From a7d46c78e242e72f6ff681f6fe56ffc4dcb74a18 Mon Sep 17 00:00:00 2001
From: NIIBE Yutaka <gniibe@fsij.org>
Date: Fri, 5 Jun 2020 09:20:21 +0900
Subject: [PATCH] agent,ssh: Tighten condition for EdDSA.

* agent/command-ssh.c (ssh_key_to_blob): Prepare for non-prefixed
point representation of EdDSA.

Signed-off-by: NIIBE Yutaka <gniibe@fsij.org>
---
 agent/command-ssh.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/agent/command-ssh.c b/agent/command-ssh.c
index fc52de2f1..2f8712b5c 100644
--- a/agent/command-ssh.c
+++ b/agent/command-ssh.c
@@ -1955,14 +1955,13 @@ ssh_key_to_blob (gcry_sexp_t sexp, int with_secret,
 	}
       if ((key_spec.flags & SPEC_FLAG_IS_EdDSA))
         {
-
           data = gcry_sexp_nth_data (value_pair, 1, &datalen);
           if (!data)
             {
               err = gpg_error (GPG_ERR_INV_SEXP);
               goto out;
             }
-          if (*p_elems == 'q' && datalen)
+          if (*p_elems == 'q' && (datalen & 1) && *data == 0x40)
             { /* Remove the prefix 0x40.  */
               data++;
               datalen--;