Add new MAC API, initially with HMAC

* cipher/Makefile.am: Add 'mac.c', 'mac-internal.h' and 'mac-hmac.c'.
* cipher/bufhelp.h (buf_eq_const): New.
* cipher/cipher-ccm.c (_gcry_cipher_ccm_tag): Use 'buf_eq_const' for
constant-time compare.
* cipher/mac-hmac.c: New.
* cipher/mac-internal.h: New.
* cipher/mac.c: New.
* doc/gcrypt.texi: Add documentation for MAC API.
* src/gcrypt-int.h [GPG_ERROR_VERSION_NUMBER < 1.13]
(GPG_ERR_MAC_ALGO): New.
* src/gcrypt.h.in (gcry_mac_handle, gcry_mac_hd_t, gcry_mac_algos)
(gcry_mac_flags, gcry_mac_open, gcry_mac_close, gcry_mac_ctl)
(gcry_mac_algo_info, gcry_mac_setkey, gcry_mac_setiv, gcry_mac_write)
(gcry_mac_read, gcry_mac_verify, gcry_mac_get_algo_maclen)
(gcry_mac_get_algo_keylen, gcry_mac_algo_name, gcry_mac_map_name)
(gcry_mac_reset, gcry_mac_test_algo): New.
* src/libgcrypt.def (gcry_mac_open, gcry_mac_close, gcry_mac_ctl)
(gcry_mac_algo_info, gcry_mac_setkey, gcry_mac_setiv, gcry_mac_write)
(gcry_mac_read, gcry_mac_verify, gcry_mac_get_algo_maclen)
(gcry_mac_get_algo_keylen, gcry_mac_algo_name, gcry_mac_map_name): New.
* src/libgcrypt.vers (gcry_mac_open, gcry_mac_close, gcry_mac_ctl)
(gcry_mac_algo_info, gcry_mac_setkey, gcry_mac_setiv, gcry_mac_write)
(gcry_mac_read, gcry_mac_verify, gcry_mac_get_algo_maclen)
(gcry_mac_get_algo_keylen, gcry_mac_algo_name, gcry_mac_map_name): New.
* src/visibility.c (gcry_mac_open, gcry_mac_close, gcry_mac_ctl)
(gcry_mac_algo_info, gcry_mac_setkey, gcry_mac_setiv, gcry_mac_write)
(gcry_mac_read, gcry_mac_verify, gcry_mac_get_algo_maclen)
(gcry_mac_get_algo_keylen, gcry_mac_algo_name, gcry_mac_map_name): New.
* src/visibility.h (gcry_mac_open, gcry_mac_close, gcry_mac_ctl)
(gcry_mac_algo_info, gcry_mac_setkey, gcry_mac_setiv, gcry_mac_write)
(gcry_mac_read, gcry_mac_verify, gcry_mac_get_algo_maclen)
(gcry_mac_get_algo_keylen, gcry_mac_algo_name, gcry_mac_map_name): New.
* tests/basic.c (check_one_mac, check_mac): New.
(main): Call 'check_mac'.
* tests/bench-slope.c (bench_print_header, bench_print_footer): Allow
variable algorithm name width.
(_cipher_bench, hash_bench): Update to above change.
(bench_hash_do_bench): Add 'gcry_md_reset'.
(bench_mac_mode, bench_mac_init, bench_mac_free, bench_mac_do_bench)
(mac_ops, mac_modes, mac_bench_one, _mac_bench, mac_bench): New.
(main): Add 'mac' benchmark options.
* tests/benchmark.c (mac_repetitions, mac_bench): New.
(main): Add 'mac' benchmark options.
--

Add MAC API, with HMAC algorithms. Internally uses HMAC functionality of the
MD module.

[v2]:
 - Add documentation for MAC API.
 - Change length argument for gcry_mac_read from size_t to size_t* for
   returning number of written bytes.
[v3]:
 - HMAC algorithm ids start from 101.
 - Fix coding style for new files.

Signed-off-by: Jussi Kivilinna <jussi.kivilinna@iki.fi>

1 files changed, 17 insertions, 0 deletions

diff --git a/cipher/bufhelp.h b/cipher/bufhelp.h
index dc39b46d..45a72094 100644
--- a/cipher/bufhelp.h
+++ b/cipher/bufhelp.h
@@ -220,6 +220,23 @@ buf_xor_n_copy(void *_dst_xor, void *_srcdst_cpy, const void *_src, size_t len)
 }
 
 
+/* Constant-time compare of two buffers.  Returns 1 if buffers are equal,
+   and 0 if buffers differ.  */
+static inline int
+buf_eq_const(const void *_a, const void *_b, size_t len)
+{
+  const byte *a = _a;
+  const byte *b = _b;
+  size_t diff, i;
+
+  /* Constant-time compare. */
+  for (i = 0, diff = 0; i < len; i++)
+    diff -= !!(a[i] - b[i]);
+
+  return !diff;
+}
+
+
 #ifndef BUFHELP_FAST_UNALIGNED_ACCESS
 
 /* Functions for loading and storing unaligned u32 values of different