d03ab969 |
1 | /* -*-c-*- |
2 | * |
3 | * $Id: cbc.h,v 1.1 1999/09/03 08:41:11 mdw Exp $ |
4 | * |
5 | * Ciphertext block chaining for block ciphers |
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.h,v $ |
33 | * Revision 1.1 1999/09/03 08:41:11 mdw |
34 | * Initial import. |
35 | * |
36 | */ |
37 | |
38 | #ifndef CBC_H |
39 | #define CBC_H |
40 | |
41 | #ifdef __cplusplus |
42 | extern "C" { |
43 | #endif |
44 | |
45 | /*----- Header files ------------------------------------------------------*/ |
46 | |
47 | #include <string.h> |
48 | |
49 | #include <mLib/bits.h> |
50 | |
51 | #ifndef BLKC_H |
52 | # include "blkc.h" |
53 | #endif |
54 | |
55 | /*----- Macros ------------------------------------------------------------*/ |
56 | |
57 | /* --- @CBC_DECL@ --- * |
58 | * |
59 | * Arguments: @PRE@, @pre@ = prefixes for the underlying block cipher |
60 | * |
61 | * Use: Creates declarations for CBC stealing mode. |
62 | */ |
63 | |
64 | #define CBC_DECL(PRE, pre) \ |
65 | \ |
66 | typedef struct pre ## _cbcctx { \ |
67 | pre ## _ctx ctx; /* Underlying cipher context */ \ |
68 | uint32 iv[PRE ## _BLKSZ / 4]; /* Previous ciphertext or IV */ \ |
69 | } pre ## _cbcctx; \ |
70 | \ |
71 | extern void pre ## _cbcgetiv(const pre ## _cbcctx */*ctx*/, \ |
72 | void */*iv*/); \ |
73 | \ |
74 | extern void pre ## _cbcsetiv(pre ## _cbcctx */*ctx*/, \ |
75 | const void */*iv*/); \ |
76 | \ |
77 | extern void pre ## _cbcsetkey(pre ## _cbcctx */*ctx*/, \ |
78 | const pre ## _ctx */*k*/); \ |
79 | \ |
80 | extern void pre ## _cbcinit(pre ## _cbcctx */*ctx*/, \ |
81 | const void */*key*/, size_t /*sz*/, \ |
82 | const void */*iv*/); \ |
83 | \ |
84 | extern void pre ## _cbcencrypt(pre ## _cbcctx */*ctx*/, \ |
85 | const void */*src*/, void */*dest*/, \ |
86 | size_t /*sz*/); \ |
87 | \ |
88 | extern void pre ## _cbcdecrypt(pre ## _cbcctx */*ctx*/, \ |
89 | const void */*src*/, void */*dest*/, \ |
90 | size_t /*sz*/); \ |
91 | |
92 | /* --- @CBC_DEF@ --- * |
93 | * |
94 | * Arguments: @PRE@, @pre@ = prefixes for the underlying block cipher |
95 | * |
96 | * Use: Creates an implementation for CBC stealing mode. |
97 | */ |
98 | |
99 | #define CBC_DEF(PRE, pre) \ |
100 | \ |
101 | /* --- @pre_cbcgetiv@ --- * \ |
102 | * \ |
103 | * Arguments: @const pre_cbcctx *ctx@ = pointer to CBC context block \ |
104 | * @void *iv#@ = pointer to output data block \ |
105 | * \ |
106 | * Returns: --- \ |
107 | * \ |
108 | * Use: Reads the currently set IV. Reading and setting an IV \ |
109 | * is transparent to the CBC encryption or decryption \ |
110 | * process. \ |
111 | */ \ |
112 | \ |
113 | void pre ## _cbcgetiv(const pre ## _cbcctx *ctx, void *iv) \ |
114 | { \ |
115 | BLKC_STORE(PRE, iv, ctx->iv); \ |
116 | } \ |
117 | \ |
118 | /* --- @pre_cbcsetiv@ --- * \ |
119 | * \ |
120 | * Arguments: @pre_cbcctx *ctx@ = pointer to CBC context block \ |
121 | * @cnost void *iv@ = pointer to IV to set \ |
122 | * \ |
123 | * Returns: --- \ |
124 | * \ |
125 | * Use: Sets the IV to use for subsequent encryption. \ |
126 | */ \ |
127 | \ |
128 | void pre ## _cbcsetiv(pre ## _cbcctx *ctx, const void *iv) \ |
129 | { \ |
130 | BLKC_LOAD(PRE, ctx->iv, iv); \ |
131 | } \ |
132 | \ |
133 | /* --- @pre_cbcsetkey@ --- * \ |
134 | * \ |
135 | * Arguments: @pre_cbcctx *ctx@ = pointer to CBC context block \ |
136 | * @const pre_ctx *k@ = pointer to cipher context \ |
137 | * \ |
138 | * Returns: --- \ |
139 | * \ |
140 | * Use: Sets the CBC context to use a different cipher key. \ |
141 | */ \ |
142 | \ |
143 | void pre ## _cbcsetkey(pre ## _cbcctx *ctx, const pre ## _ctx *k) \ |
144 | { \ |
145 | ctx->ctx = *k; \ |
146 | } \ |
147 | \ |
148 | /* --- @pre_cbcinit@ --- * \ |
149 | * \ |
150 | * Arguments: @pre_cbcctx *ctx@ = pointer to cipher context \ |
151 | * @const void *key@ = pointer to the key buffer \ |
152 | * @size_t sz@ = size of the key \ |
153 | * @const void *iv@ = pointer to initialization vector \ |
154 | * \ |
155 | * Returns: --- \ |
156 | * \ |
157 | * Use: Initializes a CBC context ready for use. The @iv@ \ |
158 | * argument may be passed as a null pointer to set a zero \ |
159 | * IV. Apart from that, this call is equivalent to calls \ |
160 | * to @pre_init@, @pre_cbcsetkey@ and @pre_cbcsetiv@. \ |
161 | */ \ |
162 | \ |
163 | void pre ## _cbcinit(pre ## _cbcctx *ctx, \ |
164 | const void *key, size_t sz, \ |
165 | const void *iv) \ |
166 | { \ |
167 | static octet zero[PRE ## _BLKSZ] = { 0 }; \ |
168 | pre ## _init(&ctx->ctx, key, sz); \ |
169 | BLKC_LOAD(PRE, ctx->iv, iv ? iv : zero); \ |
170 | } \ |
171 | \ |
172 | /* --- @pre_cbcencrypt@ --- * \ |
173 | * \ |
174 | * Arguments: @pre_cbcctx *ctx@ = pointer to CBC context block \ |
175 | * @const void *src@ = pointer to source data \ |
176 | * @void *dest@ = pointer to destination data \ |
177 | * @size_t sz@ = size of block to be encrypted \ |
178 | * \ |
179 | * Returns: --- \ |
180 | * \ |
181 | * Use: Encrypts a block with a block cipher in CBC mode, with \ |
182 | * ciphertext stealing and other clever tricks. \ |
183 | * Essentially, data can be encrypted in arbitrary sized \ |
184 | * chunks, although decryption must use the same chunks. \ |
185 | */ \ |
186 | \ |
187 | void pre ## _cbcencrypt(pre ## _cbcctx *ctx, \ |
188 | const void *src, void *dest, \ |
189 | size_t sz) \ |
190 | { \ |
191 | const octet *s = src; \ |
192 | octet *d = dest; \ |
193 | \ |
194 | /* --- Empty blocks are trivial --- */ \ |
195 | \ |
196 | if (!sz) \ |
197 | return; \ |
198 | \ |
199 | /* --- Extra magical case for a short block --- * \ |
200 | * \ |
201 | * Encrypt the IV, then exclusive-or the plaintext with the octets \ |
202 | * of the encrypted IV, shifting ciphertext octets in instead. This \ |
203 | * basically switches over to CFB. \ |
204 | */ \ |
205 | \ |
206 | if (sz < PRE ## _BLKSZ) { \ |
207 | octet b[PRE ## _BLKSZ]; \ |
208 | unsigned i; \ |
209 | \ |
210 | pre ## _eblk(&ctx->ctx, ctx->iv, ctx->iv); \ |
211 | BLKC_STORE(PRE, b, ctx->iv); \ |
212 | for (i = 0; i < sz; i++) \ |
213 | d[i] = b[i] ^ s[i]; \ |
214 | memmove(b, b + sz, PRE ## _BLKSZ - sz); \ |
215 | memcpy(b + PRE ## _BLKSZ - sz, d, sz); \ |
216 | BLKC_LOAD(PRE, ctx->iv, b); \ |
217 | return; \ |
218 | } \ |
219 | \ |
220 | /* --- Do the main chunk of encryption --- * \ |
221 | * \ |
222 | * This will do the whole lot if it's a whole number of blocks. For \ |
223 | * each block, XOR it with the previous ciphertext in @iv@, encrypt, \ |
224 | * and keep a copy of the ciphertext for the next block. \ |
225 | */ \ |
226 | \ |
227 | while (sz >= 2 * PRE ## _BLKSZ || sz == PRE ## _BLKSZ) { \ |
228 | BLKC_XLOAD(PRE, ctx->iv, s); \ |
229 | pre ## _eblk(&ctx->ctx, ctx->iv, ctx->iv); \ |
230 | BLKC_STORE(PRE, d, ctx->iv); \ |
231 | s += PRE ## _BLKSZ; \ |
232 | d += PRE ## _BLKSZ; \ |
233 | sz -= PRE ## _BLKSZ; \ |
234 | } \ |
235 | \ |
236 | /* --- Do the tail-end block and bit-left-over --- * \ |
237 | * \ |
238 | * This isn't very efficient. That shouldn't matter much. \ |
239 | */ \ |
240 | \ |
241 | if (sz) { \ |
242 | octet b[PRE ## _BLKSZ]; \ |
243 | unsigned i; \ |
244 | \ |
245 | /* --- Let @sz@ be the size of the partial block --- */ \ |
246 | \ |
247 | sz -= PRE ## _BLKSZ; \ |
248 | \ |
249 | /* --- First stage --- * \ |
250 | * \ |
251 | * XOR the complete block with the current IV, and encrypt it. The \ |
252 | * first part of the result is the partial ciphertext block. Don't \ |
253 | * write that out yet, because I've not read the partial plaintext \ |
254 | * block. \ |
255 | */ \ |
256 | \ |
257 | BLKC_XLOAD(PRE, ctx->iv, s); \ |
258 | pre ## _eblk(&ctx->ctx, ctx->iv, ctx->iv); \ |
259 | BLKC_STORE(PRE, b, ctx->iv); \ |
260 | \ |
261 | /* --- Second stage --- * \ |
262 | * \ |
263 | * Now XOR in the partial plaintext block, writing out the \ |
264 | * ciphertext as I go. Then encrypt, and write the complete \ |
265 | * ciphertext block. \ |
266 | */ \ |
267 | \ |
268 | s += PRE ## _BLKSZ; \ |
269 | d += PRE ## _BLKSZ; \ |
270 | for (i = 0; i < sz; i++) { \ |
271 | register octet x = b[i]; \ |
272 | b[i] ^= s[i]; \ |
273 | d[i] = x; \ |
274 | } \ |
275 | BLKC_LOAD(PRE, ctx->iv, b); \ |
276 | pre ## _eblk(&ctx->ctx, ctx->iv, ctx->iv); \ |
277 | BLKC_STORE(PRE, d - PRE ## _BLKSZ, ctx->iv); \ |
278 | } \ |
279 | \ |
280 | /* --- Done --- */ \ |
281 | \ |
282 | return; \ |
283 | } \ |
284 | \ |
285 | /* --- @pre_cbcdecrypt@ --- * \ |
286 | * \ |
287 | * Arguments: @pre_cbcctx *ctx@ = pointer to CBC context block \ |
288 | * @const void *src@ = pointer to source data \ |
289 | * @void *dest@ = pointer to destination data \ |
290 | * @size_t sz@ = size of block to be encrypted \ |
291 | * \ |
292 | * Returns: --- \ |
293 | * \ |
294 | * Use: Encrypts a block with a block cipher in CBC mode, with \ |
295 | * ciphertext stealing and other clever tricks. \ |
296 | * Essentially, data can be encrypted in arbitrary sized \ |
297 | * chunks, although decryption must use the same chunks. \ |
298 | */ \ |
299 | \ |
300 | void pre ## _cbcdecrypt(pre ## _cbcctx *ctx, \ |
301 | const void *src, void *dest, \ |
302 | size_t sz) \ |
303 | { \ |
304 | const octet *s = src; \ |
305 | octet *d = dest; \ |
306 | \ |
307 | /* --- Empty blocks are trivial --- */ \ |
308 | \ |
309 | if (!sz) \ |
310 | return; \ |
311 | \ |
312 | /* --- Extra magical case for a short block --- * \ |
313 | * \ |
314 | * Encrypt the IV, then exclusive-or the ciphertext with the octets \ |
315 | * of the encrypted IV, shifting ciphertext octets in instead. This \ |
316 | * basically switches over to CFB. \ |
317 | */ \ |
318 | \ |
319 | if (sz < PRE ## _BLKSZ) { \ |
320 | octet b[PRE ## _BLKSZ], c[PRE ## _BLKSZ]; \ |
321 | unsigned i; \ |
322 | \ |
323 | pre ## _eblk(&ctx->ctx, ctx->iv, ctx->iv); \ |
324 | BLKC_STORE(PRE, b, ctx->iv); \ |
325 | for (i = 0; i < sz; i++) { \ |
326 | register octet x = s[i]; \ |
327 | d[i] = b[i] ^ x; \ |
328 | c[i] = x; \ |
329 | } \ |
330 | memmove(b, b + sz, PRE ## _BLKSZ - sz); \ |
331 | memcpy(b + PRE ## _BLKSZ - sz, c, sz); \ |
332 | BLKC_LOAD(PRE, ctx->iv, b); \ |
333 | return; \ |
334 | } \ |
335 | \ |
336 | /* --- Do the main chunk of decryption --- * \ |
337 | * \ |
338 | * This will do the whole lot if it's a whole number of blocks. For \ |
339 | * each block, decrypt, XOR it with the previous ciphertext in @iv@, \ |
340 | * and keep a copy of the ciphertext for the next block. \ |
341 | */ \ |
342 | \ |
343 | while (sz >= 2 * PRE ## _BLKSZ || sz == PRE ## _BLKSZ) { \ |
344 | uint32 b[PRE ## _BLKSZ / 4], niv[PRE ## _BLKSZ / 4]; \ |
345 | BLKC_LOAD(PRE, niv, s); \ |
346 | pre ## _dblk(&ctx->ctx, niv, b); \ |
347 | BLKC_XSTORE(PRE, d, b, ctx->iv); \ |
348 | BLKC_MOVE(PRE, ctx->iv, niv); \ |
349 | s += PRE ## _BLKSZ; \ |
350 | d += PRE ## _BLKSZ; \ |
351 | sz -= PRE ## _BLKSZ; \ |
352 | } \ |
353 | \ |
354 | /* --- Do the tail-end block and bit-left-over --- * \ |
355 | * \ |
356 | * This isn't very efficient. That shouldn't matter much. \ |
357 | */ \ |
358 | \ |
359 | if (sz) { \ |
360 | octet b[PRE ## _BLKSZ]; \ |
361 | uint32 bk[PRE ## _BLKSZ / 4], niv[PRE ## _BLKSZ / 4]; \ |
362 | unsigned i; \ |
363 | \ |
364 | /* --- Let @sz@ be the size of the partial block --- */ \ |
365 | \ |
366 | sz -= PRE ## _BLKSZ; \ |
367 | \ |
368 | /* --- First stage --- * \ |
369 | * \ |
370 | * Take the complete ciphertext block, and decrypt it. This block \ |
371 | * is carried over for the next encryption operation. \ |
372 | */ \ |
373 | \ |
374 | BLKC_LOAD(PRE, niv, s); \ |
375 | pre ## _dblk(&ctx->ctx, niv, bk); \ |
376 | \ |
377 | /* --- Second stage --- * \ |
378 | * \ |
379 | * XORing the first few bytes of this with the partial ciphertext \ |
380 | * block recovers the partial plaintext block. At the same time, \ |
381 | * write the partial ciphertext block's contents in ready for stage \ |
382 | * three. \ |
383 | */ \ |
384 | \ |
385 | BLKC_STORE(PRE, b, bk); \ |
386 | s += PRE ## _BLKSZ; \ |
387 | d += PRE ## _BLKSZ; \ |
388 | for (i = 0; i < sz; i++) { \ |
389 | register octet x = s[i]; \ |
390 | d[i] = b[i] ^ x; \ |
391 | b[i] = x; \ |
392 | } \ |
393 | \ |
394 | /* --- Third stage --- * \ |
395 | * \ |
396 | * Decrypt the block we've got left, and XOR with the initial IV to \ |
397 | * recover the complete plaintext block. \ |
398 | */ \ |
399 | \ |
400 | BLKC_LOAD(PRE, bk, b); \ |
401 | pre ## _dblk(&ctx->ctx, bk, bk); \ |
402 | BLKC_XSTORE(PRE, d - PRE ## _BLKSZ, bk, ctx->iv); \ |
403 | BLKC_MOVE(PRE, ctx->iv, niv); \ |
404 | } \ |
405 | \ |
406 | /* --- Done --- */ \ |
407 | \ |
408 | return; \ |
409 | } \ |
410 | \ |
411 | CBC_TEST(PRE, pre) |
412 | |
413 | /*----- Test rig ----------------------------------------------------------*/ |
414 | |
415 | #ifdef TEST_RIG |
416 | |
417 | #include <stdio.h> |
418 | |
419 | #include "daftstory.h" |
420 | |
421 | /* --- @CBC_TEST@ --- * |
422 | * |
423 | * Arguments: @PRE@, @pre@ = prefixes for block cipher definitions |
424 | * |
425 | * Use: Standard test rig for CBC functions. |
426 | */ |
427 | |
428 | #define CBC_TEST(PRE, pre) \ |
429 | \ |
430 | /* --- Initial plaintext for the test --- */ \ |
431 | \ |
432 | static const octet text[] = TEXT; \ |
433 | \ |
434 | /* --- Key and IV to use --- */ \ |
435 | \ |
436 | static const octet key[] = KEY; \ |
437 | static const octet iv[] = IV; \ |
438 | \ |
439 | /* --- Buffers for encryption and decryption output --- */ \ |
440 | \ |
441 | static octet ct[sizeof(text)]; \ |
442 | static octet pt[sizeof(text)]; \ |
443 | \ |
444 | static void hexdump(const octet *p, size_t sz) \ |
445 | { \ |
446 | const octet *q = p + sz; \ |
447 | for (sz = 0; p < q; p++, sz++) { \ |
448 | printf("%02x", *p); \ |
449 | if ((sz + 1) % PRE ## _BLKSZ == 0) \ |
450 | putchar(':'); \ |
451 | } \ |
452 | } \ |
453 | \ |
454 | int main(void) \ |
455 | { \ |
456 | size_t sz = 0, rest; \ |
457 | pre ## _cbcctx ctx; \ |
458 | pre ## _ctx k; \ |
459 | int status = 0; \ |
460 | int done = 0; \ |
461 | \ |
462 | size_t keysz = PRE ## _KEYSZ ? \ |
463 | PRE ## _KEYSZ : strlen((const char *)key); \ |
464 | \ |
465 | fputs(#pre "-cbc: ", stdout); \ |
466 | \ |
467 | pre ## _init(&k, key, keysz); \ |
468 | pre ## _cbcsetkey(&ctx, &k); \ |
469 | \ |
470 | while (sz <= sizeof(text)) { \ |
471 | rest = sizeof(text) - sz; \ |
472 | memcpy(ct, text, sizeof(text)); \ |
473 | pre ## _cbcsetiv(&ctx, iv); \ |
474 | pre ## _cbcencrypt(&ctx, ct, ct, sz); \ |
475 | pre ## _cbcencrypt(&ctx, ct + sz, ct + sz, rest); \ |
476 | memcpy(pt, ct, sizeof(text)); \ |
477 | pre ## _cbcsetiv(&ctx, iv); \ |
478 | pre ## _cbcdecrypt(&ctx, pt, pt, sz); \ |
479 | pre ## _cbcdecrypt(&ctx, pt + sz, pt + sz, rest); \ |
480 | if (memcmp(pt, text, sizeof(text)) == 0) { \ |
481 | done++; \ |
482 | if (sizeof(text) < 40 || done % 8 == 0) \ |
483 | fputc('.', stdout); \ |
484 | if (done % 480 == 0) \ |
485 | fputs("\n\t", stdout); \ |
486 | fflush(stdout); \ |
487 | } else { \ |
488 | printf("\nError (sz = %lu)\n", (unsigned long)sz); \ |
489 | status = 1; \ |
490 | printf("\tplaintext = "); hexdump(text, sz); \ |
491 | printf(", "); hexdump(text + sz, rest); \ |
492 | fputc('\n', stdout); \ |
493 | printf("\tciphertext = "); hexdump(ct, sz); \ |
494 | printf(", "); hexdump(ct + sz, rest); \ |
495 | fputc('\n', stdout); \ |
496 | printf("\trecovered text = "); hexdump(pt, sz); \ |
497 | printf(", "); hexdump(pt + sz, rest); \ |
498 | fputc('\n', stdout); \ |
499 | fputc('\n', stdout); \ |
500 | } \ |
501 | if (sz < 63) \ |
502 | sz++; \ |
503 | else \ |
504 | sz += 9; \ |
505 | } \ |
506 | \ |
507 | fputs(status ? " failed\n" : " ok\n", stdout); \ |
508 | return (status); \ |
509 | } |
510 | |
511 | #else |
512 | # define CBC_TEST(PRE, pre) |
513 | #endif |
514 | |
515 | /*----- That's all, folks -------------------------------------------------*/ |
516 | |
517 | #ifdef __cplusplus |
518 | } |
519 | #endif |
520 | |
521 | #endif |