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, 4 insertions, 9 deletions

diff --git a/cipher/cipher-ccm.c b/cipher/cipher-ccm.c
index 2a1fc74a..1eba7f0f 100644
--- a/cipher/cipher-ccm.c
+++ b/cipher/cipher-ccm.c
@@ -289,13 +289,8 @@ _gcry_cipher_ccm_tag (gcry_cipher_hd_t c, unsigned char *outbuf,
     }
   else
     {
-      int diff, i;
-
-      /* Constant-time compare. */
-      for (i = 0, diff = 0; i < outbuflen; i++)
-        diff -= !!(outbuf[i] - c->u_iv.iv[i]);
-
-      return !diff ? GPG_ERR_NO_ERROR : GPG_ERR_CHECKSUM;
+      return buf_eq_const(outbuf, c->u_iv.iv, outbuflen) ?
+             GPG_ERR_NO_ERROR : GPG_ERR_CHECKSUM;
     }
 }
 
@@ -304,7 +299,7 @@ gcry_err_code_t
 _gcry_cipher_ccm_get_tag (gcry_cipher_hd_t c, unsigned char *outtag,
 			  size_t taglen)
 {
-	return _gcry_cipher_ccm_tag (c, outtag, taglen, 0);
+  return _gcry_cipher_ccm_tag (c, outtag, taglen, 0);
 }
 
 
@@ -312,7 +307,7 @@ gcry_err_code_t
 _gcry_cipher_ccm_check_tag (gcry_cipher_hd_t c, const unsigned char *intag,
 			    size_t taglen)
 {
-	return _gcry_cipher_ccm_tag (c, (unsigned char *)intag, taglen, 1);
+  return _gcry_cipher_ccm_tag (c, (unsigned char *)intag, taglen, 1);
 }