR v0 .
+Names the bulk-crypto transform to use.  See below.
+.TP
+.B blkc
+Names a block cipher, used by some bulk-crypto transforms (e.g.,
+.BR iiv ).
+The default is to use the block cipher underlying the chosen
+.BR cipher ,
+if any.
 .TP
 .B cipher
 Names the symmetric encryption scheme to use.  The default is
@@ -384,6 +392,26 @@ at half the underlying hash function's output length.
 A `mask-generation function', used in the key-exchange.  The default is
 .IB hash \-mgf
 and there's no good reason to change it.
+.PP
+The available bulk-crypto transforms are as follows.
+.TP
+.B v0
+Originally this was the only transform available.  It's a standard
+generic composition of a CPA-secure symmetric encryption scheme with a
+MAC; initialization vectors for symmetric encryption are chosen at
+random and included explicitly in the cryptogram.
+.TP
+.B iiv
+A newer `implicit-IV' transform.  Rather than having an explicit random
+IV, the IV is computed from the sequence number using a block cipher.
+This has two advantages over the
+.B v0
+transform.  Firstly, it adds less overhead to encrypted messages
+(because the IV no longer needs to be sent explicitly).  Secondly, and
+more significantly, the transform is entirely deterministic, so (a) it
+doesn't need the (possibly slow) random number generator, and (b) it
+closes a kleptographic channel, over which a compromised implementation
+could leak secret information to a third party.
 .SS "Using SLIP interfaces"
 Though not for the faint of heart, it is possible to get
 .B tripe