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[u/mdw/catacomb] / cfb-def.h
1 /* -*-c-*-
2 *
3 * $Id: cfb-def.h,v 1.6 2004/04/17 09:58:37 mdw Exp $
4 *
5 * Definitions for ciphertext feedback 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_CFB_DEF_H
31 #define CATACOMB_CFB_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 #ifndef CATACOMB_PARANOIA_H
61 # include "paranoia.h"
62 #endif
63
64 /*----- Macros ------------------------------------------------------------*/
65
66 /* --- @CFB_DEF@ --- *
67 *
68 * Arguments: @PRE@, @pre@ = prefixes for the underlying block cipher
69 *
70 * Use: Creates an implementation for CFB mode.
71 */
72
73 #define CFB_DEF(PRE, pre) \
74 \
75 /* --- @pre_cfbgetiv@ --- * \
76 * \
77 * Arguments: @const pre_cfbctx *ctx@ = pointer to CFB context block \
78 * @void *iv@ = pointer to output data block \
79 * \
80 * Returns: --- \
81 * \
82 * Use: Reads the currently set IV. Reading and setting an IV \
83 * is not transparent to the cipher. It will add a `step' \
84 * which must be matched by a similar operation during \
85 * decryption. \
86 */ \
87 \
88 void pre##_cfbgetiv(const pre##_cfbctx *ctx, void *iv) \
89 { \
90 octet *p = iv; \
91 unsigned off = ctx->off; \
92 unsigned rest = PRE##_BLKSZ - off; \
93 memcpy(p, ctx->iv + off, rest); \
94 memcpy(p + rest, ctx->iv, off); \
95 } \
96 \
97 /* --- @pre_cfbsetiv@ --- * \
98 * \
99 * Arguments: @pre_cfbctx *ctx@ = pointer to CFB context block \
100 * @cnost void *iv@ = pointer to IV to set \
101 * \
102 * Returns: --- \
103 * \
104 * Use: Sets the IV to use for subsequent encryption. \
105 */ \
106 \
107 void pre##_cfbsetiv(pre##_cfbctx *ctx, const void *iv) \
108 { \
109 memcpy(ctx->iv, iv, PRE##_BLKSZ); \
110 ctx->off = PRE##_BLKSZ; \
111 } \
112 \
113 /* --- @pre_cfbbdry@ --- * \
114 * \
115 * Arguments: @pre_cfbctx *ctx@ = pointer to CFB context block \
116 * \
117 * Returns: --- \
118 * \
119 * Use: Inserts a boundary during encryption. Successful \
120 * decryption must place a similar boundary. \
121 */ \
122 \
123 void pre##_cfbbdry(pre##_cfbctx *ctx) \
124 { \
125 uint32 niv[PRE##_BLKSZ / 4]; \
126 BLKC_LOAD(PRE, niv, ctx->iv); \
127 pre##_eblk(&ctx->ctx, niv, niv); \
128 BLKC_STORE(PRE, ctx->iv, niv); \
129 ctx->off = PRE##_BLKSZ; \
130 BURN(niv); \
131 } \
132 \
133 /* --- @pre_cfbsetkey@ --- * \
134 * \
135 * Arguments: @pre_cfbctx *ctx@ = pointer to CFB context block \
136 * @const pre_ctx *k@ = pointer to cipher context \
137 * \
138 * Returns: --- \
139 * \
140 * Use: Sets the CFB context to use a different cipher key. \
141 */ \
142 \
143 void pre##_cfbsetkey(pre##_cfbctx *ctx, const pre##_ctx *k) \
144 { \
145 ctx->ctx = *k; \
146 ctx->off = PRE##_BLKSZ; \
147 } \
148 \
149 /* --- @pre_cfbinit@ --- * \
150 * \
151 * Arguments: @pre_cfbctx *ctx@ = pointer to cipher context \
152 * @const void *key@ = pointer to the key buffer \
153 * @size_t sz@ = size of the key \
154 * @const void *iv@ = pointer to initialization vector \
155 * \
156 * Returns: --- \
157 * \
158 * Use: Initializes a CFB context ready for use. You should \
159 * ensure that the IV chosen is unique: reusing an IV will \
160 * compromise the security of at least the first block \
161 * encrypted. This is equivalent to calls to @pre_init@, \
162 * @pre_cfbsetkey@ and @pre_cfbsetiv@. \
163 */ \
164 \
165 void pre##_cfbinit(pre##_cfbctx *ctx, \
166 const void *key, size_t sz, \
167 const void *iv) \
168 { \
169 static const octet zero[PRE##_BLKSZ] = { 0 }; \
170 pre##_init(&ctx->ctx, key, sz); \
171 pre##_cfbsetiv(ctx, iv ? iv : zero); \
172 } \
173 \
174 /* --- @pre_cfbencrypt@ --- * \
175 * \
176 * Arguments: @pre_cfbctx *ctx@ = pointer to CFB context block \
177 * @const void *src@ = pointer to source data \
178 * @void *dest@ = pointer to destination data \
179 * @size_t sz@ = size of block to be encrypted \
180 * \
181 * Returns: --- \
182 * \
183 * Use: Encrypts a block with a block cipher in CFB mode. The \
184 * input block may be arbitrary in size. CFB mode is not \
185 * sensitive to block boundaries. \
186 */ \
187 \
188 void pre##_cfbencrypt(pre##_cfbctx *ctx, \
189 const void *src, void *dest, \
190 size_t sz) \
191 { \
192 const octet *s = src; \
193 octet *d = dest; \
194 unsigned off = ctx->off; \
195 \
196 /* --- Empty blocks are trivial --- */ \
197 \
198 if (!sz) \
199 return; \
200 \
201 /* --- If I can deal with the block from my buffer, do that --- */ \
202 \
203 if (sz < PRE##_BLKSZ - off) \
204 goto small; \
205 \
206 /* --- Finish off what's left in my buffer --- */ \
207 \
208 while (off < PRE##_BLKSZ) { \
209 register octet x = *s++; \
210 ctx->iv[off] ^= x; \
211 if (d) *d++ = ctx->iv[off]; \
212 off++; \
213 sz--; \
214 } \
215 \
216 /* --- Main encryption loop --- */ \
217 \
218 { \
219 uint32 iv[PRE##_BLKSZ / 4]; \
220 BLKC_LOAD(PRE, iv, ctx->iv); \
221 \
222 for (;;) { \
223 pre##_eblk(&ctx->ctx, iv, iv); \
224 if (sz < PRE##_BLKSZ) \
225 break; \
226 if (s) { \
227 BLKC_XLOAD(PRE, iv, s); \
228 s += PRE##_BLKSZ; \
229 } \
230 if (d) { \
231 BLKC_STORE(PRE, d, iv); \
232 d += PRE##_BLKSZ; \
233 } \
234 sz -= PRE##_BLKSZ; \
235 } \
236 off = 0; \
237 BLKC_STORE(PRE, ctx->iv, iv); \
238 } \
239 \
240 /* --- Tidying up the tail end --- */ \
241 \
242 if (sz) { \
243 small: \
244 do { \
245 register octet x = *s++; \
246 ctx->iv[off] ^= x; \
247 if (d) *d++ = ctx->iv[off]; \
248 off++; \
249 sz--; \
250 } while (sz); \
251 } \
252 \
253 /* --- Done --- */ \
254 \
255 ctx->off = off; \
256 return; \
257 } \
258 \
259 /* --- @pre_cfbdecrypt@ --- * \
260 * \
261 * Arguments: @pre_cfbctx *ctx@ = pointer to CFB context block \
262 * @const void *src@ = pointer to source data \
263 * @void *dest@ = pointer to destination data \
264 * @size_t sz@ = size of block to be encrypted \
265 * \
266 * Returns: --- \
267 * \
268 * Use: Decrypts a block with a block cipher in CFB mode. The \
269 * input block may be arbitrary in size. CFB mode is not \
270 * sensitive to block boundaries. \
271 */ \
272 \
273 void pre##_cfbdecrypt(pre##_cfbctx *ctx, \
274 const void *src, void *dest, \
275 size_t sz) \
276 { \
277 const octet *s = src; \
278 octet *d = dest; \
279 unsigned off = ctx->off; \
280 \
281 /* --- Empty blocks are trivial --- */ \
282 \
283 if (!sz) \
284 return; \
285 \
286 /* --- If I can deal with the block from my buffer, do that --- */ \
287 \
288 if (sz < PRE##_BLKSZ - off) \
289 goto small; \
290 \
291 /* --- Finish off what's left in my buffer --- */ \
292 \
293 while (off < PRE##_BLKSZ) { \
294 register octet x = *s++; \
295 *d++ = ctx->iv[off] ^ x; \
296 ctx->iv[off++] = x; \
297 sz--; \
298 } \
299 \
300 /* --- Main encryption loop --- */ \
301 \
302 { \
303 uint32 iv[PRE##_BLKSZ / 4]; \
304 BLKC_LOAD(PRE, iv, ctx->iv); \
305 \
306 for (;;) { \
307 uint32 x[PRE##_BLKSZ / 4]; \
308 pre##_eblk(&ctx->ctx, iv, iv); \
309 if (sz < PRE##_BLKSZ) \
310 break; \
311 BLKC_LOAD(PRE, x, s); \
312 BLKC_XSTORE(PRE, d, iv, x); \
313 BLKC_MOVE(PRE, iv, x); \
314 s += PRE##_BLKSZ; \
315 d += PRE##_BLKSZ; \
316 sz -= PRE##_BLKSZ; \
317 } \
318 off = 0; \
319 BLKC_STORE(PRE, ctx->iv, iv); \
320 } \
321 \
322 /* --- Tidying up the tail end --- */ \
323 \
324 if (sz) { \
325 small: \
326 do { \
327 register octet x = *s++; \
328 *d++ = ctx->iv[off] ^ x; \
329 ctx->iv[off++] = x; \
330 sz--; \
331 } while (sz); \
332 } \
333 \
334 /* --- Done --- */ \
335 \
336 ctx->off = off; \
337 return; \
338 } \
339 \
340 /* --- Generic cipher interface --- */ \
341 \
342 static const gcipher_ops gops; \
343 \
344 typedef struct gctx { \
345 gcipher c; \
346 pre##_cfbctx k; \
347 } gctx; \
348 \
349 static gcipher *ginit(const void *k, size_t sz) \
350 { \
351 gctx *g = S_CREATE(gctx); \
352 g->c.ops = &gops; \
353 pre##_cfbinit(&g->k, k, sz, 0); \
354 return (&g->c); \
355 } \
356 \
357 static void gencrypt(gcipher *c, const void *s, void *t, size_t sz) \
358 { \
359 gctx *g = (gctx *)c; \
360 pre##_cfbencrypt(&g->k, s, t, sz); \
361 } \
362 \
363 static void gdecrypt(gcipher *c, const void *s, void *t, size_t sz) \
364 { \
365 gctx *g = (gctx *)c; \
366 pre##_cfbdecrypt(&g->k, s, t, sz); \
367 } \
368 \
369 static void gdestroy(gcipher *c) \
370 { \
371 gctx *g = (gctx *)c; \
372 BURN(*g); \
373 S_DESTROY(g); \
374 } \
375 \
376 static void gsetiv(gcipher *c, const void *iv) \
377 { \
378 gctx *g = (gctx *)c; \
379 pre##_cfbsetiv(&g->k, iv); \
380 } \
381 \
382 static void gbdry(gcipher *c) \
383 { \
384 gctx *g = (gctx *)c; \
385 pre##_cfbbdry(&g->k); \
386 } \
387 \
388 static const gcipher_ops gops = { \
389 &pre##_cfb, \
390 gencrypt, gdecrypt, gdestroy, gsetiv, gbdry \
391 }; \
392 \
393 const gccipher pre##_cfb = { \
394 #pre "-cfb", pre##_keysz, PRE##_BLKSZ, \
395 ginit \
396 }; \
397 \
398 CFB_TEST(PRE, pre)
399
400 /*----- Test rig ----------------------------------------------------------*/
401
402 #ifdef TEST_RIG
403
404 #include <stdio.h>
405
406 #include "daftstory.h"
407
408 /* --- @CFB_TEST@ --- *
409 *
410 * Arguments: @PRE@, @pre@ = prefixes for block cipher definitions
411 *
412 * Use: Standard test rig for CFB functions.
413 */
414
415 #define CFB_TEST(PRE, pre) \
416 \
417 /* --- Initial plaintext for the test --- */ \
418 \
419 static const octet text[] = TEXT; \
420 \
421 /* --- Key and IV to use --- */ \
422 \
423 static const octet key[] = KEY; \
424 static const octet iv[] = IV; \
425 \
426 /* --- Buffers for encryption and decryption output --- */ \
427 \
428 static octet ct[sizeof(text)]; \
429 static octet pt[sizeof(text)]; \
430 \
431 static void hexdump(const octet *p, size_t sz) \
432 { \
433 const octet *q = p + sz; \
434 for (sz = 0; p < q; p++, sz++) { \
435 printf("%02x", *p); \
436 if ((sz + 1) % PRE##_BLKSZ == 0) \
437 putchar(':'); \
438 } \
439 } \
440 \
441 int main(void) \
442 { \
443 size_t sz = 0, rest; \
444 pre##_cfbctx ctx; \
445 int status = 0; \
446 int done = 0; \
447 pre##_ctx k; \
448 \
449 size_t keysz = PRE##_KEYSZ ? \
450 PRE##_KEYSZ : strlen((const char *)key); \
451 \
452 fputs(#pre "-cfb: ", stdout); \
453 \
454 pre##_init(&k, key, keysz); \
455 pre##_cfbsetkey(&ctx, &k); \
456 \
457 while (sz <= sizeof(text)) { \
458 rest = sizeof(text) - sz; \
459 memcpy(ct, text, sizeof(text)); \
460 pre##_cfbsetiv(&ctx, iv); \
461 pre##_cfbencrypt(&ctx, ct, ct, sz); \
462 pre##_cfbencrypt(&ctx, ct + sz, ct + sz, rest); \
463 memcpy(pt, ct, sizeof(text)); \
464 pre##_cfbsetiv(&ctx, iv); \
465 pre##_cfbdecrypt(&ctx, pt, pt, rest); \
466 pre##_cfbdecrypt(&ctx, pt + rest, pt + rest, sz); \
467 if (memcmp(pt, text, sizeof(text)) == 0) { \
468 done++; \
469 if (sizeof(text) < 40 || done % 8 == 0) \
470 fputc('.', stdout); \
471 if (done % 480 == 0) \
472 fputs("\n\t", stdout); \
473 fflush(stdout); \
474 } else { \
475 printf("\nError (sz = %lu)\n", (unsigned long)sz); \
476 status = 1; \
477 printf("\tplaintext = "); hexdump(text, sz); \
478 printf(", "); hexdump(text + sz, rest); \
479 fputc('\n', stdout); \
480 printf("\tciphertext = "); hexdump(ct, sz); \
481 printf(", "); hexdump(ct + sz, rest); \
482 fputc('\n', stdout); \
483 printf("\trecovered text = "); hexdump(pt, sz); \
484 printf(", "); hexdump(pt + sz, rest); \
485 fputc('\n', stdout); \
486 fputc('\n', stdout); \
487 } \
488 if (sz < 63) \
489 sz++; \
490 else \
491 sz += 9; \
492 } \
493 \
494 fputs(status ? " failed\n" : " ok\n", stdout); \
495 return (status); \
496 }
497
498 #else
499 # define CFB_TEST(PRE, pre)
500 #endif
501
502 /*----- That's all, folks -------------------------------------------------*/
503
504 #ifdef __cplusplus
505 }
506 #endif
507
508 #endif
Catacomb cryptographic library (downstream of http://git.distorted.org.uk/~mdw/catacomb/)