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, 2 deletions

diff --git a/cipher/sha256.c b/cipher/sha256.c
index 601e9c0b..4efaec6f 100644
--- a/cipher/sha256.c
+++ b/cipher/sha256.c
@@ -92,11 +92,13 @@ transform (void *c, const unsigned char *data, size_t nblks);
 
 
 static void
-sha256_init (void *context)
+sha256_init (void *context, unsigned int flags)
 {
   SHA256_CONTEXT *hd = context;
   unsigned int features = _gcry_get_hw_features ();
 
+  (void)flags;
+
   hd->h0 = 0x6a09e667;
   hd->h1 = 0xbb67ae85;
   hd->h2 = 0x3c6ef372;
@@ -128,11 +130,13 @@ sha256_init (void *context)
 
 
 static void
-sha224_init (void *context)
+sha224_init (void *context, unsigned int flags)
 {
   SHA256_CONTEXT *hd = context;
   unsigned int features = _gcry_get_hw_features ();
 
+  (void)flags;
+
   hd->h0 = 0xc1059ed8;
   hd->h1 = 0x367cd507;
   hd->h2 = 0x3070dd17;