ctaes.c raw
1 /*********************************************************************
2 * Copyright (c) 2016 Pieter Wuille *
3 * Distributed under the MIT software license, see the accompanying *
4 * file COPYING or http://www.opensource.org/licenses/mit-license.php.*
5 **********************************************************************/
6
7 /* Constant time, unoptimized, concise, plain C, AES implementation
8 * Based On:
9 * Emilia Kasper and Peter Schwabe, Faster and Timing-Attack Resistant AES-GCM
10 * http://www.iacr.org/archive/ches2009/57470001/57470001.pdf
11 * But using 8 16-bit integers representing a single AES state rather than 8 128-bit
12 * integers representing 8 AES states.
13 */
14
15 #include "ctaes.h"
16
17 /* Slice variable slice_i contains the i'th bit of the 16 state variables in this order:
18 * 0 1 2 3
19 * 4 5 6 7
20 * 8 9 10 11
21 * 12 13 14 15
22 */
23
24 /** Convert a byte to sliced form, storing it corresponding to given row and column in s */
25 static void LoadByte(AES_state* s, unsigned char byte, int r, int c) {
26 int i;
27 for (i = 0; i < 8; i++) {
28 s->slice[i] |= (byte & 1) << (r * 4 + c);
29 byte >>= 1;
30 }
31 }
32
33 /** Load 16 bytes of data into 8 sliced integers */
34 static void LoadBytes(AES_state *s, const unsigned char* data16) {
35 int c;
36 for (c = 0; c < 4; c++) {
37 int r;
38 for (r = 0; r < 4; r++) {
39 LoadByte(s, *(data16++), r, c);
40 }
41 }
42 }
43
44 /** Convert 8 sliced integers into 16 bytes of data */
45 static void SaveBytes(unsigned char* data16, const AES_state *s) {
46 int c;
47 for (c = 0; c < 4; c++) {
48 int r;
49 for (r = 0; r < 4; r++) {
50 int b;
51 uint8_t v = 0;
52 for (b = 0; b < 8; b++) {
53 v |= ((s->slice[b] >> (r * 4 + c)) & 1) << b;
54 }
55 *(data16++) = v;
56 }
57 }
58 }
59
60 /* S-box implementation based on the gate logic from:
61 * Joan Boyar and Rene Peralta, A depth-16 circuit for the AES S-box.
62 * https://eprint.iacr.org/2011/332.pdf
63 */
64 static void SubBytes(AES_state *s, int inv) {
65 /* Load the bit slices */
66 uint16_t U0 = s->slice[7], U1 = s->slice[6], U2 = s->slice[5], U3 = s->slice[4];
67 uint16_t U4 = s->slice[3], U5 = s->slice[2], U6 = s->slice[1], U7 = s->slice[0];
68
69 uint16_t T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, T15, T16;
70 uint16_t T17, T18, T19, T20, T21, T22, T23, T24, T25, T26, T27, D;
71 uint16_t M1, M6, M11, M13, M15, M20, M21, M22, M23, M25, M37, M38, M39, M40;
72 uint16_t M41, M42, M43, M44, M45, M46, M47, M48, M49, M50, M51, M52, M53, M54;
73 uint16_t M55, M56, M57, M58, M59, M60, M61, M62, M63;
74
75 if (inv) {
76 uint16_t R5, R13, R17, R18, R19;
77 /* Undo linear postprocessing */
78 T23 = U0 ^ U3;
79 T22 = ~(U1 ^ U3);
80 T2 = ~(U0 ^ U1);
81 T1 = U3 ^ U4;
82 T24 = ~(U4 ^ U7);
83 R5 = U6 ^ U7;
84 T8 = ~(U1 ^ T23);
85 T19 = T22 ^ R5;
86 T9 = ~(U7 ^ T1);
87 T10 = T2 ^ T24;
88 T13 = T2 ^ R5;
89 T3 = T1 ^ R5;
90 T25 = ~(U2 ^ T1);
91 R13 = U1 ^ U6;
92 T17 = ~(U2 ^ T19);
93 T20 = T24 ^ R13;
94 T4 = U4 ^ T8;
95 R17 = ~(U2 ^ U5);
96 R18 = ~(U5 ^ U6);
97 R19 = ~(U2 ^ U4);
98 D = U0 ^ R17;
99 T6 = T22 ^ R17;
100 T16 = R13 ^ R19;
101 T27 = T1 ^ R18;
102 T15 = T10 ^ T27;
103 T14 = T10 ^ R18;
104 T26 = T3 ^ T16;
105 } else {
106 /* Linear preprocessing. */
107 T1 = U0 ^ U3;
108 T2 = U0 ^ U5;
109 T3 = U0 ^ U6;
110 T4 = U3 ^ U5;
111 T5 = U4 ^ U6;
112 T6 = T1 ^ T5;
113 T7 = U1 ^ U2;
114 T8 = U7 ^ T6;
115 T9 = U7 ^ T7;
116 T10 = T6 ^ T7;
117 T11 = U1 ^ U5;
118 T12 = U2 ^ U5;
119 T13 = T3 ^ T4;
120 T14 = T6 ^ T11;
121 T15 = T5 ^ T11;
122 T16 = T5 ^ T12;
123 T17 = T9 ^ T16;
124 T18 = U3 ^ U7;
125 T19 = T7 ^ T18;
126 T20 = T1 ^ T19;
127 T21 = U6 ^ U7;
128 T22 = T7 ^ T21;
129 T23 = T2 ^ T22;
130 T24 = T2 ^ T10;
131 T25 = T20 ^ T17;
132 T26 = T3 ^ T16;
133 T27 = T1 ^ T12;
134 D = U7;
135 }
136
137 /* Non-linear transformation (shared between the forward and backward case) */
138 M1 = T13 & T6;
139 M6 = T3 & T16;
140 M11 = T1 & T15;
141 M13 = (T4 & T27) ^ M11;
142 M15 = (T2 & T10) ^ M11;
143 M20 = T14 ^ M1 ^ (T23 & T8) ^ M13;
144 M21 = (T19 & D) ^ M1 ^ T24 ^ M15;
145 M22 = T26 ^ M6 ^ (T22 & T9) ^ M13;
146 M23 = (T20 & T17) ^ M6 ^ M15 ^ T25;
147 M25 = M22 & M20;
148 M37 = M21 ^ ((M20 ^ M21) & (M23 ^ M25));
149 M38 = M20 ^ M25 ^ (M21 | (M20 & M23));
150 M39 = M23 ^ ((M22 ^ M23) & (M21 ^ M25));
151 M40 = M22 ^ M25 ^ (M23 | (M21 & M22));
152 M41 = M38 ^ M40;
153 M42 = M37 ^ M39;
154 M43 = M37 ^ M38;
155 M44 = M39 ^ M40;
156 M45 = M42 ^ M41;
157 M46 = M44 & T6;
158 M47 = M40 & T8;
159 M48 = M39 & D;
160 M49 = M43 & T16;
161 M50 = M38 & T9;
162 M51 = M37 & T17;
163 M52 = M42 & T15;
164 M53 = M45 & T27;
165 M54 = M41 & T10;
166 M55 = M44 & T13;
167 M56 = M40 & T23;
168 M57 = M39 & T19;
169 M58 = M43 & T3;
170 M59 = M38 & T22;
171 M60 = M37 & T20;
172 M61 = M42 & T1;
173 M62 = M45 & T4;
174 M63 = M41 & T2;
175
176 if (inv){
177 /* Undo linear preprocessing */
178 uint16_t P0 = M52 ^ M61;
179 uint16_t P1 = M58 ^ M59;
180 uint16_t P2 = M54 ^ M62;
181 uint16_t P3 = M47 ^ M50;
182 uint16_t P4 = M48 ^ M56;
183 uint16_t P5 = M46 ^ M51;
184 uint16_t P6 = M49 ^ M60;
185 uint16_t P7 = P0 ^ P1;
186 uint16_t P8 = M50 ^ M53;
187 uint16_t P9 = M55 ^ M63;
188 uint16_t P10 = M57 ^ P4;
189 uint16_t P11 = P0 ^ P3;
190 uint16_t P12 = M46 ^ M48;
191 uint16_t P13 = M49 ^ M51;
192 uint16_t P14 = M49 ^ M62;
193 uint16_t P15 = M54 ^ M59;
194 uint16_t P16 = M57 ^ M61;
195 uint16_t P17 = M58 ^ P2;
196 uint16_t P18 = M63 ^ P5;
197 uint16_t P19 = P2 ^ P3;
198 uint16_t P20 = P4 ^ P6;
199 uint16_t P22 = P2 ^ P7;
200 uint16_t P23 = P7 ^ P8;
201 uint16_t P24 = P5 ^ P7;
202 uint16_t P25 = P6 ^ P10;
203 uint16_t P26 = P9 ^ P11;
204 uint16_t P27 = P10 ^ P18;
205 uint16_t P28 = P11 ^ P25;
206 uint16_t P29 = P15 ^ P20;
207 s->slice[7] = P13 ^ P22;
208 s->slice[6] = P26 ^ P29;
209 s->slice[5] = P17 ^ P28;
210 s->slice[4] = P12 ^ P22;
211 s->slice[3] = P23 ^ P27;
212 s->slice[2] = P19 ^ P24;
213 s->slice[1] = P14 ^ P23;
214 s->slice[0] = P9 ^ P16;
215 } else {
216 /* Linear postprocessing */
217 uint16_t L0 = M61 ^ M62;
218 uint16_t L1 = M50 ^ M56;
219 uint16_t L2 = M46 ^ M48;
220 uint16_t L3 = M47 ^ M55;
221 uint16_t L4 = M54 ^ M58;
222 uint16_t L5 = M49 ^ M61;
223 uint16_t L6 = M62 ^ L5;
224 uint16_t L7 = M46 ^ L3;
225 uint16_t L8 = M51 ^ M59;
226 uint16_t L9 = M52 ^ M53;
227 uint16_t L10 = M53 ^ L4;
228 uint16_t L11 = M60 ^ L2;
229 uint16_t L12 = M48 ^ M51;
230 uint16_t L13 = M50 ^ L0;
231 uint16_t L14 = M52 ^ M61;
232 uint16_t L15 = M55 ^ L1;
233 uint16_t L16 = M56 ^ L0;
234 uint16_t L17 = M57 ^ L1;
235 uint16_t L18 = M58 ^ L8;
236 uint16_t L19 = M63 ^ L4;
237 uint16_t L20 = L0 ^ L1;
238 uint16_t L21 = L1 ^ L7;
239 uint16_t L22 = L3 ^ L12;
240 uint16_t L23 = L18 ^ L2;
241 uint16_t L24 = L15 ^ L9;
242 uint16_t L25 = L6 ^ L10;
243 uint16_t L26 = L7 ^ L9;
244 uint16_t L27 = L8 ^ L10;
245 uint16_t L28 = L11 ^ L14;
246 uint16_t L29 = L11 ^ L17;
247 s->slice[7] = L6 ^ L24;
248 s->slice[6] = ~(L16 ^ L26);
249 s->slice[5] = ~(L19 ^ L28);
250 s->slice[4] = L6 ^ L21;
251 s->slice[3] = L20 ^ L22;
252 s->slice[2] = L25 ^ L29;
253 s->slice[1] = ~(L13 ^ L27);
254 s->slice[0] = ~(L6 ^ L23);
255 }
256 }
257
258 #define BIT_RANGE(from,to) (((1 << ((to) - (from))) - 1) << (from))
259
260 #define BIT_RANGE_LEFT(x,from,to,shift) (((x) & BIT_RANGE((from), (to))) << (shift))
261 #define BIT_RANGE_RIGHT(x,from,to,shift) (((x) & BIT_RANGE((from), (to))) >> (shift))
262
263 static void ShiftRows(AES_state* s) {
264 int i;
265 for (i = 0; i < 8; i++) {
266 uint16_t v = s->slice[i];
267 s->slice[i] =
268 (v & BIT_RANGE(0, 4)) |
269 BIT_RANGE_LEFT(v, 4, 5, 3) | BIT_RANGE_RIGHT(v, 5, 8, 1) |
270 BIT_RANGE_LEFT(v, 8, 10, 2) | BIT_RANGE_RIGHT(v, 10, 12, 2) |
271 BIT_RANGE_LEFT(v, 12, 15, 1) | BIT_RANGE_RIGHT(v, 15, 16, 3);
272 }
273 }
274
275 static void InvShiftRows(AES_state* s) {
276 int i;
277 for (i = 0; i < 8; i++) {
278 uint16_t v = s->slice[i];
279 s->slice[i] =
280 (v & BIT_RANGE(0, 4)) |
281 BIT_RANGE_LEFT(v, 4, 7, 1) | BIT_RANGE_RIGHT(v, 7, 8, 3) |
282 BIT_RANGE_LEFT(v, 8, 10, 2) | BIT_RANGE_RIGHT(v, 10, 12, 2) |
283 BIT_RANGE_LEFT(v, 12, 13, 3) | BIT_RANGE_RIGHT(v, 13, 16, 1);
284 }
285 }
286
287 #define ROT(x,b) (((x) >> ((b) * 4)) | ((x) << ((4-(b)) * 4)))
288
289 static void MixColumns(AES_state* s, int inv) {
290 /* The MixColumns transform treats the bytes of the columns of the state as
291 * coefficients of a 3rd degree polynomial over GF(2^8) and multiplies them
292 * by the fixed polynomial a(x) = {03}x^3 + {01}x^2 + {01}x + {02}, modulo
293 * x^4 + {01}.
294 *
295 * In the inverse transform, we multiply by the inverse of a(x),
296 * a^-1(x) = {0b}x^3 + {0d}x^2 + {09}x + {0e}. This is equal to
297 * a(x) * ({04}x^2 + {05}), so we can reuse the forward transform's code
298 * (found in OpenSSL's bsaes-x86_64.pl, attributed to Jussi Kivilinna)
299 *
300 * In the bitsliced representation, a multiplication of every column by x
301 * mod x^4 + 1 is simply a right rotation.
302 */
303
304 /* Shared for both directions is a multiplication by a(x), which can be
305 * rewritten as (x^3 + x^2 + x) + {02}*(x^3 + {01}).
306 *
307 * First compute s into the s? variables, (x^3 + {01}) * s into the s?_01
308 * variables and (x^3 + x^2 + x)*s into the s?_123 variables.
309 */
310 uint16_t s0 = s->slice[0], s1 = s->slice[1], s2 = s->slice[2], s3 = s->slice[3];
311 uint16_t s4 = s->slice[4], s5 = s->slice[5], s6 = s->slice[6], s7 = s->slice[7];
312 uint16_t s0_01 = s0 ^ ROT(s0, 1), s0_123 = ROT(s0_01, 1) ^ ROT(s0, 3);
313 uint16_t s1_01 = s1 ^ ROT(s1, 1), s1_123 = ROT(s1_01, 1) ^ ROT(s1, 3);
314 uint16_t s2_01 = s2 ^ ROT(s2, 1), s2_123 = ROT(s2_01, 1) ^ ROT(s2, 3);
315 uint16_t s3_01 = s3 ^ ROT(s3, 1), s3_123 = ROT(s3_01, 1) ^ ROT(s3, 3);
316 uint16_t s4_01 = s4 ^ ROT(s4, 1), s4_123 = ROT(s4_01, 1) ^ ROT(s4, 3);
317 uint16_t s5_01 = s5 ^ ROT(s5, 1), s5_123 = ROT(s5_01, 1) ^ ROT(s5, 3);
318 uint16_t s6_01 = s6 ^ ROT(s6, 1), s6_123 = ROT(s6_01, 1) ^ ROT(s6, 3);
319 uint16_t s7_01 = s7 ^ ROT(s7, 1), s7_123 = ROT(s7_01, 1) ^ ROT(s7, 3);
320 /* Now compute s = s?_123 + {02} * s?_01. */
321 s->slice[0] = s7_01 ^ s0_123;
322 s->slice[1] = s7_01 ^ s0_01 ^ s1_123;
323 s->slice[2] = s1_01 ^ s2_123;
324 s->slice[3] = s7_01 ^ s2_01 ^ s3_123;
325 s->slice[4] = s7_01 ^ s3_01 ^ s4_123;
326 s->slice[5] = s4_01 ^ s5_123;
327 s->slice[6] = s5_01 ^ s6_123;
328 s->slice[7] = s6_01 ^ s7_123;
329 if (inv) {
330 /* In the reverse direction, we further need to multiply by
331 * {04}x^2 + {05}, which can be written as {04} * (x^2 + {01}) + {01}.
332 *
333 * First compute (x^2 + {01}) * s into the t?_02 variables: */
334 uint16_t t0_02 = s->slice[0] ^ ROT(s->slice[0], 2);
335 uint16_t t1_02 = s->slice[1] ^ ROT(s->slice[1], 2);
336 uint16_t t2_02 = s->slice[2] ^ ROT(s->slice[2], 2);
337 uint16_t t3_02 = s->slice[3] ^ ROT(s->slice[3], 2);
338 uint16_t t4_02 = s->slice[4] ^ ROT(s->slice[4], 2);
339 uint16_t t5_02 = s->slice[5] ^ ROT(s->slice[5], 2);
340 uint16_t t6_02 = s->slice[6] ^ ROT(s->slice[6], 2);
341 uint16_t t7_02 = s->slice[7] ^ ROT(s->slice[7], 2);
342 /* And then update s += {04} * t?_02 */
343 s->slice[0] ^= t6_02;
344 s->slice[1] ^= t6_02 ^ t7_02;
345 s->slice[2] ^= t0_02 ^ t7_02;
346 s->slice[3] ^= t1_02 ^ t6_02;
347 s->slice[4] ^= t2_02 ^ t6_02 ^ t7_02;
348 s->slice[5] ^= t3_02 ^ t7_02;
349 s->slice[6] ^= t4_02;
350 s->slice[7] ^= t5_02;
351 }
352 }
353
354 static void AddRoundKey(AES_state* s, const AES_state* round) {
355 int b;
356 for (b = 0; b < 8; b++) {
357 s->slice[b] ^= round->slice[b];
358 }
359 }
360
361 /** column_0(s) = column_c(a) */
362 static void GetOneColumn(AES_state* s, const AES_state* a, int c) {
363 int b;
364 for (b = 0; b < 8; b++) {
365 s->slice[b] = (a->slice[b] >> c) & 0x1111;
366 }
367 }
368
369 /** column_c1(r) |= (column_0(s) ^= column_c2(a)) */
370 static void KeySetupColumnMix(AES_state* s, AES_state* r, const AES_state* a, int c1, int c2) {
371 int b;
372 for (b = 0; b < 8; b++) {
373 r->slice[b] |= ((s->slice[b] ^= ((a->slice[b] >> c2) & 0x1111)) & 0x1111) << c1;
374 }
375 }
376
377 /** Rotate the rows in s one position upwards, and xor in r */
378 static void KeySetupTransform(AES_state* s, const AES_state* r) {
379 int b;
380 for (b = 0; b < 8; b++) {
381 s->slice[b] = ((s->slice[b] >> 4) | (s->slice[b] << 12)) ^ r->slice[b];
382 }
383 }
384
385 /* Multiply the cells in s by x, as polynomials over GF(2) mod x^8 + x^4 + x^3 + x + 1 */
386 static void MultX(AES_state* s) {
387 uint16_t top = s->slice[7];
388 s->slice[7] = s->slice[6];
389 s->slice[6] = s->slice[5];
390 s->slice[5] = s->slice[4];
391 s->slice[4] = s->slice[3] ^ top;
392 s->slice[3] = s->slice[2] ^ top;
393 s->slice[2] = s->slice[1];
394 s->slice[1] = s->slice[0] ^ top;
395 s->slice[0] = top;
396 }
397
398 /** Expand the cipher key into the key schedule.
399 *
400 * state must be a pointer to an array of size nrounds + 1.
401 * key must be a pointer to 4 * nkeywords bytes.
402 *
403 * AES128 uses nkeywords = 4, nrounds = 10
404 * AES192 uses nkeywords = 6, nrounds = 12
405 * AES256 uses nkeywords = 8, nrounds = 14
406 */
407 static void AES_setup(AES_state* rounds, const uint8_t* key, int nkeywords, int nrounds)
408 {
409 int i;
410
411 /* The one-byte round constant */
412 AES_state rcon = {{1,0,0,0,0,0,0,0}};
413 /* The number of the word being generated, modulo nkeywords */
414 int pos = 0;
415 /* The column representing the word currently being processed */
416 AES_state column;
417
418 for (i = 0; i < nrounds + 1; i++) {
419 int b;
420 for (b = 0; b < 8; b++) {
421 rounds[i].slice[b] = 0;
422 }
423 }
424
425 /* The first nkeywords round columns are just taken from the key directly. */
426 for (i = 0; i < nkeywords; i++) {
427 int r;
428 for (r = 0; r < 4; r++) {
429 LoadByte(&rounds[i >> 2], *(key++), r, i & 3);
430 }
431 }
432
433 GetOneColumn(&column, &rounds[(nkeywords - 1) >> 2], (nkeywords - 1) & 3);
434
435 for (i = nkeywords; i < 4 * (nrounds + 1); i++) {
436 /* Transform column */
437 if (pos == 0) {
438 SubBytes(&column, 0);
439 KeySetupTransform(&column, &rcon);
440 MultX(&rcon);
441 } else if (nkeywords > 6 && pos == 4) {
442 SubBytes(&column, 0);
443 }
444 if (++pos == nkeywords) pos = 0;
445 KeySetupColumnMix(&column, &rounds[i >> 2], &rounds[(i - nkeywords) >> 2], i & 3, (i - nkeywords) & 3);
446 }
447 }
448
449 static void AES_encrypt(const AES_state* rounds, int nrounds, unsigned char* cipher16, const unsigned char* plain16) {
450 AES_state s = {{0}};
451 int round;
452
453 LoadBytes(&s, plain16);
454 AddRoundKey(&s, rounds++);
455
456 for (round = 1; round < nrounds; round++) {
457 SubBytes(&s, 0);
458 ShiftRows(&s);
459 MixColumns(&s, 0);
460 AddRoundKey(&s, rounds++);
461 }
462
463 SubBytes(&s, 0);
464 ShiftRows(&s);
465 AddRoundKey(&s, rounds);
466
467 SaveBytes(cipher16, &s);
468 }
469
470 static void AES_decrypt(const AES_state* rounds, int nrounds, unsigned char* plain16, const unsigned char* cipher16) {
471 /* Most AES decryption implementations use the alternate scheme
472 * (the Equivalent Inverse Cipher), which allows for more code reuse between
473 * the encryption and decryption code, but requires separate setup for both.
474 */
475 AES_state s = {{0}};
476 int round;
477
478 rounds += nrounds;
479
480 LoadBytes(&s, cipher16);
481 AddRoundKey(&s, rounds--);
482
483 for (round = 1; round < nrounds; round++) {
484 InvShiftRows(&s);
485 SubBytes(&s, 1);
486 AddRoundKey(&s, rounds--);
487 MixColumns(&s, 1);
488 }
489
490 InvShiftRows(&s);
491 SubBytes(&s, 1);
492 AddRoundKey(&s, rounds);
493
494 SaveBytes(plain16, &s);
495 }
496
497 void AES128_init(AES128_ctx* ctx, const unsigned char* key16) {
498 AES_setup(ctx->rk, key16, 4, 10);
499 }
500
501 void AES128_encrypt(const AES128_ctx* ctx, size_t blocks, unsigned char* cipher16, const unsigned char* plain16) {
502 while (blocks--) {
503 AES_encrypt(ctx->rk, 10, cipher16, plain16);
504 cipher16 += 16;
505 plain16 += 16;
506 }
507 }
508
509 void AES128_decrypt(const AES128_ctx* ctx, size_t blocks, unsigned char* plain16, const unsigned char* cipher16) {
510 while (blocks--) {
511 AES_decrypt(ctx->rk, 10, plain16, cipher16);
512 cipher16 += 16;
513 plain16 += 16;
514 }
515 }
516
517 void AES192_init(AES192_ctx* ctx, const unsigned char* key24) {
518 AES_setup(ctx->rk, key24, 6, 12);
519 }
520
521 void AES192_encrypt(const AES192_ctx* ctx, size_t blocks, unsigned char* cipher16, const unsigned char* plain16) {
522 while (blocks--) {
523 AES_encrypt(ctx->rk, 12, cipher16, plain16);
524 cipher16 += 16;
525 plain16 += 16;
526 }
527
528 }
529
530 void AES192_decrypt(const AES192_ctx* ctx, size_t blocks, unsigned char* plain16, const unsigned char* cipher16) {
531 while (blocks--) {
532 AES_decrypt(ctx->rk, 12, plain16, cipher16);
533 cipher16 += 16;
534 plain16 += 16;
535 }
536 }
537
538 void AES256_init(AES256_ctx* ctx, const unsigned char* key32) {
539 AES_setup(ctx->rk, key32, 8, 14);
540 }
541
542 void AES256_encrypt(const AES256_ctx* ctx, size_t blocks, unsigned char* cipher16, const unsigned char* plain16) {
543 while (blocks--) {
544 AES_encrypt(ctx->rk, 14, cipher16, plain16);
545 cipher16 += 16;
546 plain16 += 16;
547 }
548 }
549
550 void AES256_decrypt(const AES256_ctx* ctx, size_t blocks, unsigned char* plain16, const unsigned char* cipher16) {
551 while (blocks--) {
552 AES_decrypt(ctx->rk, 14, plain16, cipher16);
553 cipher16 += 16;
554 plain16 += 16;
555 }
556 }
557