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, 12 insertions, 3 deletions

diff --git a/cipher/crc.c b/cipher/crc.c
index 4f72ffb2..1322f0da 100644
--- a/cipher/crc.c
+++ b/cipher/crc.c
@@ -149,9 +149,12 @@ CRC_CONTEXT;
 /* CRC32 */
 
 static void
-crc32_init (void *context)
+crc32_init (void *context, unsigned int flags)
 {
   CRC_CONTEXT *ctx = (CRC_CONTEXT *) context;
+
+  (void)flags;
+
   ctx->CRC = 0 ^ 0xffffffffL;
 }
 
@@ -184,9 +187,12 @@ crc32_final (void *context)
 
 /* CRC32 a'la RFC 1510 */
 static void
-crc32rfc1510_init (void *context)
+crc32rfc1510_init (void *context, unsigned int flags)
 {
   CRC_CONTEXT *ctx = (CRC_CONTEXT *) context;
+
+  (void)flags;
+
   ctx->CRC = 0;
 }
 
@@ -237,9 +243,12 @@ crc32rfc1510_final (void *context)
 #define CRC24_POLY 0x1864cfbL
 
 static void
-crc24rfc2440_init (void *context)
+crc24rfc2440_init (void *context, unsigned int flags)
 {
   CRC_CONTEXT *ctx = (CRC_CONTEXT *) context;
+
+  (void)flags;
+
   ctx->CRC = CRC24_INIT;
 }