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symm/...: Reformat encryption mode loops and related code.
[catacomb] / symm / cbc-def.h
1 /* -*-c-*-
2 *
3 * Definitions for cipher block chaining mode
4 *
5 * (c) 1999 Straylight/Edgeware
6 */
7
8 /*----- Licensing notice --------------------------------------------------*
9 *
10 * This file is part of Catacomb.
11 *
12 * Catacomb is free software; you can redistribute it and/or modify
13 * it under the terms of the GNU Library General Public License as
14 * published by the Free Software Foundation; either version 2 of the
15 * License, or (at your option) any later version.
16 *
17 * Catacomb is distributed in the hope that it will be useful,
18 * but WITHOUT ANY WARRANTY; without even the implied warranty of
19 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
20 * GNU Library General Public License for more details.
21 *
22 * You should have received a copy of the GNU Library General Public
23 * License along with Catacomb; if not, write to the Free
24 * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
25 * MA 02111-1307, USA.
26 */
27
28 #ifndef CATACOMB_CBC_DEF_H
29 #define CATACOMB_CBC_DEF_H
30
31 #ifdef __cplusplus
32 extern "C" {
33 #endif
34
35 /*----- Header files ------------------------------------------------------*/
36
37 #include <string.h>
38
39 #include <mLib/bits.h>
40 #include <mLib/sub.h>
41
42 #ifndef CATACOMB_ARENA_H
43 # include "arena.h"
44 #endif
45
46 #ifndef CATACOMB_BLKC_H
47 # include "blkc.h"
48 #endif
49
50 #ifndef CATACOMB_GCIPHER_H
51 # include "gcipher.h"
52 #endif
53
54 #ifndef CATACOMB_PARANOIA_H
55 # include "paranoia.h"
56 #endif
57
58 /*----- Macros ------------------------------------------------------------*/
59
60 /* --- @CBC_DEF@ --- *
61 *
62 * Arguments: @PRE@, @pre@ = prefixes for the underlying block cipher
63 *
64 * Use: Creates an implementation for CBC stealing mode.
65 */
66
67 #define CBC_DEF(PRE, pre) CBC_DEFX(PRE, pre, #pre, #pre)
68
69 #define CBC_DEFX(PRE, pre, name, fname) \
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 { BLKC_STORE(PRE, iv, ctx->a); } \
85 \
86 /* --- @pre_cbcsetiv@ --- * \
87 * \
88 * Arguments: @pre_cbcctx *ctx@ = pointer to CBC context block \
89 * @cnost void *iv@ = pointer to IV to set \
90 * \
91 * Returns: --- \
92 * \
93 * Use: Sets the IV to use for subsequent encryption. \
94 */ \
95 \
96 void pre##_cbcsetiv(pre##_cbcctx *ctx, const void *iv) \
97 { BLKC_LOAD(PRE, ctx->a, iv); } \
98 \
99 /* --- @pre_cbcsetkey@ --- * \
100 * \
101 * Arguments: @pre_cbcctx *ctx@ = pointer to CBC context block \
102 * @const pre_ctx *k@ = pointer to cipher context \
103 * \
104 * Returns: --- \
105 * \
106 * Use: Sets the CBC context to use a different cipher key. \
107 */ \
108 \
109 void pre##_cbcsetkey(pre##_cbcctx *ctx, const pre##_ctx *k) \
110 { ctx->ctx = *k; } \
111 \
112 /* --- @pre_cbcinit@ --- * \
113 * \
114 * Arguments: @pre_cbcctx *ctx@ = pointer to cipher context \
115 * @const void *key@ = pointer to the key buffer \
116 * @size_t sz@ = size of the key \
117 * @const void *iv@ = pointer to initialization vector \
118 * \
119 * Returns: --- \
120 * \
121 * Use: Initializes a CBC context ready for use. The @iv@ \
122 * argument may be passed as a null pointer to set a zero \
123 * IV. Apart from that, this call is equivalent to calls \
124 * to @pre_init@, @pre_cbcsetkey@ and @pre_cbcsetiv@. \
125 */ \
126 \
127 void pre##_cbcinit(pre##_cbcctx *ctx, \
128 const void *key, size_t sz, \
129 const void *iv) \
130 { \
131 static const octet zero[PRE##_BLKSZ] = { 0 }; \
132 \
133 pre##_init(&ctx->ctx, key, sz); \
134 BLKC_LOAD(PRE, ctx->a, iv ? iv : zero); \
135 } \
136 \
137 /* --- @pre_cbcencrypt@ --- * \
138 * \
139 * Arguments: @pre_cbcctx *ctx@ = pointer to CBC context block \
140 * @const void *src@ = pointer to source data \
141 * @void *dest@ = pointer to destination data \
142 * @size_t sz@ = size of block to be encrypted \
143 * \
144 * Returns: --- \
145 * \
146 * Use: Encrypts a block with a block cipher in CBC mode, with \
147 * ciphertext stealing and other clever tricks. \
148 * Essentially, data can be encrypted in arbitrary sized \
149 * chunks, although decryption must use the same chunks. \
150 */ \
151 \
152 void pre##_cbcencrypt(pre##_cbcctx *ctx, \
153 const void *src, void *dest, \
154 size_t sz) \
155 { \
156 const octet *s = src; \
157 octet *d = dest; \
158 octet b[PRE##_BLKSZ]; \
159 octet y; \
160 unsigned i; \
161 \
162 /* --- Empty blocks are trivial --- */ \
163 \
164 if (!sz) return; \
165 \
166 /* --- Extra magical case for a short block --- * \
167 * \
168 * Encrypt the IV, then exclusive-or the plaintext with the octets \
169 * of the encrypted IV, shifting ciphertext octets in instead. This \
170 * basically switches over to CFB. \
171 */ \
172 \
173 if (sz < PRE##_BLKSZ) { \
174 pre##_eblk(&ctx->ctx, ctx->a, ctx->a); \
175 BLKC_STORE(PRE, b, ctx->a); \
176 if (d) { for (i = 0; i < sz; i++) d[i] = b[i] ^ (s ? s[i] : 0); } \
177 memmove(b, b + sz, PRE##_BLKSZ - sz); \
178 memcpy(b + PRE##_BLKSZ - sz, d, sz); \
179 BLKC_LOAD(PRE, ctx->a, b); \
180 return; \
181 } \
182 \
183 /* --- Do the main chunk of encryption --- * \
184 * \
185 * This will do the whole lot if it's a whole number of blocks. For \
186 * each block, XOR it with the previous ciphertext in @iv@, encrypt, \
187 * and keep a copy of the ciphertext for the next block. \
188 */ \
189 \
190 while (sz >= 2*PRE##_BLKSZ || sz == PRE##_BLKSZ) { \
191 if (s) { BLKC_XLOAD(PRE, ctx->a, s); s += PRE##_BLKSZ; } \
192 pre##_eblk(&ctx->ctx, ctx->a, ctx->a); \
193 if (d) { BLKC_STORE(PRE, d, ctx->a); d += PRE##_BLKSZ; } \
194 sz -= PRE##_BLKSZ; \
195 } \
196 \
197 /* --- Do the tail-end block and bit-left-over --- * \
198 * \
199 * This isn't very efficient. That shouldn't matter much. \
200 */ \
201 \
202 if (sz) { \
203 \
204 /* --- Let @sz@ be the size of the partial block --- */ \
205 \
206 sz -= PRE##_BLKSZ; \
207 \
208 /* --- First stage --- * \
209 * \
210 * XOR the complete block with the current IV, and encrypt it. The \
211 * first part of the result is the partial ciphertext block. Don't \
212 * write that out yet, because I've not read the partial plaintext \
213 * block. \
214 */ \
215 \
216 if (s) BLKC_XLOAD(PRE, ctx->a, s); \
217 pre##_eblk(&ctx->ctx, ctx->a, ctx->a); \
218 BLKC_STORE(PRE, b, ctx->a); \
219 \
220 /* --- Second stage --- * \
221 * \
222 * Now XOR in the partial plaintext block, writing out the \
223 * ciphertext as I go. Then encrypt, and write the complete \
224 * ciphertext block. \
225 */ \
226 \
227 if (s) s += PRE##_BLKSZ; \
228 if (d) d += PRE##_BLKSZ; \
229 for (i = 0; i < sz; i++) { \
230 y = b[i]; \
231 if (s) b[i] ^= s[i]; \
232 if (d) d[i] = y; \
233 } \
234 BLKC_LOAD(PRE, ctx->a, b); \
235 pre##_eblk(&ctx->ctx, ctx->a, ctx->a); \
236 if (d) BLKC_STORE(PRE, d - PRE##_BLKSZ, ctx->a); \
237 } \
238 \
239 /* --- Done --- */ \
240 \
241 return; \
242 } \
243 \
244 /* --- @pre_cbcdecrypt@ --- * \
245 * \
246 * Arguments: @pre_cbcctx *ctx@ = pointer to CBC context block \
247 * @const void *src@ = pointer to source data \
248 * @void *dest@ = pointer to destination data \
249 * @size_t sz@ = size of block to be encrypted \
250 * \
251 * Returns: --- \
252 * \
253 * Use: Decrypts a block with a block cipher in CBC mode, with \
254 * ciphertext stealing and other clever tricks. \
255 * Essentially, data can be encrypted in arbitrary sized \
256 * chunks, although decryption must use the same chunks. \
257 */ \
258 \
259 void pre##_cbcdecrypt(pre##_cbcctx *ctx, \
260 const void *src, void *dest, \
261 size_t sz) \
262 { \
263 const octet *s = src; \
264 octet *d = dest; \
265 uint32 t[PRE##_BLKSZ/4], u[PRE##_BLKSZ/4]; \
266 octet b[PRE##_BLKSZ], c[PRE##_BLKSZ]; \
267 octet y; \
268 unsigned i; \
269 \
270 /* --- Empty blocks are trivial --- */ \
271 \
272 if (!sz) return; \
273 \
274 /* --- Extra magical case for a short block --- * \
275 * \
276 * Encrypt the IV, then exclusive-or the ciphertext with the octets \
277 * of the encrypted IV, shifting ciphertext octets in instead. This \
278 * basically switches over to CFB. \
279 */ \
280 \
281 if (sz < PRE##_BLKSZ) { \
282 pre##_eblk(&ctx->ctx, ctx->a, ctx->a); \
283 BLKC_STORE(PRE, b, ctx->a); \
284 for (i = 0; i < sz; i++) { y = s[i]; d[i] = b[i] ^ y; c[i] = y; } \
285 memmove(b, b + sz, PRE##_BLKSZ - sz); \
286 memcpy(b + PRE##_BLKSZ - sz, c, sz); \
287 BLKC_LOAD(PRE, ctx->a, b); \
288 return; \
289 } \
290 \
291 /* --- Do the main chunk of decryption --- * \
292 * \
293 * This will do the whole lot if it's a whole number of blocks. For \
294 * each block, decrypt, XOR it with the previous ciphertext in @iv@, \
295 * and keep a copy of the ciphertext for the next block. \
296 */ \
297 \
298 while (sz >= 2*PRE##_BLKSZ || sz == PRE##_BLKSZ) { \
299 BLKC_LOAD(PRE, t, s); s += PRE##_BLKSZ; \
300 pre##_dblk(&ctx->ctx, t, u); \
301 BLKC_XSTORE(PRE, d, u, ctx->a); d += PRE##_BLKSZ; \
302 BLKC_MOVE(PRE, ctx->a, t); \
303 sz -= PRE##_BLKSZ; \
304 } \
305 \
306 /* --- Do the tail-end block and bit-left-over --- * \
307 * \
308 * This isn't very efficient. That shouldn't matter much. \
309 */ \
310 \
311 if (sz) { \
312 \
313 /* --- Let @sz@ be the size of the partial block --- */ \
314 \
315 sz -= PRE##_BLKSZ; \
316 \
317 /* --- First stage --- * \
318 * \
319 * Take the complete ciphertext block, and decrypt it. This block \
320 * is carried over for the next encryption operation. \
321 */ \
322 \
323 BLKC_LOAD(PRE, t, s); \
324 pre##_dblk(&ctx->ctx, t, u); \
325 \
326 /* --- Second stage --- * \
327 * \
328 * XORing the first few bytes of this with the partial ciphertext \
329 * block recovers the partial plaintext block. At the same time, \
330 * write the partial ciphertext block's contents in ready for stage \
331 * three. \
332 */ \
333 \
334 BLKC_STORE(PRE, b, u); \
335 s += PRE##_BLKSZ; \
336 d += PRE##_BLKSZ; \
337 for (i = 0; i < sz; i++) { y = s[i]; d[i] = b[i] ^ y; b[i] = y; } \
338 \
339 /* --- Third stage --- * \
340 * \
341 * Decrypt the block we've got left, and XOR with the initial IV to \
342 * recover the complete plaintext block. \
343 */ \
344 \
345 BLKC_LOAD(PRE, u, b); \
346 pre##_dblk(&ctx->ctx, u, u); \
347 BLKC_XSTORE(PRE, d - PRE##_BLKSZ, u, ctx->a); \
348 BLKC_MOVE(PRE, ctx->a, t); \
349 } \
350 \
351 /* --- Done --- */ \
352 \
353 return; \
354 } \
355 \
356 /* --- Generic cipher interface --- */ \
357 \
358 static const gcipher_ops gops; \
359 \
360 typedef struct gctx { \
361 gcipher c; \
362 pre##_cbcctx k; \
363 } gctx; \
364 \
365 static gcipher *ginit(const void *k, size_t sz) \
366 { \
367 gctx *g = S_CREATE(gctx); \
368 g->c.ops = &gops; \
369 pre##_cbcinit(&g->k, k, sz, 0); \
370 return (&g->c); \
371 } \
372 \
373 static void gencrypt(gcipher *c, const void *s, void *t, size_t sz) \
374 { gctx *g = (gctx *)c; pre##_cbcencrypt(&g->k, s, t, sz); } \
375 \
376 static void gdecrypt(gcipher *c, const void *s, void *t, size_t sz) \
377 { gctx *g = (gctx *)c; pre##_cbcdecrypt(&g->k, s, t, sz); } \
378 \
379 static void gdestroy(gcipher *c) \
380 { gctx *g = (gctx *)c; BURN(*g); S_DESTROY(g); } \
381 \
382 static void gsetiv(gcipher *c, const void *iv) \
383 { gctx *g = (gctx *)c; pre##_cbcsetiv(&g->k, iv); } \
384 \
385 static const gcipher_ops gops = { \
386 &pre##_cbc, \
387 gencrypt, gdecrypt, gdestroy, gsetiv, 0 \
388 }; \
389 \
390 const gccipher pre##_cbc = { \
391 name "-cbc", pre##_keysz, PRE##_BLKSZ, \
392 ginit \
393 }; \
394 \
395 CBC_TESTX(PRE, pre, name, fname)
396
397 /*----- Test rig ----------------------------------------------------------*/
398
399 #define CBC_TEST(PRE, pre) CBC_TESTX(PRE, pre, #pre, #pre)
400
401 #ifdef TEST_RIG
402
403 #include "modes-test.h"
404
405 /* --- @CBC_TEST@ --- *
406 *
407 * Arguments: @PRE@, @pre@ = prefixes for block cipher definitions
408 *
409 * Use: Standard test rig for CBC functions.
410 */
411
412 #define CBC_TESTX(PRE, pre, name, fname) \
413 \
414 static pre##_ctx key; \
415 static pre##_cbcctx ctx; \
416 \
417 static void pre##_cbc_test_setup(const octet *k, size_t ksz) \
418 { pre##_init(&key, k, ksz); pre##_cbcsetkey(&ctx, &key); } \
419 \
420 static void pre##_cbc_test_reset(const octet *iv) \
421 { pre##_cbcsetiv(&ctx, iv); } \
422 \
423 static void pre##_cbc_test_enc(const octet *s, octet *d, size_t sz) \
424 { pre##_cbcencrypt(&ctx, s, d, sz); } \
425 \
426 static void pre##_cbc_test_dec(const octet *s, octet *d, size_t sz) \
427 { pre##_cbcdecrypt(&ctx, s, d, sz); } \
428 \
429 int main(int argc, char *argv[]) \
430 { \
431 return test_encmode(fname "-cbc", PRE##_KEYSZ, PRE##_BLKSZ, \
432 1, TEMF_REFALIGN, \
433 pre##_cbc_test_setup, pre##_cbc_test_reset, \
434 pre##_cbc_test_enc, pre##_cbc_test_dec, \
435 argc, argv); \
436 }
437
438 #else
439 # define CBC_TESTX(PRE, pre, name, fname)
440 #endif
441
442 /*----- That's all, folks -------------------------------------------------*/
443
444 #ifdef __cplusplus
445 }
446 #endif
447
448 #endif
Catacomb cryptographic library