/* * Byte-oriented AES-256 implementation. * All lookup tables replaced with 'on the fly' calculations. * * Copyright (c) 2007-2011 Ilya O. Levin, http://www.literatecode.com * Other contributors: Hal Finney * * Permission to use, copy, modify, and distribute this software for any * purpose with or without fee is hereby granted, provided that the above * copyright notice and this permission notice appear in all copies. * * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. */ #include "aes256.h" #define FD(x) (((x) >> 1) ^ (((x) & 1) ? 0x8d : 0)) #define BACK_TO_TABLES static uint8_t rj_xtime(uint8_t); static void aes_subBytes(uint8_t *); static void aes_subBytes_inv(uint8_t *); static void aes_addRoundKey(uint8_t *, uint8_t *); static void aes_addRoundKey_cpy(uint8_t *, uint8_t *, uint8_t *); static void aes_shiftRows(uint8_t *); static void aes_shiftRows_inv(uint8_t *); static void aes_mixColumns(uint8_t *); static void aes_mixColumns_inv(uint8_t *); static void aes_expandEncKey(uint8_t *, uint8_t *); static void aes_expandDecKey(uint8_t *, uint8_t *); #ifndef BACK_TO_TABLES static uint8_t gf_alog(uint8_t); static uint8_t gf_log(uint8_t); static uint8_t gf_mulinv(uint8_t); static uint8_t rj_sbox(uint8_t); static uint8_t rj_sbox_inv(uint8_t); #endif #ifdef BACK_TO_TABLES static const uint8_t sbox[256] = { 0x63, 0x7c, 0x77, 0x7b, 0xf2, 0x6b, 0x6f, 0xc5, 0x30, 0x01, 0x67, 0x2b, 0xfe, 0xd7, 0xab, 0x76, 0xca, 0x82, 0xc9, 0x7d, 0xfa, 0x59, 0x47, 0xf0, 0xad, 0xd4, 0xa2, 0xaf, 0x9c, 0xa4, 0x72, 0xc0, 0xb7, 0xfd, 0x93, 0x26, 0x36, 0x3f, 0xf7, 0xcc, 0x34, 0xa5, 0xe5, 0xf1, 0x71, 0xd8, 0x31, 0x15, 0x04, 0xc7, 0x23, 0xc3, 0x18, 0x96, 0x05, 0x9a, 0x07, 0x12, 0x80, 0xe2, 0xeb, 0x27, 0xb2, 0x75, 0x09, 0x83, 0x2c, 0x1a, 0x1b, 0x6e, 0x5a, 0xa0, 0x52, 0x3b, 0xd6, 0xb3, 0x29, 0xe3, 0x2f, 0x84, 0x53, 0xd1, 0x00, 0xed, 0x20, 0xfc, 0xb1, 0x5b, 0x6a, 0xcb, 0xbe, 0x39, 0x4a, 0x4c, 0x58, 0xcf, 0xd0, 0xef, 0xaa, 0xfb, 0x43, 0x4d, 0x33, 0x85, 0x45, 0xf9, 0x02, 0x7f, 0x50, 0x3c, 0x9f, 0xa8, 0x51, 0xa3, 0x40, 0x8f, 0x92, 0x9d, 0x38, 0xf5, 0xbc, 0xb6, 0xda, 0x21, 0x10, 0xff, 0xf3, 0xd2, 0xcd, 0x0c, 0x13, 0xec, 0x5f, 0x97, 0x44, 0x17, 0xc4, 0xa7, 0x7e, 0x3d, 0x64, 0x5d, 0x19, 0x73, 0x60, 0x81, 0x4f, 0xdc, 0x22, 0x2a, 0x90, 0x88, 0x46, 0xee, 0xb8, 0x14, 0xde, 0x5e, 0x0b, 0xdb, 0xe0, 0x32, 0x3a, 0x0a, 0x49, 0x06, 0x24, 0x5c, 0xc2, 0xd3, 0xac, 0x62, 0x91, 0x95, 0xe4, 0x79, 0xe7, 0xc8, 0x37, 0x6d, 0x8d, 0xd5, 0x4e, 0xa9, 0x6c, 0x56, 0xf4, 0xea, 0x65, 0x7a, 0xae, 0x08, 0xba, 0x78, 0x25, 0x2e, 0x1c, 0xa6, 0xb4, 0xc6, 0xe8, 0xdd, 0x74, 0x1f, 0x4b, 0xbd, 0x8b, 0x8a, 0x70, 0x3e, 0xb5, 0x66, 0x48, 0x03, 0xf6, 0x0e, 0x61, 0x35, 0x57, 0xb9, 0x86, 0xc1, 0x1d, 0x9e, 0xe1, 0xf8, 0x98, 0x11, 0x69, 0xd9, 0x8e, 0x94, 0x9b, 0x1e, 0x87, 0xe9, 0xce, 0x55, 0x28, 0xdf, 0x8c, 0xa1, 0x89, 0x0d, 0xbf, 0xe6, 0x42, 0x68, 0x41, 0x99, 0x2d, 0x0f, 0xb0, 0x54, 0xbb, 0x16 }; static const uint8_t sboxinv[256] = { 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 }; #define rj_sbox(x) sbox[(x)] #define rj_sbox_inv(x) sboxinv[(x)] #else /* tableless subroutines */ /* -------------------------------------------------------------------------- */ static uint8_t gf_alog(uint8_t x) // calculate anti-logarithm gen 3 { uint8_t y = 1, i; for (i = 0; i < x; i++) y ^= rj_xtime(y); return y; } /* gf_alog */ /* -------------------------------------------------------------------------- */ static uint8_t gf_log(uint8_t x) // calculate logarithm gen 3 { uint8_t y, i = 0; if (x) for (i = 1, y = 1; i > 0; i++ ) { y ^= rj_xtime(y); if (y == x) break; } return i; } /* gf_log */ /* -------------------------------------------------------------------------- */ static uint8_t gf_mulinv(uint8_t x) // calculate multiplicative inverse { return (x) ? gf_alog(255 - gf_log(x)) : 0; } /* gf_mulinv */ /* -------------------------------------------------------------------------- */ static uint8_t rj_sbox(uint8_t x) { uint8_t y, sb; sb = y = gf_mulinv(x); y = (uint8_t)(y << 1) | (y >> 7), sb ^= y; y = (uint8_t)(y << 1) | (y >> 7), sb ^= y; y = (uint8_t)(y << 1) | (y >> 7), sb ^= y; y = (uint8_t)(y << 1) | (y >> 7), sb ^= y; return (sb ^ 0x63); } /* rj_sbox */ /* -------------------------------------------------------------------------- */ static uint8_t rj_sbox_inv(uint8_t x) { uint8_t y, sb; y = x ^ 0x63; sb = y = (uint8_t)(y << 1) | (y >> 7); y = (uint8_t)(y << 2) | (y >> 6); sb ^= y; y = (uint8_t)(y << 3) | (y >> 5); sb ^= y; return gf_mulinv(sb); } /* rj_sbox_inv */ #endif /* -------------------------------------------------------------------------- */ static uint8_t rj_xtime(uint8_t x) { uint8_t y = (uint8_t)(x << 1); return (x & 0x80) ? (y ^ 0x1b) : y; } /* rj_xtime */ /* -------------------------------------------------------------------------- */ static void aes_subBytes(uint8_t *buf) { register uint8_t i = 16; while (i--) buf[i] = rj_sbox(buf[i]); } /* aes_subBytes */ /* -------------------------------------------------------------------------- */ static void aes_subBytes_inv(uint8_t *buf) { register uint8_t i = 16; while (i--) buf[i] = rj_sbox_inv(buf[i]); } /* aes_subBytes_inv */ /* -------------------------------------------------------------------------- */ static void aes_addRoundKey(uint8_t *buf, uint8_t *key) { register uint8_t i = 16; while (i--) buf[i] ^= key[i]; } /* aes_addRoundKey */ /* -------------------------------------------------------------------------- */ static void aes_addRoundKey_cpy(uint8_t *buf, uint8_t *key, uint8_t *cpk) { register uint8_t i = 16; while (i--) buf[i] ^= (cpk[i] = key[i]), cpk[16 + i] = key[16 + i]; } /* aes_addRoundKey_cpy */ /* -------------------------------------------------------------------------- */ static void aes_shiftRows(uint8_t *buf) { register uint8_t i, j; /* to make it potentially parallelable :) */ i = buf[1], buf[1] = buf[5], buf[5] = buf[9], buf[9] = buf[13], buf[13] = i; i = buf[10], buf[10] = buf[2], buf[2] = i; j = buf[3], buf[3] = buf[15], buf[15] = buf[11], buf[11] = buf[7], buf[7] = j; j = buf[14], buf[14] = buf[6], buf[6] = j; } /* aes_shiftRows */ /* -------------------------------------------------------------------------- */ static void aes_shiftRows_inv(uint8_t *buf) { register uint8_t i, j; /* same as above :) */ i = buf[1], buf[1] = buf[13], buf[13] = buf[9], buf[9] = buf[5], buf[5] = i; i = buf[2], buf[2] = buf[10], buf[10] = i; j = buf[3], buf[3] = buf[7], buf[7] = buf[11], buf[11] = buf[15], buf[15] = j; j = buf[6], buf[6] = buf[14], buf[14] = j; } /* aes_shiftRows_inv */ /* -------------------------------------------------------------------------- */ static void aes_mixColumns(uint8_t *buf) { register uint8_t i, a, b, c, d, e; for (i = 0; i < 16; i += 4) { a = buf[i]; b = buf[i + 1]; c = buf[i + 2]; d = buf[i + 3]; e = a ^ b ^ c ^ d; buf[i] ^= e ^ rj_xtime(a ^ b); buf[i + 1] ^= e ^ rj_xtime(b ^ c); buf[i + 2] ^= e ^ rj_xtime(c ^ d); buf[i + 3] ^= e ^ rj_xtime(d ^ a); } } /* aes_mixColumns */ /* -------------------------------------------------------------------------- */ void aes_mixColumns_inv(uint8_t *buf) { register uint8_t i, a, b, c, d, e, x, y, z; for (i = 0; i < 16; i += 4) { a = buf[i]; b = buf[i + 1]; c = buf[i + 2]; d = buf[i + 3]; e = a ^ b ^ c ^ d; z = rj_xtime(e); x = e ^ rj_xtime(rj_xtime(z ^ a ^ c)); y = e ^ rj_xtime(rj_xtime(z ^ b ^ d)); buf[i] ^= x ^ rj_xtime(a ^ b); buf[i + 1] ^= y ^ rj_xtime(b ^ c); buf[i + 2] ^= x ^ rj_xtime(c ^ d); buf[i + 3] ^= y ^ rj_xtime(d ^ a); } } /* aes_mixColumns_inv */ /* -------------------------------------------------------------------------- */ static void aes_expandEncKey(uint8_t *k, uint8_t *rc) { register uint8_t i; k[0] ^= rj_sbox(k[29]) ^ (*rc); k[1] ^= rj_sbox(k[30]); k[2] ^= rj_sbox(k[31]); k[3] ^= rj_sbox(k[28]); *rc = rj_xtime( *rc); for(i = 4; i < 16; i += 4) k[i] ^= k[i - 4], k[i + 1] ^= k[i - 3], k[i + 2] ^= k[i - 2], k[i + 3] ^= k[i - 1]; k[16] ^= rj_sbox(k[12]); k[17] ^= rj_sbox(k[13]); k[18] ^= rj_sbox(k[14]); k[19] ^= rj_sbox(k[15]); for(i = 20; i < 32; i += 4) k[i] ^= k[i - 4], k[i + 1] ^= k[i - 3], k[i + 2] ^= k[i - 2], k[i + 3] ^= k[i - 1]; } /* aes_expandEncKey */ /* -------------------------------------------------------------------------- */ void aes_expandDecKey(uint8_t *k, uint8_t *rc) { uint8_t i; for(i = 28; i > 16; i -= 4) k[i + 0] ^= k[i - 4], k[i + 1] ^= k[i - 3], k[i + 2] ^= k[i - 2], k[i + 3] ^= k[i - 1]; k[16] ^= rj_sbox(k[12]); k[17] ^= rj_sbox(k[13]); k[18] ^= rj_sbox(k[14]); k[19] ^= rj_sbox(k[15]); for(i = 12; i > 0; i -= 4) k[i + 0] ^= k[i - 4], k[i + 1] ^= k[i - 3], k[i + 2] ^= k[i - 2], k[i + 3] ^= k[i - 1]; *rc = FD(*rc); k[0] ^= rj_sbox(k[29]) ^ (*rc); k[1] ^= rj_sbox(k[30]); k[2] ^= rj_sbox(k[31]); k[3] ^= rj_sbox(k[28]); } /* aes_expandDecKey */ /* -------------------------------------------------------------------------- */ void aes256_init(aes256_context *ctx, uint8_t *k) { uint8_t rcon = 1; register uint8_t i; for (i = 0; i < sizeof(ctx->key); i++) ctx->enckey[i] = ctx->deckey[i] = k[i]; for (i = 8; --i;) aes_expandEncKey(ctx->deckey, &rcon); } /* aes256_init */ /* -------------------------------------------------------------------------- */ void aes256_done(aes256_context *ctx) { register uint8_t i; for (i = 0; i < sizeof(ctx->key); i++) ctx->key[i] = ctx->enckey[i] = ctx->deckey[i] = 0; } /* aes256_done */ /* -------------------------------------------------------------------------- */ void aes256_encrypt_ecb(aes256_context *ctx, uint8_t *buf) { uint8_t i, rcon; aes_addRoundKey_cpy(buf, ctx->enckey, ctx->key); for(i = 1, rcon = 1; i < 14; ++i) { aes_subBytes(buf); aes_shiftRows(buf); aes_mixColumns(buf); if( i & 1 ) aes_addRoundKey( buf, &ctx->key[16]); else aes_expandEncKey(ctx->key, &rcon), aes_addRoundKey(buf, ctx->key); } aes_subBytes(buf); aes_shiftRows(buf); aes_expandEncKey(ctx->key, &rcon); aes_addRoundKey(buf, ctx->key); } /* aes256_encrypt */ /* -------------------------------------------------------------------------- */ void aes256_decrypt_ecb(aes256_context *ctx, uint8_t *buf) { uint8_t i, rcon; aes_addRoundKey_cpy(buf, ctx->deckey, ctx->key); aes_shiftRows_inv(buf); aes_subBytes_inv(buf); for (i = 14, rcon = 0x80; --i;) { if( ( i & 1 ) ) { aes_expandDecKey(ctx->key, &rcon); aes_addRoundKey(buf, &ctx->key[16]); } else aes_addRoundKey(buf, ctx->key); aes_mixColumns_inv(buf); aes_shiftRows_inv(buf); aes_subBytes_inv(buf); } aes_addRoundKey( buf, ctx->key); } /* aes256_decrypt */