md: Add Whirlpool bug emulation feature.

* src/gcrypt.h.in (GCRY_MD_FLAG_BUGEMU1): New.
* src/cipher-proto.h (gcry_md_init_t): Add arg FLAGS.  Change all code
to implement that flag.
* cipher/md.c (gcry_md_context):  Replace SECURE and FINALIZED by bit
field FLAGS.  Add flag BUGEMU1.  Change all users.
(md_open): Replace args SECURE and HMAC by FLAGS.  Init flags.bugemu1.
(_gcry_md_open): Add for GCRY_MD_FLAG_BUGEMU1.
(md_enable): Pass bugemu1 flag to the hash init function.
(_gcry_md_reset): Ditto.
--

This problem is for example exhibited in the Linux cryptsetup tool.
See https://bbs.archlinux.org/viewtopic.php?id=175737 .  It has be
been tracked down by Milan Broz.

The suggested way of using the flag is:

  if (whirlpool_bug_assumed)
    {
#if GCRYPT_VERSION_NUMBER >= 0x010601
      err = gcry_md_open (&hd, GCRY_MD_WHIRLPOOL, GCRY_MD_FLAG_BUGEMU1)
      if (gpg_err_code (err) == GPG_ERR_INV_ARG)
         error ("Need at least Libggcrypt 1.6.1 for the fix");
      else
         {
            do_hash (hd);
            gcry_md_close (hd);
          }
#endif
    }

Signed-off-by: Werner Koch <wk@gnupg.org>

1 files changed, 6 insertions, 3 deletions

diff --git a/cipher/stribog.c b/cipher/stribog.c
index 6d1d3422..942bbf4c 100644
--- a/cipher/stribog.c
+++ b/cipher/stribog.c
@@ -1198,10 +1198,12 @@ transform (void *context, const unsigned char *inbuf_arg, size_t datalen);
 
 
 static void
-stribog_init_512 (void *context)
+stribog_init_512 (void *context, unsigned int flags)
 {
   STRIBOG_CONTEXT *hd = context;
 
+  (void)flags;
+
   memset (hd, 0, sizeof (*hd));
 
   hd->bctx.blocksize = 64;
@@ -1209,10 +1211,11 @@ stribog_init_512 (void *context)
 }
 
 static void
-stribog_init_256 (void *context)
+stribog_init_256 (void *context, unsigned int flags)
 {
   STRIBOG_CONTEXT *hd = context;
-  stribog_init_512 (context);
+
+  stribog_init_512 (context, flags);
   memset (hd->h, 1, 64);
 }