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  }