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, 5 insertions, 3 deletions

diff --git a/cipher/sha1.c b/cipher/sha1.c
index 889a7ea1..65bd6866 100644
--- a/cipher/sha1.c
+++ b/cipher/sha1.c
@@ -106,11 +106,13 @@ transform (void *c, const unsigned char *data, size_t nblks);
 
 
 static void
-sha1_init (void *context)
+sha1_init (void *context, unsigned int flags)
 {
   SHA1_CONTEXT *hd = context;
   unsigned int features = _gcry_get_hw_features ();
 
+  (void)flags;
+
   hd->h0 = 0x67452301;
   hd->h1 = 0xefcdab89;
   hd->h2 = 0x98badcfe;
@@ -425,7 +427,7 @@ _gcry_sha1_hash_buffer (void *outbuf, const void *buffer, size_t length)
 {
   SHA1_CONTEXT hd;
 
-  sha1_init (&hd);
+  sha1_init (&hd, 0);
   _gcry_md_block_write (&hd, buffer, length);
   sha1_final (&hd);
   memcpy (outbuf, hd.bctx.buf, 20);
@@ -438,7 +440,7 @@ _gcry_sha1_hash_buffers (void *outbuf, const gcry_buffer_t *iov, int iovcnt)
 {
   SHA1_CONTEXT hd;
 
-  sha1_init (&hd);
+  sha1_init (&hd, 0);
   for (;iovcnt > 0; iov++, iovcnt--)
     _gcry_md_block_write (&hd,
                           (const char*)iov[0].data + iov[0].off, iov[0].len);