| 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) OFB_DEFX(PRE, pre, #pre, #pre) |
| 69 | |
| 70 | #define OFB_DEFX(PRE, pre, name, fname) \ |
| 71 | \ |
| 72 | /* --- @pre_ofbgetiv@ --- * \ |
| 73 | * \ |
| 74 | * Arguments: @const pre_ofbctx *ctx@ = pointer to OFB context block \ |
| 75 | * @void *iv@ = pointer to output data block \ |
| 76 | * \ |
| 77 | * Returns: --- \ |
| 78 | * \ |
| 79 | * Use: Reads the currently set IV. Reading and setting an IV \ |
| 80 | * is not transparent to the cipher. It will add a `step' \ |
| 81 | * which must be matched by a similar operation during \ |
| 82 | * decryption. \ |
| 83 | */ \ |
| 84 | \ |
| 85 | void pre##_ofbgetiv(const pre##_ofbctx *ctx, void *iv) \ |
| 86 | { \ |
| 87 | octet *p = iv; \ |
| 88 | unsigned off = ctx->off; \ |
| 89 | unsigned rest = PRE##_BLKSZ - off; \ |
| 90 | \ |
| 91 | memcpy(p, ctx->b + off, rest); \ |
| 92 | memcpy(p + rest, ctx->b, off); \ |
| 93 | } \ |
| 94 | \ |
| 95 | /* --- @pre_ofbsetiv@ --- * \ |
| 96 | * \ |
| 97 | * Arguments: @pre_ofbctx *ctx@ = pointer to OFB context block \ |
| 98 | * @cnost void *iv@ = pointer to IV to set \ |
| 99 | * \ |
| 100 | * Returns: --- \ |
| 101 | * \ |
| 102 | * Use: Sets the IV to use for subsequent encryption. \ |
| 103 | */ \ |
| 104 | \ |
| 105 | void pre##_ofbsetiv(pre##_ofbctx *ctx, const void *iv) \ |
| 106 | { memcpy(ctx->b, iv, PRE##_BLKSZ); ctx->off = PRE##_BLKSZ; } \ |
| 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 t[PRE##_BLKSZ/4]; \ |
| 121 | \ |
| 122 | BLKC_LOAD(PRE, t, ctx->b); \ |
| 123 | pre##_eblk(&ctx->ctx, t, t); \ |
| 124 | BLKC_STORE(PRE, ctx->b, t); \ |
| 125 | ctx->off = PRE##_BLKSZ; \ |
| 126 | BURN(t); \ |
| 127 | } \ |
| 128 | \ |
| 129 | /* --- @pre_ofbsetkey@ --- * \ |
| 130 | * \ |
| 131 | * Arguments: @pre_ofbctx *ctx@ = pointer to OFB context block \ |
| 132 | * @const pre_ctx *k@ = pointer to cipher context \ |
| 133 | * \ |
| 134 | * Returns: --- \ |
| 135 | * \ |
| 136 | * Use: Sets the OFB context to use a different cipher key. \ |
| 137 | */ \ |
| 138 | \ |
| 139 | void pre##_ofbsetkey(pre##_ofbctx *ctx, const pre##_ctx *k) \ |
| 140 | { ctx->ctx = *k; } \ |
| 141 | \ |
| 142 | /* --- @pre_ofbinit@ --- * \ |
| 143 | * \ |
| 144 | * Arguments: @pre_ofbctx *ctx@ = pointer to cipher context \ |
| 145 | * @const void *key@ = pointer to the key buffer \ |
| 146 | * @size_t sz@ = size of the key \ |
| 147 | * @const void *iv@ = pointer to initialization vector \ |
| 148 | * \ |
| 149 | * Returns: --- \ |
| 150 | * \ |
| 151 | * Use: Initializes a OFB context ready for use. You should \ |
| 152 | * ensure that the IV chosen is unique: reusing an IV will \ |
| 153 | * compromise the security of the entire plaintext. This \ |
| 154 | * is equivalent to calls to @pre_init@, @pre_ofbsetkey@ \ |
| 155 | * and @pre_ofbsetiv@. \ |
| 156 | */ \ |
| 157 | \ |
| 158 | void pre##_ofbinit(pre##_ofbctx *ctx, \ |
| 159 | const void *key, size_t sz, \ |
| 160 | const void *iv) \ |
| 161 | { \ |
| 162 | static const octet zero[PRE##_BLKSZ] = { 0 }; \ |
| 163 | \ |
| 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 | uint32 t[PRE##_BLKSZ/4], u[PRE##_BLKSZ/4]; \ |
| 192 | octet y; \ |
| 193 | \ |
| 194 | /* --- Empty blocks are trivial --- */ \ |
| 195 | \ |
| 196 | if (!sz) return; \ |
| 197 | \ |
| 198 | /* --- If I can deal with the block from my buffer, do that --- */ \ |
| 199 | \ |
| 200 | if (sz < PRE##_BLKSZ - off) goto small; \ |
| 201 | \ |
| 202 | /* --- Finish off what's left in my buffer --- */ \ |
| 203 | \ |
| 204 | if (!d) sz -= PRE##_BLKSZ - off; \ |
| 205 | else while (off < PRE##_BLKSZ) \ |
| 206 | { y = s ? *s++ : 0; *d++ = ctx->b[off++] ^ y; sz--; } \ |
| 207 | \ |
| 208 | /* --- Main encryption loop --- */ \ |
| 209 | \ |
| 210 | BLKC_LOAD(PRE, t, ctx->b); \ |
| 211 | \ |
| 212 | for (;;) { \ |
| 213 | pre##_eblk(&ctx->ctx, t, t); \ |
| 214 | if (sz < PRE##_BLKSZ) break; \ |
| 215 | if (!d) /* do nothing */; \ |
| 216 | else if (!s) { BLKC_STORE(PRE, d, t); d += PRE##_BLKSZ; } \ |
| 217 | else { \ |
| 218 | BLKC_LOAD(PRE, u, s); s += PRE##_BLKSZ; \ |
| 219 | BLKC_XSTORE(PRE, d, t, u); d += PRE##_BLKSZ; \ |
| 220 | } \ |
| 221 | sz -= PRE##_BLKSZ; \ |
| 222 | } \ |
| 223 | \ |
| 224 | BLKC_STORE(PRE, ctx->b, t); \ |
| 225 | off = 0; \ |
| 226 | \ |
| 227 | /* --- Tidying up the tail end --- */ \ |
| 228 | \ |
| 229 | if (sz) { \ |
| 230 | small: \ |
| 231 | if (!d) off += sz; \ |
| 232 | else do { y = s ? *s++ : 0; *d++ = ctx->b[off++] ^ y; sz--; } \ |
| 233 | while (sz); \ |
| 234 | } \ |
| 235 | \ |
| 236 | /* --- Done --- */ \ |
| 237 | \ |
| 238 | ctx->off = off; \ |
| 239 | return; \ |
| 240 | } \ |
| 241 | \ |
| 242 | /* --- Generic cipher interface --- */ \ |
| 243 | \ |
| 244 | static const gcipher_ops gops; \ |
| 245 | \ |
| 246 | typedef struct gctx { \ |
| 247 | gcipher c; \ |
| 248 | pre##_ofbctx k; \ |
| 249 | } gctx; \ |
| 250 | \ |
| 251 | static gcipher *ginit(const void *k, size_t sz) \ |
| 252 | { \ |
| 253 | gctx *g = S_CREATE(gctx); \ |
| 254 | g->c.ops = &gops; \ |
| 255 | pre##_ofbinit(&g->k, k, sz, 0); \ |
| 256 | return (&g->c); \ |
| 257 | } \ |
| 258 | \ |
| 259 | static void gencrypt(gcipher *c, const void *s, void *t, size_t sz) \ |
| 260 | { gctx *g = (gctx *)c; pre##_ofbencrypt(&g->k, s, t, sz); } \ |
| 261 | \ |
| 262 | static void gdestroy(gcipher *c) \ |
| 263 | { gctx *g = (gctx *)c; BURN(*g); S_DESTROY(g); } \ |
| 264 | \ |
| 265 | static void gsetiv(gcipher *c, const void *iv) \ |
| 266 | { gctx *g = (gctx *)c; pre##_ofbsetiv(&g->k, iv); } \ |
| 267 | \ |
| 268 | static void gbdry(gcipher *c) \ |
| 269 | { \ |
| 270 | gctx *g = (gctx *)c; \ |
| 271 | pre##_ofbbdry(&g->k); \ |
| 272 | } \ |
| 273 | \ |
| 274 | static const gcipher_ops gops = { \ |
| 275 | &pre##_ofb, \ |
| 276 | gencrypt, gencrypt, gdestroy, gsetiv, gbdry \ |
| 277 | }; \ |
| 278 | \ |
| 279 | const gccipher pre##_ofb = { \ |
| 280 | name "-ofb", pre##_keysz, PRE##_BLKSZ, \ |
| 281 | ginit \ |
| 282 | }; \ |
| 283 | \ |
| 284 | /* --- Generic random number generator interface --- */ \ |
| 285 | \ |
| 286 | typedef struct grctx { \ |
| 287 | grand r; \ |
| 288 | pre##_ofbctx k; \ |
| 289 | } grctx; \ |
| 290 | \ |
| 291 | static void grdestroy(grand *r) \ |
| 292 | { grctx *g = (grctx *)r; BURN(*g); S_DESTROY(g); } \ |
| 293 | \ |
| 294 | static int grmisc(grand *r, unsigned op, ...) \ |
| 295 | { \ |
| 296 | grctx *g = (grctx *)r; \ |
| 297 | va_list ap; \ |
| 298 | int rc = 0; \ |
| 299 | uint32 i; \ |
| 300 | octet buf[PRE##_BLKSZ]; \ |
| 301 | va_start(ap, op); \ |
| 302 | \ |
| 303 | switch (op) { \ |
| 304 | case GRAND_CHECK: \ |
| 305 | switch (va_arg(ap, unsigned)) { \ |
| 306 | case GRAND_CHECK: \ |
| 307 | case GRAND_SEEDINT: \ |
| 308 | case GRAND_SEEDUINT32: \ |
| 309 | case GRAND_SEEDBLOCK: \ |
| 310 | case GRAND_SEEDRAND: \ |
| 311 | rc = 1; \ |
| 312 | break; \ |
| 313 | default: \ |
| 314 | rc = 0; \ |
| 315 | break; \ |
| 316 | } \ |
| 317 | break; \ |
| 318 | case GRAND_SEEDINT: \ |
| 319 | memset(buf, 0, sizeof(buf)); \ |
| 320 | i = va_arg(ap, unsigned); \ |
| 321 | STORE32(buf, i); \ |
| 322 | pre##_ofbsetiv(&g->k, buf); \ |
| 323 | break; \ |
| 324 | case GRAND_SEEDUINT32: \ |
| 325 | memset(buf, 0, sizeof(buf)); \ |
| 326 | i = va_arg(ap, uint32); \ |
| 327 | STORE32(buf, i); \ |
| 328 | pre##_ofbsetiv(&g->k, buf); \ |
| 329 | break; \ |
| 330 | case GRAND_SEEDBLOCK: { \ |
| 331 | const void *p = va_arg(ap, const void *); \ |
| 332 | size_t sz = va_arg(ap, size_t); \ |
| 333 | if (sz < sizeof(buf)) { \ |
| 334 | memset(buf, 0, sizeof(buf)); \ |
| 335 | memcpy(buf, p, sz); \ |
| 336 | p = buf; \ |
| 337 | } \ |
| 338 | pre##_ofbsetiv(&g->k, p); \ |
| 339 | } break; \ |
| 340 | case GRAND_SEEDRAND: { \ |
| 341 | grand *rr = va_arg(ap, grand *); \ |
| 342 | rr->ops->fill(rr, buf, sizeof(buf)); \ |
| 343 | pre##_ofbsetiv(&g->k, buf); \ |
| 344 | } break; \ |
| 345 | default: \ |
| 346 | GRAND_BADOP; \ |
| 347 | break; \ |
| 348 | } \ |
| 349 | \ |
| 350 | va_end(ap); \ |
| 351 | return (rc); \ |
| 352 | } \ |
| 353 | \ |
| 354 | static octet grbyte(grand *r) \ |
| 355 | { \ |
| 356 | grctx *g = (grctx *)r; \ |
| 357 | octet o; \ |
| 358 | pre##_ofbencrypt(&g->k, 0, &o, 1); \ |
| 359 | return (o); \ |
| 360 | } \ |
| 361 | \ |
| 362 | static uint32 grword(grand *r) \ |
| 363 | { \ |
| 364 | grctx *g = (grctx *)r; \ |
| 365 | octet b[4]; \ |
| 366 | pre##_ofbencrypt(&g->k, 0, b, sizeof(b)); \ |
| 367 | return (LOAD32(b)); \ |
| 368 | } \ |
| 369 | \ |
| 370 | static void grfill(grand *r, void *p, size_t sz) \ |
| 371 | { grctx *g = (grctx *)r; pre##_ofbencrypt(&g->k, 0, p, sz); } \ |
| 372 | \ |
| 373 | static const grand_ops grops = { \ |
| 374 | name "-ofb", \ |
| 375 | GRAND_CRYPTO, 0, \ |
| 376 | grmisc, grdestroy, \ |
| 377 | grword, grbyte, grword, grand_defaultrange, grfill \ |
| 378 | }; \ |
| 379 | \ |
| 380 | /* --- @pre_ofbrand@ --- * \ |
| 381 | * \ |
| 382 | * Arguments: @const void *k@ = pointer to key material \ |
| 383 | * @size_t sz@ = size of key material \ |
| 384 | * \ |
| 385 | * Returns: Pointer to generic random number generator interface. \ |
| 386 | * \ |
| 387 | * Use: Creates a random number interface wrapper around an \ |
| 388 | * OFB-mode block cipher. \ |
| 389 | */ \ |
| 390 | \ |
| 391 | grand *pre##_ofbrand(const void *k, size_t sz) \ |
| 392 | { \ |
| 393 | grctx *g = S_CREATE(grctx); \ |
| 394 | g->r.ops = &grops; \ |
| 395 | pre##_ofbinit(&g->k, k, sz, 0); \ |
| 396 | return (&g->r); \ |
| 397 | } \ |
| 398 | \ |
| 399 | OFB_TESTX(PRE, pre, name, name) |
| 400 | |
| 401 | /*----- Test rig ----------------------------------------------------------*/ |
| 402 | |
| 403 | #define OFB_TEST(PRE, pre) OFB_TESTX(PRE, pre, #pre, #pre) |
| 404 | |
| 405 | #ifdef TEST_RIG |
| 406 | |
| 407 | #include "modes-test.h" |
| 408 | |
| 409 | /* --- @OFB_TEST@ --- * |
| 410 | * |
| 411 | * Arguments: @PRE@, @pre@ = prefixes for block cipher definitions |
| 412 | * |
| 413 | * Use: Standard test rig for OFB functions. |
| 414 | */ |
| 415 | |
| 416 | #define OFB_TESTX(PRE, pre, name, fname) \ |
| 417 | \ |
| 418 | static pre##_ctx key; \ |
| 419 | static pre##_ofbctx ctx; \ |
| 420 | \ |
| 421 | static void pre##_ofb_test_setup(const octet *k, size_t ksz) \ |
| 422 | { pre##_init(&key, k, ksz); pre##_ofbsetkey(&ctx, &key); } \ |
| 423 | \ |
| 424 | static void pre##_ofb_test_reset(const octet *iv) \ |
| 425 | { pre##_ofbsetiv(&ctx, iv); } \ |
| 426 | \ |
| 427 | static void pre##_ofb_test_enc(const octet *s, octet *d, size_t sz) \ |
| 428 | { pre##_ofbencrypt(&ctx, s, d, sz); } \ |
| 429 | \ |
| 430 | int main(int argc, char *argv[]) \ |
| 431 | { \ |
| 432 | return test_encmode(fname "-ofb", PRE##_KEYSZ, PRE##_BLKSZ, 1, 0, \ |
| 433 | pre##_ofb_test_setup, pre##_ofb_test_reset, \ |
| 434 | pre##_ofb_test_enc, pre##_ofb_test_enc, \ |
| 435 | argc, argv); \ |
| 436 | } |
| 437 | |
| 438 | #else |
| 439 | # define OFB_TESTX(PRE, pre, name, fname) |
| 440 | #endif |
| 441 | |
| 442 | /*----- That's all, folks -------------------------------------------------*/ |
| 443 | |
| 444 | #ifdef __cplusplus |
| 445 | } |
| 446 | #endif |
| 447 | |
| 448 | #endif |