d03ab969 |
1 | /* -*-c-*- |
2 | * |
3 | * $Id: cfb.h,v 1.1 1999/09/03 08:41:11 mdw Exp $ |
4 | * |
5 | * Ciphertext feedback 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: cfb.h,v $ |
33 | * Revision 1.1 1999/09/03 08:41:11 mdw |
34 | * Initial import. |
35 | * |
36 | */ |
37 | |
38 | #ifndef CFB_H |
39 | #define CFB_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 | #ifndef PARANOIA_H |
56 | # include "paranoia.h" |
57 | #endif |
58 | |
59 | /*----- Data structures ---------------------------------------------------*/ |
60 | |
61 | /* --- @CFB_DECL@ --- * |
62 | * |
63 | * Arguments: @PRE@, @pre@ = prefixes for the underlying block cipher |
64 | * |
65 | * Use: Creates declarations for CFB mode. |
66 | */ |
67 | |
68 | #define CFB_DECL(PRE, pre) \ |
69 | \ |
70 | typedef struct pre ## _cfbctx { \ |
71 | pre ## _ctx ctx; /* Underlying cipher context */ \ |
72 | int off; /* Offset into @iv@ buffer */ \ |
73 | octet iv[PRE ## _BLKSZ]; /* Previous ciphertext or IV */ \ |
74 | } pre ## _cfbctx; \ |
75 | \ |
76 | extern void pre ## _cfbgetiv(const pre ## _cfbctx */*ctx*/, \ |
77 | void */*iv*/); \ |
78 | \ |
79 | extern void pre ## _cfbsetiv(pre ## _cfbctx */*ctx*/, \ |
80 | const void */*iv*/); \ |
81 | \ |
82 | extern void pre ## _cfbbdry(pre ## _cfbctx */*ctx*/); \ |
83 | \ |
84 | extern void pre ## _cfbsetkey(pre ## _cfbctx */*ctx*/, \ |
85 | const pre ## _ctx */*k*/); \ |
86 | \ |
87 | extern void pre ## _cfbinit(pre ## _cfbctx */*ctx*/, \ |
88 | const void */*key*/, size_t /*sz*/, \ |
89 | const void */*iv*/); \ |
90 | \ |
91 | extern void pre ## _cfbencrypt(pre ## _cfbctx */*ctx*/, \ |
92 | const void */*src*/, void */*dest*/, \ |
93 | size_t /*sz*/); \ |
94 | \ |
95 | extern void pre ## _cfbdecrypt(pre ## _cfbctx */*ctx*/, \ |
96 | const void */*src*/, void */*dest*/, \ |
97 | size_t /*sz*/); \ |
98 | |
99 | |
100 | /* --- @CFB_DEF@ --- * |
101 | * |
102 | * Arguments: @PRE@, @pre@ = prefixes for the underlying block cipher |
103 | * |
104 | * Use: Creates an implementation for CFB mode. |
105 | */ |
106 | |
107 | #define CFB_DEF(PRE, pre) \ |
108 | \ |
109 | /* --- @pre_cfbgetiv@ --- * \ |
110 | * \ |
111 | * Arguments: @const pre_cfbctx *ctx@ = pointer to CFB context block \ |
112 | * @void *iv#@ = pointer to output data block \ |
113 | * \ |
114 | * Returns: --- \ |
115 | * \ |
116 | * Use: Reads the currently set IV. Reading and setting an IV \ |
117 | * is not transparent to the cipher. It will add a `step' \ |
118 | * which must be matched by a similar operation during \ |
119 | * decryption. \ |
120 | */ \ |
121 | \ |
122 | void pre ## _cfbgetiv(const pre ## _cfbctx *ctx, void *iv) \ |
123 | { \ |
124 | octet *p = iv; \ |
125 | int off = ctx->off; \ |
126 | int rest = PRE ## _BLKSZ - off; \ |
127 | memcpy(p, ctx->iv + off, rest); \ |
128 | memcpy(p + rest, ctx->iv, off); \ |
129 | } \ |
130 | \ |
131 | /* --- @pre_cfbsetiv@ --- * \ |
132 | * \ |
133 | * Arguments: @pre_cfbctx *ctx@ = pointer to CFB context block \ |
134 | * @cnost void *iv@ = pointer to IV to set \ |
135 | * \ |
136 | * Returns: --- \ |
137 | * \ |
138 | * Use: Sets the IV to use for subsequent encryption. \ |
139 | */ \ |
140 | \ |
141 | void pre ## _cfbsetiv(pre ## _cfbctx *ctx, const void *iv) \ |
142 | { \ |
143 | uint32 niv[PRE ## _BLKSZ / 4]; \ |
144 | BLKC_LOAD(PRE, niv, iv); \ |
145 | pre ## _eblk(&ctx->ctx, niv, niv); \ |
146 | BLKC_STORE(PRE, ctx->iv, niv); \ |
147 | ctx->off = 0; \ |
148 | } \ |
149 | \ |
150 | /* --- @pre_cfbbdry@ --- * \ |
151 | * \ |
152 | * Arguments: @pre_cfbctx *ctx@ = pointer to CFB context block \ |
153 | * \ |
154 | * Returns: --- \ |
155 | * \ |
156 | * Use: Inserts a boundary during encryption. Successful \ |
157 | * decryption must place a similar boundary. \ |
158 | */ \ |
159 | \ |
160 | void pre ## _cfbbdry(pre ## _cfbctx *ctx) \ |
161 | { \ |
162 | octet iv[PRE ## _BLKSZ]; \ |
163 | pre ## _cfbgetiv(ctx, iv); \ |
164 | pre ## _cfbsetiv(ctx, iv); \ |
165 | BURN(iv); \ |
166 | } \ |
167 | \ |
168 | /* --- @pre_cfbsetkey@ --- * \ |
169 | * \ |
170 | * Arguments: @pre_cfbctx *ctx@ = pointer to CFB context block \ |
171 | * @const pre_ctx *k@ = pointer to cipher context \ |
172 | * \ |
173 | * Returns: --- \ |
174 | * \ |
175 | * Use: Sets the CFB context to use a different cipher key. \ |
176 | */ \ |
177 | \ |
178 | void pre ## _cfbsetkey(pre ## _cfbctx *ctx, const pre ## _ctx *k) \ |
179 | { \ |
180 | ctx->ctx = *k; \ |
181 | } \ |
182 | \ |
183 | /* --- @pre_cfbinit@ --- * \ |
184 | * \ |
185 | * Arguments: @pre_cfbctx *ctx@ = pointer to cipher context \ |
186 | * @const void *key@ = pointer to the key buffer \ |
187 | * @size_t sz@ = size of the key \ |
188 | * @const void *iv@ = pointer to initialization vector \ |
189 | * \ |
190 | * Returns: --- \ |
191 | * \ |
192 | * Use: Initializes a CFB context ready for use. You should \ |
193 | * ensure that the IV chosen is unique: reusing an IV will \ |
194 | * compromise the security of at least the first block \ |
195 | * encrypted. This is equivalent to calls to @pre_init@, \ |
196 | * @pre_cfbsetkey@ and @pre_cfbsetiv@. \ |
197 | */ \ |
198 | \ |
199 | void pre ## _cfbinit(pre ## _cfbctx *ctx, \ |
200 | const void *key, size_t sz, \ |
201 | const void *iv) \ |
202 | { \ |
203 | static octet zero[PRE ## _BLKSZ] = { 0 }; \ |
204 | pre ## _init(&ctx->ctx, key, sz); \ |
205 | pre ## _cfbsetiv(ctx, iv ? iv : zero); \ |
206 | } \ |
207 | \ |
208 | /* --- @pre_cfbencrypt@ --- * \ |
209 | * \ |
210 | * Arguments: @pre_cfbctx *ctx@ = pointer to CFB context block \ |
211 | * @const void *src@ = pointer to source data \ |
212 | * @void *dest@ = pointer to destination data \ |
213 | * @size_t sz@ = size of block to be encrypted \ |
214 | * \ |
215 | * Returns: --- \ |
216 | * \ |
217 | * Use: Encrypts a block with a block cipher in CFB mode. The \ |
218 | * input block may be arbitrary in size. CFB mode is not \ |
219 | * sensitive to block boundaries. \ |
220 | */ \ |
221 | \ |
222 | void pre ## _cfbencrypt(pre ## _cfbctx *ctx, \ |
223 | const void *src, void *dest, \ |
224 | size_t sz) \ |
225 | { \ |
226 | const octet *s = src; \ |
227 | octet *d = dest; \ |
228 | int off = ctx->off; \ |
229 | \ |
230 | /* --- Empty blocks are trivial --- */ \ |
231 | \ |
232 | if (!sz) \ |
233 | return; \ |
234 | \ |
235 | /* --- If I can deal with the block from my buffer, do that --- */ \ |
236 | \ |
237 | if (sz < PRE ## _BLKSZ - off) \ |
238 | goto small; \ |
239 | \ |
240 | /* --- Finish off what's left in my buffer --- */ \ |
241 | \ |
242 | while (off < PRE ## _BLKSZ) { \ |
243 | register octet x = *s++; \ |
244 | *d++ = ctx->iv[off++] ^= x; \ |
245 | sz--; \ |
246 | } \ |
247 | \ |
248 | /* --- Main encryption loop --- */ \ |
249 | \ |
250 | { \ |
251 | uint32 iv[PRE ## _BLKSZ / 4]; \ |
252 | BLKC_LOAD(PRE, iv, ctx->iv); \ |
253 | \ |
254 | for (;;) { \ |
255 | pre ## _eblk(&ctx->ctx, iv, iv); \ |
256 | if (sz < PRE ## _BLKSZ) \ |
257 | break; \ |
258 | BLKC_XLOAD(PRE, iv, s); \ |
259 | BLKC_STORE(PRE, d, iv); \ |
260 | s += PRE ## _BLKSZ; \ |
261 | d += PRE ## _BLKSZ; \ |
262 | sz -= PRE ## _BLKSZ; \ |
263 | } \ |
264 | off = 0; \ |
265 | BLKC_STORE(PRE, ctx->iv, iv); \ |
266 | } \ |
267 | \ |
268 | /* --- Tidying up the tail end --- */ \ |
269 | \ |
270 | if (sz) { \ |
271 | small: \ |
272 | do { \ |
273 | register octet x = *s++; \ |
274 | *d++ = ctx->iv[off++] ^= x; \ |
275 | sz--; \ |
276 | } while (sz); \ |
277 | } \ |
278 | \ |
279 | /* --- Done --- */ \ |
280 | \ |
281 | ctx->off = off; \ |
282 | return; \ |
283 | } \ |
284 | \ |
285 | /* --- @pre_cfbdecrypt@ --- * \ |
286 | * \ |
287 | * Arguments: @pre_cfbctx *ctx@ = pointer to CFB 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 CFB 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 ## _cfbdecrypt(pre ## _cfbctx *ctx, \ |
301 | const void *src, void *dest, \ |
302 | size_t sz) \ |
303 | { \ |
304 | const octet *s = src; \ |
305 | octet *d = dest; \ |
306 | int off = ctx->off; \ |
307 | \ |
308 | /* --- Empty blocks are trivial --- */ \ |
309 | \ |
310 | if (!sz) \ |
311 | return; \ |
312 | \ |
313 | /* --- If I can deal with the block from my buffer, do that --- */ \ |
314 | \ |
315 | if (sz < PRE ## _BLKSZ - off) \ |
316 | goto small; \ |
317 | \ |
318 | /* --- Finish off what's left in my buffer --- */ \ |
319 | \ |
320 | while (off < PRE ## _BLKSZ) { \ |
321 | register octet x = *s++; \ |
322 | *d++ = ctx->iv[off] ^ x; \ |
323 | ctx->iv[off++] = x; \ |
324 | sz--; \ |
325 | } \ |
326 | \ |
327 | /* --- Main encryption loop --- */ \ |
328 | \ |
329 | { \ |
330 | uint32 iv[PRE ## _BLKSZ / 4]; \ |
331 | BLKC_LOAD(PRE, iv, ctx->iv); \ |
332 | \ |
333 | for (;;) { \ |
334 | uint32 x[PRE ## _BLKSZ / 4]; \ |
335 | pre ## _eblk(&ctx->ctx, iv, iv); \ |
336 | if (sz < PRE ## _BLKSZ) \ |
337 | break; \ |
338 | BLKC_LOAD(PRE, x, s); \ |
339 | BLKC_XSTORE(PRE, d, iv, x); \ |
340 | BLKC_MOVE(PRE, iv, x); \ |
341 | s += PRE ## _BLKSZ; \ |
342 | d += PRE ## _BLKSZ; \ |
343 | sz -= PRE ## _BLKSZ; \ |
344 | } \ |
345 | off = 0; \ |
346 | BLKC_STORE(PRE, ctx->iv, iv); \ |
347 | } \ |
348 | \ |
349 | /* --- Tidying up the tail end --- */ \ |
350 | \ |
351 | if (sz) { \ |
352 | small: \ |
353 | do { \ |
354 | register octet x = *s++; \ |
355 | *d++ = ctx->iv[off] ^ x; \ |
356 | ctx->iv[off++] = x; \ |
357 | sz--; \ |
358 | } while (sz); \ |
359 | } \ |
360 | \ |
361 | /* --- Done --- */ \ |
362 | \ |
363 | ctx->off = off; \ |
364 | return; \ |
365 | } \ |
366 | \ |
367 | CFB_TEST(PRE, pre) |
368 | |
369 | /*----- Test rig ----------------------------------------------------------*/ |
370 | |
371 | #ifdef TEST_RIG |
372 | |
373 | #include <stdio.h> |
374 | |
375 | #include "daftstory.h" |
376 | |
377 | /* --- @CFB_TEST@ --- * |
378 | * |
379 | * Arguments: @PRE@, @pre@ = prefixes for block cipher definitions |
380 | * |
381 | * Use: Standard test rig for CFB functions. |
382 | */ |
383 | |
384 | #define CFB_TEST(PRE, pre) \ |
385 | \ |
386 | /* --- Initial plaintext for the test --- */ \ |
387 | \ |
388 | static const octet text[] = TEXT; \ |
389 | \ |
390 | /* --- Key and IV to use --- */ \ |
391 | \ |
392 | static const octet key[] = KEY; \ |
393 | static const octet iv[] = IV; \ |
394 | \ |
395 | /* --- Buffers for encryption and decryption output --- */ \ |
396 | \ |
397 | static octet ct[sizeof(text)]; \ |
398 | static octet pt[sizeof(text)]; \ |
399 | \ |
400 | static void hexdump(const octet *p, size_t sz) \ |
401 | { \ |
402 | const octet *q = p + sz; \ |
403 | for (sz = 0; p < q; p++, sz++) { \ |
404 | printf("%02x", *p); \ |
405 | if ((sz + 1) % PRE ## _BLKSZ == 0) \ |
406 | putchar(':'); \ |
407 | } \ |
408 | } \ |
409 | \ |
410 | int main(void) \ |
411 | { \ |
412 | size_t sz = 0, rest; \ |
413 | pre ## _cfbctx ctx; \ |
414 | int status = 0; \ |
415 | int done = 0; \ |
416 | pre ## _ctx k; \ |
417 | \ |
418 | size_t keysz = PRE ## _KEYSZ ? \ |
419 | PRE ## _KEYSZ : strlen((const char *)key); \ |
420 | \ |
421 | fputs(#pre "-cfb: ", stdout); \ |
422 | \ |
423 | pre ## _init(&k, key, keysz); \ |
424 | pre ## _cfbsetkey(&ctx, &k); \ |
425 | \ |
426 | while (sz <= sizeof(text)) { \ |
427 | rest = sizeof(text) - sz; \ |
428 | memcpy(ct, text, sizeof(text)); \ |
429 | pre ## _cfbsetiv(&ctx, iv); \ |
430 | pre ## _cfbencrypt(&ctx, ct, ct, sz); \ |
431 | pre ## _cfbencrypt(&ctx, ct + sz, ct + sz, rest); \ |
432 | memcpy(pt, ct, sizeof(text)); \ |
433 | pre ## _cfbsetiv(&ctx, iv); \ |
434 | pre ## _cfbdecrypt(&ctx, pt, pt, rest); \ |
435 | pre ## _cfbdecrypt(&ctx, pt + rest, pt + rest, sz); \ |
436 | if (memcmp(pt, text, sizeof(text)) == 0) { \ |
437 | done++; \ |
438 | if (sizeof(text) < 40 || done % 8 == 0) \ |
439 | fputc('.', stdout); \ |
440 | if (done % 480 == 0) \ |
441 | fputs("\n\t", stdout); \ |
442 | fflush(stdout); \ |
443 | } else { \ |
444 | printf("\nError (sz = %lu)\n", (unsigned long)sz); \ |
445 | status = 1; \ |
446 | printf("\tplaintext = "); hexdump(text, sz); \ |
447 | printf(", "); hexdump(text + sz, rest); \ |
448 | fputc('\n', stdout); \ |
449 | printf("\tciphertext = "); hexdump(ct, sz); \ |
450 | printf(", "); hexdump(ct + sz, rest); \ |
451 | fputc('\n', stdout); \ |
452 | printf("\trecovered text = "); hexdump(pt, sz); \ |
453 | printf(", "); hexdump(pt + sz, rest); \ |
454 | fputc('\n', stdout); \ |
455 | fputc('\n', stdout); \ |
456 | } \ |
457 | if (sz < 63) \ |
458 | sz++; \ |
459 | else \ |
460 | sz += 9; \ |
461 | } \ |
462 | \ |
463 | fputs(status ? " failed\n" : " ok\n", stdout); \ |
464 | return (status); \ |
465 | } |
466 | |
467 | #else |
468 | # define CFB_TEST(PRE, pre) |
469 | #endif |
470 | |
471 | /*----- That's all, folks -------------------------------------------------*/ |
472 | |
473 | #ifdef __cplusplus |
474 | } |
475 | #endif |
476 | |
477 | #endif |