X-Git-Url: http://www.chiark.greenend.org.uk/ucgi/~mdw/git/tripe/blobdiff_plain/1a19f86595b5c07ebf7ca7193093c54a75a15310..b5c45da15703d85b506a1ea1eb38c318c3418ed3:/doc/tripe.8

diff --git a/doc/tripe.8 b/doc/tripe.8
index caacbe79..929f0191 100644
--- a/doc/tripe.8
+++ b/doc/tripe.8
@@ -37,12 +37,20 @@ tripe \- a simple VPN daemon
 .RB [ \-D ]
 .RB [ \-d
 .IR dir ]
+.RB [ \-b
+.IR addr ]
 .RB [ \-p
 .IR port ]
+.br
+	
 .RB [ \-U
 .IR user ]
 .RB [ \-G
 .IR group ]
+.RB [ \-a
+.IR socket ]
+.RB [ \-T
+.IR trace-opts ]
 .br
 	
 .RB [ \-k
@@ -51,12 +59,6 @@ tripe \- a simple VPN daemon
 .IR pub-keyring ]
 .RB [ \-t
 .IR key-tag ]
-.br
-	
-.RB [ \-a
-.IR socket ]
-.RB [ \-T
-.IR trace-opts ]
 .SH "DESCRIPTION"
 The
 .B tripe
@@ -166,6 +168,14 @@ Give a current directory of
 .B .
 if you don't want it to change directory at all.
 .TP
+.BI "\-b, \-\-bind-address="addr
+Bind the UDP socket to IP address
+.I addr
+rather than the default of
+.BR INADDR_ANY .
+This is useful if your main globally-routable IP address is one you want
+to tunnel through the VPN.
+.TP
 .BI "\-p, \-\-port=" port
 Use the specified UDP port for all communications with peers, rather
 than an arbitarary kernel-assigned port.
@@ -399,6 +409,69 @@ server to talk to
 .hP 7.
 Congratulations.  The two servers will exchange keys and begin sending
 packets almost immediately.  You've set up a virtual private network.
+.SS "Using elliptic curve keys"
+The
+.B tripe
+server can use elliptic curve Diffie-Hellman for key exchange, rather
+than traditional integer Diffie-Hellman.  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
+The server works out which it
+should be doing based on the key type, which is either
+.B tripe\-dh
+for standard Diffie-Hellman, or
+.B tripe\-ec
+for elliptic curves.  To create elliptic curve keys, say something like
+.VS
+key add \-aec\-param \-Cnist-p192 \-eforever \e
+	\-tparam tripe\-ec\-param
+.VE
+to construct a parameters key, using your preferred elliptic curve in
+the
+.B \-C
+option (see
+.BR key (1)
+for details); and create the private keys by
+.VS
+key add \-aec \-pparam \-talice \e
+	\-e"now + 1 year" tripe\-ec
+.VE
+Now start
+.B tripe
+with the
+.B \-ttripe\-ec
+option, and all should be well.
+.SS "Using other symmetric algorithms"
+The default symmetric algorithms
+.B tripe
+uses are Blowfish (by Schneier) for symmetric encryption, and RIPEMD-160
+(by Dobbertin, Bosselaers and Preneel) for hashing and as a MAC (in HMAC
+mode, designed by Bellare, Canetti and Krawczyk).  These can all be
+overridden by setting attributes on your private key, as follows.
+.TP
+.B cipher
+Names the symmetric encryption scheme to use.  The default is
+.BR blowfish\-cbc .
+.TP
+.B hash
+Names the hash function to use.  The default is
+.BR rmd160 .
+.TP
+.B mac
+Names the message authentication code to use.  The name of the MAC may
+be followed by a
+.RB ` / '
+and the desired tag length in bits.  The default is
+.IB hash \-hmac
+at half the underlying hash function's output length.
+.TP
+.B mgf
+A `mask-generation function', used in the key-exchange.  The default is
+.IB hash \-mgf
+and there's no good reason to change it.
 .SS "About the name"
 The program's name is
 .BR tripe ,