gpg: Hard fail on a missing MDC even for legacy algorithms.

* g10/mainproc.c (proc_encrypted): Require an MDC or AEAD
* tests/openpgp/defs.scm (create-gpghome): Use --ignore-mdc-error to
allow testing with the current files.
--

Signed-off-by: Werner Koch <[email protected]>
(cherry picked from commit d1431901f0143cdc7af8d1a23387e0c6b5bb613f)

Resolved Conflicts:
	g10/mainproc.c - Remove AEAD stuff.

1 files changed, 5 insertions, 8 deletions

diff --git a/g10/mainproc.c b/g10/mainproc.c
index fc5b9e556..5cf15151f 100644
--- a/g10/mainproc.c
+++ b/g10/mainproc.c
@@ -649,15 +649,12 @@ proc_encrypted (CTX c, PACKET *pkt)
     ;
   else if (!result
            && !opt.ignore_mdc_error
-           && !pkt->pkt.encrypted->mdc_method
-           && openpgp_cipher_get_algo_blklen (c->dek->algo) != 8
-           && c->dek->algo != CIPHER_ALGO_TWOFISH)
+           && !pkt->pkt.encrypted->mdc_method)
     {
-      /* The message has been decrypted but has no MDC despite that a
-         modern cipher (blocklength != 64 bit, except for Twofish) is
-         used and the option to ignore MDC errors is not used: To
-         avoid attacks changing an MDC message to a non-MDC message,
-         we fail here.  */
+      /* The message has been decrypted but does not carry an MDC.
+       * The option --ignore-mdc-error has also not been used.  To
+       * avoid attacks changing an MDC message to a non-MDC message,
+       * we fail here.  */
       log_error (_("WARNING: message was not integrity protected\n"));
       if (opt.verbose > 1)
         log_info ("decryption forced to fail\n");