===================================================================
RCS file: /cvsrepo/anoncvs/cvs/src/usr.bin/ssh/PROTOCOL.u2f,v
retrieving revision 1.3
retrieving revision 1.4
diff -u -r1.3 -r1.4
--- src/usr.bin/ssh/PROTOCOL.u2f	2019/11/12 19:32:30	1.3
+++ src/usr.bin/ssh/PROTOCOL.u2f	2019/11/12 19:34:40	1.4
@@ -148,6 +148,14 @@
 Where 'r' and 's' are extracted by the client or token middleware from the
 ecdsa_signature field returned from the hardware.
 
+For Ed25519 keys the signature is encoded as:
+
+	string		"sk-ssh-ed25519@openssh.com"
+	string		signature
+	byte		flags
+	uint32		counter
+
+
 ssh-agent protocol extensions
 -----------------------------