Fixed test code (removed static reference to aes_x86ni code).
[BearSSL] / src / rsa / rsa_pkcs1_sig_pad.c
1 /*
2 * Copyright (c) 2017 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 /* see inner.h */
28 uint32_t
29 br_rsa_pkcs1_sig_pad(const unsigned char *hash_oid,
30 const unsigned char *hash, size_t hash_len,
31 uint32_t n_bitlen, unsigned char *x)
32 {
33 size_t u, x3, xlen;
34
35 /*
36 * Padded hash value has format:
37 * 00 01 FF .. FF 00 30 x1 30 x2 06 x3 OID 05 00 04 x4 HASH
38 *
39 * with the following rules:
40 *
41 * -- Total length is equal to the modulus length (unsigned
42 * encoding).
43 *
44 * -- There must be at least eight bytes of value 0xFF.
45 *
46 * -- x4 is equal to the hash length (hash_len).
47 *
48 * -- x3 is equal to the encoded OID value length (hash_oid[0]).
49 *
50 * -- x2 = x3 + 4.
51 *
52 * -- x1 = x2 + x4 + 4 = x3 + x4 + 8.
53 *
54 * Note: the "05 00" is optional (signatures with and without
55 * that sequence exist in practice), but notes in PKCS#1 seem to
56 * indicate that the presence of that sequence (specifically,
57 * an ASN.1 NULL value for the hash parameters) may be slightly
58 * more "standard" than the opposite.
59 */
60 xlen = (n_bitlen + 7) >> 3;
61
62 if (hash_oid == NULL) {
63 if (xlen < hash_len + 11) {
64 return 0;
65 }
66 x[0] = 0x00;
67 x[1] = 0x01;
68 u = xlen - hash_len;
69 memset(x + 2, 0xFF, u - 3);
70 x[u - 1] = 0x00;
71 } else {
72 x3 = hash_oid[0];
73
74 /*
75 * Check that there is enough room for all the elements,
76 * including at least eight bytes of value 0xFF.
77 */
78 if (xlen < (x3 + hash_len + 21)) {
79 return 0;
80 }
81 x[0] = 0x00;
82 x[1] = 0x01;
83 u = xlen - x3 - hash_len - 11;
84 memset(x + 2, 0xFF, u - 2);
85 x[u] = 0x00;
86 x[u + 1] = 0x30;
87 x[u + 2] = x3 + hash_len + 8;
88 x[u + 3] = 0x30;
89 x[u + 4] = x3 + 4;
90 x[u + 5] = 0x06;
91 memcpy(x + u + 6, hash_oid, x3 + 1);
92 u += x3 + 7;
93 x[u ++] = 0x05;
94 x[u ++] = 0x00;
95 x[u ++] = 0x04;
96 x[u ++] = hash_len;
97 }
98 memcpy(x + u, hash, hash_len);
99 return 1;
100 }