d03ab969 |
1 | /* -*-c-*- |
2 | * |
3 | * $Id: ofb.h,v 1.1 1999/09/03 08:41:12 mdw Exp $ |
4 | * |
5 | * Output 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: ofb.h,v $ |
33 | * Revision 1.1 1999/09/03 08:41:12 mdw |
34 | * Initial import. |
35 | * |
36 | */ |
37 | |
38 | #ifndef OFB_H |
39 | #define OFB_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 | /*----- Macros ------------------------------------------------------------*/ |
60 | |
61 | /* --- @OFB_DECL@ --- * |
62 | * |
63 | * Arguments: @PRE@, @pre@ = prefixes for block cipher definitions |
64 | * |
65 | * Use: Makes declarations for output feedback mode. |
66 | */ |
67 | |
68 | #define OFB_DECL(PRE, pre) \ |
69 | \ |
70 | typedef struct pre ## _ofbctx { \ |
71 | pre ## _ctx ctx; /* Underlying cipher context */ \ |
72 | int off; /* Current offset in buffer */ \ |
73 | octet iv[PRE ## _BLKSZ]; /* Output buffer and IV */ \ |
74 | } pre ## _ofbctx; \ |
75 | \ |
76 | extern void pre ## _ofbgetiv(const pre ## _ofbctx */*ctx*/, \ |
77 | void */*iv*/); \ |
78 | \ |
79 | extern void pre ## _ofbsetiv(pre ## _ofbctx */*ctx*/, \ |
80 | const void */*iv*/); \ |
81 | \ |
82 | extern void pre ## _ofbbdry(pre ## _ofbctx */*ctx*/); \ |
83 | \ |
84 | extern void pre ## _ofbsetkey(pre ## _ofbctx */*ctx*/, \ |
85 | const pre ## _ctx */*k*/); \ |
86 | \ |
87 | extern void pre ## _ofbinit(pre ## _ofbctx */*ctx*/, \ |
88 | const void */*key*/, size_t /*sz*/, \ |
89 | const void */*iv*/); \ |
90 | \ |
91 | extern void pre ## _ofbencrypt(pre ## _ofbctx */*ctx*/, \ |
92 | const void */*src*/, void */*dest*/, \ |
93 | size_t /*sz*/); |
94 | |
95 | /* --- @OFB_DEF@ --- * |
96 | * |
97 | * Arguments: @PRE@, @pre@ = prefixes for the underlying block cipher |
98 | * |
99 | * Use: Creates definitions for output feedback mode. |
100 | */ |
101 | |
102 | #define OFB_DEF(PRE, pre) \ |
103 | \ |
104 | /* --- @pre_ofbgetiv@ --- * \ |
105 | * \ |
106 | * Arguments: @const pre_ofbctx *ctx@ = pointer to OFB context block \ |
107 | * @void *iv#@ = pointer to output data block \ |
108 | * \ |
109 | * Returns: --- \ |
110 | * \ |
111 | * Use: Reads the currently set IV. Reading and setting an IV \ |
112 | * is not transparent to the cipher. It will add a `step' \ |
113 | * which must be matched by a similar operation during \ |
114 | * decryption. \ |
115 | */ \ |
116 | \ |
117 | void pre ## _ofbgetiv(const pre ## _ofbctx *ctx, void *iv) \ |
118 | { \ |
119 | octet *p = iv; \ |
120 | int off = ctx->off; \ |
121 | int rest = PRE ## _BLKSZ - off; \ |
122 | memcpy(p, ctx->iv + off, rest); \ |
123 | memcpy(p + rest, ctx->iv, off); \ |
124 | } \ |
125 | \ |
126 | /* --- @pre_ofbsetiv@ --- * \ |
127 | * \ |
128 | * Arguments: @pre_ofbctx *ctx@ = pointer to OFB context block \ |
129 | * @cnost void *iv@ = pointer to IV to set \ |
130 | * \ |
131 | * Returns: --- \ |
132 | * \ |
133 | * Use: Sets the IV to use for subsequent encryption. \ |
134 | */ \ |
135 | \ |
136 | void pre ## _ofbsetiv(pre ## _ofbctx *ctx, const void *iv) \ |
137 | { \ |
138 | uint32 niv[PRE ## _BLKSZ / 4]; \ |
139 | BLKC_LOAD(PRE, niv, iv); \ |
140 | pre ## _eblk(&ctx->ctx, niv, niv); \ |
141 | BLKC_STORE(PRE, ctx->iv, niv); \ |
142 | ctx->off = 0; \ |
143 | } \ |
144 | \ |
145 | /* --- @pre_ofbbdry@ --- * \ |
146 | * \ |
147 | * Arguments: @pre_ofbctx *ctx@ = pointer to OFB context block \ |
148 | * \ |
149 | * Returns: --- \ |
150 | * \ |
151 | * Use: Inserts a boundary during encryption. Successful \ |
152 | * decryption must place a similar boundary. \ |
153 | */ \ |
154 | \ |
155 | void pre ## _ofbbdry(pre ## _ofbctx *ctx) \ |
156 | { \ |
157 | octet iv[PRE ## _BLKSZ]; \ |
158 | pre ## _ofbgetiv(ctx, iv); \ |
159 | pre ## _ofbsetiv(ctx, iv); \ |
160 | BURN(iv); \ |
161 | } \ |
162 | \ |
163 | /* --- @pre_ofbsetkey@ --- * \ |
164 | * \ |
165 | * Arguments: @pre_ofbctx *ctx@ = pointer to OFB context block \ |
166 | * @const pre_ctx *k@ = pointer to cipher context \ |
167 | * \ |
168 | * Returns: --- \ |
169 | * \ |
170 | * Use: Sets the OFB context to use a different cipher key. \ |
171 | */ \ |
172 | \ |
173 | void pre ## _ofbsetkey(pre ## _ofbctx *ctx, const pre ## _ctx *k) \ |
174 | { \ |
175 | ctx->ctx = *k; \ |
176 | } \ |
177 | \ |
178 | /* --- @pre_ofbinit@ --- * \ |
179 | * \ |
180 | * Arguments: @pre_ofbctx *ctx@ = pointer to cipher context \ |
181 | * @const void *key@ = pointer to the key buffer \ |
182 | * @size_t sz@ = size of the key \ |
183 | * @const void *iv@ = pointer to initialization vector \ |
184 | * \ |
185 | * Returns: --- \ |
186 | * \ |
187 | * Use: Initializes a OFB context ready for use. You should \ |
188 | * ensure that the IV chosen is unique: reusing an IV will \ |
189 | * compromise the security of the entire plaintext. This \ |
190 | * is equivalent to calls to @pre_init@, @pre_ofbsetkey@ \ |
191 | * and @pre_ofbsetiv@. \ |
192 | */ \ |
193 | \ |
194 | void pre ## _ofbinit(pre ## _ofbctx *ctx, \ |
195 | const void *key, size_t sz, \ |
196 | const void *iv) \ |
197 | { \ |
198 | static octet zero[PRE ## _BLKSZ] = { 0 }; \ |
199 | pre ## _init(&ctx->ctx, key, sz); \ |
200 | pre ## _ofbsetiv(ctx, iv ? iv : zero); \ |
201 | } \ |
202 | \ |
203 | /* --- @pre_ofbencrypt@ --- * \ |
204 | * \ |
205 | * Arguments: @pre_ofbctx *ctx@ = pointer to OFB context block \ |
206 | * @const void *src@ = pointer to source data \ |
207 | * @void *dest@ = pointer to destination data \ |
208 | * @size_t sz@ = size of block to be encrypted \ |
209 | * \ |
210 | * Returns: --- \ |
211 | * \ |
212 | * Use: Encrypts or decrypts a block with a block cipher in OFB \ |
213 | * mode: encryption and decryption are the same in OFB. \ |
214 | * The destination may be null to just churn the feedback \ |
215 | * round for a bit. The source may be null to use the \ |
216 | * cipher as a random data generator. \ |
217 | */ \ |
218 | \ |
219 | void pre ## _ofbencrypt(pre ## _ofbctx *ctx, \ |
220 | const void *src, void *dest, \ |
221 | size_t sz) \ |
222 | { \ |
223 | const octet *s = src; \ |
224 | octet *d = dest; \ |
225 | int off = ctx->off; \ |
226 | \ |
227 | /* --- Empty blocks are trivial --- */ \ |
228 | \ |
229 | if (!sz) \ |
230 | return; \ |
231 | \ |
232 | /* --- If I can deal with the block from my buffer, do that --- */ \ |
233 | \ |
234 | if (sz < PRE ## _BLKSZ - off) \ |
235 | goto small; \ |
236 | \ |
237 | /* --- Finish off what's left in my buffer --- */ \ |
238 | \ |
239 | if (!d) \ |
240 | sz -= off; \ |
241 | else { \ |
242 | while (off < PRE ## _BLKSZ) { \ |
243 | register octet x = s ? *s++ : 0; \ |
244 | *d++ = ctx->iv[off++] ^ x; \ |
245 | sz--; \ |
246 | } \ |
247 | } \ |
248 | \ |
249 | /* --- Main encryption loop --- */ \ |
250 | \ |
251 | { \ |
252 | uint32 iv[PRE ## _BLKSZ / 4]; \ |
253 | BLKC_LOAD(PRE, iv, ctx->iv); \ |
254 | \ |
255 | for (;;) { \ |
256 | pre ## _eblk(&ctx->ctx, iv, iv); \ |
257 | if (sz < PRE ## _BLKSZ) \ |
258 | break; \ |
259 | if (d) { \ |
260 | if (!s) \ |
261 | BLKC_STORE(PRE, d, iv); \ |
262 | else { \ |
263 | uint32 x[PRE ## _BLKSZ / 4]; \ |
264 | BLKC_LOAD(PRE, x, s); \ |
265 | BLKC_XSTORE(PRE, d, iv, x); \ |
266 | s += PRE ## _BLKSZ; \ |
267 | } \ |
268 | d += PRE ## _BLKSZ; \ |
269 | } \ |
270 | sz -= PRE ## _BLKSZ; \ |
271 | } \ |
272 | \ |
273 | BLKC_STORE(PRE, ctx->iv, iv); \ |
274 | off = 0; \ |
275 | } \ |
276 | \ |
277 | /* --- Tidying up the tail end --- */ \ |
278 | \ |
279 | if (sz) { \ |
280 | small: \ |
281 | if (!d) \ |
282 | off += sz; \ |
283 | else do { \ |
284 | register octet x = s ? *s++ : 0; \ |
285 | *d++ = ctx->iv[off++] ^ x; \ |
286 | sz--; \ |
287 | } while (sz); \ |
288 | } \ |
289 | \ |
290 | /* --- Done --- */ \ |
291 | \ |
292 | ctx->off = off; \ |
293 | return; \ |
294 | } \ |
295 | \ |
296 | OFB_TEST(PRE, pre) |
297 | |
298 | /*----- Test rig ----------------------------------------------------------*/ |
299 | |
300 | #ifdef TEST_RIG |
301 | |
302 | #include <stdio.h> |
303 | |
304 | #include "daftstory.h" |
305 | |
306 | /* --- @OFB_TEST@ --- * |
307 | * |
308 | * Arguments: @PRE@, @pre@ = prefixes for block cipher definitions |
309 | * |
310 | * Use: Standard test rig for OFB functions. |
311 | */ |
312 | |
313 | #define OFB_TEST(PRE, pre) \ |
314 | \ |
315 | /* --- Initial plaintext for the test --- */ \ |
316 | \ |
317 | static const octet text[] = TEXT; \ |
318 | \ |
319 | /* --- Key and IV to use --- */ \ |
320 | \ |
321 | static const octet key[] = KEY; \ |
322 | static const octet iv[] = IV; \ |
323 | \ |
324 | /* --- Buffers for encryption and decryption output --- */ \ |
325 | \ |
326 | static octet ct[sizeof(text)]; \ |
327 | static octet pt[sizeof(text)]; \ |
328 | \ |
329 | static void hexdump(const octet *p, size_t sz) \ |
330 | { \ |
331 | const octet *q = p + sz; \ |
332 | for (sz = 0; p < q; p++, sz++) { \ |
333 | printf("%02x", *p); \ |
334 | if ((sz + 1) % PRE ## _BLKSZ == 0) \ |
335 | putchar(':'); \ |
336 | } \ |
337 | } \ |
338 | \ |
339 | int main(void) \ |
340 | { \ |
341 | size_t sz = 0, rest; \ |
342 | pre ## _ofbctx ctx; \ |
343 | int status = 0; \ |
344 | int done = 0; \ |
345 | pre ## _ctx k; \ |
346 | \ |
347 | size_t keysz = PRE ## _KEYSZ ? \ |
348 | PRE ## _KEYSZ : strlen((const char *)key); \ |
349 | \ |
350 | fputs(#pre "-ofb: ", stdout); \ |
351 | \ |
352 | pre ## _init(&k, key, keysz); \ |
353 | pre ## _ofbsetkey(&ctx, &k); \ |
354 | \ |
355 | while (sz <= sizeof(text)) { \ |
356 | rest = sizeof(text) - sz; \ |
357 | memcpy(ct, text, sizeof(text)); \ |
358 | pre ## _ofbsetiv(&ctx, iv); \ |
359 | pre ## _ofbencrypt(&ctx, ct, ct, sz); \ |
360 | pre ## _ofbencrypt(&ctx, ct + sz, ct + sz, rest); \ |
361 | memcpy(pt, ct, sizeof(text)); \ |
362 | pre ## _ofbsetiv(&ctx, iv); \ |
363 | pre ## _ofbencrypt(&ctx, pt, pt, rest); \ |
364 | pre ## _ofbencrypt(&ctx, pt + rest, pt + rest, sz); \ |
365 | if (memcmp(pt, text, sizeof(text)) == 0) { \ |
366 | done++; \ |
367 | if (sizeof(text) < 40 || done % 8 == 0) \ |
368 | fputc('.', stdout); \ |
369 | if (done % 480 == 0) \ |
370 | fputs("\n\t", stdout); \ |
371 | fflush(stdout); \ |
372 | } else { \ |
373 | printf("\nError (sz = %lu)\n", (unsigned long)sz); \ |
374 | status = 1; \ |
375 | printf("\tplaintext = "); hexdump(text, sz); \ |
376 | printf(", "); hexdump(text + sz, rest); \ |
377 | fputc('\n', stdout); \ |
378 | printf("\tciphertext = "); hexdump(ct, sz); \ |
379 | printf(", "); hexdump(ct + sz, rest); \ |
380 | fputc('\n', stdout); \ |
381 | printf("\trecovered text = "); hexdump(pt, sz); \ |
382 | printf(", "); hexdump(pt + sz, rest); \ |
383 | fputc('\n', stdout); \ |
384 | fputc('\n', stdout); \ |
385 | } \ |
386 | if (sz < 63) \ |
387 | sz++; \ |
388 | else \ |
389 | sz += 9; \ |
390 | } \ |
391 | \ |
392 | fputs(status ? " failed\n" : " ok\n", stdout); \ |
393 | return (status); \ |
394 | } |
395 | |
396 | #else |
397 | # define OFB_TEST(PRE, pre) |
398 | #endif |
399 | |
400 | /*----- That's all, folks -------------------------------------------------*/ |
401 | |
402 | #ifdef __cplusplus |
403 | } |
404 | #endif |
405 | |
406 | #endif |