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ffmpeg / libavutil / aes.c @ 597e3232

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/*
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 * copyright (c) 2007 Michael Niedermayer <michaelni@gmx.at>
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 *
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 * This file is part of FFmpeg.
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 *
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 * FFmpeg is free software; you can redistribute it and/or
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 * modify it under the terms of the GNU Lesser General Public
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 * License as published by the Free Software Foundation; either
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 * version 2.1 of the License, or (at your option) any later version.
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 *
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 * FFmpeg is distributed in the hope that it will be useful,
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 * but WITHOUT ANY WARRANTY; without even the implied warranty of
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 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
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 * Lesser General Public License for more details.
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 *
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 * You should have received a copy of the GNU Lesser General Public
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 * License along with FFmpeg; if not, write to the Free Software
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 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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 *
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 * some optimization ideas from aes128.c by Reimar Doeffinger
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 */
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#include "common.h"
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#include "log.h"
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#include "aes.h"
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typedef struct AVAES{
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    uint8_t round_key[15][4][4];
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    uint8_t state[4][4];
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    int rounds;
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}AVAES;
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static const uint8_t rcon[10] = {
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  0x01, 0x02, 0x04, 0x08, 0x10, 0x20, 0x40, 0x80, 0x1b, 0x36
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};
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static uint8_t     sbox[256];
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static uint8_t inv_sbox[256];
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#ifdef CONFIG_SMALL
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static uint32_t enc_multbl[1][256];
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static uint32_t dec_multbl[1][256];
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#else
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static uint32_t enc_multbl[4][256];
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static uint32_t dec_multbl[4][256];
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#endif
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static inline void addkey(uint64_t state[2], uint64_t round_key[2]){
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    state[0] ^= round_key[0];
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    state[1] ^= round_key[1];
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}
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#define SUBSHIFT0(s, box)         s[0]=box[s[ 0]]; s[ 4]=box[s[ 4]];          s[ 8]=box[s[ 8]]; s[12]=box[s[12]];
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#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];
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#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];
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#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];
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#define SUBSHIFT1x(s) t=s[0]; s[0]=s[ 4]; s[ 4]=s[ 8];          s[ 8]=s[12]; s[12]=t;
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#define SUBSHIFT2x(s) t=s[0]; s[0]=s[ 8]; s[ 8]=    t; t=s[ 4]; s[ 4]=s[12]; s[12]=t;
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#define SUBSHIFT3x(s) t=s[0]; s[0]=s[12]; s[12]=s[ 8];          s[ 8]=s[ 4]; s[ 4]=t;
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#define ROT(x,s) ((x<<s)|(x>>(32-s)))
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static inline void mix(uint8_t state[4][4], uint32_t multbl[4][256]){
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    int i;
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    for(i=0; i<4; i++)
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#ifdef CONFIG_SMALL
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        ((uint32_t *)(state))[i] =     multbl[0][state[i][0]]     ^ ROT(multbl[0][state[i][1]], 8)
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                                  ^ROT(multbl[0][state[i][2]],16) ^ ROT(multbl[0][state[i][3]],24);
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#else
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        ((uint32_t *)(state))[i] = multbl[0][state[i][0]] ^ multbl[1][state[i][1]]
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                                  ^multbl[2][state[i][2]] ^ multbl[3][state[i][3]];
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#endif
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}
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static inline void crypt(AVAES *a, int s, uint8_t *sbox, uint32_t *multbl){
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    int t, r;
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    for(r=a->rounds; r>1; r--){
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        addkey(a->state, a->round_key[r]);
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        SUBSHIFT3x((a->state[0]+1+s))
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        SUBSHIFT2x((a->state[0]+2))
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        SUBSHIFT1x((a->state[0]+3-s))
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        mix(a->state, multbl);
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    }
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    addkey(a->state, a->round_key[1]);
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    SUBSHIFT0((a->state[0]+0  ), sbox)
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    SUBSHIFT3((a->state[0]+1+s), sbox)
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    SUBSHIFT2((a->state[0]+2  ), sbox)
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    SUBSHIFT1((a->state[0]+3-s), sbox)
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    addkey(a->state, a->round_key[0]);
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}
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void av_aes_decrypt(AVAES *a){
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    crypt(a, 0, inv_sbox, dec_multbl);
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}
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void av_aes_encrypt(AVAES *a){
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    crypt(a, 2, sbox, enc_multbl);
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}
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static void init_multbl2(uint8_t tbl[1024], int c[4], uint8_t *log8, uint8_t *alog8, uint8_t *sbox){
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    int i, j;
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    for(i=0; i<1024; i++){
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        int x= sbox[i/4];
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        if(x) tbl[i]= alog8[ log8[x] + log8[c[i&3]] ];
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    }
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#ifndef CONFIG_SMALL
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    for(j=256; j<1024; j++)
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        for(i=0; i<4; i++)
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            tbl[4*j+i]= tbl[4*j + ((i-1)&3) - 1024];
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#endif
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}
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// this is based on the reference AES code by Paulo Barreto and Vincent Rijmen
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AVAES *av_aes_init(uint8_t *key, int key_bits, int decrypt) {
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    AVAES *a;
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    int i, j, t, rconpointer = 0;
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    uint8_t tk[8][4];
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    int KC= key_bits/32;
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    int rounds= KC + 6;
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    uint8_t  log8[256];
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    uint8_t alog8[512];
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    if(!sbox[255]){
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        j=1;
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        for(i=0; i<255; i++){
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            alog8[i]=
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            alog8[i+255]= j;
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            log8[j]= i;
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            j^= j+j;
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            if(j>255) j^= 0x11B;
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        }
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        for(i=0; i<256; i++){
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            j= i ? alog8[255-log8[i]] : 0;
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            j ^= (j<<1) ^ (j<<2) ^ (j<<3) ^ (j<<4);
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            j = (j ^ (j>>8) ^ 99) & 255;
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            inv_sbox[j]= i;
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            sbox    [i]= j;
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//            av_log(NULL, AV_LOG_ERROR, "%d, ", log8[i]);
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        }
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        init_multbl2(dec_multbl[0], (int[4]){0xe, 0x9, 0xd, 0xb}, log8, alog8, inv_sbox);
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        init_multbl2(enc_multbl[0], (int[4]){0x2, 0x1, 0x1, 0x3}, log8, alog8, sbox);
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    }
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    if(key_bits!=128 && key_bits!=192 && key_bits!=256)
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        return NULL;
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    a= av_malloc(sizeof(AVAES));
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    a->rounds= rounds;
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    memcpy(tk, key, KC*4);
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    for(t= 0; t < (rounds+1)*4;) {
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        memcpy(a->round_key[0][t], tk, KC*4);
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        t+= KC;
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        for(i = 0; i < 4; i++)
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            tk[0][i] ^= sbox[tk[KC-1][(i+1)&3]];
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        tk[0][0] ^= rcon[rconpointer++];
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        for(j = 1; j < KC; j++){
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            if(KC != 8 || j != KC/2)
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                for(i = 0; i < 4; i++) tk[j][i] ^=      tk[j-1][i];
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            else
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                for(i = 0; i < 4; i++) tk[j][i] ^= sbox[tk[j-1][i]];
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        }
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    }
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    if(decrypt){
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        for(i=1; i<rounds; i++){
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            for(j=0; j<16; j++)
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                a->round_key[i][0][j]= sbox[a->round_key[i][0][j]];
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            mix(a->round_key[i], dec_multbl);
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        }
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    }else{
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        for(i=0; i<(rounds+1)/2; i++){
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            for(j=0; j<16; j++)
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                FFSWAP(int, a->round_key[i][0][j], a->round_key[rounds-i][0][j]);
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        }
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    }
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    return a;
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}
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#ifdef TEST
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int main(){
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    int i,j;
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    AVAES *ae= av_aes_init("PI=3.141592654..", 128, 0);
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    AVAES *ad= av_aes_init("PI=3.141592654..", 128, 1);
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    uint8_t rkey[2][16]= {
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        {0},
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        {0x10, 0xa5, 0x88, 0x69, 0xd7, 0x4b, 0xe5, 0xa3, 0x74, 0xcf, 0x86, 0x7c, 0xfb, 0x47, 0x38, 0x59}};
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    uint8_t pt[16], rpt[2][16]= {
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        {0x6a, 0x84, 0x86, 0x7c, 0xd7, 0x7e, 0x12, 0xad, 0x07, 0xea, 0x1b, 0xe8, 0x95, 0xc5, 0x3f, 0xa3},
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        {0}};
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    uint8_t rct[2][16]= {
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        {0x73, 0x22, 0x81, 0xc0, 0xa0, 0xaa, 0xb8, 0xf7, 0xa5, 0x4a, 0x0c, 0x67, 0xa0, 0xc4, 0x5e, 0xcf},
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        {0x6d, 0x25, 0x1e, 0x69, 0x44, 0xb0, 0x51, 0xe0, 0x4e, 0xaa, 0x6f, 0xb4, 0xdb, 0xf7, 0x84, 0x65}};
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    av_log_level= AV_LOG_DEBUG;
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    for(i=0; i<2; i++){
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        AVAES *b= av_aes_init(rkey[i], 128, 1);
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        memcpy(b->state, rct[i], 16);
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        av_aes_decrypt(b);
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        for(j=0; j<16; j++)
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            if(rpt[i][j] != b->state[0][j])
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                av_log(NULL, AV_LOG_ERROR, "%d %02X %02X\n", j, rpt[i][j], b->state[0][j]);
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    }
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    for(i=0; i<10000; i++){
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        for(j=0; j<16; j++){
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            pt[j]= random();
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        }
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        memcpy(ae->state, pt, 16);
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{START_TIMER
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        av_aes_encrypt(ae);
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        if(!(i&(i-1)))
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            av_log(NULL, AV_LOG_ERROR, "%02X %02X %02X %02X\n", ae->state[0][0], ae->state[1][1], ae->state[2][2], ae->state[3][3]);
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        memcpy(ad->state, ae->state, 16);
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        av_aes_decrypt(ad);
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STOP_TIMER("aes")}
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        for(j=0; j<16; j++){
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            if(pt[j] != ad->state[0][j]){
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                av_log(NULL, AV_LOG_ERROR, "%d %d %02X %02X\n", i,j, pt[j], ad->state[0][j]);
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            }
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        }
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    }
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    return 0;
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}
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#endif