Fixed buffer overrun (read only, usually harmless, but sloppy nonetheless).
[BearSSL] / src / symcipher / aes_common.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 static const uint32_t Rcon[] = {
28 0x01000000, 0x02000000, 0x04000000, 0x08000000, 0x10000000, 0x20000000,
29 0x40000000, 0x80000000, 0x1B000000, 0x36000000
30 };
31
32 #define S br_aes_S
33
34 /* see inner.h */
35 const unsigned char br_aes_S[] = {
36 0x63, 0x7C, 0x77, 0x7B, 0xF2, 0x6B, 0x6F, 0xC5, 0x30, 0x01, 0x67, 0x2B,
37 0xFE, 0xD7, 0xAB, 0x76, 0xCA, 0x82, 0xC9, 0x7D, 0xFA, 0x59, 0x47, 0xF0,
38 0xAD, 0xD4, 0xA2, 0xAF, 0x9C, 0xA4, 0x72, 0xC0, 0xB7, 0xFD, 0x93, 0x26,
39 0x36, 0x3F, 0xF7, 0xCC, 0x34, 0xA5, 0xE5, 0xF1, 0x71, 0xD8, 0x31, 0x15,
40 0x04, 0xC7, 0x23, 0xC3, 0x18, 0x96, 0x05, 0x9A, 0x07, 0x12, 0x80, 0xE2,
41 0xEB, 0x27, 0xB2, 0x75, 0x09, 0x83, 0x2C, 0x1A, 0x1B, 0x6E, 0x5A, 0xA0,
42 0x52, 0x3B, 0xD6, 0xB3, 0x29, 0xE3, 0x2F, 0x84, 0x53, 0xD1, 0x00, 0xED,
43 0x20, 0xFC, 0xB1, 0x5B, 0x6A, 0xCB, 0xBE, 0x39, 0x4A, 0x4C, 0x58, 0xCF,
44 0xD0, 0xEF, 0xAA, 0xFB, 0x43, 0x4D, 0x33, 0x85, 0x45, 0xF9, 0x02, 0x7F,
45 0x50, 0x3C, 0x9F, 0xA8, 0x51, 0xA3, 0x40, 0x8F, 0x92, 0x9D, 0x38, 0xF5,
46 0xBC, 0xB6, 0xDA, 0x21, 0x10, 0xFF, 0xF3, 0xD2, 0xCD, 0x0C, 0x13, 0xEC,
47 0x5F, 0x97, 0x44, 0x17, 0xC4, 0xA7, 0x7E, 0x3D, 0x64, 0x5D, 0x19, 0x73,
48 0x60, 0x81, 0x4F, 0xDC, 0x22, 0x2A, 0x90, 0x88, 0x46, 0xEE, 0xB8, 0x14,
49 0xDE, 0x5E, 0x0B, 0xDB, 0xE0, 0x32, 0x3A, 0x0A, 0x49, 0x06, 0x24, 0x5C,
50 0xC2, 0xD3, 0xAC, 0x62, 0x91, 0x95, 0xE4, 0x79, 0xE7, 0xC8, 0x37, 0x6D,
51 0x8D, 0xD5, 0x4E, 0xA9, 0x6C, 0x56, 0xF4, 0xEA, 0x65, 0x7A, 0xAE, 0x08,
52 0xBA, 0x78, 0x25, 0x2E, 0x1C, 0xA6, 0xB4, 0xC6, 0xE8, 0xDD, 0x74, 0x1F,
53 0x4B, 0xBD, 0x8B, 0x8A, 0x70, 0x3E, 0xB5, 0x66, 0x48, 0x03, 0xF6, 0x0E,
54 0x61, 0x35, 0x57, 0xB9, 0x86, 0xC1, 0x1D, 0x9E, 0xE1, 0xF8, 0x98, 0x11,
55 0x69, 0xD9, 0x8E, 0x94, 0x9B, 0x1E, 0x87, 0xE9, 0xCE, 0x55, 0x28, 0xDF,
56 0x8C, 0xA1, 0x89, 0x0D, 0xBF, 0xE6, 0x42, 0x68, 0x41, 0x99, 0x2D, 0x0F,
57 0xB0, 0x54, 0xBB, 0x16
58 };
59
60 static uint32_t
61 SubWord(uint32_t x)
62 {
63 return ((uint32_t)S[x >> 24] << 24)
64 | ((uint32_t)S[(x >> 16) & 0xFF] << 16)
65 | ((uint32_t)S[(x >> 8) & 0xFF] << 8)
66 | (uint32_t)S[x & 0xFF];
67 }
68
69 /* see inner.h */
70 unsigned
71 br_aes_keysched(uint32_t *skey, const void *key, size_t key_len)
72 {
73 unsigned num_rounds;
74 int i, j, k, nk, nkf;
75
76 switch (key_len) {
77 case 16:
78 num_rounds = 10;
79 break;
80 case 24:
81 num_rounds = 12;
82 break;
83 case 32:
84 num_rounds = 14;
85 break;
86 default:
87 /* abort(); */
88 return 0;
89 }
90 nk = (int)(key_len >> 2);
91 nkf = (int)((num_rounds + 1) << 2);
92 for (i = 0; i < nk; i ++) {
93 skey[i] = br_dec32be((const unsigned char *)key + (i << 2));
94 }
95 for (i = nk, j = 0, k = 0; i < nkf; i ++) {
96 uint32_t tmp;
97
98 tmp = skey[i - 1];
99 if (j == 0) {
100 tmp = (tmp << 8) | (tmp >> 24);
101 tmp = SubWord(tmp) ^ Rcon[k];
102 } else if (nk > 6 && j == 4) {
103 tmp = SubWord(tmp);
104 }
105 skey[i] = skey[i - nk] ^ tmp;
106 if (++ j == nk) {
107 j = 0;
108 k ++;
109 }
110 }
111 return num_rounds;
112 }