1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
|
/*
* copyright (c) 2007 Michael Niedermayer <michaelni@gmx.at>
*
* 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; r<a->rounds; 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 = (j ^ (j>>8) ^ 99) & 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
|
