/* * copyright (c) 2007 Michael Niedermayer <michaelni@gmx.at> * * some optimization ideas from aes128.c by Reimar Doeffinger * * This file is part of FFmpeg. * * FFmpeg is free software; you can redistribute it and/or * modify it under the terms of the GNU Lesser General Public * License as published by the Free Software Foundation; either * version 2.1 of the License, or (at your option) any later version. * * FFmpeg is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU * Lesser General Public License for more details. * * You should have received a copy of the GNU Lesser General Public * License along with FFmpeg; if not, write to the Free Software * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA */ #include <string.h> #include "config.h" #include "aes.h" #include "aes_internal.h" #include "error.h" #include "intreadwrite.h" #include "macros.h" #include "mem.h" const int av_aes_size= sizeof(AVAES); struct AVAES *av_aes_alloc(void) { return av_mallocz(sizeof(struct AVAES)); } static const uint8_t rcon[10] = { 0x01, 0x02, 0x04, 0x08, 0x10, 0x20, 0x40, 0x80, 0x1b, 0x36 }; static uint8_t sbox[256]; static uint8_t inv_sbox[256]; #if CONFIG_SMALL static uint32_t enc_multbl[1][256]; static uint32_t dec_multbl[1][256]; #else static uint32_t enc_multbl[4][256]; static uint32_t dec_multbl[4][256]; #endif #if HAVE_BIGENDIAN # define ROT(x, s) (((x) >> (s)) | ((x) << (32-(s)))) #else # define ROT(x, s) (((x) << (s)) | ((x) >> (32-(s)))) #endif static inline void addkey(av_aes_block *dst, const av_aes_block *src, const av_aes_block *round_key) { dst->u64[0] = src->u64[0] ^ round_key->u64[0]; dst->u64[1] = src->u64[1] ^ round_key->u64[1]; } static inline void addkey_s(av_aes_block *dst, const uint8_t *src, const av_aes_block *round_key) { dst->u64[0] = AV_RN64(src) ^ round_key->u64[0]; dst->u64[1] = AV_RN64(src + 8) ^ round_key->u64[1]; } static inline void addkey_d(uint8_t *dst, const av_aes_block *src, const av_aes_block *round_key) { AV_WN64(dst, src->u64[0] ^ round_key->u64[0]); AV_WN64(dst + 8, src->u64[1] ^ round_key->u64[1]); } static void subshift(av_aes_block s0[2], int s, const uint8_t *box) { unsigned char *s1_dst = (unsigned char*)s0[0].u8 + 3 - s; const unsigned char *s1_src = s1_dst + sizeof(*s0); unsigned char *s3_dst = (unsigned char*)s0[0].u8 + s + 1; const unsigned char *s3_src = s3_dst + sizeof(*s0); s0[0].u8[ 0] = box[s0[1].u8[ 0]]; s0[0].u8[ 4] = box[s0[1].u8[ 4]]; s0[0].u8[ 8] = box[s0[1].u8[ 8]]; s0[0].u8[12] = box[s0[1].u8[12]]; s1_dst[ 0] = box[s1_src[ 4]]; s1_dst[ 4] = box[s1_src[ 8]]; s1_dst[ 8] = box[s1_src[12]]; s1_dst[12] = box[s1_src[ 0]]; s0[0].u8[ 2] = box[s0[1].u8[10]]; s0[0].u8[10] = box[s0[1].u8[ 2]]; s0[0].u8[ 6] = box[s0[1].u8[14]]; s0[0].u8[14] = box[s0[1].u8[ 6]]; s3_dst[ 0] = box[s3_src[12]]; s3_dst[12] = box[s3_src[ 8]]; s3_dst[ 8] = box[s3_src[ 4]]; s3_dst[ 4] = box[s3_src[ 0]]; } static inline int mix_core(uint32_t multbl[][256], int a, int b, int c, int d) { #if CONFIG_SMALL return multbl[0][a] ^ ROT(multbl[0][b], 8) ^ ROT(multbl[0][c], 16) ^ ROT(multbl[0][d], 24); #else return multbl[0][a] ^ multbl[1][b] ^ multbl[2][c] ^ multbl[3][d]; #endif } static inline void mix(av_aes_block state[2], uint32_t multbl[][256], int s1, int s3) { uint8_t (*src)[4] = state[1].u8x4; state[0].u32[0] = mix_core(multbl, src[0][0], src[s1 ][1], src[2][2], src[s3 ][3]); state[0].u32[1] = mix_core(multbl, src[1][0], src[s3 - 1][1], src[3][2], src[s1 - 1][3]); state[0].u32[2] = mix_core(multbl, src[2][0], src[s3 ][1], src[0][2], src[s1 ][3]); state[0].u32[3] = mix_core(multbl, src[3][0], src[s1 - 1][1], src[1][2], src[s3 - 1][3]); } static inline void aes_crypt(AVAES *a, int s, const uint8_t *sbox, uint32_t multbl[][256]) { int r; for (r = a->rounds - 1; r > 0; r--) { mix(a->state, multbl, 3 - s, 1 + s); addkey(&a->state[1], &a->state[0], &a->round_key[r]); } subshift(&a->state[0], s, sbox); } static void aes_encrypt(AVAES *a, uint8_t *dst, const uint8_t *src, int count, uint8_t *iv, int rounds) { while (count--) { addkey_s(&a->state[1], src, &a->round_key[rounds]); if (iv) addkey_s(&a->state[1], iv, &a->state[1]); aes_crypt(a, 2, sbox, enc_multbl); addkey_d(dst, &a->state[0], &a->round_key[0]); if (iv) memcpy(iv, dst, 16); src += 16; dst += 16; } } static void aes_decrypt(AVAES *a, uint8_t *dst, const uint8_t *src, int count, uint8_t *iv, int rounds) { while (count--) { addkey_s(&a->state[1], src, &a->round_key[rounds]); aes_crypt(a, 0, inv_sbox, dec_multbl); if (iv) { addkey_s(&a->state[0], iv, &a->state[0]); memcpy(iv, src, 16); } addkey_d(dst, &a->state[0], &a->round_key[0]); src += 16; dst += 16; } } void av_aes_crypt(AVAES *a, uint8_t *dst, const uint8_t *src, int count, uint8_t *iv, int decrypt) { a->crypt(a, dst, src, count, iv, a->rounds); } static void init_multbl2(uint32_t tbl[][256], const int c[4], const uint8_t *log8, const uint8_t *alog8, const uint8_t *sbox) { int i; for (i = 0; i < 256; i++) { int x = sbox[i]; if (x) { int k, l, m, n; x = log8[x]; k = alog8[x + log8[c[0]]]; l = alog8[x + log8[c[1]]]; m = alog8[x + log8[c[2]]]; n = alog8[x + log8[c[3]]]; tbl[0][i] = AV_NE(MKBETAG(k, l, m, n), MKTAG(k, l, m, n)); #if !CONFIG_SMALL tbl[1][i] = ROT(tbl[0][i], 8); tbl[2][i] = ROT(tbl[0][i], 16); tbl[3][i] = ROT(tbl[0][i], 24); #endif } } } // this is based on the reference AES code by Paulo Barreto and Vincent Rijmen int av_aes_init(AVAES *a, const uint8_t *key, int key_bits, int decrypt) { int i, j, t, rconpointer = 0; uint8_t tk[8][4]; int KC = key_bits >> 5; int rounds = KC + 6; uint8_t log8[256]; uint8_t alog8[512]; a->crypt = decrypt ? aes_decrypt : aes_encrypt; if (!enc_multbl[FF_ARRAY_ELEMS(enc_multbl) - 1][FF_ARRAY_ELEMS(enc_multbl[0]) - 1]) { j = 1; for (i = 0; i < 255; i++) { alog8[i] = alog8[i + 255] = j; log8[j] = i; j ^= j + j; if (j > 255) j ^= 0x11B; } for (i = 0; i < 256; i++) { j = i ? alog8[255 - log8[i]] : 0; j ^= (j << 1) ^ (j << 2) ^ (j << 3) ^ (j << 4); j = (j ^ (j >> 8) ^ 99) & 255; inv_sbox[j] = i; sbox[i] = j; } init_multbl2(dec_multbl, (const int[4]) { 0xe, 0x9, 0xd, 0xb }, log8, alog8, inv_sbox); init_multbl2(enc_multbl, (const int[4]) { 0x2, 0x1, 0x1, 0x3 }, log8, alog8, sbox); } if (key_bits != 128 && key_bits != 192 && key_bits != 256) return AVERROR(EINVAL); a->rounds = rounds; memcpy(tk, key, KC * 4); memcpy(a->round_key[0].u8, key, KC * 4); for (t = KC * 4; t < (rounds + 1) * 16; t += KC * 4) { for (i = 0; i < 4; i++) tk[0][i] ^= sbox[tk[KC - 1][(i + 1) & 3]]; tk[0][0] ^= rcon[rconpointer++]; for (j = 1; j < KC; j++) { if (KC != 8 || j != KC >> 1) for (i = 0; i < 4; i++) tk[j][i] ^= tk[j - 1][i]; else for (i = 0; i < 4; i++) tk[j][i] ^= sbox[tk[j - 1][i]]; } memcpy((unsigned char*)a->round_key + t, tk, KC * 4); } if (decrypt) { for (i = 1; i < rounds; i++) { av_aes_block tmp[3]; tmp[2] = a->round_key[i]; subshift(&tmp[1], 0, sbox); mix(tmp, dec_multbl, 1, 3); a->round_key[i] = tmp[0]; } } else { for (i = 0; i < (rounds + 1) >> 1; i++) FFSWAP(av_aes_block, a->round_key[i], a->round_key[rounds - i]); } return 0; }