aes.c 7.89 KB
Newer Older
michael's avatar
michael committed
1
/*
2
 * copyright (c) 2007 Michael Niedermayer <michaelni@gmx.at>
michael's avatar
michael committed
3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18
 *
 * 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
19 20
 *
 * some optimization ideas from aes128.c by Reimar Doeffinger
michael's avatar
michael committed
21 22 23 24 25 26
 */

#include "common.h"
#include "aes.h"

typedef struct AVAES{
michael's avatar
michael committed
27
    uint8_t round_key[15][4][4];
28
    uint8_t state[2][4][4];
michael's avatar
michael committed
29 30 31
    int rounds;
}AVAES;

michael's avatar
michael committed
32 33
const int av_aes_size= sizeof(AVAES);

michael's avatar
michael committed
34 35
static const uint8_t rcon[10] = {
  0x01, 0x02, 0x04, 0x08, 0x10, 0x20, 0x40, 0x80, 0x1b, 0x36
michael's avatar
michael committed
36 37 38 39
};

static uint8_t     sbox[256];
static uint8_t inv_sbox[256];
michael's avatar
michael committed
40 41 42 43 44 45 46
#ifdef 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
michael's avatar
michael committed
47

michael's avatar
michael committed
48 49 50
static inline void addkey(uint64_t dst[2], uint64_t src[2], uint64_t round_key[2]){
    dst[0] = src[0] ^ round_key[0];
    dst[1] = src[1] ^ round_key[1];
michael's avatar
michael committed
51 52
}

53 54 55
static void subshift(uint8_t s0[2][16], int s, uint8_t *box){
    uint8_t (*s1)[16]= s0[0] - s;
    uint8_t (*s3)[16]= s0[0] + s;
56
    s0[0][0]=box[s0[1][ 0]]; s0[0][ 4]=box[s0[1][ 4]]; s0[0][ 8]=box[s0[1][ 8]]; s0[0][12]=box[s0[1][12]];
57
    s1[0][3]=box[s1[1][ 7]]; s1[0][ 7]=box[s1[1][11]]; s1[0][11]=box[s1[1][15]]; s1[0][15]=box[s1[1][ 3]];
58
    s0[0][2]=box[s0[1][10]]; s0[0][10]=box[s0[1][ 2]]; s0[0][ 6]=box[s0[1][14]]; s0[0][14]=box[s0[1][ 6]];
59
    s3[0][1]=box[s3[1][13]]; s3[0][13]=box[s3[1][ 9]]; s3[0][ 9]=box[s3[1][ 5]]; s3[0][ 5]=box[s3[1][ 1]];
michael's avatar
michael committed
60
}
61

michael's avatar
michael committed
62
#define ROT(x,s) ((x<<s)|(x>>(32-s)))
michael's avatar
michael committed
63
#if 0
michael's avatar
michael committed
64 65 66 67 68 69 70 71 72 73
static inline void mix(uint8_t state[4][4], uint32_t multbl[4][256]){
    int i;
    for(i=0; i<4; i++)
#ifdef CONFIG_SMALL
        ((uint32_t *)(state))[i] =     multbl[0][state[i][0]]     ^ ROT(multbl[0][state[i][1]], 8)
                                  ^ROT(multbl[0][state[i][2]],16) ^ ROT(multbl[0][state[i][3]],24);
#else
        ((uint32_t *)(state))[i] = multbl[0][state[i][0]] ^ multbl[1][state[i][1]]
                                  ^multbl[2][state[i][2]] ^ multbl[3][state[i][3]];
#endif
michael's avatar
michael committed
74
}
michael's avatar
michael committed
75
#endif
76 77 78 79 80 81 82 83 84 85

static inline void mix(uint8_t state[2][4][4], uint32_t multbl[4][256], int s1, int s3){
    ((uint32_t *)(state))[0] = multbl[0][state[1][0][0]] ^ multbl[1][state[1][s1  ][1]]
                              ^multbl[2][state[1][2][2]] ^ multbl[3][state[1][s3  ][3]];
    ((uint32_t *)(state))[1] = multbl[0][state[1][1][0]] ^ multbl[1][state[1][s3-1][1]]
                              ^multbl[2][state[1][3][2]] ^ multbl[3][state[1][s1-1][3]];
    ((uint32_t *)(state))[2] = multbl[0][state[1][2][0]] ^ multbl[1][state[1][s3  ][1]]
                              ^multbl[2][state[1][0][2]] ^ multbl[3][state[1][s1  ][3]];
    ((uint32_t *)(state))[3] = multbl[0][state[1][3][0]] ^ multbl[1][state[1][s1-1][1]]
                              ^multbl[2][state[1][1][2]] ^ multbl[3][state[1][s3-1][3]];
michael's avatar
michael committed
86
}
michael's avatar
michael committed
87

michael's avatar
michael committed
88
static inline void crypt(AVAES *a, int s, uint8_t *sbox, uint32_t *multbl, uint8_t *dst, uint8_t *src){
michael's avatar
michael committed
89
    int r;
michael's avatar
michael committed
90

michael's avatar
michael committed
91 92
    addkey(a->state[1], src, a->round_key[a->rounds]);
    for(r=a->rounds-1; r>0; r--){
93
        mix(a->state, multbl, 3-s, 1+s);
michael's avatar
michael committed
94
        addkey(a->state[1], a->state[0], a->round_key[r]);
michael's avatar
michael committed
95
    }
96
    subshift(a->state[0][0], s, sbox);
michael's avatar
michael committed
97
    addkey(dst, a->state[0], a->round_key[0]);
michael's avatar
michael committed
98 99
}

michael's avatar
michael committed
100 101
static void aes_decrypt(AVAES *a, uint8_t *dst, uint8_t *src){
    crypt(a, 0, inv_sbox, dec_multbl, dst, src);
102
}
michael's avatar
michael committed
103

michael's avatar
michael committed
104 105
static void aes_encrypt(AVAES *a, uint8_t *dst, uint8_t *src){
    crypt(a, 2, sbox, enc_multbl, dst, src);
michael's avatar
michael committed
106 107
}

michael's avatar
michael committed
108
static void init_multbl2(uint8_t tbl[1024], int c[4], uint8_t *log8, uint8_t *alog8, uint8_t *sbox){
michael's avatar
michael committed
109
    int i, j;
110
    for(i=0; i<1024; i++){
111
        int x= sbox[i>>2];
112 113
        if(x) tbl[i]= alog8[ log8[x] + log8[c[i&3]] ];
    }
michael's avatar
michael committed
114
#ifndef CONFIG_SMALL
michael's avatar
michael committed
115 116 117
    for(j=256; j<1024; j++)
        for(i=0; i<4; i++)
            tbl[4*j+i]= tbl[4*j + ((i-1)&3) - 1024];
michael's avatar
michael committed
118
#endif
119 120
}

michael's avatar
michael committed
121
// this is based on the reference AES code by Paulo Barreto and Vincent Rijmen
michael's avatar
michael committed
122
int av_aes_init(AVAES *a, uint8_t *key, int key_bits, int decrypt) {
michael's avatar
michael committed
123 124
    int i, j, t, rconpointer = 0;
    uint8_t tk[8][4];
125
    int KC= key_bits>>5;
michael's avatar
michael committed
126
    int rounds= KC + 6;
michael's avatar
michael committed
127 128
    uint8_t  log8[256];
    uint8_t alog8[512];
michael's avatar
michael committed
129

130
    if(!enc_multbl[4][1023]){
michael's avatar
michael committed
131 132 133 134 135 136 137 138 139 140
        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;
michael's avatar
michael committed
141 142
            j ^= (j<<1) ^ (j<<2) ^ (j<<3) ^ (j<<4);
            j = (j ^ (j>>8) ^ 99) & 255;
michael's avatar
michael committed
143 144 145
            inv_sbox[j]= i;
            sbox    [i]= j;
        }
michael's avatar
michael committed
146
        init_multbl2(dec_multbl[0], (int[4]){0xe, 0x9, 0xd, 0xb}, log8, alog8, inv_sbox);
147
        init_multbl2(enc_multbl[0], (int[4]){0x2, 0x1, 0x1, 0x3}, log8, alog8, sbox);
michael's avatar
michael committed
148 149
    }

michael's avatar
michael committed
150
    if(key_bits!=128 && key_bits!=192 && key_bits!=256)
michael's avatar
michael committed
151
        return -1;
michael's avatar
michael committed
152

michael's avatar
michael committed
153
    a->rounds= rounds;
michael's avatar
michael committed
154

michael's avatar
michael committed
155 156
    memcpy(tk, key, KC*4);

157
    for(t= 0; t < (rounds+1)*4;) {
158
        memcpy(a->round_key[0][t], tk, KC*4);
159
        t+= KC;
michael's avatar
michael committed
160 161

        for(i = 0; i < 4; i++)
michael's avatar
michael committed
162
            tk[0][i] ^= sbox[tk[KC-1][(i+1)&3]];
michael's avatar
michael committed
163 164 165
        tk[0][0] ^= rcon[rconpointer++];

        for(j = 1; j < KC; j++){
166
            if(KC != 8 || j != KC>>1)
michael's avatar
michael committed
167
                for(i = 0; i < 4; i++) tk[j][i] ^=      tk[j-1][i];
michael's avatar
michael committed
168
            else
michael's avatar
michael committed
169
                for(i = 0; i < 4; i++) tk[j][i] ^= sbox[tk[j-1][i]];
michael's avatar
michael committed
170 171
        }
    }
michael's avatar
michael committed
172

michael's avatar
michael committed
173
    if(decrypt){
michael's avatar
michael committed
174
        for(i=1; i<rounds; i++){
175 176
            uint8_t tmp[2][16];
            memcpy(tmp[1], a->round_key[i][0], 16);
177
            subshift(tmp[0], 0, sbox);
178 179 180
            memcpy(tmp[1], tmp[0], 16);
            mix(tmp, dec_multbl, 1, 3);
            memcpy(a->round_key[i][0], tmp[0], 16);
michael's avatar
michael committed
181
        }
182
    }else{
183
        for(i=0; i<(rounds+1)>>1; i++){
184 185 186
            for(j=0; j<16; j++)
                FFSWAP(int, a->round_key[i][0][j], a->round_key[rounds-i][0][j]);
        }
187
    }
michael's avatar
michael committed
188

michael's avatar
michael committed
189
    return 0;
michael's avatar
michael committed
190 191 192
}

#ifdef TEST
193
#include "log.h"
michael's avatar
michael committed
194 195

int main(){
michael's avatar
michael committed
196
    int i,j;
michael's avatar
michael committed
197
    AVAES ae, ad, b;
michael's avatar
michael committed
198 199 200 201 202 203 204 205 206
    uint8_t rkey[2][16]= {
        {0},
        {0x10, 0xa5, 0x88, 0x69, 0xd7, 0x4b, 0xe5, 0xa3, 0x74, 0xcf, 0x86, 0x7c, 0xfb, 0x47, 0x38, 0x59}};
    uint8_t pt[16], rpt[2][16]= {
        {0x6a, 0x84, 0x86, 0x7c, 0xd7, 0x7e, 0x12, 0xad, 0x07, 0xea, 0x1b, 0xe8, 0x95, 0xc5, 0x3f, 0xa3},
        {0}};
    uint8_t rct[2][16]= {
        {0x73, 0x22, 0x81, 0xc0, 0xa0, 0xaa, 0xb8, 0xf7, 0xa5, 0x4a, 0x0c, 0x67, 0xa0, 0xc4, 0x5e, 0xcf},
        {0x6d, 0x25, 0x1e, 0x69, 0x44, 0xb0, 0x51, 0xe0, 0x4e, 0xaa, 0x6f, 0xb4, 0xdb, 0xf7, 0x84, 0x65}};
michael's avatar
michael committed
207
    uint8_t temp[16];
michael's avatar
michael committed
208

michael's avatar
michael committed
209 210
    av_aes_init(&ae, "PI=3.141592654..", 128, 0);
    av_aes_init(&ad, "PI=3.141592654..", 128, 1);
michael's avatar
michael committed
211 212
    av_log_level= AV_LOG_DEBUG;

michael's avatar
michael committed
213
    for(i=0; i<2; i++){
michael's avatar
michael committed
214
        av_aes_init(&b, rkey[i], 128, 1);
michael's avatar
michael committed
215
        aes_decrypt(&b, temp, rct[i]);
michael's avatar
michael committed
216
        for(j=0; j<16; j++)
michael's avatar
michael committed
217 218
            if(rpt[i][j] != temp[j])
                av_log(NULL, AV_LOG_ERROR, "%d %02X %02X\n", j, rpt[i][j], temp[j]);
michael's avatar
michael committed
219
    }
220

michael's avatar
michael committed
221
    for(i=0; i<10000; i++){
michael's avatar
michael committed
222 223 224
        for(j=0; j<16; j++){
            pt[j]= random();
        }
michael's avatar
michael committed
225
{START_TIMER
michael's avatar
michael committed
226
        aes_encrypt(&ae, temp, pt);
michael's avatar
michael committed
227
        if(!(i&(i-1)))
michael's avatar
michael committed
228 229
            av_log(NULL, AV_LOG_ERROR, "%02X %02X %02X %02X\n", temp[0], temp[5], temp[10], temp[15]);
        aes_decrypt(&ad, temp, temp);
michael's avatar
michael committed
230
STOP_TIMER("aes")}
michael's avatar
michael committed
231
        for(j=0; j<16; j++){
michael's avatar
michael committed
232 233
            if(pt[j] != temp[j]){
                av_log(NULL, AV_LOG_ERROR, "%d %d %02X %02X\n", i,j, pt[j], temp[j]);
michael's avatar
michael committed
234 235
            }
        }
michael's avatar
michael committed
236 237 238 239
    }
    return 0;
}
#endif