Add OCB cipher mode

* cipher/cipher-ocb.c: New.
* cipher/Makefile.am (libcipher_la_SOURCES): Add cipher-ocb.c
* cipher/cipher-internal.h (OCB_BLOCK_LEN, OCB_L_TABLE_SIZE): New.
(gcry_cipher_handle): Add fields marks.finalize and u_mode.ocb.
* cipher/cipher.c (_gcry_cipher_open_internal): Add OCB mode.
(_gcry_cipher_open_internal): Setup default taglen of OCB.
(cipher_reset): Clear OCB specific data.
(cipher_encrypt, cipher_decrypt, _gcry_cipher_authenticate)
(_gcry_cipher_gettag, _gcry_cipher_checktag): Call OCB functions.
(_gcry_cipher_setiv): Add OCB specific nonce setting.
(_gcry_cipher_ctl): Add GCRYCTL_FINALIZE and GCRYCTL_SET_TAGLEN

* src/gcrypt.h.in (GCRYCTL_SET_TAGLEN): New.
(gcry_cipher_final): New.

* cipher/bufhelp.h (buf_xor_1): New.

* tests/basic.c (hex2buffer): New.
(check_ocb_cipher): New.
(main): Call it here.  Add option --cipher-modes.
* tests/bench-slope.c (bench_aead_encrypt_do_bench): Call
gcry_cipher_final.
(bench_aead_decrypt_do_bench): Ditto.
(bench_aead_authenticate_do_bench): Ditto.  Check error code.
(bench_ocb_encrypt_do_bench): New.
(bench_ocb_decrypt_do_bench): New.
(bench_ocb_authenticate_do_bench): New.
(ocb_encrypt_ops): New.
(ocb_decrypt_ops): New.
(ocb_authenticate_ops): New.
(cipher_modes): Add them.
(cipher_bench_one): Skip wrong block length for OCB.
* tests/benchmark.c (cipher_bench): Add field noncelen to MODES.  Add
OCB support.

--

See the comments on top of cipher/cipher-ocb.c for the patent status
of the OCB mode.

The implementation has not yet been optimized and as such is not faster
that the other AEAD modes.  A first candidate for optimization is the
double_block function.  Large improvements can be expected by writing
an AES ECB function to work on multiple blocks.

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

1 files changed, 34 insertions, 0 deletions

diff --git a/cipher/bufhelp.h b/cipher/bufhelp.h
index 464b1416..a372acb4 100644
--- a/cipher/bufhelp.h
+++ b/cipher/bufhelp.h
@@ -120,6 +120,40 @@ do_bytes:
 }
 
 
+/* Optimized function for in-place buffer xoring. */
+static inline void
+buf_xor_1(void *_dst, const void *_src, size_t len)
+{
+  byte *dst = _dst;
+  const byte *src = _src;
+  uintptr_t *ldst;
+  const uintptr_t *lsrc;
+#ifndef BUFHELP_FAST_UNALIGNED_ACCESS
+  const unsigned int longmask = sizeof(uintptr_t) - 1;
+
+  /* Skip fast processing if buffers are unaligned.  */
+  if (((uintptr_t)dst | (uintptr_t)src) & longmask)
+    goto do_bytes;
+#endif
+
+  ldst = (uintptr_t *)(void *)dst;
+  lsrc = (const uintptr_t *)(const void *)src;
+
+  for (; len >= sizeof(uintptr_t); len -= sizeof(uintptr_t))
+    *ldst++ ^= *lsrc++;
+
+  dst = (byte *)ldst;
+  src = (const byte *)lsrc;
+
+#ifndef BUFHELP_FAST_UNALIGNED_ACCESS
+do_bytes:
+#endif
+  /* Handle tail.  */
+  for (; len; len--)
+    *dst++ ^= *src;
+}
+
+
 /* Optimized function for buffer xoring with two destination buffers.  Used
    mainly by CFB mode encryption.  */
 static inline void