1 files changed, 8 insertions, 0 deletions

diff --git a/PROTOCOL.u2f b/PROTOCOL.u2f
index bd60f9fac..ca55c4297 100644
--- a/PROTOCOL.u2f
+++ b/PROTOCOL.u2f
@@ -148,6 +148,14 @@ be reformatted slightly and the ecdsa_signature_blob value has the encoding:
 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
 -----------------------------