3 * Definitions for cipher block chaining mode
5 * (c) 1999 Straylight/Edgeware
8 /*----- Licensing notice --------------------------------------------------*
10 * This file is part of Catacomb.
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.
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.
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,
28 #ifndef CATACOMB_CBC_DEF_H
29 #define CATACOMB_CBC_DEF_H
35 /*----- Header files ------------------------------------------------------*/
39 #include <mLib/bits.h>
42 #ifndef CATACOMB_ARENA_H
46 #ifndef CATACOMB_BLKC_H
50 #ifndef CATACOMB_GCIPHER_H
54 #ifndef CATACOMB_PARANOIA_H
55 # include "paranoia.h"
58 /*----- Macros ------------------------------------------------------------*/
60 /* --- @CBC_DEF@ --- *
62 * Arguments: @PRE@, @pre@ = prefixes for the underlying block cipher
64 * Use: Creates an implementation for CBC stealing mode.
67 #define CBC_DEF(PRE, pre) CBC_DEFX(PRE, pre, #pre, #pre)
69 #define CBC_DEFX(PRE, pre, name, fname) \
71 /* --- @pre_cbcgetiv@ --- * \
73 * Arguments: @const pre_cbcctx *ctx@ = pointer to CBC context block \
74 * @void *iv@ = pointer to output data block \
78 * Use: Reads the currently set IV. Reading and setting an IV \
79 * is transparent to the CBC encryption or decryption \
83 void pre##_cbcgetiv(const pre##_cbcctx *ctx, void *iv) \
85 BLKC_STORE(PRE, iv, ctx->iv); \
88 /* --- @pre_cbcsetiv@ --- * \
90 * Arguments: @pre_cbcctx *ctx@ = pointer to CBC context block \
91 * @cnost void *iv@ = pointer to IV to set \
95 * Use: Sets the IV to use for subsequent encryption. \
98 void pre##_cbcsetiv(pre##_cbcctx *ctx, const void *iv) \
100 BLKC_LOAD(PRE, ctx->iv, iv); \
103 /* --- @pre_cbcsetkey@ --- * \
105 * Arguments: @pre_cbcctx *ctx@ = pointer to CBC context block \
106 * @const pre_ctx *k@ = pointer to cipher context \
110 * Use: Sets the CBC context to use a different cipher key. \
113 void pre##_cbcsetkey(pre##_cbcctx *ctx, const pre##_ctx *k) \
118 /* --- @pre_cbcinit@ --- * \
120 * Arguments: @pre_cbcctx *ctx@ = pointer to cipher context \
121 * @const void *key@ = pointer to the key buffer \
122 * @size_t sz@ = size of the key \
123 * @const void *iv@ = pointer to initialization vector \
127 * Use: Initializes a CBC context ready for use. The @iv@ \
128 * argument may be passed as a null pointer to set a zero \
129 * IV. Apart from that, this call is equivalent to calls \
130 * to @pre_init@, @pre_cbcsetkey@ and @pre_cbcsetiv@. \
133 void pre##_cbcinit(pre##_cbcctx *ctx, \
134 const void *key, size_t sz, \
137 static const octet zero[PRE##_BLKSZ] = { 0 }; \
138 pre##_init(&ctx->ctx, key, sz); \
139 BLKC_LOAD(PRE, ctx->iv, iv ? iv : zero); \
142 /* --- @pre_cbcencrypt@ --- * \
144 * Arguments: @pre_cbcctx *ctx@ = pointer to CBC context block \
145 * @const void *src@ = pointer to source data \
146 * @void *dest@ = pointer to destination data \
147 * @size_t sz@ = size of block to be encrypted \
151 * Use: Encrypts a block with a block cipher in CBC mode, with \
152 * ciphertext stealing and other clever tricks. \
153 * Essentially, data can be encrypted in arbitrary sized \
154 * chunks, although decryption must use the same chunks. \
157 void pre##_cbcencrypt(pre##_cbcctx *ctx, \
158 const void *src, void *dest, \
161 const octet *s = src; \
164 /* --- Empty blocks are trivial --- */ \
169 /* --- Extra magical case for a short block --- * \
171 * Encrypt the IV, then exclusive-or the plaintext with the octets \
172 * of the encrypted IV, shifting ciphertext octets in instead. This \
173 * basically switches over to CFB. \
176 if (sz < PRE##_BLKSZ) { \
177 octet b[PRE##_BLKSZ]; \
180 pre##_eblk(&ctx->ctx, ctx->iv, ctx->iv); \
181 BLKC_STORE(PRE, b, ctx->iv); \
183 for (i = 0; i < sz; i++) \
184 d[i] = b[i] ^ (s ? s[i] : 0); \
186 memmove(b, b + sz, PRE##_BLKSZ - sz); \
187 memcpy(b + PRE##_BLKSZ - sz, d, sz); \
188 BLKC_LOAD(PRE, ctx->iv, b); \
192 /* --- Do the main chunk of encryption --- * \
194 * This will do the whole lot if it's a whole number of blocks. For \
195 * each block, XOR it with the previous ciphertext in @iv@, encrypt, \
196 * and keep a copy of the ciphertext for the next block. \
199 while (sz >= 2 * PRE##_BLKSZ || sz == PRE##_BLKSZ) { \
201 BLKC_XLOAD(PRE, ctx->iv, s); \
204 pre##_eblk(&ctx->ctx, ctx->iv, ctx->iv); \
206 BLKC_STORE(PRE, d, ctx->iv); \
212 /* --- Do the tail-end block and bit-left-over --- * \
214 * This isn't very efficient. That shouldn't matter much. \
218 octet b[PRE##_BLKSZ]; \
221 /* --- Let @sz@ be the size of the partial block --- */ \
225 /* --- First stage --- * \
227 * XOR the complete block with the current IV, and encrypt it. The \
228 * first part of the result is the partial ciphertext block. Don't \
229 * write that out yet, because I've not read the partial plaintext \
233 if (s) BLKC_XLOAD(PRE, ctx->iv, s); \
234 pre##_eblk(&ctx->ctx, ctx->iv, ctx->iv); \
235 BLKC_STORE(PRE, b, ctx->iv); \
237 /* --- Second stage --- * \
239 * Now XOR in the partial plaintext block, writing out the \
240 * ciphertext as I go. Then encrypt, and write the complete \
241 * ciphertext block. \
244 if (s) s += PRE##_BLKSZ; \
245 if (d) d += PRE##_BLKSZ; \
246 for (i = 0; i < sz; i++) { \
247 register octet x = b[i]; \
248 if (s) b[i] ^= s[i]; \
251 BLKC_LOAD(PRE, ctx->iv, b); \
252 pre##_eblk(&ctx->ctx, ctx->iv, ctx->iv); \
253 if (d) BLKC_STORE(PRE, d - PRE##_BLKSZ, ctx->iv); \
261 /* --- @pre_cbcdecrypt@ --- * \
263 * Arguments: @pre_cbcctx *ctx@ = pointer to CBC context block \
264 * @const void *src@ = pointer to source data \
265 * @void *dest@ = pointer to destination data \
266 * @size_t sz@ = size of block to be encrypted \
270 * Use: Decrypts a block with a block cipher in CBC mode, with \
271 * ciphertext stealing and other clever tricks. \
272 * Essentially, data can be encrypted in arbitrary sized \
273 * chunks, although decryption must use the same chunks. \
276 void pre##_cbcdecrypt(pre##_cbcctx *ctx, \
277 const void *src, void *dest, \
280 const octet *s = src; \
283 /* --- Empty blocks are trivial --- */ \
288 /* --- Extra magical case for a short block --- * \
290 * Encrypt the IV, then exclusive-or the ciphertext with the octets \
291 * of the encrypted IV, shifting ciphertext octets in instead. This \
292 * basically switches over to CFB. \
295 if (sz < PRE##_BLKSZ) { \
296 octet b[PRE##_BLKSZ], c[PRE##_BLKSZ]; \
299 pre##_eblk(&ctx->ctx, ctx->iv, ctx->iv); \
300 BLKC_STORE(PRE, b, ctx->iv); \
301 for (i = 0; i < sz; i++) { \
302 register octet x = s[i]; \
306 memmove(b, b + sz, PRE##_BLKSZ - sz); \
307 memcpy(b + PRE##_BLKSZ - sz, c, sz); \
308 BLKC_LOAD(PRE, ctx->iv, b); \
312 /* --- Do the main chunk of decryption --- * \
314 * This will do the whole lot if it's a whole number of blocks. For \
315 * each block, decrypt, XOR it with the previous ciphertext in @iv@, \
316 * and keep a copy of the ciphertext for the next block. \
319 while (sz >= 2 * PRE##_BLKSZ || sz == PRE##_BLKSZ) { \
320 uint32 b[PRE##_BLKSZ / 4], niv[PRE##_BLKSZ / 4]; \
321 BLKC_LOAD(PRE, niv, s); \
322 pre##_dblk(&ctx->ctx, niv, b); \
323 BLKC_XSTORE(PRE, d, b, ctx->iv); \
324 BLKC_MOVE(PRE, ctx->iv, niv); \
330 /* --- Do the tail-end block and bit-left-over --- * \
332 * This isn't very efficient. That shouldn't matter much. \
336 octet b[PRE##_BLKSZ]; \
337 uint32 bk[PRE##_BLKSZ / 4], niv[PRE##_BLKSZ / 4]; \
340 /* --- Let @sz@ be the size of the partial block --- */ \
344 /* --- First stage --- * \
346 * Take the complete ciphertext block, and decrypt it. This block \
347 * is carried over for the next encryption operation. \
350 BLKC_LOAD(PRE, niv, s); \
351 pre##_dblk(&ctx->ctx, niv, bk); \
353 /* --- Second stage --- * \
355 * XORing the first few bytes of this with the partial ciphertext \
356 * block recovers the partial plaintext block. At the same time, \
357 * write the partial ciphertext block's contents in ready for stage \
361 BLKC_STORE(PRE, b, bk); \
364 for (i = 0; i < sz; i++) { \
365 register octet x = s[i]; \
370 /* --- Third stage --- * \
372 * Decrypt the block we've got left, and XOR with the initial IV to \
373 * recover the complete plaintext block. \
376 BLKC_LOAD(PRE, bk, b); \
377 pre##_dblk(&ctx->ctx, bk, bk); \
378 BLKC_XSTORE(PRE, d - PRE##_BLKSZ, bk, ctx->iv); \
379 BLKC_MOVE(PRE, ctx->iv, niv); \
387 /* --- Generic cipher interface --- */ \
389 static const gcipher_ops gops; \
391 typedef struct gctx { \
396 static gcipher *ginit(const void *k, size_t sz) \
398 gctx *g = S_CREATE(gctx); \
400 pre##_cbcinit(&g->k, k, sz, 0); \
404 static void gencrypt(gcipher *c, const void *s, void *t, size_t sz) \
406 gctx *g = (gctx *)c; \
407 pre##_cbcencrypt(&g->k, s, t, sz); \
410 static void gdecrypt(gcipher *c, const void *s, void *t, size_t sz) \
412 gctx *g = (gctx *)c; \
413 pre##_cbcdecrypt(&g->k, s, t, sz); \
416 static void gdestroy(gcipher *c) \
418 gctx *g = (gctx *)c; \
423 static void gsetiv(gcipher *c, const void *iv) \
425 gctx *g = (gctx *)c; \
426 pre##_cbcsetiv(&g->k, iv); \
429 static const gcipher_ops gops = { \
431 gencrypt, gdecrypt, gdestroy, gsetiv, 0 \
434 const gccipher pre##_cbc = { \
435 name "-cbc", pre##_keysz, PRE##_BLKSZ, \
439 CBC_TESTX(PRE, pre, name, fname)
441 /*----- Test rig ----------------------------------------------------------*/
443 #define CBC_TEST(PRE, pre) CBC_TESTX(PRE, pre, #pre, #pre)
449 #include "daftstory.h"
451 /* --- @CBC_TEST@ --- *
453 * Arguments: @PRE@, @pre@ = prefixes for block cipher definitions
455 * Use: Standard test rig for CBC functions.
458 #define CBC_TESTX(PRE, pre, name, fname) \
460 /* --- Initial plaintext for the test --- */ \
462 static const octet text[] = TEXT; \
464 /* --- Key and IV to use --- */ \
466 static const octet key[] = KEY; \
467 static const octet iv[] = IV; \
469 /* --- Buffers for encryption and decryption output --- */ \
471 static octet ct[sizeof(text)]; \
472 static octet pt[sizeof(text)]; \
474 static void hexdump(const octet *p, size_t sz, size_t off) \
476 const octet *q = p + sz; \
477 for (sz = 0; p < q; p++, sz++) { \
478 printf("%02x", *p); \
479 if ((off + sz + 1) % PRE##_BLKSZ == 0) \
486 size_t sz = 0, rest; \
492 size_t keysz = PRE##_KEYSZ ? \
493 PRE##_KEYSZ : strlen((const char *)key); \
495 fputs(name "-cbc: ", stdout); \
497 pre##_init(&k, key, keysz); \
498 pre##_cbcsetkey(&ctx, &k); \
500 while (sz <= sizeof(text)) { \
501 rest = sizeof(text) - sz; \
502 memcpy(ct, text, sizeof(text)); \
503 pre##_cbcsetiv(&ctx, iv); \
504 pre##_cbcencrypt(&ctx, ct, ct, sz); \
505 pre##_cbcencrypt(&ctx, ct + sz, ct + sz, rest); \
506 memcpy(pt, ct, sizeof(text)); \
507 pre##_cbcsetiv(&ctx, iv); \
508 pre##_cbcdecrypt(&ctx, pt, pt, sz); \
509 pre##_cbcdecrypt(&ctx, pt + sz, pt + sz, rest); \
510 if (memcmp(pt, text, sizeof(text)) == 0) { \
512 if (sizeof(text) < 40 || done % 8 == 0) \
513 fputc('.', stdout); \
514 if (done % 480 == 0) \
515 fputs("\n\t", stdout); \
518 printf("\nError (sz = %lu)\n", (unsigned long)sz); \
520 printf("\tplaintext = "); hexdump(text, sz, 0); \
521 printf(", "); hexdump(text + sz, rest, sz); \
522 fputc('\n', stdout); \
523 printf("\tciphertext = "); hexdump(ct, sz, 0); \
524 printf(", "); hexdump(ct + sz, rest, sz); \
525 fputc('\n', stdout); \
526 printf("\trecovered text = "); hexdump(pt, sz, 0); \
527 printf(", "); hexdump(pt + sz, rest, sz); \
528 fputc('\n', stdout); \
529 fputc('\n', stdout); \
537 fputs(status ? " failed\n" : " ok\n", stdout); \
542 # define CBC_TESTX(PRE, pre, name, fname)
545 /*----- That's all, folks -------------------------------------------------*/