| 1 | /* -*-c-*- |
| 2 | * |
| 3 | * Definitions for output feedback 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_OFB_DEF_H |
| 29 | #define CATACOMB_OFB_DEF_H |
| 30 | |
| 31 | #ifdef __cplusplus |
| 32 | extern "C" { |
| 33 | #endif |
| 34 | |
| 35 | /*----- Header files ------------------------------------------------------*/ |
| 36 | |
| 37 | #include <stdarg.h> |
| 38 | #include <string.h> |
| 39 | |
| 40 | #include <mLib/bits.h> |
| 41 | #include <mLib/sub.h> |
| 42 | |
| 43 | #ifndef CATACOMB_ARENA_H |
| 44 | # include "arena.h" |
| 45 | #endif |
| 46 | |
| 47 | #ifndef CATACOMB_BLKC_H |
| 48 | # include "blkc.h" |
| 49 | #endif |
| 50 | |
| 51 | #ifndef CATACOMB_GCIPHER_H |
| 52 | # include "gcipher.h" |
| 53 | #endif |
| 54 | |
| 55 | #ifndef CATACOMB_PARANOIA_H |
| 56 | # include "paranoia.h" |
| 57 | #endif |
| 58 | |
| 59 | /*----- Macros ------------------------------------------------------------*/ |
| 60 | |
| 61 | /* --- @OFB_DEF@ --- * |
| 62 | * |
| 63 | * Arguments: @PRE@, @pre@ = prefixes for the underlying block cipher |
| 64 | * |
| 65 | * Use: Creates definitions for output feedback mode. |
| 66 | */ |
| 67 | |
| 68 | #define OFB_DEF(PRE, pre) \ |
| 69 | \ |
| 70 | /* --- @pre_ofbgetiv@ --- * \ |
| 71 | * \ |
| 72 | * Arguments: @const pre_ofbctx *ctx@ = pointer to OFB context block \ |
| 73 | * @void *iv@ = pointer to output data block \ |
| 74 | * \ |
| 75 | * Returns: --- \ |
| 76 | * \ |
| 77 | * Use: Reads the currently set IV. Reading and setting an IV \ |
| 78 | * is not transparent to the cipher. It will add a `step' \ |
| 79 | * which must be matched by a similar operation during \ |
| 80 | * decryption. \ |
| 81 | */ \ |
| 82 | \ |
| 83 | void pre##_ofbgetiv(const pre##_ofbctx *ctx, void *iv) \ |
| 84 | { \ |
| 85 | octet *p = iv; \ |
| 86 | unsigned off = ctx->off; \ |
| 87 | unsigned rest = PRE##_BLKSZ - off; \ |
| 88 | memcpy(p, ctx->iv + off, rest); \ |
| 89 | memcpy(p + rest, ctx->iv, off); \ |
| 90 | } \ |
| 91 | \ |
| 92 | /* --- @pre_ofbsetiv@ --- * \ |
| 93 | * \ |
| 94 | * Arguments: @pre_ofbctx *ctx@ = pointer to OFB context block \ |
| 95 | * @cnost void *iv@ = pointer to IV to set \ |
| 96 | * \ |
| 97 | * Returns: --- \ |
| 98 | * \ |
| 99 | * Use: Sets the IV to use for subsequent encryption. \ |
| 100 | */ \ |
| 101 | \ |
| 102 | void pre##_ofbsetiv(pre##_ofbctx *ctx, const void *iv) \ |
| 103 | { \ |
| 104 | memcpy(ctx->iv, iv, PRE##_BLKSZ); \ |
| 105 | ctx->off = PRE##_BLKSZ; \ |
| 106 | } \ |
| 107 | \ |
| 108 | /* --- @pre_ofbbdry@ --- * \ |
| 109 | * \ |
| 110 | * Arguments: @pre_ofbctx *ctx@ = pointer to OFB context block \ |
| 111 | * \ |
| 112 | * Returns: --- \ |
| 113 | * \ |
| 114 | * Use: Inserts a boundary during encryption. Successful \ |
| 115 | * decryption must place a similar boundary. \ |
| 116 | */ \ |
| 117 | \ |
| 118 | void pre##_ofbbdry(pre##_ofbctx *ctx) \ |
| 119 | { \ |
| 120 | uint32 niv[PRE##_BLKSZ / 4]; \ |
| 121 | BLKC_LOAD(PRE, niv, ctx->iv); \ |
| 122 | pre##_eblk(&ctx->ctx, niv, niv); \ |
| 123 | BLKC_STORE(PRE, ctx->iv, niv); \ |
| 124 | ctx->off = PRE##_BLKSZ; \ |
| 125 | BURN(niv); \ |
| 126 | } \ |
| 127 | \ |
| 128 | /* --- @pre_ofbsetkey@ --- * \ |
| 129 | * \ |
| 130 | * Arguments: @pre_ofbctx *ctx@ = pointer to OFB context block \ |
| 131 | * @const pre_ctx *k@ = pointer to cipher context \ |
| 132 | * \ |
| 133 | * Returns: --- \ |
| 134 | * \ |
| 135 | * Use: Sets the OFB context to use a different cipher key. \ |
| 136 | */ \ |
| 137 | \ |
| 138 | void pre##_ofbsetkey(pre##_ofbctx *ctx, const pre##_ctx *k) \ |
| 139 | { \ |
| 140 | ctx->ctx = *k; \ |
| 141 | } \ |
| 142 | \ |
| 143 | /* --- @pre_ofbinit@ --- * \ |
| 144 | * \ |
| 145 | * Arguments: @pre_ofbctx *ctx@ = pointer to cipher context \ |
| 146 | * @const void *key@ = pointer to the key buffer \ |
| 147 | * @size_t sz@ = size of the key \ |
| 148 | * @const void *iv@ = pointer to initialization vector \ |
| 149 | * \ |
| 150 | * Returns: --- \ |
| 151 | * \ |
| 152 | * Use: Initializes a OFB context ready for use. You should \ |
| 153 | * ensure that the IV chosen is unique: reusing an IV will \ |
| 154 | * compromise the security of the entire plaintext. This \ |
| 155 | * is equivalent to calls to @pre_init@, @pre_ofbsetkey@ \ |
| 156 | * and @pre_ofbsetiv@. \ |
| 157 | */ \ |
| 158 | \ |
| 159 | void pre##_ofbinit(pre##_ofbctx *ctx, \ |
| 160 | const void *key, size_t sz, \ |
| 161 | const void *iv) \ |
| 162 | { \ |
| 163 | static const octet zero[PRE##_BLKSZ] = { 0 }; \ |
| 164 | pre##_init(&ctx->ctx, key, sz); \ |
| 165 | pre##_ofbsetiv(ctx, iv ? iv : zero); \ |
| 166 | } \ |
| 167 | \ |
| 168 | /* --- @pre_ofbencrypt@ --- * \ |
| 169 | * \ |
| 170 | * Arguments: @pre_ofbctx *ctx@ = pointer to OFB context block \ |
| 171 | * @const void *src@ = pointer to source data \ |
| 172 | * @void *dest@ = pointer to destination data \ |
| 173 | * @size_t sz@ = size of block to be encrypted \ |
| 174 | * \ |
| 175 | * Returns: --- \ |
| 176 | * \ |
| 177 | * Use: Encrypts or decrypts a block with a block cipher in OFB \ |
| 178 | * mode: encryption and decryption are the same in OFB. \ |
| 179 | * The destination may be null to just churn the feedback \ |
| 180 | * round for a bit. The source may be null to use the \ |
| 181 | * cipher as a random data generator. \ |
| 182 | */ \ |
| 183 | \ |
| 184 | void pre##_ofbencrypt(pre##_ofbctx *ctx, \ |
| 185 | const void *src, void *dest, \ |
| 186 | size_t sz) \ |
| 187 | { \ |
| 188 | const octet *s = src; \ |
| 189 | octet *d = dest; \ |
| 190 | unsigned off = ctx->off; \ |
| 191 | \ |
| 192 | /* --- Empty blocks are trivial --- */ \ |
| 193 | \ |
| 194 | if (!sz) \ |
| 195 | return; \ |
| 196 | \ |
| 197 | /* --- If I can deal with the block from my buffer, do that --- */ \ |
| 198 | \ |
| 199 | if (sz < PRE##_BLKSZ - off) \ |
| 200 | goto small; \ |
| 201 | \ |
| 202 | /* --- Finish off what's left in my buffer --- */ \ |
| 203 | \ |
| 204 | if (!d) \ |
| 205 | sz -= PRE##_BLKSZ - off; \ |
| 206 | else { \ |
| 207 | while (off < PRE##_BLKSZ) { \ |
| 208 | register octet x = s ? *s++ : 0; \ |
| 209 | *d++ = ctx->iv[off++] ^ x; \ |
| 210 | sz--; \ |
| 211 | } \ |
| 212 | } \ |
| 213 | \ |
| 214 | /* --- Main encryption loop --- */ \ |
| 215 | \ |
| 216 | { \ |
| 217 | uint32 iv[PRE##_BLKSZ / 4]; \ |
| 218 | BLKC_LOAD(PRE, iv, ctx->iv); \ |
| 219 | \ |
| 220 | for (;;) { \ |
| 221 | pre##_eblk(&ctx->ctx, iv, iv); \ |
| 222 | if (sz < PRE##_BLKSZ) \ |
| 223 | break; \ |
| 224 | if (d) { \ |
| 225 | if (!s) \ |
| 226 | BLKC_STORE(PRE, d, iv); \ |
| 227 | else { \ |
| 228 | uint32 x[PRE##_BLKSZ / 4]; \ |
| 229 | BLKC_LOAD(PRE, x, s); \ |
| 230 | BLKC_XSTORE(PRE, d, iv, x); \ |
| 231 | s += PRE##_BLKSZ; \ |
| 232 | } \ |
| 233 | d += PRE##_BLKSZ; \ |
| 234 | } \ |
| 235 | sz -= PRE##_BLKSZ; \ |
| 236 | } \ |
| 237 | \ |
| 238 | BLKC_STORE(PRE, ctx->iv, iv); \ |
| 239 | off = 0; \ |
| 240 | } \ |
| 241 | \ |
| 242 | /* --- Tidying up the tail end --- */ \ |
| 243 | \ |
| 244 | if (sz) { \ |
| 245 | small: \ |
| 246 | if (!d) \ |
| 247 | off += sz; \ |
| 248 | else do { \ |
| 249 | register octet x = s ? *s++ : 0; \ |
| 250 | *d++ = ctx->iv[off++] ^ x; \ |
| 251 | sz--; \ |
| 252 | } while (sz); \ |
| 253 | } \ |
| 254 | \ |
| 255 | /* --- Done --- */ \ |
| 256 | \ |
| 257 | ctx->off = off; \ |
| 258 | return; \ |
| 259 | } \ |
| 260 | \ |
| 261 | /* --- Generic cipher interface --- */ \ |
| 262 | \ |
| 263 | static const gcipher_ops gops; \ |
| 264 | \ |
| 265 | typedef struct gctx { \ |
| 266 | gcipher c; \ |
| 267 | pre##_ofbctx k; \ |
| 268 | } gctx; \ |
| 269 | \ |
| 270 | static gcipher *ginit(const void *k, size_t sz) \ |
| 271 | { \ |
| 272 | gctx *g = S_CREATE(gctx); \ |
| 273 | g->c.ops = &gops; \ |
| 274 | pre##_ofbinit(&g->k, k, sz, 0); \ |
| 275 | return (&g->c); \ |
| 276 | } \ |
| 277 | \ |
| 278 | static void gencrypt(gcipher *c, const void *s, void *t, size_t sz) \ |
| 279 | { \ |
| 280 | gctx *g = (gctx *)c; \ |
| 281 | pre##_ofbencrypt(&g->k, s, t, sz); \ |
| 282 | } \ |
| 283 | \ |
| 284 | static void gdestroy(gcipher *c) \ |
| 285 | { \ |
| 286 | gctx *g = (gctx *)c; \ |
| 287 | BURN(*g); \ |
| 288 | S_DESTROY(g); \ |
| 289 | } \ |
| 290 | \ |
| 291 | static void gsetiv(gcipher *c, const void *iv) \ |
| 292 | { \ |
| 293 | gctx *g = (gctx *)c; \ |
| 294 | pre##_ofbsetiv(&g->k, iv); \ |
| 295 | } \ |
| 296 | \ |
| 297 | static void gbdry(gcipher *c) \ |
| 298 | { \ |
| 299 | gctx *g = (gctx *)c; \ |
| 300 | pre##_ofbbdry(&g->k); \ |
| 301 | } \ |
| 302 | \ |
| 303 | static const gcipher_ops gops = { \ |
| 304 | &pre##_ofb, \ |
| 305 | gencrypt, gencrypt, gdestroy, gsetiv, gbdry \ |
| 306 | }; \ |
| 307 | \ |
| 308 | const gccipher pre##_ofb = { \ |
| 309 | #pre "-ofb", pre##_keysz, PRE##_BLKSZ, \ |
| 310 | ginit \ |
| 311 | }; \ |
| 312 | \ |
| 313 | /* --- Generic random number generator interface --- */ \ |
| 314 | \ |
| 315 | typedef struct grctx { \ |
| 316 | grand r; \ |
| 317 | pre##_ofbctx k; \ |
| 318 | } grctx; \ |
| 319 | \ |
| 320 | static void grdestroy(grand *r) \ |
| 321 | { \ |
| 322 | grctx *g = (grctx *)r; \ |
| 323 | BURN(*g); \ |
| 324 | S_DESTROY(g); \ |
| 325 | } \ |
| 326 | \ |
| 327 | static int grmisc(grand *r, unsigned op, ...) \ |
| 328 | { \ |
| 329 | grctx *g = (grctx *)r; \ |
| 330 | va_list ap; \ |
| 331 | int rc = 0; \ |
| 332 | uint32 i; \ |
| 333 | octet buf[PRE##_BLKSZ]; \ |
| 334 | va_start(ap, op); \ |
| 335 | \ |
| 336 | switch (op) { \ |
| 337 | case GRAND_CHECK: \ |
| 338 | switch (va_arg(ap, unsigned)) { \ |
| 339 | case GRAND_CHECK: \ |
| 340 | case GRAND_SEEDINT: \ |
| 341 | case GRAND_SEEDUINT32: \ |
| 342 | case GRAND_SEEDBLOCK: \ |
| 343 | case GRAND_SEEDRAND: \ |
| 344 | rc = 1; \ |
| 345 | break; \ |
| 346 | default: \ |
| 347 | rc = 0; \ |
| 348 | break; \ |
| 349 | } \ |
| 350 | break; \ |
| 351 | case GRAND_SEEDINT: \ |
| 352 | memset(buf, 0, sizeof(buf)); \ |
| 353 | i = va_arg(ap, unsigned); \ |
| 354 | STORE32(buf, i); \ |
| 355 | pre##_ofbsetiv(&g->k, buf); \ |
| 356 | break; \ |
| 357 | case GRAND_SEEDUINT32: \ |
| 358 | memset(buf, 0, sizeof(buf)); \ |
| 359 | i = va_arg(ap, uint32); \ |
| 360 | STORE32(buf, i); \ |
| 361 | pre##_ofbsetiv(&g->k, buf); \ |
| 362 | break; \ |
| 363 | case GRAND_SEEDBLOCK: { \ |
| 364 | const void *p = va_arg(ap, const void *); \ |
| 365 | size_t sz = va_arg(ap, size_t); \ |
| 366 | if (sz < sizeof(buf)) { \ |
| 367 | memset(buf, 0, sizeof(buf)); \ |
| 368 | memcpy(buf, p, sz); \ |
| 369 | p = buf; \ |
| 370 | } \ |
| 371 | pre##_ofbsetiv(&g->k, p); \ |
| 372 | } break; \ |
| 373 | case GRAND_SEEDRAND: { \ |
| 374 | grand *rr = va_arg(ap, grand *); \ |
| 375 | rr->ops->fill(rr, buf, sizeof(buf)); \ |
| 376 | pre##_ofbsetiv(&g->k, buf); \ |
| 377 | } break; \ |
| 378 | default: \ |
| 379 | GRAND_BADOP; \ |
| 380 | break; \ |
| 381 | } \ |
| 382 | \ |
| 383 | va_end(ap); \ |
| 384 | return (rc); \ |
| 385 | } \ |
| 386 | \ |
| 387 | static octet grbyte(grand *r) \ |
| 388 | { \ |
| 389 | grctx *g = (grctx *)r; \ |
| 390 | octet o; \ |
| 391 | pre##_ofbencrypt(&g->k, 0, &o, 1); \ |
| 392 | return (o); \ |
| 393 | } \ |
| 394 | \ |
| 395 | static uint32 grword(grand *r) \ |
| 396 | { \ |
| 397 | grctx *g = (grctx *)r; \ |
| 398 | octet b[4]; \ |
| 399 | pre##_ofbencrypt(&g->k, 0, b, sizeof(b)); \ |
| 400 | return (LOAD32(b)); \ |
| 401 | } \ |
| 402 | \ |
| 403 | static void grfill(grand *r, void *p, size_t sz) \ |
| 404 | { \ |
| 405 | grctx *g = (grctx *)r; \ |
| 406 | pre##_ofbencrypt(&g->k, 0, p, sz); \ |
| 407 | } \ |
| 408 | \ |
| 409 | static const grand_ops grops = { \ |
| 410 | #pre "-ofb", \ |
| 411 | GRAND_CRYPTO, 0, \ |
| 412 | grmisc, grdestroy, \ |
| 413 | grword, grbyte, grword, grand_defaultrange, grfill \ |
| 414 | }; \ |
| 415 | \ |
| 416 | /* --- @pre_ofbrand@ --- * \ |
| 417 | * \ |
| 418 | * Arguments: @const void *k@ = pointer to key material \ |
| 419 | * @size_t sz@ = size of key material \ |
| 420 | * \ |
| 421 | * Returns: Pointer to generic random number generator interface. \ |
| 422 | * \ |
| 423 | * Use: Creates a random number interface wrapper around an \ |
| 424 | * OFB-mode block cipher. \ |
| 425 | */ \ |
| 426 | \ |
| 427 | grand *pre##_ofbrand(const void *k, size_t sz) \ |
| 428 | { \ |
| 429 | grctx *g = S_CREATE(grctx); \ |
| 430 | g->r.ops = &grops; \ |
| 431 | pre##_ofbinit(&g->k, k, sz, 0); \ |
| 432 | return (&g->r); \ |
| 433 | } \ |
| 434 | \ |
| 435 | OFB_TEST(PRE, pre) |
| 436 | |
| 437 | /*----- Test rig ----------------------------------------------------------*/ |
| 438 | |
| 439 | #ifdef TEST_RIG |
| 440 | |
| 441 | #include <stdio.h> |
| 442 | |
| 443 | #include "daftstory.h" |
| 444 | |
| 445 | /* --- @OFB_TEST@ --- * |
| 446 | * |
| 447 | * Arguments: @PRE@, @pre@ = prefixes for block cipher definitions |
| 448 | * |
| 449 | * Use: Standard test rig for OFB functions. |
| 450 | */ |
| 451 | |
| 452 | #define OFB_TEST(PRE, pre) \ |
| 453 | \ |
| 454 | /* --- Initial plaintext for the test --- */ \ |
| 455 | \ |
| 456 | static const octet text[] = TEXT; \ |
| 457 | \ |
| 458 | /* --- Key and IV to use --- */ \ |
| 459 | \ |
| 460 | static const octet key[] = KEY; \ |
| 461 | static const octet iv[] = IV; \ |
| 462 | \ |
| 463 | /* --- Buffers for encryption and decryption output --- */ \ |
| 464 | \ |
| 465 | static octet ct[sizeof(text)]; \ |
| 466 | static octet pt[sizeof(text)]; \ |
| 467 | \ |
| 468 | static void hexdump(const octet *p, size_t sz, size_t off) \ |
| 469 | { \ |
| 470 | const octet *q = p + sz; \ |
| 471 | for (sz = 0; p < q; p++, sz++) { \ |
| 472 | printf("%02x", *p); \ |
| 473 | if ((off + sz + 1) % PRE##_BLKSZ == 0) \ |
| 474 | putchar(':'); \ |
| 475 | } \ |
| 476 | } \ |
| 477 | \ |
| 478 | int main(void) \ |
| 479 | { \ |
| 480 | size_t sz = 0, rest; \ |
| 481 | pre##_ofbctx ctx; \ |
| 482 | int status = 0; \ |
| 483 | int done = 0; \ |
| 484 | pre##_ctx k; \ |
| 485 | \ |
| 486 | size_t keysz = PRE##_KEYSZ ? \ |
| 487 | PRE##_KEYSZ : strlen((const char *)key); \ |
| 488 | \ |
| 489 | fputs(#pre "-ofb: ", stdout); \ |
| 490 | \ |
| 491 | pre##_init(&k, key, keysz); \ |
| 492 | pre##_ofbsetkey(&ctx, &k); \ |
| 493 | \ |
| 494 | while (sz <= sizeof(text)) { \ |
| 495 | rest = sizeof(text) - sz; \ |
| 496 | memcpy(ct, text, sizeof(text)); \ |
| 497 | pre##_ofbsetiv(&ctx, iv); \ |
| 498 | pre##_ofbencrypt(&ctx, ct, ct, sz); \ |
| 499 | pre##_ofbencrypt(&ctx, ct + sz, ct + sz, rest); \ |
| 500 | memcpy(pt, ct, sizeof(text)); \ |
| 501 | pre##_ofbsetiv(&ctx, iv); \ |
| 502 | pre##_ofbencrypt(&ctx, pt, pt, rest); \ |
| 503 | pre##_ofbencrypt(&ctx, pt + rest, pt + rest, sz); \ |
| 504 | if (memcmp(pt, text, sizeof(text)) == 0) { \ |
| 505 | done++; \ |
| 506 | if (sizeof(text) < 40 || done % 8 == 0) \ |
| 507 | fputc('.', stdout); \ |
| 508 | if (done % 480 == 0) \ |
| 509 | fputs("\n\t", stdout); \ |
| 510 | fflush(stdout); \ |
| 511 | } else { \ |
| 512 | printf("\nError (sz = %lu)\n", (unsigned long)sz); \ |
| 513 | status = 1; \ |
| 514 | printf("\tplaintext = "); hexdump(text, sz, 0); \ |
| 515 | printf(", "); hexdump(text + sz, rest, sz); \ |
| 516 | fputc('\n', stdout); \ |
| 517 | printf("\tciphertext = "); hexdump(ct, sz, 0); \ |
| 518 | printf(", "); hexdump(ct + sz, rest, sz); \ |
| 519 | fputc('\n', stdout); \ |
| 520 | printf("\trecovered text = "); hexdump(pt, sz, 0); \ |
| 521 | printf(", "); hexdump(pt + sz, rest, sz); \ |
| 522 | fputc('\n', stdout); \ |
| 523 | fputc('\n', stdout); \ |
| 524 | } \ |
| 525 | if (sz < 63) \ |
| 526 | sz++; \ |
| 527 | else \ |
| 528 | sz += 9; \ |
| 529 | } \ |
| 530 | \ |
| 531 | fputs(status ? " failed\n" : " ok\n", stdout); \ |
| 532 | return (status); \ |
| 533 | } |
| 534 | |
| 535 | #else |
| 536 | # define OFB_TEST(PRE, pre) |
| 537 | #endif |
| 538 | |
| 539 | /*----- That's all, folks -------------------------------------------------*/ |
| 540 | |
| 541 | #ifdef __cplusplus |
| 542 | } |
| 543 | #endif |
| 544 | |
| 545 | #endif |