All output written has been checked for authenticity. However, output
can fail madway through for many reasons, and the resulting message may
therefore be truncated. Don't rely on the output being complete until
-.B OK is printed or
+.B OK
+is printed or
.B catcrypt decrypt
exits successfully.
.SS "encode"
warranties. But it does avoid the usual problem with separate signing
and encryption that a careful leak by the recipient can produce evidence
that you signed some incriminating message.
+.PP
+Note that
+.BR catcrypt 's
+signatures do
+.I not
+provide `non-repudiation' in any useful way. This is deliberate: the
+purpose of signing is to convince the recipient of the sender's
+identity, rather than to allow the recipient to persuade anyone else.
+Indeed, given an encrypted and signed message, the recipient can
+straightforwardly construct a new message, apparently from the same
+sender, and whose signature still verifies, but with arbitrarily chosen
+content.
.SH "CRYPTOGRAPHIC THEORY"
Encryption of a message proceeds as follows.
.hP 0.
.BR hashsum (1),
.BR keyring (5).
.SH AUTHOR
-Mark Wooding, <mdw@nsict.org>
+Mark Wooding, <mdw@distorted.org.uk>