OLD | NEW |
| (Empty) |
1 // Copyright 2007-2009 Google Inc. | |
2 // | |
3 // Licensed under the Apache License, Version 2.0 (the "License"); | |
4 // you may not use this file except in compliance with the License. | |
5 // You may obtain a copy of the License at | |
6 // | |
7 // http://www.apache.org/licenses/LICENSE-2.0 | |
8 // | |
9 // Unless required by applicable law or agreed to in writing, software | |
10 // distributed under the License is distributed on an "AS IS" BASIS, | |
11 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. | |
12 // See the License for the specific language governing permissions and | |
13 // limitations under the License. | |
14 // ======================================================================== | |
15 // | |
16 // Optimized for code size. Lacking decrypt functionality. | |
17 // Currently 1042 bytes of code. | |
18 | |
19 #include "aes.h" | |
20 | |
21 #include <stdio.h> | |
22 #include <stdlib.h> | |
23 #include <memory.h> | |
24 #include <inttypes.h> | |
25 | |
26 static const uint8_t sbox_e[256]= { | |
27 99 , 124 , 119 , 123 , 242 , 107 , 111 , 197 | |
28 , 48 , 1 , 103 , 43 , 254 , 215 , 171 , 118 | |
29 , 202 , 130 , 201 , 125 , 250 , 89 , 71 , 240 | |
30 , 173 , 212 , 162 , 175 , 156 , 164 , 114 , 192 | |
31 , 183 , 253 , 147 , 38 , 54 , 63 , 247 , 204 | |
32 , 52 , 165 , 229 , 241 , 113 , 216 , 49 , 21 | |
33 , 4 , 199 , 35 , 195 , 24 , 150 , 5 , 154 | |
34 , 7 , 18 , 128 , 226 , 235 , 39 , 178 , 117 | |
35 , 9 , 131 , 44 , 26 , 27 , 110 , 90 , 160 | |
36 , 82 , 59 , 214 , 179 , 41 , 227 , 47 , 132 | |
37 , 83 , 209 , 0 , 237 , 32 , 252 , 177 , 91 | |
38 , 106 , 203 , 190 , 57 , 74 , 76 , 88 , 207 | |
39 , 208 , 239 , 170 , 251 , 67 , 77 , 51 , 133 | |
40 , 69 , 249 , 2 , 127 , 80 , 60 , 159 , 168 | |
41 , 81 , 163 , 64 , 143 , 146 , 157 , 56 , 245 | |
42 , 188 , 182 , 218 , 33 , 16 , 255 , 243 , 210 | |
43 , 205 , 12 , 19 , 236 , 95 , 151 , 68 , 23 | |
44 , 196 , 167 , 126 , 61 , 100 , 93 , 25 , 115 | |
45 , 96 , 129 , 79 , 220 , 34 , 42 , 144 , 136 | |
46 , 70 , 238 , 184 , 20 , 222 , 94 , 11 , 219 | |
47 , 224 , 50 , 58 , 10 , 73 , 6 , 36 , 92 | |
48 , 194 , 211 , 172 , 98 , 145 , 149 , 228 , 121 | |
49 , 231 , 200 , 55 , 109 , 141 , 213 , 78 , 169 | |
50 , 108 , 86 , 244 , 234 , 101 , 122 , 174 , 8 | |
51 , 186 , 120 , 37 , 46 , 28 , 166 , 180 , 198 | |
52 , 232 , 221 , 116 , 31 , 75 , 189 , 139 , 138 | |
53 , 112 , 62 , 181 , 102 , 72 , 3 , 246 , 14 | |
54 , 97 , 53 , 87 , 185 , 134 , 193 , 29 , 158 | |
55 , 225 , 248 , 152 , 17 , 105 , 217 , 142 , 148 | |
56 , 155 , 30 , 135 , 233 , 206 , 85 , 40 , 223 | |
57 , 140 , 161 , 137 , 13 , 191 , 230 , 66 , 104 | |
58 , 65 , 153 , 45 , 15 , 176 , 84 , 187 , 22 | |
59 }; | |
60 | |
61 static uint8_t xtime(int in) { | |
62 in <<= 1; | |
63 if( in&0x100 ) in ^= 0x11b; | |
64 return (uint8_t)in; | |
65 } | |
66 | |
67 static void expand_key(const uint8_t* key, uint32_t* expanded_key) { | |
68 int nrounds; | |
69 union { | |
70 uint8_t b[16]; | |
71 uint32_t w[4]; | |
72 } W; | |
73 uint8_t xor = 1; | |
74 | |
75 memcpy( &W, key, 16 ); | |
76 memcpy( expanded_key, &W, 16 ); | |
77 | |
78 for( nrounds = 0; nrounds < 10; ++nrounds ) { | |
79 | |
80 // update key schedule | |
81 W.b[0] ^= sbox_e[W.b[12+1]] ^ xor; | |
82 W.b[1] ^= sbox_e[W.b[12+2]]; | |
83 W.b[2] ^= sbox_e[W.b[12+3]]; | |
84 W.b[3] ^= sbox_e[W.b[12+0]]; | |
85 W.w[1] ^= W.w[0]; | |
86 W.w[2] ^= W.w[1]; | |
87 W.w[3] ^= W.w[2]; | |
88 | |
89 xor = xtime( xor ); | |
90 | |
91 expanded_key += 4; | |
92 memcpy( expanded_key, &W, 16 ); | |
93 } | |
94 } | |
95 | |
96 void AES_encrypt_block(const uint8_t* key, const uint8_t* in, uint8_t* out) { | |
97 int j, nrounds; | |
98 union { | |
99 uint8_t b[16]; | |
100 uint32_t w[4]; | |
101 } rd_state; | |
102 uint32_t expanded_key[11 * 4]; | |
103 uint32_t* expkey = &expanded_key[0]; | |
104 | |
105 expand_key( key, expanded_key ); | |
106 | |
107 memcpy( &rd_state, in, 16 ); | |
108 | |
109 // xor with initial key | |
110 rd_state.w[0] ^= *expkey++; | |
111 rd_state.w[1] ^= *expkey++; | |
112 rd_state.w[2] ^= *expkey++; | |
113 rd_state.w[3] ^= *expkey++; | |
114 | |
115 nrounds = 10; | |
116 | |
117 do { | |
118 uint8_t tmp; | |
119 | |
120 // bytesub && shiftrow | |
121 | |
122 // 1st | |
123 rd_state.b[0] = sbox_e[rd_state.b[0]]; | |
124 rd_state.b[4] = sbox_e[rd_state.b[4]]; | |
125 rd_state.b[8] = sbox_e[rd_state.b[8]]; | |
126 rd_state.b[12] = sbox_e[rd_state.b[12]]; | |
127 | |
128 // 2nd | |
129 tmp = rd_state.b[1]; | |
130 rd_state.b[1] = sbox_e[rd_state.b[5]]; | |
131 rd_state.b[5] = sbox_e[rd_state.b[9]]; | |
132 rd_state.b[9] = sbox_e[rd_state.b[13]]; | |
133 rd_state.b[13] = sbox_e[tmp]; | |
134 | |
135 // 3th | |
136 tmp = rd_state.b[2]; | |
137 rd_state.b[2] = sbox_e[rd_state.b[10]]; | |
138 rd_state.b[10] = sbox_e[tmp]; | |
139 tmp = rd_state.b[6]; | |
140 rd_state.b[6] = sbox_e[rd_state.b[14]]; | |
141 rd_state.b[14] = sbox_e[tmp]; | |
142 | |
143 // 4th | |
144 tmp = rd_state.b[3]; | |
145 rd_state.b[3] = sbox_e[rd_state.b[15]]; | |
146 rd_state.b[15] = sbox_e[rd_state.b[11]]; | |
147 rd_state.b[11] = sbox_e[rd_state.b[7]]; | |
148 rd_state.b[7] = sbox_e[tmp]; | |
149 | |
150 // mixcolumn except for last round | |
151 if( --nrounds ) { | |
152 for( j = 0; j < 16; j += 4 ) { | |
153 uint8_t tmp = | |
154 rd_state.b[j+0] ^ | |
155 rd_state.b[j+1] ^ | |
156 rd_state.b[j+2] ^ | |
157 rd_state.b[j+3]; | |
158 | |
159 rd_state.b[j+0] ^= xtime( rd_state.b[j+0] ^ rd_state.b[j+1] ) ^ tmp; | |
160 rd_state.b[j+1] ^= xtime( rd_state.b[j+1] ^ rd_state.b[j+2] ) ^ tmp; | |
161 rd_state.b[j+2] ^= xtime( rd_state.b[j+2] ^ rd_state.b[j+3] ) ^ tmp; | |
162 rd_state.b[j+3] = | |
163 rd_state.b[j+0] ^ | |
164 rd_state.b[j+1] ^ | |
165 rd_state.b[j+2] ^ | |
166 tmp; | |
167 } | |
168 } | |
169 | |
170 rd_state.w[0] ^= *expkey++; | |
171 rd_state.w[1] ^= *expkey++; | |
172 rd_state.w[2] ^= *expkey++; | |
173 rd_state.w[3] ^= *expkey++; | |
174 } while( nrounds ); | |
175 | |
176 memcpy( out, &rd_state, 16 ); | |
177 } | |
OLD | NEW |