_ Git - BearSSL/blob - src/ec/ecdsa_i31_vrfy_asn1.c

   1 /*
   2  * Copyright (c) 2016 Thomas Pornin <pornin@bolet.org>
   3  *
   4  * Permission is hereby granted, free of charge, to any person obtaining
   5  * a copy of this software and associated documentation files (the
   6  * "Software"), to deal in the Software without restriction, including
   7  * without limitation the rights to use, copy, modify, merge, publish,
   8  * distribute, sublicense, and/or sell copies of the Software, and to
   9  * permit persons to whom the Software is furnished to do so, subject to
  10  * the following conditions:
  11  *
  12  * The above copyright notice and this permission notice shall be
  13  * included in all copies or substantial portions of the Software.
  14  *
  15  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  16  * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  17  * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  18  * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
  19  * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
  20  * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
  21  * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  22  * SOFTWARE.
  23  */
  24
  25 #include "inner.h"
  26
  27 #define FIELD_LEN   ((BR_MAX_EC_SIZE + 7) >> 3)
  28
  29 /* see bearssl_ec.h */
  30 uint32_t
  31 br_ecdsa_i31_vrfy_asn1(const br_ec_impl *impl,
  32         const void *hash, size_t hash_len,
  33         const br_ec_public_key *pk,
  34         const void *sig, size_t sig_len)
  35 {
  36         /*
  37          * We use a double-sized buffer because a malformed ASN.1 signature
  38          * may trigger a size expansion when converting to "raw" format.
  39          */
  40         unsigned char rsig[(FIELD_LEN << 2) + 24];
  41
  42         if (sig_len > ((sizeof rsig) >> 1)) {
  43                 return 0;
  44         }
  45         memcpy(rsig, sig, sig_len);
  46         sig_len = br_ecdsa_asn1_to_raw(rsig, sig_len);
  47         return br_ecdsa_i31_vrfy_raw(impl, hash, hash_len, pk, rsig, sig_len);
  48 }