projects / u / mdw / catacomb / blob
? search:
summary | shortlog | log | commit | commitdiff | tree
blame | history | raw | HEAD
Gather up another utility.
[u/mdw/catacomb] / cbc-def.h
1 /* -*-c-*-
2 *
3 * $Id: cbc-def.h,v 1.6 2004/04/17 09:58:36 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 #ifndef CATACOMB_CBC_DEF_H
31 #define CATACOMB_CBC_DEF_H
32
33 #ifdef __cplusplus
34 extern "C" {
35 #endif
36
37 /*----- Header files ------------------------------------------------------*/
38
39 #include <string.h>
40
41 #include <mLib/bits.h>
42 #include <mLib/sub.h>
43
44 #ifndef CATACOMB_ARENA_H
45 # include "arena.h"
46 #endif
47
48 #ifndef CATACOMB_BLKC_H
49 # include "blkc.h"
50 #endif
51
52 #ifndef CATACOMB_GCIPHER_H
53 # include "gcipher.h"
54 #endif
55
56 #ifndef CATACOMB_PARANOIA_H
57 # include "paranoia.h"
58 #endif
59
60 /*----- Macros ------------------------------------------------------------*/
61
62 /* --- @CBC_DEF@ --- *
63 *
64 * Arguments: @PRE@, @pre@ = prefixes for the underlying block cipher
65 *
66 * Use: Creates an implementation for CBC stealing mode.
67 */
68
69 #define CBC_DEF(PRE, pre) \
70 \
71 /* --- @pre_cbcgetiv@ --- * \
72 * \
73 * Arguments: @const pre_cbcctx *ctx@ = pointer to CBC context block \
74 * @void *iv@ = pointer to output data block \
75 * \
76 * Returns: --- \
77 * \
78 * Use: Reads the currently set IV. Reading and setting an IV \
79 * is transparent to the CBC encryption or decryption \
80 * process. \
81 */ \
82 \
83 void pre##_cbcgetiv(const pre##_cbcctx *ctx, void *iv) \
84 { \
85 BLKC_STORE(PRE, iv, ctx->iv); \
86 } \
87 \
88 /* --- @pre_cbcsetiv@ --- * \
89 * \
90 * Arguments: @pre_cbcctx *ctx@ = pointer to CBC context block \
91 * @cnost void *iv@ = pointer to IV to set \
92 * \
93 * Returns: --- \
94 * \
95 * Use: Sets the IV to use for subsequent encryption. \
96 */ \
97 \
98 void pre##_cbcsetiv(pre##_cbcctx *ctx, const void *iv) \
99 { \
100 BLKC_LOAD(PRE, ctx->iv, iv); \
101 } \
102 \
103 /* --- @pre_cbcsetkey@ --- * \
104 * \
105 * Arguments: @pre_cbcctx *ctx@ = pointer to CBC context block \
106 * @const pre_ctx *k@ = pointer to cipher context \
107 * \
108 * Returns: --- \
109 * \
110 * Use: Sets the CBC context to use a different cipher key. \
111 */ \
112 \
113 void pre##_cbcsetkey(pre##_cbcctx *ctx, const pre##_ctx *k) \
114 { \
115 ctx->ctx = *k; \
116 } \
117 \
118 /* --- @pre_cbcinit@ --- * \
119 * \
120 * Arguments: @pre_cbcctx *ctx@ = pointer to cipher context \
121 * @const void *key@ = pointer to the key buffer \
122 * @size_t sz@ = size of the key \
123 * @const void *iv@ = pointer to initialization vector \
124 * \
125 * Returns: --- \
126 * \
127 * Use: Initializes a CBC context ready for use. The @iv@ \
128 * argument may be passed as a null pointer to set a zero \
129 * IV. Apart from that, this call is equivalent to calls \
130 * to @pre_init@, @pre_cbcsetkey@ and @pre_cbcsetiv@. \
131 */ \
132 \
133 void pre##_cbcinit(pre##_cbcctx *ctx, \
134 const void *key, size_t sz, \
135 const void *iv) \
136 { \
137 static const octet zero[PRE##_BLKSZ] = { 0 }; \
138 pre##_init(&ctx->ctx, key, sz); \
139 BLKC_LOAD(PRE, ctx->iv, iv ? iv : zero); \
140 } \
141 \
142 /* --- @pre_cbcencrypt@ --- * \
143 * \
144 * Arguments: @pre_cbcctx *ctx@ = pointer to CBC context block \
145 * @const void *src@ = pointer to source data \
146 * @void *dest@ = pointer to destination data \
147 * @size_t sz@ = size of block to be encrypted \
148 * \
149 * Returns: --- \
150 * \
151 * Use: Encrypts a block with a block cipher in CBC mode, with \
152 * ciphertext stealing and other clever tricks. \
153 * Essentially, data can be encrypted in arbitrary sized \
154 * chunks, although decryption must use the same chunks. \
155 */ \
156 \
157 void pre##_cbcencrypt(pre##_cbcctx *ctx, \
158 const void *src, void *dest, \
159 size_t sz) \
160 { \
161 const octet *s = src; \
162 octet *d = dest; \
163 \
164 /* --- Empty blocks are trivial --- */ \
165 \
166 if (!sz) \
167 return; \
168 \
169 /* --- Extra magical case for a short block --- * \
170 * \
171 * Encrypt the IV, then exclusive-or the plaintext with the octets \
172 * of the encrypted IV, shifting ciphertext octets in instead. This \
173 * basically switches over to CFB. \
174 */ \
175 \
176 if (sz < PRE##_BLKSZ) { \
177 octet b[PRE##_BLKSZ]; \
178 unsigned i; \
179 \
180 pre##_eblk(&ctx->ctx, ctx->iv, ctx->iv); \
181 BLKC_STORE(PRE, b, ctx->iv); \
182 if (d) { \
183 for (i = 0; i < sz; i++) \
184 d[i] = b[i] ^ (s ? s[i] : 0); \
185 } \
186 memmove(b, b + sz, PRE##_BLKSZ - sz); \
187 memcpy(b + PRE##_BLKSZ - sz, d, sz); \
188 BLKC_LOAD(PRE, ctx->iv, b); \
189 return; \
190 } \
191 \
192 /* --- Do the main chunk of encryption --- * \
193 * \
194 * This will do the whole lot if it's a whole number of blocks. For \
195 * each block, XOR it with the previous ciphertext in @iv@, encrypt, \
196 * and keep a copy of the ciphertext for the next block. \
197 */ \
198 \
199 while (sz >= 2 * PRE##_BLKSZ || sz == PRE##_BLKSZ) { \
200 if (s) { \
201 BLKC_XLOAD(PRE, ctx->iv, s); \
202 s += PRE##_BLKSZ; \
203 } \
204 pre##_eblk(&ctx->ctx, ctx->iv, ctx->iv); \
205 if (d) { \
206 BLKC_STORE(PRE, d, ctx->iv); \
207 d += PRE##_BLKSZ; \
208 } \
209 sz -= PRE##_BLKSZ; \
210 } \
211 \
212 /* --- Do the tail-end block and bit-left-over --- * \
213 * \
214 * This isn't very efficient. That shouldn't matter much. \
215 */ \
216 \
217 if (sz) { \
218 octet b[PRE##_BLKSZ]; \
219 unsigned i; \
220 \
221 /* --- Let @sz@ be the size of the partial block --- */ \
222 \
223 sz -= PRE##_BLKSZ; \
224 \
225 /* --- First stage --- * \
226 * \
227 * XOR the complete block with the current IV, and encrypt it. The \
228 * first part of the result is the partial ciphertext block. Don't \
229 * write that out yet, because I've not read the partial plaintext \
230 * block. \
231 */ \
232 \
233 if (s) BLKC_XLOAD(PRE, ctx->iv, s); \
234 pre##_eblk(&ctx->ctx, ctx->iv, ctx->iv); \
235 BLKC_STORE(PRE, b, ctx->iv); \
236 \
237 /* --- Second stage --- * \
238 * \
239 * Now XOR in the partial plaintext block, writing out the \
240 * ciphertext as I go. Then encrypt, and write the complete \
241 * ciphertext block. \
242 */ \
243 \
244 if (s) s += PRE##_BLKSZ; \
245 if (d) d += PRE##_BLKSZ; \
246 for (i = 0; i < sz; i++) { \
247 register octet x = b[i]; \
248 if (s) b[i] ^= s[i]; \
249 if (d) d[i] = x; \
250 } \
251 BLKC_LOAD(PRE, ctx->iv, b); \
252 pre##_eblk(&ctx->ctx, ctx->iv, ctx->iv); \
253 if (d) BLKC_STORE(PRE, d - PRE##_BLKSZ, ctx->iv); \
254 } \
255 \
256 /* --- Done --- */ \
257 \
258 return; \
259 } \
260 \
261 /* --- @pre_cbcdecrypt@ --- * \
262 * \
263 * Arguments: @pre_cbcctx *ctx@ = pointer to CBC context block \
264 * @const void *src@ = pointer to source data \
265 * @void *dest@ = pointer to destination data \
266 * @size_t sz@ = size of block to be encrypted \
267 * \
268 * Returns: --- \
269 * \
270 * Use: Decrypts a block with a block cipher in CBC mode, with \
271 * ciphertext stealing and other clever tricks. \
272 * Essentially, data can be encrypted in arbitrary sized \
273 * chunks, although decryption must use the same chunks. \
274 */ \
275 \
276 void pre##_cbcdecrypt(pre##_cbcctx *ctx, \
277 const void *src, void *dest, \
278 size_t sz) \
279 { \
280 const octet *s = src; \
281 octet *d = dest; \
282 \
283 /* --- Empty blocks are trivial --- */ \
284 \
285 if (!sz) \
286 return; \
287 \
288 /* --- Extra magical case for a short block --- * \
289 * \
290 * Encrypt the IV, then exclusive-or the ciphertext with the octets \
291 * of the encrypted IV, shifting ciphertext octets in instead. This \
292 * basically switches over to CFB. \
293 */ \
294 \
295 if (sz < PRE##_BLKSZ) { \
296 octet b[PRE##_BLKSZ], c[PRE##_BLKSZ]; \
297 unsigned i; \
298 \
299 pre##_eblk(&ctx->ctx, ctx->iv, ctx->iv); \
300 BLKC_STORE(PRE, b, ctx->iv); \
301 for (i = 0; i < sz; i++) { \
302 register octet x = s[i]; \
303 d[i] = b[i] ^ x; \
304 c[i] = x; \
305 } \
306 memmove(b, b + sz, PRE##_BLKSZ - sz); \
307 memcpy(b + PRE##_BLKSZ - sz, c, sz); \
308 BLKC_LOAD(PRE, ctx->iv, b); \
309 return; \
310 } \
311 \
312 /* --- Do the main chunk of decryption --- * \
313 * \
314 * This will do the whole lot if it's a whole number of blocks. For \
315 * each block, decrypt, XOR it with the previous ciphertext in @iv@, \
316 * and keep a copy of the ciphertext for the next block. \
317 */ \
318 \
319 while (sz >= 2 * PRE##_BLKSZ || sz == PRE##_BLKSZ) { \
320 uint32 b[PRE##_BLKSZ / 4], niv[PRE##_BLKSZ / 4]; \
321 BLKC_LOAD(PRE, niv, s); \
322 pre##_dblk(&ctx->ctx, niv, b); \
323 BLKC_XSTORE(PRE, d, b, ctx->iv); \
324 BLKC_MOVE(PRE, ctx->iv, niv); \
325 s += PRE##_BLKSZ; \
326 d += PRE##_BLKSZ; \
327 sz -= PRE##_BLKSZ; \
328 } \
329 \
330 /* --- Do the tail-end block and bit-left-over --- * \
331 * \
332 * This isn't very efficient. That shouldn't matter much. \
333 */ \
334 \
335 if (sz) { \
336 octet b[PRE##_BLKSZ]; \
337 uint32 bk[PRE##_BLKSZ / 4], niv[PRE##_BLKSZ / 4]; \
338 unsigned i; \
339 \
340 /* --- Let @sz@ be the size of the partial block --- */ \
341 \
342 sz -= PRE##_BLKSZ; \
343 \
344 /* --- First stage --- * \
345 * \
346 * Take the complete ciphertext block, and decrypt it. This block \
347 * is carried over for the next encryption operation. \
348 */ \
349 \
350 BLKC_LOAD(PRE, niv, s); \
351 pre##_dblk(&ctx->ctx, niv, bk); \
352 \
353 /* --- Second stage --- * \
354 * \
355 * XORing the first few bytes of this with the partial ciphertext \
356 * block recovers the partial plaintext block. At the same time, \
357 * write the partial ciphertext block's contents in ready for stage \
358 * three. \
359 */ \
360 \
361 BLKC_STORE(PRE, b, bk); \
362 s += PRE##_BLKSZ; \
363 d += PRE##_BLKSZ; \
364 for (i = 0; i < sz; i++) { \
365 register octet x = s[i]; \
366 d[i] = b[i] ^ x; \
367 b[i] = x; \
368 } \
369 \
370 /* --- Third stage --- * \
371 * \
372 * Decrypt the block we've got left, and XOR with the initial IV to \
373 * recover the complete plaintext block. \
374 */ \
375 \
376 BLKC_LOAD(PRE, bk, b); \
377 pre##_dblk(&ctx->ctx, bk, bk); \
378 BLKC_XSTORE(PRE, d - PRE##_BLKSZ, bk, ctx->iv); \
379 BLKC_MOVE(PRE, ctx->iv, niv); \
380 } \
381 \
382 /* --- Done --- */ \
383 \
384 return; \
385 } \
386 \
387 /* --- Generic cipher interface --- */ \
388 \
389 static const gcipher_ops gops; \
390 \
391 typedef struct gctx { \
392 gcipher c; \
393 pre##_cbcctx k; \
394 } gctx; \
395 \
396 static gcipher *ginit(const void *k, size_t sz) \
397 { \
398 gctx *g = S_CREATE(gctx); \
399 g->c.ops = &gops; \
400 pre##_cbcinit(&g->k, k, sz, 0); \
401 return (&g->c); \
402 } \
403 \
404 static void gencrypt(gcipher *c, const void *s, void *t, size_t sz) \
405 { \
406 gctx *g = (gctx *)c; \
407 pre##_cbcencrypt(&g->k, s, t, sz); \
408 } \
409 \
410 static void gdecrypt(gcipher *c, const void *s, void *t, size_t sz) \
411 { \
412 gctx *g = (gctx *)c; \
413 pre##_cbcdecrypt(&g->k, s, t, sz); \
414 } \
415 \
416 static void gdestroy(gcipher *c) \
417 { \
418 gctx *g = (gctx *)c; \
419 BURN(*g); \
420 S_DESTROY(g); \
421 } \
422 \
423 static void gsetiv(gcipher *c, const void *iv) \
424 { \
425 gctx *g = (gctx *)c; \
426 pre##_cbcsetiv(&g->k, iv); \
427 } \
428 \
429 static const gcipher_ops gops = { \
430 &pre##_cbc, \
431 gencrypt, gdecrypt, gdestroy, gsetiv, 0 \
432 }; \
433 \
434 const gccipher pre##_cbc = { \
435 #pre "-cbc", pre##_keysz, PRE##_BLKSZ, \
436 ginit \
437 }; \
438 \
439 CBC_TEST(PRE, pre)
440
441 /*----- Test rig ----------------------------------------------------------*/
442
443 #ifdef TEST_RIG
444
445 #include <stdio.h>
446
447 #include "daftstory.h"
448
449 /* --- @CBC_TEST@ --- *
450 *
451 * Arguments: @PRE@, @pre@ = prefixes for block cipher definitions
452 *
453 * Use: Standard test rig for CBC functions.
454 */
455
456 #define CBC_TEST(PRE, pre) \
457 \
458 /* --- Initial plaintext for the test --- */ \
459 \
460 static const octet text[] = TEXT; \
461 \
462 /* --- Key and IV to use --- */ \
463 \
464 static const octet key[] = KEY; \
465 static const octet iv[] = IV; \
466 \
467 /* --- Buffers for encryption and decryption output --- */ \
468 \
469 static octet ct[sizeof(text)]; \
470 static octet pt[sizeof(text)]; \
471 \
472 static void hexdump(const octet *p, size_t sz) \
473 { \
474 const octet *q = p + sz; \
475 for (sz = 0; p < q; p++, sz++) { \
476 printf("%02x", *p); \
477 if ((sz + 1) % PRE##_BLKSZ == 0) \
478 putchar(':'); \
479 } \
480 } \
481 \
482 int main(void) \
483 { \
484 size_t sz = 0, rest; \
485 pre##_cbcctx ctx; \
486 pre##_ctx k; \
487 int status = 0; \
488 int done = 0; \
489 \
490 size_t keysz = PRE##_KEYSZ ? \
491 PRE##_KEYSZ : strlen((const char *)key); \
492 \
493 fputs(#pre "-cbc: ", stdout); \
494 \
495 pre##_init(&k, key, keysz); \
496 pre##_cbcsetkey(&ctx, &k); \
497 \
498 while (sz <= sizeof(text)) { \
499 rest = sizeof(text) - sz; \
500 memcpy(ct, text, sizeof(text)); \
501 pre##_cbcsetiv(&ctx, iv); \
502 pre##_cbcencrypt(&ctx, ct, ct, sz); \
503 pre##_cbcencrypt(&ctx, ct + sz, ct + sz, rest); \
504 memcpy(pt, ct, sizeof(text)); \
505 pre##_cbcsetiv(&ctx, iv); \
506 pre##_cbcdecrypt(&ctx, pt, pt, sz); \
507 pre##_cbcdecrypt(&ctx, pt + sz, pt + sz, rest); \
508 if (memcmp(pt, text, sizeof(text)) == 0) { \
509 done++; \
510 if (sizeof(text) < 40 || done % 8 == 0) \
511 fputc('.', stdout); \
512 if (done % 480 == 0) \
513 fputs("\n\t", stdout); \
514 fflush(stdout); \
515 } else { \
516 printf("\nError (sz = %lu)\n", (unsigned long)sz); \
517 status = 1; \
518 printf("\tplaintext = "); hexdump(text, sz); \
519 printf(", "); hexdump(text + sz, rest); \
520 fputc('\n', stdout); \
521 printf("\tciphertext = "); hexdump(ct, sz); \
522 printf(", "); hexdump(ct + sz, rest); \
523 fputc('\n', stdout); \
524 printf("\trecovered text = "); hexdump(pt, sz); \
525 printf(", "); hexdump(pt + sz, rest); \
526 fputc('\n', stdout); \
527 fputc('\n', stdout); \
528 } \
529 if (sz < 63) \
530 sz++; \
531 else \
532 sz += 9; \
533 } \
534 \
535 fputs(status ? " failed\n" : " ok\n", stdout); \
536 return (status); \
537 }
538
539 #else
540 # define CBC_TEST(PRE, pre)
541 #endif
542
543 /*----- That's all, folks -------------------------------------------------*/
544
545 #ifdef __cplusplus
546 }
547 #endif
548
549 #endif
Catacomb cryptographic library (downstream of http://git.distorted.org.uk/~mdw/catacomb/)