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1 | /* -*-c-*- |
2 | * |
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3 | * $Id: ofb-def.h,v 1.2 1999/12/13 15:34:01 mdw Exp $ |
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4 | * |
5 | * Definitions for output 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 | /*----- Revision history --------------------------------------------------* |
31 | * |
32 | * $Log: ofb-def.h,v $ |
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33 | * Revision 1.2 1999/12/13 15:34:01 mdw |
34 | * Add support for seeding from a generic pseudorandom source. |
35 | * |
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36 | * Revision 1.1 1999/12/10 23:16:40 mdw |
37 | * Split mode macros into interface and implementation. |
38 | * |
39 | */ |
40 | |
41 | #ifndef CATACOMB_OFB_DEF_H |
42 | #define CATACOMB_OFB_DEF_H |
43 | |
44 | #ifdef __cplusplus |
45 | extern "C" { |
46 | #endif |
47 | |
48 | /*----- Header files ------------------------------------------------------*/ |
49 | |
50 | #include <stdarg.h> |
51 | #include <string.h> |
52 | |
53 | #include <mLib/bits.h> |
54 | #include <mLib/sub.h> |
55 | |
56 | #ifndef CATACOMB_BLKC_H |
57 | # include "blkc.h" |
58 | #endif |
59 | |
60 | #ifndef CATACOMB_GCIPHER_H |
61 | # include "gcipher.h" |
62 | #endif |
63 | |
64 | #ifndef CATACOMB_PARANOIA_H |
65 | # include "paranoia.h" |
66 | #endif |
67 | |
68 | /*----- Macros ------------------------------------------------------------*/ |
69 | |
70 | /* --- @OFB_DEF@ --- * |
71 | * |
72 | * Arguments: @PRE@, @pre@ = prefixes for the underlying block cipher |
73 | * |
74 | * Use: Creates definitions for output feedback mode. |
75 | */ |
76 | |
77 | #define OFB_DEF(PRE, pre) \ |
78 | \ |
79 | /* --- @pre_ofbgetiv@ --- * \ |
80 | * \ |
81 | * Arguments: @const pre_ofbctx *ctx@ = pointer to OFB context block \ |
82 | * @void *iv#@ = pointer to output data block \ |
83 | * \ |
84 | * Returns: --- \ |
85 | * \ |
86 | * Use: Reads the currently set IV. Reading and setting an IV \ |
87 | * is not transparent to the cipher. It will add a `step' \ |
88 | * which must be matched by a similar operation during \ |
89 | * decryption. \ |
90 | */ \ |
91 | \ |
92 | void pre##_ofbgetiv(const pre##_ofbctx *ctx, void *iv) \ |
93 | { \ |
94 | octet *p = iv; \ |
95 | int off = ctx->off; \ |
96 | int rest = PRE##_BLKSZ - off; \ |
97 | memcpy(p, ctx->iv + off, rest); \ |
98 | memcpy(p + rest, ctx->iv, off); \ |
99 | } \ |
100 | \ |
101 | /* --- @pre_ofbsetiv@ --- * \ |
102 | * \ |
103 | * Arguments: @pre_ofbctx *ctx@ = pointer to OFB context block \ |
104 | * @cnost void *iv@ = pointer to IV to set \ |
105 | * \ |
106 | * Returns: --- \ |
107 | * \ |
108 | * Use: Sets the IV to use for subsequent encryption. \ |
109 | */ \ |
110 | \ |
111 | void pre##_ofbsetiv(pre##_ofbctx *ctx, const void *iv) \ |
112 | { \ |
113 | uint32 niv[PRE##_BLKSZ / 4]; \ |
114 | BLKC_LOAD(PRE, niv, iv); \ |
115 | pre##_eblk(&ctx->ctx, niv, niv); \ |
116 | BLKC_STORE(PRE, ctx->iv, niv); \ |
117 | ctx->off = 0; \ |
118 | } \ |
119 | \ |
120 | /* --- @pre_ofbbdry@ --- * \ |
121 | * \ |
122 | * Arguments: @pre_ofbctx *ctx@ = pointer to OFB context block \ |
123 | * \ |
124 | * Returns: --- \ |
125 | * \ |
126 | * Use: Inserts a boundary during encryption. Successful \ |
127 | * decryption must place a similar boundary. \ |
128 | */ \ |
129 | \ |
130 | void pre##_ofbbdry(pre##_ofbctx *ctx) \ |
131 | { \ |
132 | octet iv[PRE##_BLKSZ]; \ |
133 | pre##_ofbgetiv(ctx, iv); \ |
134 | pre##_ofbsetiv(ctx, iv); \ |
135 | BURN(iv); \ |
136 | } \ |
137 | \ |
138 | /* --- @pre_ofbsetkey@ --- * \ |
139 | * \ |
140 | * Arguments: @pre_ofbctx *ctx@ = pointer to OFB context block \ |
141 | * @const pre_ctx *k@ = pointer to cipher context \ |
142 | * \ |
143 | * Returns: --- \ |
144 | * \ |
145 | * Use: Sets the OFB context to use a different cipher key. \ |
146 | */ \ |
147 | \ |
148 | void pre##_ofbsetkey(pre##_ofbctx *ctx, const pre##_ctx *k) \ |
149 | { \ |
150 | ctx->ctx = *k; \ |
151 | } \ |
152 | \ |
153 | /* --- @pre_ofbinit@ --- * \ |
154 | * \ |
155 | * Arguments: @pre_ofbctx *ctx@ = pointer to cipher context \ |
156 | * @const void *key@ = pointer to the key buffer \ |
157 | * @size_t sz@ = size of the key \ |
158 | * @const void *iv@ = pointer to initialization vector \ |
159 | * \ |
160 | * Returns: --- \ |
161 | * \ |
162 | * Use: Initializes a OFB context ready for use. You should \ |
163 | * ensure that the IV chosen is unique: reusing an IV will \ |
164 | * compromise the security of the entire plaintext. This \ |
165 | * is equivalent to calls to @pre_init@, @pre_ofbsetkey@ \ |
166 | * and @pre_ofbsetiv@. \ |
167 | */ \ |
168 | \ |
169 | void pre##_ofbinit(pre##_ofbctx *ctx, \ |
170 | const void *key, size_t sz, \ |
171 | const void *iv) \ |
172 | { \ |
173 | static octet zero[PRE##_BLKSZ] = { 0 }; \ |
174 | pre##_init(&ctx->ctx, key, sz); \ |
175 | pre##_ofbsetiv(ctx, iv ? iv : zero); \ |
176 | } \ |
177 | \ |
178 | /* --- @pre_ofbencrypt@ --- * \ |
179 | * \ |
180 | * Arguments: @pre_ofbctx *ctx@ = pointer to OFB context block \ |
181 | * @const void *src@ = pointer to source data \ |
182 | * @void *dest@ = pointer to destination data \ |
183 | * @size_t sz@ = size of block to be encrypted \ |
184 | * \ |
185 | * Returns: --- \ |
186 | * \ |
187 | * Use: Encrypts or decrypts a block with a block cipher in OFB \ |
188 | * mode: encryption and decryption are the same in OFB. \ |
189 | * The destination may be null to just churn the feedback \ |
190 | * round for a bit. The source may be null to use the \ |
191 | * cipher as a random data generator. \ |
192 | */ \ |
193 | \ |
194 | void pre##_ofbencrypt(pre##_ofbctx *ctx, \ |
195 | const void *src, void *dest, \ |
196 | size_t sz) \ |
197 | { \ |
198 | const octet *s = src; \ |
199 | octet *d = dest; \ |
200 | int off = ctx->off; \ |
201 | \ |
202 | /* --- Empty blocks are trivial --- */ \ |
203 | \ |
204 | if (!sz) \ |
205 | return; \ |
206 | \ |
207 | /* --- If I can deal with the block from my buffer, do that --- */ \ |
208 | \ |
209 | if (sz < PRE##_BLKSZ - off) \ |
210 | goto small; \ |
211 | \ |
212 | /* --- Finish off what's left in my buffer --- */ \ |
213 | \ |
214 | if (!d) \ |
215 | sz -= off; \ |
216 | else { \ |
217 | while (off < PRE##_BLKSZ) { \ |
218 | register octet x = s ? *s++ : 0; \ |
219 | *d++ = ctx->iv[off++] ^ x; \ |
220 | sz--; \ |
221 | } \ |
222 | } \ |
223 | \ |
224 | /* --- Main encryption loop --- */ \ |
225 | \ |
226 | { \ |
227 | uint32 iv[PRE##_BLKSZ / 4]; \ |
228 | BLKC_LOAD(PRE, iv, ctx->iv); \ |
229 | \ |
230 | for (;;) { \ |
231 | pre##_eblk(&ctx->ctx, iv, iv); \ |
232 | if (sz < PRE##_BLKSZ) \ |
233 | break; \ |
234 | if (d) { \ |
235 | if (!s) \ |
236 | BLKC_STORE(PRE, d, iv); \ |
237 | else { \ |
238 | uint32 x[PRE##_BLKSZ / 4]; \ |
239 | BLKC_LOAD(PRE, x, s); \ |
240 | BLKC_XSTORE(PRE, d, iv, x); \ |
241 | s += PRE##_BLKSZ; \ |
242 | } \ |
243 | d += PRE##_BLKSZ; \ |
244 | } \ |
245 | sz -= PRE##_BLKSZ; \ |
246 | } \ |
247 | \ |
248 | BLKC_STORE(PRE, ctx->iv, iv); \ |
249 | off = 0; \ |
250 | } \ |
251 | \ |
252 | /* --- Tidying up the tail end --- */ \ |
253 | \ |
254 | if (sz) { \ |
255 | small: \ |
256 | if (!d) \ |
257 | off += sz; \ |
258 | else do { \ |
259 | register octet x = s ? *s++ : 0; \ |
260 | *d++ = ctx->iv[off++] ^ x; \ |
261 | sz--; \ |
262 | } while (sz); \ |
263 | } \ |
264 | \ |
265 | /* --- Done --- */ \ |
266 | \ |
267 | ctx->off = off; \ |
268 | return; \ |
269 | } \ |
270 | \ |
271 | /* --- Generic cipher interface --- */ \ |
272 | \ |
273 | static const gcipher_ops gops; \ |
274 | \ |
275 | typedef struct gctx { \ |
276 | gcipher c; \ |
277 | pre##_ofbctx k; \ |
278 | } gctx; \ |
279 | \ |
280 | static gcipher *ginit(const void *k, size_t sz) \ |
281 | { \ |
282 | gctx *g = CREATE(gctx); \ |
283 | g->c.ops = &gops; \ |
284 | pre##_ofbinit(&g->k, k, sz, 0); \ |
285 | return (&g->c); \ |
286 | } \ |
287 | \ |
288 | static void gencrypt(gcipher *c, const void *s, void *t, size_t sz) \ |
289 | { \ |
290 | gctx *g = (gctx *)c; \ |
291 | pre##_ofbencrypt(&g->k, s, t, sz); \ |
292 | } \ |
293 | \ |
294 | static void gdestroy(gcipher *c) \ |
295 | { \ |
296 | gctx *g = (gctx *)c; \ |
297 | DESTROY(g); \ |
298 | } \ |
299 | \ |
300 | static void gsetiv(gcipher *c, const void *iv) \ |
301 | { \ |
302 | gctx *g = (gctx *)c; \ |
303 | pre##_ofbsetiv(&g->k, iv); \ |
304 | } \ |
305 | \ |
306 | static void gbdry(gcipher *c) \ |
307 | { \ |
308 | gctx *g = (gctx *)c; \ |
309 | pre##_ofbbdry(&g->k); \ |
310 | } \ |
311 | \ |
312 | static const gcipher_ops gops = { \ |
313 | &pre##_ofb.b, \ |
314 | gencrypt, gencrypt, gdestroy, gsetiv, gbdry \ |
315 | }; \ |
316 | \ |
317 | const gccipher pre##_ofb = { \ |
318 | { #pre "-ofb", PRE##_KEYSZ, PRE##_BLKSZ }, \ |
319 | ginit \ |
320 | }; \ |
321 | \ |
322 | /* --- Generic random number generator interface --- */ \ |
323 | \ |
324 | typedef struct grctx { \ |
325 | grand r; \ |
326 | pre##_ofbctx k; \ |
327 | } grctx; \ |
328 | \ |
329 | static void grdestroy(grand *r) \ |
330 | { \ |
331 | grctx *g = (grctx *)r; \ |
332 | DESTROY(g); \ |
333 | } \ |
334 | \ |
335 | static int grmisc(grand *r, unsigned op, ...) \ |
336 | { \ |
337 | grctx *g = (grctx *)r; \ |
338 | va_list ap; \ |
339 | int rc = 0; \ |
340 | octet buf[PRE##_BLKSZ]; \ |
341 | va_start(ap, op); \ |
342 | \ |
343 | switch (op) { \ |
344 | case GRAND_CHECK: \ |
345 | switch (va_arg(ap, unsigned)) { \ |
346 | case GRAND_CHECK: \ |
347 | case GRAND_SEEDINT: \ |
348 | case GRAND_SEEDUINT32: \ |
349 | case GRAND_SEEDBLOCK: \ |
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350 | case GRAND_SEEDRAND: \ |
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351 | rc = 1; \ |
352 | break; \ |
353 | default: \ |
354 | rc = 0; \ |
355 | break; \ |
356 | } \ |
357 | break; \ |
358 | case GRAND_SEEDINT: \ |
359 | memset(buf, 0, sizeof(buf)); \ |
360 | STORE32(buf, va_arg(ap, unsigned)); \ |
361 | pre##_ofbsetiv(&g->k, buf); \ |
362 | break; \ |
363 | case GRAND_SEEDUINT32: \ |
364 | memset(buf, 0, sizeof(buf)); \ |
365 | STORE32(buf, va_arg(ap, uint32)); \ |
366 | pre##_ofbsetiv(&g->k, buf); \ |
367 | break; \ |
368 | case GRAND_SEEDBLOCK: { \ |
369 | const void *p = va_arg(ap, const void *); \ |
370 | size_t sz = va_arg(ap, size_t); \ |
371 | if (sz < sizeof(buf)) { \ |
372 | memset(buf, 0, sizeof(buf)); \ |
373 | memcpy(buf, p, sz); \ |
374 | p = buf; \ |
375 | } \ |
376 | pre##_ofbsetiv(&g->k, p); \ |
377 | } break; \ |
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378 | case GRAND_SEEDRAND: { \ |
379 | grand *rr = va_arg(ap, grand *); \ |
380 | rr->ops->fill(rr, buf, sizeof(buf)); \ |
381 | pre##_ofbsetiv(&g->k, buf); \ |
382 | } break; \ |
383 | default: \ |
384 | GRAND_BADOP; \ |
385 | break; \ |
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386 | } \ |
387 | \ |
388 | va_end(ap); \ |
389 | return (rc); \ |
390 | } \ |
391 | \ |
392 | static octet grbyte(grand *r) \ |
393 | { \ |
394 | grctx *g = (grctx *)r; \ |
395 | octet o; \ |
396 | pre##_ofbencrypt(&g->k, 0, &o, 1); \ |
397 | return (o); \ |
398 | } \ |
399 | \ |
400 | static uint32 grword(grand *r) \ |
401 | { \ |
402 | grctx *g = (grctx *)r; \ |
403 | octet b[4]; \ |
404 | pre##_ofbencrypt(&g->k, 0, b, sizeof(b)); \ |
405 | return (LOAD32(b)); \ |
406 | } \ |
407 | \ |
408 | static void grfill(grand *r, void *p, size_t sz) \ |
409 | { \ |
410 | grctx *g = (grctx *)r; \ |
411 | pre##_ofbencrypt(&g->k, 0, p, sz); \ |
412 | } \ |
413 | \ |
414 | static const grand_ops grops = { \ |
415 | #pre "-ofb", \ |
416 | 0, \ |
417 | grmisc, grdestroy, \ |
418 | grword, grbyte, grword, grand_range, grfill \ |
419 | }; \ |
420 | \ |
421 | /* --- @pre_ofbrand@ --- * \ |
422 | * \ |
423 | * Arguments: @const void *k@ = pointer to key material \ |
424 | * @size_t sz@ = size of key material \ |
425 | * \ |
426 | * Returns: Pointer to generic random number generator interface. \ |
427 | * \ |
428 | * Use: Creates a random number interface wrapper around an \ |
429 | * OFB-mode block cipher. \ |
430 | */ \ |
431 | \ |
432 | grand *pre##_ofbrand(const void *k, size_t sz) \ |
433 | { \ |
434 | grctx *g = CREATE(grctx); \ |
435 | g->r.ops = &grops; \ |
436 | pre##_ofbinit(&g->k, k, sz, 0); \ |
437 | return (&g->r); \ |
438 | } \ |
439 | \ |
440 | OFB_TEST(PRE, pre) |
441 | |
442 | /*----- Test rig ----------------------------------------------------------*/ |
443 | |
444 | #ifdef TEST_RIG |
445 | |
446 | #include <stdio.h> |
447 | |
448 | #include "daftstory.h" |
449 | |
450 | /* --- @OFB_TEST@ --- * |
451 | * |
452 | * Arguments: @PRE@, @pre@ = prefixes for block cipher definitions |
453 | * |
454 | * Use: Standard test rig for OFB functions. |
455 | */ |
456 | |
457 | #define OFB_TEST(PRE, pre) \ |
458 | \ |
459 | /* --- Initial plaintext for the test --- */ \ |
460 | \ |
461 | static const octet text[] = TEXT; \ |
462 | \ |
463 | /* --- Key and IV to use --- */ \ |
464 | \ |
465 | static const octet key[] = KEY; \ |
466 | static const octet iv[] = IV; \ |
467 | \ |
468 | /* --- Buffers for encryption and decryption output --- */ \ |
469 | \ |
470 | static octet ct[sizeof(text)]; \ |
471 | static octet pt[sizeof(text)]; \ |
472 | \ |
473 | static void hexdump(const octet *p, size_t sz) \ |
474 | { \ |
475 | const octet *q = p + sz; \ |
476 | for (sz = 0; p < q; p++, sz++) { \ |
477 | printf("%02x", *p); \ |
478 | if ((sz + 1) % PRE##_BLKSZ == 0) \ |
479 | putchar(':'); \ |
480 | } \ |
481 | } \ |
482 | \ |
483 | int main(void) \ |
484 | { \ |
485 | size_t sz = 0, rest; \ |
486 | pre##_ofbctx ctx; \ |
487 | int status = 0; \ |
488 | int done = 0; \ |
489 | pre##_ctx k; \ |
490 | \ |
491 | size_t keysz = PRE##_KEYSZ ? \ |
492 | PRE##_KEYSZ : strlen((const char *)key); \ |
493 | \ |
494 | fputs(#pre "-ofb: ", stdout); \ |
495 | \ |
496 | pre##_init(&k, key, keysz); \ |
497 | pre##_ofbsetkey(&ctx, &k); \ |
498 | \ |
499 | while (sz <= sizeof(text)) { \ |
500 | rest = sizeof(text) - sz; \ |
501 | memcpy(ct, text, sizeof(text)); \ |
502 | pre##_ofbsetiv(&ctx, iv); \ |
503 | pre##_ofbencrypt(&ctx, ct, ct, sz); \ |
504 | pre##_ofbencrypt(&ctx, ct + sz, ct + sz, rest); \ |
505 | memcpy(pt, ct, sizeof(text)); \ |
506 | pre##_ofbsetiv(&ctx, iv); \ |
507 | pre##_ofbencrypt(&ctx, pt, pt, rest); \ |
508 | pre##_ofbencrypt(&ctx, pt + rest, pt + rest, sz); \ |
509 | if (memcmp(pt, text, sizeof(text)) == 0) { \ |
510 | done++; \ |
511 | if (sizeof(text) < 40 || done % 8 == 0) \ |
512 | fputc('.', stdout); \ |
513 | if (done % 480 == 0) \ |
514 | fputs("\n\t", stdout); \ |
515 | fflush(stdout); \ |
516 | } else { \ |
517 | printf("\nError (sz = %lu)\n", (unsigned long)sz); \ |
518 | status = 1; \ |
519 | printf("\tplaintext = "); hexdump(text, sz); \ |
520 | printf(", "); hexdump(text + sz, rest); \ |
521 | fputc('\n', stdout); \ |
522 | printf("\tciphertext = "); hexdump(ct, sz); \ |
523 | printf(", "); hexdump(ct + sz, rest); \ |
524 | fputc('\n', stdout); \ |
525 | printf("\trecovered text = "); hexdump(pt, sz); \ |
526 | printf(", "); hexdump(pt + sz, rest); \ |
527 | fputc('\n', stdout); \ |
528 | fputc('\n', stdout); \ |
529 | } \ |
530 | if (sz < 63) \ |
531 | sz++; \ |
532 | else \ |
533 | sz += 9; \ |
534 | } \ |
535 | \ |
536 | fputs(status ? " failed\n" : " ok\n", stdout); \ |
537 | return (status); \ |
538 | } |
539 | |
540 | #else |
541 | # define OFB_TEST(PRE, pre) |
542 | #endif |
543 | |
544 | /*----- That's all, folks -------------------------------------------------*/ |
545 | |
546 | #ifdef __cplusplus |
547 | } |
548 | #endif |
549 | |
550 | #endif |