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[u/mdw/catacomb] / cbc-def.h
1 /* -*-c-*-
2 *
3 * $Id: cbc-def.h,v 1.3 2001/06/17 00:10:51 mdw Exp $
4 *
5 * Definitions for cipher block chaining mode
6 *
7 * (c) 1999 Straylight/Edgeware
8 */
9
10 /*----- Licensing notice --------------------------------------------------*
11 *
12 * This file is part of Catacomb.
13 *
14 * Catacomb is free software; you can redistribute it and/or modify
15 * it under the terms of the GNU Library General Public License as
16 * published by the Free Software Foundation; either version 2 of the
17 * License, or (at your option) any later version.
18 *
19 * Catacomb is distributed in the hope that it will be useful,
20 * but WITHOUT ANY WARRANTY; without even the implied warranty of
21 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
22 * GNU Library General Public License for more details.
23 *
24 * You should have received a copy of the GNU Library General Public
25 * License along with Catacomb; if not, write to the Free
26 * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
27 * MA 02111-1307, USA.
28 */
29
30 /*----- Revision history --------------------------------------------------*
31 *
32 * $Log: cbc-def.h,v $
33 * Revision 1.3 2001/06/17 00:10:51 mdw
34 * Typesetting fixes
35 *
36 * Revision 1.2 2000/06/17 10:49:52 mdw
37 * Use secure arena for memory allocation.
38 *
39 * Revision 1.1 1999/12/10 23:16:39 mdw
40 * Split mode macros into interface and implementation.
41 *
42 */
43
44 #ifndef CATACOMB_CBC_DEF_H
45 #define CATACOMB_CBC_DEF_H
46
47 #ifdef __cplusplus
48 extern "C" {
49 #endif
50
51 /*----- Header files ------------------------------------------------------*/
52
53 #include <string.h>
54
55 #include <mLib/bits.h>
56 #include <mLib/sub.h>
57
58 #ifndef CATACOMB_ARENA_H
59 # include "arena.h"
60 #endif
61
62 #ifndef CATACOMB_BLKC_H
63 # include "blkc.h"
64 #endif
65
66 #ifndef CATACOMB_GCIPHER_H
67 # include "gcipher.h"
68 #endif
69
70 #ifndef CATACOMB_PARANOIA_H
71 # include "paranoia.h"
72 #endif
73
74 /*----- Macros ------------------------------------------------------------*/
75
76 /* --- @CBC_DEF@ --- *
77 *
78 * Arguments: @PRE@, @pre@ = prefixes for the underlying block cipher
79 *
80 * Use: Creates an implementation for CBC stealing mode.
81 */
82
83 #define CBC_DEF(PRE, pre) \
84 \
85 /* --- @pre_cbcgetiv@ --- * \
86 * \
87 * Arguments: @const pre_cbcctx *ctx@ = pointer to CBC context block \
88 * @void *iv@ = pointer to output data block \
89 * \
90 * Returns: --- \
91 * \
92 * Use: Reads the currently set IV. Reading and setting an IV \
93 * is transparent to the CBC encryption or decryption \
94 * process. \
95 */ \
96 \
97 void pre##_cbcgetiv(const pre##_cbcctx *ctx, void *iv) \
98 { \
99 BLKC_STORE(PRE, iv, ctx->iv); \
100 } \
101 \
102 /* --- @pre_cbcsetiv@ --- * \
103 * \
104 * Arguments: @pre_cbcctx *ctx@ = pointer to CBC context block \
105 * @cnost void *iv@ = pointer to IV to set \
106 * \
107 * Returns: --- \
108 * \
109 * Use: Sets the IV to use for subsequent encryption. \
110 */ \
111 \
112 void pre##_cbcsetiv(pre##_cbcctx *ctx, const void *iv) \
113 { \
114 BLKC_LOAD(PRE, ctx->iv, iv); \
115 } \
116 \
117 /* --- @pre_cbcsetkey@ --- * \
118 * \
119 * Arguments: @pre_cbcctx *ctx@ = pointer to CBC context block \
120 * @const pre_ctx *k@ = pointer to cipher context \
121 * \
122 * Returns: --- \
123 * \
124 * Use: Sets the CBC context to use a different cipher key. \
125 */ \
126 \
127 void pre##_cbcsetkey(pre##_cbcctx *ctx, const pre##_ctx *k) \
128 { \
129 ctx->ctx = *k; \
130 } \
131 \
132 /* --- @pre_cbcinit@ --- * \
133 * \
134 * Arguments: @pre_cbcctx *ctx@ = pointer to cipher context \
135 * @const void *key@ = pointer to the key buffer \
136 * @size_t sz@ = size of the key \
137 * @const void *iv@ = pointer to initialization vector \
138 * \
139 * Returns: --- \
140 * \
141 * Use: Initializes a CBC context ready for use. The @iv@ \
142 * argument may be passed as a null pointer to set a zero \
143 * IV. Apart from that, this call is equivalent to calls \
144 * to @pre_init@, @pre_cbcsetkey@ and @pre_cbcsetiv@. \
145 */ \
146 \
147 void pre##_cbcinit(pre##_cbcctx *ctx, \
148 const void *key, size_t sz, \
149 const void *iv) \
150 { \
151 static octet zero[PRE##_BLKSZ] = { 0 }; \
152 pre##_init(&ctx->ctx, key, sz); \
153 BLKC_LOAD(PRE, ctx->iv, iv ? iv : zero); \
154 } \
155 \
156 /* --- @pre_cbcencrypt@ --- * \
157 * \
158 * Arguments: @pre_cbcctx *ctx@ = pointer to CBC context block \
159 * @const void *src@ = pointer to source data \
160 * @void *dest@ = pointer to destination data \
161 * @size_t sz@ = size of block to be encrypted \
162 * \
163 * Returns: --- \
164 * \
165 * Use: Encrypts a block with a block cipher in CBC mode, with \
166 * ciphertext stealing and other clever tricks. \
167 * Essentially, data can be encrypted in arbitrary sized \
168 * chunks, although decryption must use the same chunks. \
169 */ \
170 \
171 void pre##_cbcencrypt(pre##_cbcctx *ctx, \
172 const void *src, void *dest, \
173 size_t sz) \
174 { \
175 const octet *s = src; \
176 octet *d = dest; \
177 \
178 /* --- Empty blocks are trivial --- */ \
179 \
180 if (!sz) \
181 return; \
182 \
183 /* --- Extra magical case for a short block --- * \
184 * \
185 * Encrypt the IV, then exclusive-or the plaintext with the octets \
186 * of the encrypted IV, shifting ciphertext octets in instead. This \
187 * basically switches over to CFB. \
188 */ \
189 \
190 if (sz < PRE##_BLKSZ) { \
191 octet b[PRE##_BLKSZ]; \
192 unsigned i; \
193 \
194 pre##_eblk(&ctx->ctx, ctx->iv, ctx->iv); \
195 BLKC_STORE(PRE, b, ctx->iv); \
196 for (i = 0; i < sz; i++) \
197 d[i] = b[i] ^ s[i]; \
198 memmove(b, b + sz, PRE##_BLKSZ - sz); \
199 memcpy(b + PRE##_BLKSZ - sz, d, sz); \
200 BLKC_LOAD(PRE, ctx->iv, b); \
201 return; \
202 } \
203 \
204 /* --- Do the main chunk of encryption --- * \
205 * \
206 * This will do the whole lot if it's a whole number of blocks. For \
207 * each block, XOR it with the previous ciphertext in @iv@, encrypt, \
208 * and keep a copy of the ciphertext for the next block. \
209 */ \
210 \
211 while (sz >= 2 * PRE##_BLKSZ || sz == PRE##_BLKSZ) { \
212 BLKC_XLOAD(PRE, ctx->iv, s); \
213 pre##_eblk(&ctx->ctx, ctx->iv, ctx->iv); \
214 BLKC_STORE(PRE, d, ctx->iv); \
215 s += PRE##_BLKSZ; \
216 d += PRE##_BLKSZ; \
217 sz -= PRE##_BLKSZ; \
218 } \
219 \
220 /* --- Do the tail-end block and bit-left-over --- * \
221 * \
222 * This isn't very efficient. That shouldn't matter much. \
223 */ \
224 \
225 if (sz) { \
226 octet b[PRE##_BLKSZ]; \
227 unsigned i; \
228 \
229 /* --- Let @sz@ be the size of the partial block --- */ \
230 \
231 sz -= PRE##_BLKSZ; \
232 \
233 /* --- First stage --- * \
234 * \
235 * XOR the complete block with the current IV, and encrypt it. The \
236 * first part of the result is the partial ciphertext block. Don't \
237 * write that out yet, because I've not read the partial plaintext \
238 * block. \
239 */ \
240 \
241 BLKC_XLOAD(PRE, ctx->iv, s); \
242 pre##_eblk(&ctx->ctx, ctx->iv, ctx->iv); \
243 BLKC_STORE(PRE, b, ctx->iv); \
244 \
245 /* --- Second stage --- * \
246 * \
247 * Now XOR in the partial plaintext block, writing out the \
248 * ciphertext as I go. Then encrypt, and write the complete \
249 * ciphertext block. \
250 */ \
251 \
252 s += PRE##_BLKSZ; \
253 d += PRE##_BLKSZ; \
254 for (i = 0; i < sz; i++) { \
255 register octet x = b[i]; \
256 b[i] ^= s[i]; \
257 d[i] = x; \
258 } \
259 BLKC_LOAD(PRE, ctx->iv, b); \
260 pre##_eblk(&ctx->ctx, ctx->iv, ctx->iv); \
261 BLKC_STORE(PRE, d - PRE##_BLKSZ, ctx->iv); \
262 } \
263 \
264 /* --- Done --- */ \
265 \
266 return; \
267 } \
268 \
269 /* --- @pre_cbcdecrypt@ --- * \
270 * \
271 * Arguments: @pre_cbcctx *ctx@ = pointer to CBC context block \
272 * @const void *src@ = pointer to source data \
273 * @void *dest@ = pointer to destination data \
274 * @size_t sz@ = size of block to be encrypted \
275 * \
276 * Returns: --- \
277 * \
278 * Use: Decrypts a block with a block cipher in CBC mode, with \
279 * ciphertext stealing and other clever tricks. \
280 * Essentially, data can be encrypted in arbitrary sized \
281 * chunks, although decryption must use the same chunks. \
282 */ \
283 \
284 void pre##_cbcdecrypt(pre##_cbcctx *ctx, \
285 const void *src, void *dest, \
286 size_t sz) \
287 { \
288 const octet *s = src; \
289 octet *d = dest; \
290 \
291 /* --- Empty blocks are trivial --- */ \
292 \
293 if (!sz) \
294 return; \
295 \
296 /* --- Extra magical case for a short block --- * \
297 * \
298 * Encrypt the IV, then exclusive-or the ciphertext with the octets \
299 * of the encrypted IV, shifting ciphertext octets in instead. This \
300 * basically switches over to CFB. \
301 */ \
302 \
303 if (sz < PRE##_BLKSZ) { \
304 octet b[PRE##_BLKSZ], c[PRE##_BLKSZ]; \
305 unsigned i; \
306 \
307 pre##_eblk(&ctx->ctx, ctx->iv, ctx->iv); \
308 BLKC_STORE(PRE, b, ctx->iv); \
309 for (i = 0; i < sz; i++) { \
310 register octet x = s[i]; \
311 d[i] = b[i] ^ x; \
312 c[i] = x; \
313 } \
314 memmove(b, b + sz, PRE##_BLKSZ - sz); \
315 memcpy(b + PRE##_BLKSZ - sz, c, sz); \
316 BLKC_LOAD(PRE, ctx->iv, b); \
317 return; \
318 } \
319 \
320 /* --- Do the main chunk of decryption --- * \
321 * \
322 * This will do the whole lot if it's a whole number of blocks. For \
323 * each block, decrypt, XOR it with the previous ciphertext in @iv@, \
324 * and keep a copy of the ciphertext for the next block. \
325 */ \
326 \
327 while (sz >= 2 * PRE##_BLKSZ || sz == PRE##_BLKSZ) { \
328 uint32 b[PRE##_BLKSZ / 4], niv[PRE##_BLKSZ / 4]; \
329 BLKC_LOAD(PRE, niv, s); \
330 pre##_dblk(&ctx->ctx, niv, b); \
331 BLKC_XSTORE(PRE, d, b, ctx->iv); \
332 BLKC_MOVE(PRE, ctx->iv, niv); \
333 s += PRE##_BLKSZ; \
334 d += PRE##_BLKSZ; \
335 sz -= PRE##_BLKSZ; \
336 } \
337 \
338 /* --- Do the tail-end block and bit-left-over --- * \
339 * \
340 * This isn't very efficient. That shouldn't matter much. \
341 */ \
342 \
343 if (sz) { \
344 octet b[PRE##_BLKSZ]; \
345 uint32 bk[PRE##_BLKSZ / 4], niv[PRE##_BLKSZ / 4]; \
346 unsigned i; \
347 \
348 /* --- Let @sz@ be the size of the partial block --- */ \
349 \
350 sz -= PRE##_BLKSZ; \
351 \
352 /* --- First stage --- * \
353 * \
354 * Take the complete ciphertext block, and decrypt it. This block \
355 * is carried over for the next encryption operation. \
356 */ \
357 \
358 BLKC_LOAD(PRE, niv, s); \
359 pre##_dblk(&ctx->ctx, niv, bk); \
360 \
361 /* --- Second stage --- * \
362 * \
363 * XORing the first few bytes of this with the partial ciphertext \
364 * block recovers the partial plaintext block. At the same time, \
365 * write the partial ciphertext block's contents in ready for stage \
366 * three. \
367 */ \
368 \
369 BLKC_STORE(PRE, b, bk); \
370 s += PRE##_BLKSZ; \
371 d += PRE##_BLKSZ; \
372 for (i = 0; i < sz; i++) { \
373 register octet x = s[i]; \
374 d[i] = b[i] ^ x; \
375 b[i] = x; \
376 } \
377 \
378 /* --- Third stage --- * \
379 * \
380 * Decrypt the block we've got left, and XOR with the initial IV to \
381 * recover the complete plaintext block. \
382 */ \
383 \
384 BLKC_LOAD(PRE, bk, b); \
385 pre##_dblk(&ctx->ctx, bk, bk); \
386 BLKC_XSTORE(PRE, d - PRE##_BLKSZ, bk, ctx->iv); \
387 BLKC_MOVE(PRE, ctx->iv, niv); \
388 } \
389 \
390 /* --- Done --- */ \
391 \
392 return; \
393 } \
394 \
395 /* --- Generic cipher interface --- */ \
396 \
397 static const gcipher_ops gops; \
398 \
399 typedef struct gctx { \
400 gcipher c; \
401 pre##_cbcctx k; \
402 } gctx; \
403 \
404 static gcipher *ginit(const void *k, size_t sz) \
405 { \
406 gctx *g = S_CREATE(gctx); \
407 g->c.ops = &gops; \
408 pre##_cbcinit(&g->k, k, sz, 0); \
409 return (&g->c); \
410 } \
411 \
412 static void gencrypt(gcipher *c, const void *s, void *t, size_t sz) \
413 { \
414 gctx *g = (gctx *)c; \
415 pre##_cbcencrypt(&g->k, s, t, sz); \
416 } \
417 \
418 static void gdecrypt(gcipher *c, const void *s, void *t, size_t sz) \
419 { \
420 gctx *g = (gctx *)c; \
421 pre##_cbcdecrypt(&g->k, s, t, sz); \
422 } \
423 \
424 static void gdestroy(gcipher *c) \
425 { \
426 gctx *g = (gctx *)c; \
427 BURN(*g); \
428 S_DESTROY(g); \
429 } \
430 \
431 static void gsetiv(gcipher *c, const void *iv) \
432 { \
433 gctx *g = (gctx *)c; \
434 pre##_cbcsetiv(&g->k, iv); \
435 } \
436 \
437 static const gcipher_ops gops = { \
438 &pre##_cbc, \
439 gencrypt, gdecrypt, gdestroy, gsetiv, 0 \
440 }; \
441 \
442 const gccipher pre##_cbc = { \
443 #pre "-cbc", pre##_keysz, PRE##_BLKSZ, \
444 ginit \
445 }; \
446 \
447 CBC_TEST(PRE, pre)
448
449 /*----- Test rig ----------------------------------------------------------*/
450
451 #ifdef TEST_RIG
452
453 #include <stdio.h>
454
455 #include "daftstory.h"
456
457 /* --- @CBC_TEST@ --- *
458 *
459 * Arguments: @PRE@, @pre@ = prefixes for block cipher definitions
460 *
461 * Use: Standard test rig for CBC functions.
462 */
463
464 #define CBC_TEST(PRE, pre) \
465 \
466 /* --- Initial plaintext for the test --- */ \
467 \
468 static const octet text[] = TEXT; \
469 \
470 /* --- Key and IV to use --- */ \
471 \
472 static const octet key[] = KEY; \
473 static const octet iv[] = IV; \
474 \
475 /* --- Buffers for encryption and decryption output --- */ \
476 \
477 static octet ct[sizeof(text)]; \
478 static octet pt[sizeof(text)]; \
479 \
480 static void hexdump(const octet *p, size_t sz) \
481 { \
482 const octet *q = p + sz; \
483 for (sz = 0; p < q; p++, sz++) { \
484 printf("%02x", *p); \
485 if ((sz + 1) % PRE##_BLKSZ == 0) \
486 putchar(':'); \
487 } \
488 } \
489 \
490 int main(void) \
491 { \
492 size_t sz = 0, rest; \
493 pre##_cbcctx ctx; \
494 pre##_ctx k; \
495 int status = 0; \
496 int done = 0; \
497 \
498 size_t keysz = PRE##_KEYSZ ? \
499 PRE##_KEYSZ : strlen((const char *)key); \
500 \
501 fputs(#pre "-cbc: ", stdout); \
502 \
503 pre##_init(&k, key, keysz); \
504 pre##_cbcsetkey(&ctx, &k); \
505 \
506 while (sz <= sizeof(text)) { \
507 rest = sizeof(text) - sz; \
508 memcpy(ct, text, sizeof(text)); \
509 pre##_cbcsetiv(&ctx, iv); \
510 pre##_cbcencrypt(&ctx, ct, ct, sz); \
511 pre##_cbcencrypt(&ctx, ct + sz, ct + sz, rest); \
512 memcpy(pt, ct, sizeof(text)); \
513 pre##_cbcsetiv(&ctx, iv); \
514 pre##_cbcdecrypt(&ctx, pt, pt, sz); \
515 pre##_cbcdecrypt(&ctx, pt + sz, pt + sz, rest); \
516 if (memcmp(pt, text, sizeof(text)) == 0) { \
517 done++; \
518 if (sizeof(text) < 40 || done % 8 == 0) \
519 fputc('.', stdout); \
520 if (done % 480 == 0) \
521 fputs("\n\t", stdout); \
522 fflush(stdout); \
523 } else { \
524 printf("\nError (sz = %lu)\n", (unsigned long)sz); \
525 status = 1; \
526 printf("\tplaintext = "); hexdump(text, sz); \
527 printf(", "); hexdump(text + sz, rest); \
528 fputc('\n', stdout); \
529 printf("\tciphertext = "); hexdump(ct, sz); \
530 printf(", "); hexdump(ct + sz, rest); \
531 fputc('\n', stdout); \
532 printf("\trecovered text = "); hexdump(pt, sz); \
533 printf(", "); hexdump(pt + sz, rest); \
534 fputc('\n', stdout); \
535 fputc('\n', stdout); \
536 } \
537 if (sz < 63) \
538 sz++; \
539 else \
540 sz += 9; \
541 } \
542 \
543 fputs(status ? " failed\n" : " ok\n", stdout); \
544 return (status); \
545 }
546
547 #else
548 # define CBC_TEST(PRE, pre)
549 #endif
550
551 /*----- That's all, folks -------------------------------------------------*/
552
553 #ifdef __cplusplus
554 }
555 #endif
556
557 #endif
Catacomb cryptographic library (downstream of http://git.distorted.org.uk/~mdw/catacomb/)