X-Git-Url: https://www.chiark.greenend.org.uk/ucgi/~mdw/git/secnet/blobdiff_plain/0bcb8184cfce875a4dde57621139dd44c433f3a5..7111e1f77ccb1e86cc85d09c1a36caede9725f3a:/secnet.8

diff --git a/secnet.8 b/secnet.8
index 525e854..087273d 100644
--- a/secnet.8
+++ b/secnet.8
@@ -340,6 +340,36 @@ The default capability number is 10.
 .PP
 A \fIdh closure\fR defines a group to be used for key exchange.
 
+.SS x25519
+.PP
+\fBx25519
+.PP
+A premade \fIdh closure\fR
+which uses Daniel Bernstein's X25519 key-exchange function.
+This uses an elliptic curve called Curve25519,
+defined over a 255-bit field.
+The function is fast and very well-studied.
+.PP
+A \fIdh closure\fR defines a group to be used for key exchange.
+The
+.B x25519
+Diffie\(enHellman group always uses capability number 24.
+
+.SS x448
+.PP
+\fBx448
+.PP
+A premade \fIdh closure\fR
+which uses Mike Hamburg's X448 key-exchange function.
+This uses an elliptic curve called Ed448-Goldilocks,
+defined over a 448-bit field.
+The function is unusually quick and fairly well studied.
+.PP
+A \fIdh closure\fR defines a group to be used for key exchange.
+The
+.B x448
+Diffie\(enHellman group always uses capability number 25.
+
 .SS logfile
 \fBlogfile(\fIDICT\fB)\fR => \fIlog closure\fR
 .PP