diff options
Diffstat (limited to 'third_party/bearssl/src/aes_small_dec.c')
| -rw-r--r-- | third_party/bearssl/src/aes_small_dec.c | 176 |
1 files changed, 176 insertions, 0 deletions
diff --git a/third_party/bearssl/src/aes_small_dec.c b/third_party/bearssl/src/aes_small_dec.c new file mode 100644 index 0000000..59dca8e --- /dev/null +++ b/third_party/bearssl/src/aes_small_dec.c @@ -0,0 +1,176 @@ +/* + * Copyright (c) 2016 Thomas Pornin <[email protected]> + * + * Permission is hereby granted, free of charge, to any person obtaining + * a copy of this software and associated documentation files (the + * "Software"), to deal in the Software without restriction, including + * without limitation the rights to use, copy, modify, merge, publish, + * distribute, sublicense, and/or sell copies of the Software, and to + * permit persons to whom the Software is furnished to do so, subject to + * the following conditions: + * + * The above copyright notice and this permission notice shall be + * included in all copies or substantial portions of the Software. + * + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, + * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF + * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND + * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS + * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN + * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN + * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE + * SOFTWARE. + */ + +#include "inner.h" + +/* + * Inverse S-box. + */ +static const unsigned char iS[] = { + 0x52, 0x09, 0x6A, 0xD5, 0x30, 0x36, 0xA5, 0x38, 0xBF, 0x40, 0xA3, 0x9E, + 0x81, 0xF3, 0xD7, 0xFB, 0x7C, 0xE3, 0x39, 0x82, 0x9B, 0x2F, 0xFF, 0x87, + 0x34, 0x8E, 0x43, 0x44, 0xC4, 0xDE, 0xE9, 0xCB, 0x54, 0x7B, 0x94, 0x32, + 0xA6, 0xC2, 0x23, 0x3D, 0xEE, 0x4C, 0x95, 0x0B, 0x42, 0xFA, 0xC3, 0x4E, + 0x08, 0x2E, 0xA1, 0x66, 0x28, 0xD9, 0x24, 0xB2, 0x76, 0x5B, 0xA2, 0x49, + 0x6D, 0x8B, 0xD1, 0x25, 0x72, 0xF8, 0xF6, 0x64, 0x86, 0x68, 0x98, 0x16, + 0xD4, 0xA4, 0x5C, 0xCC, 0x5D, 0x65, 0xB6, 0x92, 0x6C, 0x70, 0x48, 0x50, + 0xFD, 0xED, 0xB9, 0xDA, 0x5E, 0x15, 0x46, 0x57, 0xA7, 0x8D, 0x9D, 0x84, + 0x90, 0xD8, 0xAB, 0x00, 0x8C, 0xBC, 0xD3, 0x0A, 0xF7, 0xE4, 0x58, 0x05, + 0xB8, 0xB3, 0x45, 0x06, 0xD0, 0x2C, 0x1E, 0x8F, 0xCA, 0x3F, 0x0F, 0x02, + 0xC1, 0xAF, 0xBD, 0x03, 0x01, 0x13, 0x8A, 0x6B, 0x3A, 0x91, 0x11, 0x41, + 0x4F, 0x67, 0xDC, 0xEA, 0x97, 0xF2, 0xCF, 0xCE, 0xF0, 0xB4, 0xE6, 0x73, + 0x96, 0xAC, 0x74, 0x22, 0xE7, 0xAD, 0x35, 0x85, 0xE2, 0xF9, 0x37, 0xE8, + 0x1C, 0x75, 0xDF, 0x6E, 0x47, 0xF1, 0x1A, 0x71, 0x1D, 0x29, 0xC5, 0x89, + 0x6F, 0xB7, 0x62, 0x0E, 0xAA, 0x18, 0xBE, 0x1B, 0xFC, 0x56, 0x3E, 0x4B, + 0xC6, 0xD2, 0x79, 0x20, 0x9A, 0xDB, 0xC0, 0xFE, 0x78, 0xCD, 0x5A, 0xF4, + 0x1F, 0xDD, 0xA8, 0x33, 0x88, 0x07, 0xC7, 0x31, 0xB1, 0x12, 0x10, 0x59, + 0x27, 0x80, 0xEC, 0x5F, 0x60, 0x51, 0x7F, 0xA9, 0x19, 0xB5, 0x4A, 0x0D, + 0x2D, 0xE5, 0x7A, 0x9F, 0x93, 0xC9, 0x9C, 0xEF, 0xA0, 0xE0, 0x3B, 0x4D, + 0xAE, 0x2A, 0xF5, 0xB0, 0xC8, 0xEB, 0xBB, 0x3C, 0x83, 0x53, 0x99, 0x61, + 0x17, 0x2B, 0x04, 0x7E, 0xBA, 0x77, 0xD6, 0x26, 0xE1, 0x69, 0x14, 0x63, + 0x55, 0x21, 0x0C, 0x7D +}; + +static void +add_round_key(unsigned *state, const uint32_t *skeys) +{ + int i; + + for (i = 0; i < 16; i += 4) { + uint32_t k; + + k = *skeys ++; + state[i + 0] ^= (unsigned)(k >> 24); + state[i + 1] ^= (unsigned)(k >> 16) & 0xFF; + state[i + 2] ^= (unsigned)(k >> 8) & 0xFF; + state[i + 3] ^= (unsigned)k & 0xFF; + } +} + +static void +inv_sub_bytes(unsigned *state) +{ + int i; + + for (i = 0; i < 16; i ++) { + state[i] = iS[state[i]]; + } +} + +static void +inv_shift_rows(unsigned *state) +{ + unsigned tmp; + + tmp = state[13]; + state[13] = state[9]; + state[9] = state[5]; + state[5] = state[1]; + state[1] = tmp; + + tmp = state[2]; + state[2] = state[10]; + state[10] = tmp; + tmp = state[6]; + state[6] = state[14]; + state[14] = tmp; + + tmp = state[3]; + state[3] = state[7]; + state[7] = state[11]; + state[11] = state[15]; + state[15] = tmp; +} + +static inline unsigned +gf256red(unsigned x) +{ + unsigned y; + + y = x >> 8; + return (x ^ y ^ (y << 1) ^ (y << 3) ^ (y << 4)) & 0xFF; +} + +static void +inv_mix_columns(unsigned *state) +{ + int i; + + for (i = 0; i < 16; i += 4) { + unsigned s0, s1, s2, s3; + unsigned t0, t1, t2, t3; + + s0 = state[i + 0]; + s1 = state[i + 1]; + s2 = state[i + 2]; + s3 = state[i + 3]; + t0 = (s0 << 1) ^ (s0 << 2) ^ (s0 << 3) + ^ s1 ^ (s1 << 1) ^ (s1 << 3) + ^ s2 ^ (s2 << 2) ^ (s2 << 3) + ^ s3 ^ (s3 << 3); + t1 = s0 ^ (s0 << 3) + ^ (s1 << 1) ^ (s1 << 2) ^ (s1 << 3) + ^ s2 ^ (s2 << 1) ^ (s2 << 3) + ^ s3 ^ (s3 << 2) ^ (s3 << 3); + t2 = s0 ^ (s0 << 2) ^ (s0 << 3) + ^ s1 ^ (s1 << 3) + ^ (s2 << 1) ^ (s2 << 2) ^ (s2 << 3) + ^ s3 ^ (s3 << 1) ^ (s3 << 3); + t3 = s0 ^ (s0 << 1) ^ (s0 << 3) + ^ s1 ^ (s1 << 2) ^ (s1 << 3) + ^ s2 ^ (s2 << 3) + ^ (s3 << 1) ^ (s3 << 2) ^ (s3 << 3); + state[i + 0] = gf256red(t0); + state[i + 1] = gf256red(t1); + state[i + 2] = gf256red(t2); + state[i + 3] = gf256red(t3); + } +} + +/* see inner.h */ +void +br_aes_small_decrypt(unsigned num_rounds, const uint32_t *skey, void *data) +{ + unsigned char *buf; + unsigned state[16]; + unsigned u; + + buf = data; + for (u = 0; u < 16; u ++) { + state[u] = buf[u]; + } + add_round_key(state, skey + (num_rounds << 2)); + for (u = num_rounds - 1; u > 0; u --) { + inv_shift_rows(state); + inv_sub_bytes(state); + add_round_key(state, skey + (u << 2)); + inv_mix_columns(state); + } + inv_shift_rows(state); + inv_sub_bytes(state); + add_round_key(state, skey); + for (u = 0; u < 16; u ++) { + buf[u] = state[u]; + } +} |