-
Notifications
You must be signed in to change notification settings - Fork 0
/
AES.cpp
450 lines (391 loc) · 16.1 KB
/
AES.cpp
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
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
#include "AES.h"
/*
---------------------------------------------------------------------------
Copyright (c) 1998-2008, Brian Gladman, Worcester, UK. All rights reserved.
LICENSE TERMS
The redistribution and use of this software (with or without changes)
is allowed without the payment of fees or royalties provided that:
1. source code distributions include the above copyright notice, this
list of conditions and the following disclaimer;
2. binary distributions include the above copyright notice, this list
of conditions and the following disclaimer in their documentation;
3. the name of the copyright holder is not used to endorse products
built using this software without specific written permission.
DISCLAIMER
This software is provided 'as is' with no explicit or implied warranties
in respect of its properties, including, but not limited to, correctness
and/or fitness for purpose.
---------------------------------------------------------------------------
Issue 09/09/2006
This is an AES implementation that uses only 8-bit byte operations on the
cipher state (there are options to use 32-bit types if available).
The combination of mix columns and byte substitution used here is based on
that developed by Karl Malbrain. His contribution is acknowledged.
*/
/* This version derived by Mark Tillotson 2012-01-23, tidied up, slimmed down
and tailored to 8-bit microcontroller abilities and Arduino datatypes.
The s-box and inverse s-box were retained as tables (0.5kB PROGMEM) but all
the other transformations are coded to save table space. Many efficiency
improvments to the routines mix_sub_columns() and inv_mix_sub_columns()
(mainly common sub-expression elimination).
Only the routines with precalculated subkey schedule are retained (together
with set_key() - this does however mean each AES object takes 240 bytes of
RAM, alas)
The CBC routines side-effect the iv argument (so that successive calls work
together correctly).
All the encryption and decryption routines work with plain == cipher for
in-place encryption, note.
*/
/* functions for finite field multiplication in the AES Galois field */
// GF(2^8) stuff
#define WPOLY 0x011B
#define DPOLY 0x008D
#if defined(ARDUINO) && ARDUINO >= 100
static byte s_fwd [0x100] PROGMEM ={
0x63, 0x7c, 0x77, 0x7b, 0xf2, 0x6b, 0x6f, 0xc5, 0x30, 0x01, 0x67, 0x2b, 0xfe, 0xd7, 0xab, 0x76,
0xca, 0x82, 0xc9, 0x7d, 0xfa, 0x59, 0x47, 0xf0, 0xad, 0xd4, 0xa2, 0xaf, 0x9c, 0xa4, 0x72, 0xc0,
0xb7, 0xfd, 0x93, 0x26, 0x36, 0x3f, 0xf7, 0xcc, 0x34, 0xa5, 0xe5, 0xf1, 0x71, 0xd8, 0x31, 0x15,
0x04, 0xc7, 0x23, 0xc3, 0x18, 0x96, 0x05, 0x9a, 0x07, 0x12, 0x80, 0xe2, 0xeb, 0x27, 0xb2, 0x75,
0x09, 0x83, 0x2c, 0x1a, 0x1b, 0x6e, 0x5a, 0xa0, 0x52, 0x3b, 0xd6, 0xb3, 0x29, 0xe3, 0x2f, 0x84,
0x53, 0xd1, 0x00, 0xed, 0x20, 0xfc, 0xb1, 0x5b, 0x6a, 0xcb, 0xbe, 0x39, 0x4a, 0x4c, 0x58, 0xcf,
0xd0, 0xef, 0xaa, 0xfb, 0x43, 0x4d, 0x33, 0x85, 0x45, 0xf9, 0x02, 0x7f, 0x50, 0x3c, 0x9f, 0xa8,
0x51, 0xa3, 0x40, 0x8f, 0x92, 0x9d, 0x38, 0xf5, 0xbc, 0xb6, 0xda, 0x21, 0x10, 0xff, 0xf3, 0xd2,
0xcd, 0x0c, 0x13, 0xec, 0x5f, 0x97, 0x44, 0x17, 0xc4, 0xa7, 0x7e, 0x3d, 0x64, 0x5d, 0x19, 0x73,
0x60, 0x81, 0x4f, 0xdc, 0x22, 0x2a, 0x90, 0x88, 0x46, 0xee, 0xb8, 0x14, 0xde, 0x5e, 0x0b, 0xdb,
0xe0, 0x32, 0x3a, 0x0a, 0x49, 0x06, 0x24, 0x5c, 0xc2, 0xd3, 0xac, 0x62, 0x91, 0x95, 0xe4, 0x79,
0xe7, 0xc8, 0x37, 0x6d, 0x8d, 0xd5, 0x4e, 0xa9, 0x6c, 0x56, 0xf4, 0xea, 0x65, 0x7a, 0xae, 0x08,
0xba, 0x78, 0x25, 0x2e, 0x1c, 0xa6, 0xb4, 0xc6, 0xe8, 0xdd, 0x74, 0x1f, 0x4b, 0xbd, 0x8b, 0x8a,
0x70, 0x3e, 0xb5, 0x66, 0x48, 0x03, 0xf6, 0x0e, 0x61, 0x35, 0x57, 0xb9, 0x86, 0xc1, 0x1d, 0x9e,
0xe1, 0xf8, 0x98, 0x11, 0x69, 0xd9, 0x8e, 0x94, 0x9b, 0x1e, 0x87, 0xe9, 0xce, 0x55, 0x28, 0xdf,
0x8c, 0xa1, 0x89, 0x0d, 0xbf, 0xe6, 0x42, 0x68, 0x41, 0x99, 0x2d, 0x0f, 0xb0, 0x54, 0xbb, 0x16,
};
static byte s_inv [0x100] PROGMEM ={
0x52, 0x09, 0x6a, 0xd5, 0x30, 0x36, 0xa5, 0x38, 0xbf, 0x40, 0xa3, 0x9e, 0x81, 0xf3, 0xd7, 0xfb,
0x7c, 0xe3, 0x39, 0x82, 0x9b, 0x2f, 0xff, 0x87, 0x34, 0x8e, 0x43, 0x44, 0xc4, 0xde, 0xe9, 0xcb,
0x54, 0x7b, 0x94, 0x32, 0xa6, 0xc2, 0x23, 0x3d, 0xee, 0x4c, 0x95, 0x0b, 0x42, 0xfa, 0xc3, 0x4e,
0x08, 0x2e, 0xa1, 0x66, 0x28, 0xd9, 0x24, 0xb2, 0x76, 0x5b, 0xa2, 0x49, 0x6d, 0x8b, 0xd1, 0x25,
0x72, 0xf8, 0xf6, 0x64, 0x86, 0x68, 0x98, 0x16, 0xd4, 0xa4, 0x5c, 0xcc, 0x5d, 0x65, 0xb6, 0x92,
0x6c, 0x70, 0x48, 0x50, 0xfd, 0xed, 0xb9, 0xda, 0x5e, 0x15, 0x46, 0x57, 0xa7, 0x8d, 0x9d, 0x84,
0x90, 0xd8, 0xab, 0x00, 0x8c, 0xbc, 0xd3, 0x0a, 0xf7, 0xe4, 0x58, 0x05, 0xb8, 0xb3, 0x45, 0x06,
0xd0, 0x2c, 0x1e, 0x8f, 0xca, 0x3f, 0x0f, 0x02, 0xc1, 0xaf, 0xbd, 0x03, 0x01, 0x13, 0x8a, 0x6b,
0x3a, 0x91, 0x11, 0x41, 0x4f, 0x67, 0xdc, 0xea, 0x97, 0xf2, 0xcf, 0xce, 0xf0, 0xb4, 0xe6, 0x73,
0x96, 0xac, 0x74, 0x22, 0xe7, 0xad, 0x35, 0x85, 0xe2, 0xf9, 0x37, 0xe8, 0x1c, 0x75, 0xdf, 0x6e,
0x47, 0xf1, 0x1a, 0x71, 0x1d, 0x29, 0xc5, 0x89, 0x6f, 0xb7, 0x62, 0x0e, 0xaa, 0x18, 0xbe, 0x1b,
0xfc, 0x56, 0x3e, 0x4b, 0xc6, 0xd2, 0x79, 0x20, 0x9a, 0xdb, 0xc0, 0xfe, 0x78, 0xcd, 0x5a, 0xf4,
0x1f, 0xdd, 0xa8, 0x33, 0x88, 0x07, 0xc7, 0x31, 0xb1, 0x12, 0x10, 0x59, 0x27, 0x80, 0xec, 0x5f,
0x60, 0x51, 0x7f, 0xa9, 0x19, 0xb5, 0x4a, 0x0d, 0x2d, 0xe5, 0x7a, 0x9f, 0x93, 0xc9, 0x9c, 0xef,
0xa0, 0xe0, 0x3b, 0x4d, 0xae, 0x2a, 0xf5, 0xb0, 0xc8, 0xeb, 0xbb, 0x3c, 0x83, 0x53, 0x99, 0x61,
0x17, 0x2b, 0x04, 0x7e, 0xba, 0x77, 0xd6, 0x26, 0xe1, 0x69, 0x14, 0x63, 0x55, 0x21, 0x0c, 0x7d,
};
#else
static byte s_fwd [0x100] ={
0x63, 0x7c, 0x77, 0x7b, 0xf2, 0x6b, 0x6f, 0xc5, 0x30, 0x01, 0x67, 0x2b, 0xfe, 0xd7, 0xab, 0x76,
0xca, 0x82, 0xc9, 0x7d, 0xfa, 0x59, 0x47, 0xf0, 0xad, 0xd4, 0xa2, 0xaf, 0x9c, 0xa4, 0x72, 0xc0,
0xb7, 0xfd, 0x93, 0x26, 0x36, 0x3f, 0xf7, 0xcc, 0x34, 0xa5, 0xe5, 0xf1, 0x71, 0xd8, 0x31, 0x15,
0x04, 0xc7, 0x23, 0xc3, 0x18, 0x96, 0x05, 0x9a, 0x07, 0x12, 0x80, 0xe2, 0xeb, 0x27, 0xb2, 0x75,
0x09, 0x83, 0x2c, 0x1a, 0x1b, 0x6e, 0x5a, 0xa0, 0x52, 0x3b, 0xd6, 0xb3, 0x29, 0xe3, 0x2f, 0x84,
0x53, 0xd1, 0x00, 0xed, 0x20, 0xfc, 0xb1, 0x5b, 0x6a, 0xcb, 0xbe, 0x39, 0x4a, 0x4c, 0x58, 0xcf,
0xd0, 0xef, 0xaa, 0xfb, 0x43, 0x4d, 0x33, 0x85, 0x45, 0xf9, 0x02, 0x7f, 0x50, 0x3c, 0x9f, 0xa8,
0x51, 0xa3, 0x40, 0x8f, 0x92, 0x9d, 0x38, 0xf5, 0xbc, 0xb6, 0xda, 0x21, 0x10, 0xff, 0xf3, 0xd2,
0xcd, 0x0c, 0x13, 0xec, 0x5f, 0x97, 0x44, 0x17, 0xc4, 0xa7, 0x7e, 0x3d, 0x64, 0x5d, 0x19, 0x73,
0x60, 0x81, 0x4f, 0xdc, 0x22, 0x2a, 0x90, 0x88, 0x46, 0xee, 0xb8, 0x14, 0xde, 0x5e, 0x0b, 0xdb,
0xe0, 0x32, 0x3a, 0x0a, 0x49, 0x06, 0x24, 0x5c, 0xc2, 0xd3, 0xac, 0x62, 0x91, 0x95, 0xe4, 0x79,
0xe7, 0xc8, 0x37, 0x6d, 0x8d, 0xd5, 0x4e, 0xa9, 0x6c, 0x56, 0xf4, 0xea, 0x65, 0x7a, 0xae, 0x08,
0xba, 0x78, 0x25, 0x2e, 0x1c, 0xa6, 0xb4, 0xc6, 0xe8, 0xdd, 0x74, 0x1f, 0x4b, 0xbd, 0x8b, 0x8a,
0x70, 0x3e, 0xb5, 0x66, 0x48, 0x03, 0xf6, 0x0e, 0x61, 0x35, 0x57, 0xb9, 0x86, 0xc1, 0x1d, 0x9e,
0xe1, 0xf8, 0x98, 0x11, 0x69, 0xd9, 0x8e, 0x94, 0x9b, 0x1e, 0x87, 0xe9, 0xce, 0x55, 0x28, 0xdf,
0x8c, 0xa1, 0x89, 0x0d, 0xbf, 0xe6, 0x42, 0x68, 0x41, 0x99, 0x2d, 0x0f, 0xb0, 0x54, 0xbb, 0x16,
};
static byte s_inv [0x100] ={
0x52, 0x09, 0x6a, 0xd5, 0x30, 0x36, 0xa5, 0x38, 0xbf, 0x40, 0xa3, 0x9e, 0x81, 0xf3, 0xd7, 0xfb,
0x7c, 0xe3, 0x39, 0x82, 0x9b, 0x2f, 0xff, 0x87, 0x34, 0x8e, 0x43, 0x44, 0xc4, 0xde, 0xe9, 0xcb,
0x54, 0x7b, 0x94, 0x32, 0xa6, 0xc2, 0x23, 0x3d, 0xee, 0x4c, 0x95, 0x0b, 0x42, 0xfa, 0xc3, 0x4e,
0x08, 0x2e, 0xa1, 0x66, 0x28, 0xd9, 0x24, 0xb2, 0x76, 0x5b, 0xa2, 0x49, 0x6d, 0x8b, 0xd1, 0x25,
0x72, 0xf8, 0xf6, 0x64, 0x86, 0x68, 0x98, 0x16, 0xd4, 0xa4, 0x5c, 0xcc, 0x5d, 0x65, 0xb6, 0x92,
0x6c, 0x70, 0x48, 0x50, 0xfd, 0xed, 0xb9, 0xda, 0x5e, 0x15, 0x46, 0x57, 0xa7, 0x8d, 0x9d, 0x84,
0x90, 0xd8, 0xab, 0x00, 0x8c, 0xbc, 0xd3, 0x0a, 0xf7, 0xe4, 0x58, 0x05, 0xb8, 0xb3, 0x45, 0x06,
0xd0, 0x2c, 0x1e, 0x8f, 0xca, 0x3f, 0x0f, 0x02, 0xc1, 0xaf, 0xbd, 0x03, 0x01, 0x13, 0x8a, 0x6b,
0x3a, 0x91, 0x11, 0x41, 0x4f, 0x67, 0xdc, 0xea, 0x97, 0xf2, 0xcf, 0xce, 0xf0, 0xb4, 0xe6, 0x73,
0x96, 0xac, 0x74, 0x22, 0xe7, 0xad, 0x35, 0x85, 0xe2, 0xf9, 0x37, 0xe8, 0x1c, 0x75, 0xdf, 0x6e,
0x47, 0xf1, 0x1a, 0x71, 0x1d, 0x29, 0xc5, 0x89, 0x6f, 0xb7, 0x62, 0x0e, 0xaa, 0x18, 0xbe, 0x1b,
0xfc, 0x56, 0x3e, 0x4b, 0xc6, 0xd2, 0x79, 0x20, 0x9a, 0xdb, 0xc0, 0xfe, 0x78, 0xcd, 0x5a, 0xf4,
0x1f, 0xdd, 0xa8, 0x33, 0x88, 0x07, 0xc7, 0x31, 0xb1, 0x12, 0x10, 0x59, 0x27, 0x80, 0xec, 0x5f,
0x60, 0x51, 0x7f, 0xa9, 0x19, 0xb5, 0x4a, 0x0d, 0x2d, 0xe5, 0x7a, 0x9f, 0x93, 0xc9, 0x9c, 0xef,
0xa0, 0xe0, 0x3b, 0x4d, 0xae, 0x2a, 0xf5, 0xb0, 0xc8, 0xeb, 0xbb, 0x3c, 0x83, 0x53, 0x99, 0x61,
0x17, 0x2b, 0x04, 0x7e, 0xba, 0x77, 0xd6, 0x26, 0xe1, 0x69, 0x14, 0x63, 0x55, 0x21, 0x0c, 0x7d,
};
#endif
// times 2 in the GF(2^8)
#define f2(x) ((x) & 0x80 ? (x << 1) ^ WPOLY : x << 1)
#define d2(x) (((x) >> 1) ^ ((x) & 1 ? DPOLY : 0))
static byte s_box(byte x)
{
#if defined(ARDUINO) && ARDUINO >= 100
// return fwd_affine (pgm_read_byte (&inv [x])) ;
return pgm_read_byte(& s_fwd [x]);
#else
return (s_fwd[x]);
#endif
}
// Inverse Sbox
static byte is_box(byte x)
{
#if defined(ARDUINO) && ARDUINO >= 100
// return pgm_read_byte (&inv [inv_affine (x)]) ;
return pgm_read_byte(& s_inv [x]);
#else
return (s_inv [x]);
#endif
}
/* copying and xoring utilities */
void AES::copy_n_bytes(byte * d, byte * s, byte nn)
{
while (nn >= 4)
{
*d++ = *s++; // some unrolling
*d++ = *s++;
*d++ = *s++;
*d++ = *s++;
nn -= 4;
}
while (nn--)
*d++ = *s++;
}
static void xor_block(byte * d, byte * s)
{
for (byte i = 0; i < N_BLOCK; i += 4)
{
*d++ ^= *s++; // some unrolling
*d++ ^= *s++;
*d++ ^= *s++;
*d++ ^= *s++;
}
}
static void copy_and_key(byte * d, byte * s, byte * k)
{
for (byte i = 0; i < N_BLOCK; i += 4)
{
*d++ = *s++ ^ *k++; // some unrolling
*d++ = *s++ ^ *k++;
*d++ = *s++ ^ *k++;
*d++ = *s++ ^ *k++;
}
}
// #define add_round_key(d, k) xor_block (d, k)
/* SUB ROW PHASE */
static void shift_sub_rows(byte st [N_BLOCK])
{
st [0] = s_box(st [0]);
st [4] = s_box(st [4]);
st [8] = s_box(st [8]);
st [12] = s_box(st [12]);
byte tt = st [1];
st [1] = s_box(st [5]);
st [5] = s_box(st [9]);
st [9] = s_box(st [13]);
st [13] = s_box(tt);
tt = st[2];
st [2] = s_box(st [10]);
st [10] = s_box(tt);
tt = st[6];
st [6] = s_box(st [14]);
st [14] = s_box(tt);
tt = st[15];
st [15] = s_box(st [11]);
st [11] = s_box(st [7]);
st [7] = s_box(st [3]);
st [3] = s_box(tt);
}
static void inv_shift_sub_rows(byte st[N_BLOCK])
{
st [0] = is_box(st[0]);
st [4] = is_box(st [4]);
st [8] = is_box(st[8]);
st [12] = is_box(st [12]);
byte tt = st[13];
st [13] = is_box(st [9]);
st [9] = is_box(st [5]);
st [5] = is_box(st [1]);
st [1] = is_box(tt);
tt = st [2];
st [2] = is_box(st [10]);
st [10] = is_box(tt);
tt = st [6];
st [6] = is_box(st [14]);
st [14] = is_box(tt);
tt = st [3];
st [3] = is_box(st [7]);
st [7] = is_box(st [11]);
st [11] = is_box(st [15]);
st [15] = is_box(tt);
}
/* SUB COLUMNS PHASE */
static void mix_sub_columns(byte dt[N_BLOCK], byte st[N_BLOCK])
{
byte j = 5;
byte k = 10;
byte l = 15;
for (byte i = 0; i < N_BLOCK; i += N_COL)
{
byte a = st [i];
byte b = st [j];
j = (j + N_COL) & 15;
byte c = st [k];
k = (k + N_COL) & 15;
byte d = st [l];
l = (l + N_COL) & 15;
byte a1 = s_box(a), b1 = s_box(b), c1 = s_box(c), d1 = s_box(d);
byte a2 = f2(a1), b2 = f2(b1), c2 = f2(c1), d2 = f2(d1);
dt[i] = a2 ^ b2^b1 ^ c1 ^ d1;
dt[i + 1] = a1 ^ b2 ^ c2^c1 ^ d1;
dt[i + 2] = a1 ^ b1 ^ c2 ^ d2^d1;
dt[i + 3] = a2^a1 ^ b1 ^ c1 ^ d2;
}
}
static void inv_mix_sub_columns(byte dt[N_BLOCK], byte st[N_BLOCK])
{
for (byte i = 0; i < N_BLOCK; i += N_COL)
{
byte a1 = st [i];
byte b1 = st [i + 1];
byte c1 = st [i + 2];
byte d1 = st [i + 3];
byte a2 = f2(a1), b2 = f2(b1), c2 = f2(c1), d2 = f2(d1);
byte a4 = f2(a2), b4 = f2(b2), c4 = f2(c2), d4 = f2(d2);
byte a8 = f2(a4), b8 = f2(b4), c8 = f2(c4), d8 = f2(d4);
byte a9 = a8 ^ a1, b9 = b8 ^ b1, c9 = c8 ^ c1, d9 = d8 ^ d1;
byte ac = a8 ^ a4, bc = b8 ^ b4, cc = c8 ^ c4, dc = d8 ^ d4;
dt[i] = is_box(ac^a2 ^ b9^b2 ^ cc^c1 ^ d9);
dt[(i + 5)&15] = is_box(a9 ^ bc^b2 ^ c9^c2 ^ dc^d1);
dt[(i + 10)&15] = is_box(ac^a1 ^ b9 ^ cc^c2 ^ d9^d2);
dt[(i + 15)&15] = is_box(a9^a2 ^ bc^b1 ^ c9 ^ dc^d2);
}
}
/* Set the cipher key for the pre-keyed version */
byte AES::set_key(byte key [], int keylen)
{
byte hi;
switch (keylen)
{
case 16:
case 128:
keylen = 16; // 10 rounds
round = 10;
break;
case 24:
case 192:
keylen = 24; // 12 rounds
round = 12;
break;
case 32:
case 256:
keylen = 32; // 14 rounds
round = 14;
break;
default:
round = 0;
return FAILURE;
}
hi = (round + 1) << 4;
copy_n_bytes(key_sched, key, keylen);
byte t[4];
byte next = keylen;
for (byte cc = keylen, rc = 1; cc < hi; cc += N_COL)
{
for (byte i = 0; i < N_COL; i++)
t[i] = key_sched [cc - 4 + i];
if (cc == next)
{
next += keylen;
byte ttt = t[0];
t[0] = s_box(t[1]) ^ rc;
t[1] = s_box(t[2]);
t[2] = s_box(t[3]);
t[3] = s_box(ttt);
rc = f2(rc);
} else if (keylen == 32 && (cc & 31) == 16)
{
for (byte i = 0; i < 4; i++)
t[i] = s_box(t[i]);
}
byte tt = cc - keylen;
for (byte i = 0; i < N_COL; i++)
key_sched [cc + i] = key_sched [tt + i] ^ t[i];
}
return SUCCESS;
}
// clean up subkeys after use.
void AES::clean()
{
for (byte i = 0; i < KEY_SCHEDULE_BYTES; i++)
key_sched [i] = 0;
round = 0;
}
/* Encrypt a single block of 16 bytes */
byte AES::encrypt(byte plain [N_BLOCK], byte cipher [N_BLOCK])
{
if (round)
{
byte s1 [N_BLOCK], r;
copy_and_key(s1, plain, (byte*) (key_sched));
for (r = 1; r < round; r++)
{
byte s2 [N_BLOCK];
mix_sub_columns(s2, s1);
copy_and_key(s1, s2, (byte*) (key_sched + r * N_BLOCK));
}
shift_sub_rows(s1);
copy_and_key(cipher, s1, (byte*) (key_sched + r * N_BLOCK));
} else
return FAILURE;
return SUCCESS;
}
/* CBC encrypt a number of blocks (input and return an IV) */
byte AES::cbc_encrypt(byte * plain, byte * cipher, int n_block, byte iv [N_BLOCK])
{
while (n_block--)
{
xor_block(iv, plain);
if (encrypt(iv, iv) != SUCCESS)
return FAILURE;
copy_n_bytes(cipher, iv, N_BLOCK);
plain += N_BLOCK;
cipher += N_BLOCK;
}
return SUCCESS;
}
/* Decrypt a single block of 16 bytes */
byte AES::decrypt(byte plain [N_BLOCK], byte cipher [N_BLOCK])
{
if (round)
{
byte s1 [N_BLOCK];
copy_and_key(s1, plain, (byte*) (key_sched + round * N_BLOCK));
inv_shift_sub_rows(s1);
for (byte r = round; --r;)
{
byte s2 [N_BLOCK];
copy_and_key(s2, s1, (byte*) (key_sched + r * N_BLOCK));
inv_mix_sub_columns(s1, s2);
}
copy_and_key(cipher, s1, (byte*) (key_sched));
} else
return FAILURE;
return SUCCESS;
}
/* CBC decrypt a number of blocks (input and return an IV) */
byte AES::cbc_decrypt(byte * cipher, byte * plain, int n_block, byte iv [N_BLOCK])
{
while (n_block--)
{
byte tmp [N_BLOCK];
copy_n_bytes(tmp, cipher, N_BLOCK);
if (decrypt(cipher, plain) != SUCCESS)
return FAILURE;
xor_block(plain, iv);
copy_n_bytes(iv, tmp, N_BLOCK);
plain += N_BLOCK;
cipher += N_BLOCK;
}
return SUCCESS;
}