xref: /freebsd/contrib/bearssl/src/ec/ecdsa_i31_vrfy_asn1.c (revision f81cdf24ba5436367377f7c8e8f51f6df2a75ca7)
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 }
49