From 3306dfd5442db03f058485a22a4b4c7146942f11 Mon Sep 17 00:00:00 2001 From: Michael Niedermayer Date: Sun, 14 Jan 2007 09:06:13 +0000 Subject: [PATCH] aes support (unfinished) Originally committed as revision 7460 to svn://svn.ffmpeg.org/ffmpeg/trunk --- libavutil/aes.c | 172 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 172 insertions(+) create mode 100644 libavutil/aes.c diff --git a/libavutil/aes.c b/libavutil/aes.c new file mode 100644 index 0000000..05f3581 --- /dev/null +++ b/libavutil/aes.c @@ -0,0 +1,172 @@ +/* + * copyright (c) 2007 Michael Niedermayer + * + * 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 "common.h" +#include "log.h" +#include "aes.h" + +typedef struct AVAES{ + uint8_t state[4][4]; + uint8_t round_key[15][4][4]; + int rounds; +}AVAES; + +static const uint8_t rcon[30] = { + 0x01, 0x02, 0x04, 0x08, 0x10, 0x20, 0x40, 0x80, + 0x1b, 0x36, 0x6c, 0xd8, 0xab, 0x4d, 0x9a, 0x2f, + 0x5e, 0xbc, 0x63, 0xc6, 0x97, 0x35, 0x6a, 0xd4, + 0xb3, 0x7d, 0xfa, 0xef, 0xc5, 0x91 +}; + +static uint8_t log8[256]; +static uint8_t alog8[512]; +static uint8_t sbox[256]; +static uint8_t inv_sbox[256]; + +static inline void addkey(uint32_t state[4], uint32_t round_key[4]){ + int i; + for(i=0; i<4; i++) + state[i] ^= round_key[i]; //partial memory stall? FIXME benchmark +} + +#define SUBSHIFT0(s, box) s[0]=box[s[ 0]]; s[ 4]=box[s[ 4]]; s[ 8]=box[s[ 8]]; s[12]=box[s[12]]; +#define SUBSHIFT1(s, box) t=s[0]; s[0]=box[s[ 4]]; s[ 4]=box[s[ 8]]; s[ 8]=box[s[12]]; s[12]=box[t]; +#define SUBSHIFT2(s, box) t=s[0]; s[0]=box[s[ 8]]; s[ 8]=box[ t]; t=s[ 4]; s[ 4]=box[s[12]]; s[12]=box[t]; +#define SUBSHIFT3(s, box) t=s[0]; s[0]=box[s[12]]; s[12]=box[s[ 8]]; s[ 8]=box[s[ 4]]; s[ 4]=box[t]; + +static inline int mul(int a, int b){ + if(a==255) return 0; + else return alog8[a+b]; +} + +static inline void mix(uint8_t state[4][4], int c0, int c1, int c2, int c3){ + uint8_t tmp[4][4]; + int i, j; + + for(i=0; i<16; i++) + tmp[0][i]= log8[ state[0][i] ]; + for(j=0; j<4; j++) + for(i=0; i<4; i++) + state[j][i]= mul( tmp[j][ i ], c0 ) + ^mul( tmp[j][(i+ 1)&3], c1 ) + ^mul( tmp[j][(i+ 2)&3], c2 ) + ^mul( tmp[j][(i+ 3)&3], c3 ); +} + + +void av_aes_decrypt(AVAES *a){ + int t, r; + + for(r=a->rounds-1; r>=0; r--){ + if(r==a->rounds-1) + addkey(a->state, a->round_key[r+1]); + else + mix(a->state, log8[0xe], log8[0xb], log8[0xd], log8[9]); //FIXME replace log8 by const + SUBSHIFT0((a->state[0]+0), inv_sbox) + SUBSHIFT3((a->state[0]+1), inv_sbox) + SUBSHIFT2((a->state[0]+2), inv_sbox) + SUBSHIFT1((a->state[0]+3), inv_sbox) + addkey(a->state, a->round_key[r]); + } +} + +void av_aes_encrypt(AVAES *a){ + int r, t; + + for(r=0; rrounds; r++){ + addkey(a->state, a->round_key[r]); + SUBSHIFT0((a->state[0]+0), sbox) + SUBSHIFT1((a->state[0]+1), sbox) + SUBSHIFT2((a->state[0]+2), sbox) + SUBSHIFT3((a->state[0]+3), sbox) + if(r==a->rounds-1) + addkey(a->state, a->round_key[r+1]); + else + mix(a->state, log8[2], log8[3], 0, 0); //FIXME replace log8 by const / optimze mix as this can be simplified alot + } +} + +// this is based on the reference AES code by Paulo Barreto and Vincent Rijmen +AVAES *av_aes_init(uint8_t *key, int keyBits) { + AVAES *a= av_malloc(sizeof(AVAES)); + int i, j, t, rconpointer = 0; + uint8_t tk[8][4]; + int KC= keyBits/32; + int ROUNDS= KC + 6; + + if(!sbox[255]){ + 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; + } + log8[0]= 255; + for(i=0; i<256; i++){ + j= i ? alog8[255-log8[i]] : 0; + j ^= (j<<1) ^ (j<<2) ^ (j<<3) ^ (j<<4) + ^(j>>7) ^ (j>>6) ^ (j>>5) ^ (j>>4) ^ 99; + j&=255; + inv_sbox[j]= i; + sbox [i]= j; +// av_log(NULL, AV_LOG_ERROR, "%d, ", log8[i]); + } + } + + a->rounds= ROUNDS; + + if(keyBits!=128 && keyBits!=192 && keyBits!=256) + return NULL; + + memcpy(tk, key, KC*4); + + for(t= 0; t < (ROUNDS+1)*4; ) { + for(j = 0; (j < KC) && (t < (ROUNDS+1)*4); j++, t++) + for(i = 0; i < 4; i++) + a->round_key[0][t][i] = tk[j][i]; + + 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/2) + for(i = 0; i < 4; i++) tk[j][i] ^= tk[j-1][i]; + else + for(i = 0; i < 4; i++) + tk[KC/2][i] ^= sbox[tk[KC/2 - 1][i]]; + } + } + return a; +} + +#ifdef TEST + +int main(){ + int i,j,k; + AVAES *a= av_aes_init("PI=3.141592654..", 128); + + for(i=0; i<10000; i++){ + } + return 0; +} +#endif -- 2.7.4