| 1 | /* -*-c-*- |
| 2 | * |
| 3 | * Definitions for ciphertext 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_CFB_DEF_H |
| 29 | #define CATACOMB_CFB_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 | #ifndef CATACOMB_PARANOIA_H |
| 59 | # include "paranoia.h" |
| 60 | #endif |
| 61 | |
| 62 | #ifndef CATACOMB_RSVR_H |
| 63 | # include "rsvr.h" |
| 64 | #endif |
| 65 | |
| 66 | /*----- Macros ------------------------------------------------------------*/ |
| 67 | |
| 68 | /* --- @CFB_DEF@ --- * |
| 69 | * |
| 70 | * Arguments: @PRE@, @pre@ = prefixes for the underlying block cipher |
| 71 | * |
| 72 | * Use: Creates an implementation for CFB mode. |
| 73 | */ |
| 74 | |
| 75 | #define CFB_DEF(PRE, pre) CFB_DEFX(PRE, pre, #pre, #pre) |
| 76 | |
| 77 | #define CFB_DEFX(PRE, pre, name, fname) \ |
| 78 | \ |
| 79 | /* --- @pre_cfbgetiv@ --- * \ |
| 80 | * \ |
| 81 | * Arguments: @const pre_cfbctx *ctx@ = pointer to CFB context block \ |
| 82 | * @void *iv@ = pointer to output data block \ |
| 83 | * \ |
| 84 | * Returns: --- \ |
| 85 | * \ |
| 86 | * Use: Reads the currently set IV. Reading and setting an IV \ |
| 87 | * is not transparent to the cipher. It will add a `step' \ |
| 88 | * which must be matched by a similar operation during \ |
| 89 | * decryption. \ |
| 90 | */ \ |
| 91 | \ |
| 92 | void pre##_cfbgetiv(const pre##_cfbctx *ctx, void *iv) \ |
| 93 | { \ |
| 94 | octet *p = iv; \ |
| 95 | unsigned off = ctx->off; \ |
| 96 | unsigned rest = PRE##_BLKSZ - off; \ |
| 97 | \ |
| 98 | memcpy(p, ctx->b + off, rest); \ |
| 99 | memcpy(p + rest, ctx->b, off); \ |
| 100 | } \ |
| 101 | \ |
| 102 | /* --- @pre_cfbsetiv@ --- * \ |
| 103 | * \ |
| 104 | * Arguments: @pre_cfbctx *ctx@ = pointer to CFB context block \ |
| 105 | * @cnost void *iv@ = pointer to IV to set \ |
| 106 | * \ |
| 107 | * Returns: --- \ |
| 108 | * \ |
| 109 | * Use: Sets the IV to use for subsequent encryption. \ |
| 110 | */ \ |
| 111 | \ |
| 112 | void pre##_cfbsetiv(pre##_cfbctx *ctx, const void *iv) \ |
| 113 | { memcpy(ctx->b, iv, PRE##_BLKSZ); ctx->off = 0; } \ |
| 114 | \ |
| 115 | /* --- @pre_cfbbdry@ --- * \ |
| 116 | * \ |
| 117 | * Arguments: @pre_cfbctx *ctx@ = pointer to CFB context block \ |
| 118 | * \ |
| 119 | * Returns: --- \ |
| 120 | * \ |
| 121 | * Use: Inserts a boundary during encryption. Successful \ |
| 122 | * decryption must place a similar boundary. \ |
| 123 | */ \ |
| 124 | \ |
| 125 | void pre##_cfbbdry(pre##_cfbctx *ctx) \ |
| 126 | { \ |
| 127 | uint32 t[PRE##_BLKSZ/4]; \ |
| 128 | \ |
| 129 | BLKC_LOAD(PRE, t, ctx->b); \ |
| 130 | pre##_eblk(&ctx->ctx, t, t); \ |
| 131 | BLKC_STORE(PRE, ctx->b, t); \ |
| 132 | ctx->off = 0; \ |
| 133 | BURN(t); \ |
| 134 | } \ |
| 135 | \ |
| 136 | /* --- @pre_cfbsetkey@ --- * \ |
| 137 | * \ |
| 138 | * Arguments: @pre_cfbctx *ctx@ = pointer to CFB context block \ |
| 139 | * @const pre_ctx *k@ = pointer to cipher context \ |
| 140 | * \ |
| 141 | * Returns: --- \ |
| 142 | * \ |
| 143 | * Use: Sets the CFB context to use a different cipher key. \ |
| 144 | */ \ |
| 145 | \ |
| 146 | void pre##_cfbsetkey(pre##_cfbctx *ctx, const pre##_ctx *k) \ |
| 147 | { ctx->ctx = *k; ctx->off = 0; } \ |
| 148 | \ |
| 149 | /* --- @pre_cfbinit@ --- * \ |
| 150 | * \ |
| 151 | * Arguments: @pre_cfbctx *ctx@ = pointer to cipher context \ |
| 152 | * @const void *key@ = pointer to the key buffer \ |
| 153 | * @size_t sz@ = size of the key \ |
| 154 | * @const void *iv@ = pointer to initialization vector \ |
| 155 | * \ |
| 156 | * Returns: --- \ |
| 157 | * \ |
| 158 | * Use: Initializes a CFB context ready for use. You should \ |
| 159 | * ensure that the IV chosen is unique: reusing an IV will \ |
| 160 | * compromise the security of at least the first block \ |
| 161 | * encrypted. This is equivalent to calls to @pre_init@, \ |
| 162 | * @pre_cfbsetkey@ and @pre_cfbsetiv@. \ |
| 163 | */ \ |
| 164 | \ |
| 165 | void pre##_cfbinit(pre##_cfbctx *ctx, \ |
| 166 | const void *key, size_t sz, \ |
| 167 | const void *iv) \ |
| 168 | { \ |
| 169 | static const octet zero[PRE##_BLKSZ] = { 0 }; \ |
| 170 | \ |
| 171 | pre##_init(&ctx->ctx, key, sz); \ |
| 172 | pre##_cfbsetiv(ctx, iv ? iv : zero); \ |
| 173 | } \ |
| 174 | \ |
| 175 | /* --- @pre_cfbencrypt@ --- * \ |
| 176 | * \ |
| 177 | * Arguments: @pre_cfbctx *ctx@ = pointer to CFB context block \ |
| 178 | * @const void *src@ = pointer to source data \ |
| 179 | * @void *dest@ = pointer to destination data \ |
| 180 | * @size_t sz@ = size of block to be encrypted \ |
| 181 | * \ |
| 182 | * Returns: --- \ |
| 183 | * \ |
| 184 | * Use: Encrypts a block with a block cipher in CFB mode. The \ |
| 185 | * input block may be arbitrary in size. CFB mode is not \ |
| 186 | * sensitive to block boundaries. \ |
| 187 | */ \ |
| 188 | \ |
| 189 | static const rsvr_policy pre##_cfbpolicy = { 0, PRE##_BLKSZ, PRE##_BLKSZ }; \ |
| 190 | \ |
| 191 | void pre##_cfbencrypt(pre##_cfbctx *ctx, \ |
| 192 | const void *src, void *dest, \ |
| 193 | size_t sz) \ |
| 194 | { \ |
| 195 | rsvr_plan plan; \ |
| 196 | const octet *s = src; \ |
| 197 | octet *d = dest, *p; \ |
| 198 | uint32 t[PRE##_BLKSZ/4]; \ |
| 199 | octet y; \ |
| 200 | \ |
| 201 | /* Construct a plan and prepare to follow through. */ \ |
| 202 | rsvr_mkplan(&plan, &pre##_cfbpolicy, ctx->off, sz); \ |
| 203 | BLKC_LOAD(PRE, t, ctx->b); \ |
| 204 | \ |
| 205 | /* Initial portion, fulfilled from the buffer. If the chunk is small \ |
| 206 | * enough, then this will be the only portion. If the buffer is \ |
| 207 | * currently empty, then we must prepare it. \ |
| 208 | */ \ |
| 209 | if (plan.head) { \ |
| 210 | if (!ctx->off) { \ |
| 211 | pre##_eblk(&ctx->ctx, t, t); \ |
| 212 | BLKC_STORE(PRE, ctx->b, t); \ |
| 213 | } \ |
| 214 | p = ctx->b + ctx->off; ctx->off += plan.head; \ |
| 215 | if (s) while (plan.head--) { y = *s++ ^ *p; *p++ = y; if (d) *d++ = y; } \ |
| 216 | else if (d) { memcpy(d, p, plan.head); d += plan.head; } \ |
| 217 | BLKC_LOAD(PRE, t, ctx->b); \ |
| 218 | } \ |
| 219 | \ |
| 220 | /* If the buffer is all used, then reset it ready for next time. */ \ |
| 221 | ctx->off -= plan.from_rsvr; \ |
| 222 | \ |
| 223 | /* Handle multiple whole blocks. */ \ |
| 224 | if (!d) { \ |
| 225 | if (!s) while (plan.from_input) { \ |
| 226 | pre##_eblk(&ctx->ctx, t, t); \ |
| 227 | plan.from_input -= PRE##_BLKSZ; \ |
| 228 | } else while (plan.from_input) { \ |
| 229 | pre##_eblk(&ctx->ctx, t, t); \ |
| 230 | BLKC_XLOAD(PRE, t, s); s += PRE##_BLKSZ; \ |
| 231 | plan.from_input -= PRE##_BLKSZ; \ |
| 232 | } \ |
| 233 | } else { \ |
| 234 | if (!s) while (plan.from_input) { \ |
| 235 | pre##_eblk(&ctx->ctx, t, t); \ |
| 236 | BLKC_STORE(PRE, d, t); d += PRE##_BLKSZ; \ |
| 237 | plan.from_input -= PRE##_BLKSZ; \ |
| 238 | } else while (plan.from_input) { \ |
| 239 | pre##_eblk(&ctx->ctx, t, t); \ |
| 240 | BLKC_XLOAD(PRE, t, s); s += PRE##_BLKSZ; \ |
| 241 | BLKC_STORE(PRE, d, t); d += PRE##_BLKSZ; \ |
| 242 | plan.from_input -= PRE##_BLKSZ; \ |
| 243 | } \ |
| 244 | } \ |
| 245 | \ |
| 246 | /* Final portion. Note that the buffer must be empty if there is a \ |
| 247 | * tail, since otherwise the input data would have been part of the \ |
| 248 | * head portion instad. */ \ |
| 249 | if (!plan.tail) \ |
| 250 | BLKC_STORE(PRE, ctx->b, t); \ |
| 251 | else { \ |
| 252 | pre##_eblk(&ctx->ctx, t, t); \ |
| 253 | BLKC_STORE(PRE, ctx->b, t); \ |
| 254 | p = ctx->b; ctx->off += plan.tail; \ |
| 255 | if (s) while (plan.tail--) { y = *s++ ^ *p; *p++ = y; if (d) *d++ = y; } \ |
| 256 | else if (d) { memcpy(d, p, plan.tail); d += plan.tail; } \ |
| 257 | } \ |
| 258 | } \ |
| 259 | \ |
| 260 | /* --- @pre_cfbdecrypt@ --- * \ |
| 261 | * \ |
| 262 | * Arguments: @pre_cfbctx *ctx@ = pointer to CFB context block \ |
| 263 | * @const void *src@ = pointer to source data \ |
| 264 | * @void *dest@ = pointer to destination data \ |
| 265 | * @size_t sz@ = size of block to be encrypted \ |
| 266 | * \ |
| 267 | * Returns: --- \ |
| 268 | * \ |
| 269 | * Use: Decrypts a block with a block cipher in CFB mode. The \ |
| 270 | * input block may be arbitrary in size. CFB mode is not \ |
| 271 | * sensitive to block boundaries. \ |
| 272 | */ \ |
| 273 | \ |
| 274 | void pre##_cfbdecrypt(pre##_cfbctx *ctx, \ |
| 275 | const void *src, void *dest, \ |
| 276 | size_t sz) \ |
| 277 | { \ |
| 278 | rsvr_plan plan; \ |
| 279 | const octet *s = src; \ |
| 280 | octet *d = dest, *p; \ |
| 281 | uint32 t[PRE##_BLKSZ/4], u[PRE##_BLKSZ/4]; \ |
| 282 | octet y; \ |
| 283 | \ |
| 284 | /* Construct a plan and prepare to follow through. */ \ |
| 285 | rsvr_mkplan(&plan, &pre##_cfbpolicy, ctx->off, sz); \ |
| 286 | BLKC_LOAD(PRE, t, ctx->b); \ |
| 287 | \ |
| 288 | /* Initial portion, fulfilled from the buffer. If the chunk is small \ |
| 289 | * enough, then this will be the only portion. If the buffer is \ |
| 290 | * currently empty, then we must prepare it. \ |
| 291 | */ \ |
| 292 | if (plan.head) { \ |
| 293 | if (!ctx->off) { \ |
| 294 | pre##_eblk(&ctx->ctx, t, t); \ |
| 295 | BLKC_STORE(PRE, ctx->b, t); \ |
| 296 | } \ |
| 297 | p = ctx->b + ctx->off; \ |
| 298 | ctx->off += plan.head; \ |
| 299 | while (plan.head--) { y = *s++; *d++ = y ^ *p; *p++ = y; } \ |
| 300 | BLKC_LOAD(PRE, t, ctx->b); \ |
| 301 | } \ |
| 302 | \ |
| 303 | /* If the buffer is all used, then reset it ready for next time. */ \ |
| 304 | ctx->off -= plan.from_rsvr; \ |
| 305 | \ |
| 306 | /* Handle multiple whole blocks. */ \ |
| 307 | while (plan.from_input) { \ |
| 308 | pre##_eblk(&ctx->ctx, t, t); \ |
| 309 | BLKC_LOAD(PRE, u, s); s += PRE##_BLKSZ; \ |
| 310 | BLKC_XSTORE(PRE, d, t, u); d += PRE##_BLKSZ; \ |
| 311 | BLKC_MOVE(PRE, t, u); \ |
| 312 | plan.from_input -= PRE##_BLKSZ; \ |
| 313 | } \ |
| 314 | \ |
| 315 | /* Final portion. Note that the buffer must be empty if there is a \ |
| 316 | * tail, since otherwise the input data would have been part of the \ |
| 317 | * head portion instad. */ \ |
| 318 | if (!plan.tail) \ |
| 319 | BLKC_STORE(PRE, ctx->b, t); \ |
| 320 | else { \ |
| 321 | pre##_eblk(&ctx->ctx, t, t); \ |
| 322 | BLKC_STORE(PRE, ctx->b, t); \ |
| 323 | p = ctx->b; \ |
| 324 | ctx->off += plan.tail; \ |
| 325 | while (plan.tail--) { y = *s++; *d++ = y ^ *p; *p++ = y; } \ |
| 326 | } \ |
| 327 | } \ |
| 328 | \ |
| 329 | /* --- Generic cipher interface --- */ \ |
| 330 | \ |
| 331 | static const gcipher_ops gops; \ |
| 332 | \ |
| 333 | typedef struct gctx { \ |
| 334 | gcipher c; \ |
| 335 | pre##_cfbctx k; \ |
| 336 | } gctx; \ |
| 337 | \ |
| 338 | static gcipher *ginit(const void *k, size_t sz) \ |
| 339 | { \ |
| 340 | gctx *g = S_CREATE(gctx); \ |
| 341 | g->c.ops = &gops; \ |
| 342 | pre##_cfbinit(&g->k, k, sz, 0); \ |
| 343 | return (&g->c); \ |
| 344 | } \ |
| 345 | \ |
| 346 | static void gencrypt(gcipher *c, const void *s, void *t, size_t sz) \ |
| 347 | { gctx *g = (gctx *)c; pre##_cfbencrypt(&g->k, s, t, sz); } \ |
| 348 | \ |
| 349 | static void gdecrypt(gcipher *c, const void *s, void *t, size_t sz) \ |
| 350 | { gctx *g = (gctx *)c; pre##_cfbdecrypt(&g->k, s, t, sz); } \ |
| 351 | \ |
| 352 | static void gdestroy(gcipher *c) \ |
| 353 | { gctx *g = (gctx *)c; BURN(*g); S_DESTROY(g); } \ |
| 354 | \ |
| 355 | static void gsetiv(gcipher *c, const void *iv) \ |
| 356 | { gctx *g = (gctx *)c; pre##_cfbsetiv(&g->k, iv); } \ |
| 357 | \ |
| 358 | static void gbdry(gcipher *c) \ |
| 359 | { gctx *g = (gctx *)c; pre##_cfbbdry(&g->k); } \ |
| 360 | \ |
| 361 | static const gcipher_ops gops = { \ |
| 362 | &pre##_cfb, \ |
| 363 | gencrypt, gdecrypt, gdestroy, gsetiv, gbdry \ |
| 364 | }; \ |
| 365 | \ |
| 366 | const gccipher pre##_cfb = { \ |
| 367 | name "-cfb", pre##_keysz, PRE##_BLKSZ, \ |
| 368 | ginit \ |
| 369 | }; \ |
| 370 | \ |
| 371 | CFB_TESTX(PRE, pre, name, fname) |
| 372 | |
| 373 | /*----- Test rig ----------------------------------------------------------*/ |
| 374 | |
| 375 | #define CFB_TEST(PRE, pre) CFB_TESTX(PRE, pre, #pre, #pre) |
| 376 | |
| 377 | #ifdef TEST_RIG |
| 378 | |
| 379 | #include "modes-test.h" |
| 380 | |
| 381 | /* --- @CFB_TEST@ --- * |
| 382 | * |
| 383 | * Arguments: @PRE@, @pre@ = prefixes for block cipher definitions |
| 384 | * |
| 385 | * Use: Standard test rig for CFB functions. |
| 386 | */ |
| 387 | |
| 388 | #define CFB_TESTX(PRE, pre, name, fname) \ |
| 389 | \ |
| 390 | static pre##_ctx key; \ |
| 391 | static pre##_cfbctx ctx; \ |
| 392 | \ |
| 393 | static void pre##_cfb_test_setup(const octet *k, size_t ksz) \ |
| 394 | { pre##_init(&key, k, ksz); pre##_cfbsetkey(&ctx, &key); } \ |
| 395 | \ |
| 396 | static void pre##_cfb_test_reset(const octet *iv) \ |
| 397 | { pre##_cfbsetiv(&ctx, iv); } \ |
| 398 | \ |
| 399 | static void pre##_cfb_test_enc(const octet *s, octet *d, size_t sz) \ |
| 400 | { pre##_cfbencrypt(&ctx, s, d, sz); } \ |
| 401 | \ |
| 402 | static void pre##_cfb_test_dec(const octet *s, octet *d, size_t sz) \ |
| 403 | { pre##_cfbdecrypt(&ctx, s, d, sz); } \ |
| 404 | \ |
| 405 | int main(int argc, char *argv[]) \ |
| 406 | { \ |
| 407 | return test_encmode(fname "-cfb", PRE##_KEYSZ, PRE##_BLKSZ, 1, 0, \ |
| 408 | pre##_cfb_test_setup, pre##_cfb_test_reset, \ |
| 409 | pre##_cfb_test_enc, pre##_cfb_test_dec, \ |
| 410 | argc, argv); \ |
| 411 | } |
| 412 | |
| 413 | #else |
| 414 | # define CFB_TESTX(PRE, pre, name, fname) |
| 415 | #endif |
| 416 | |
| 417 | /*----- That's all, folks -------------------------------------------------*/ |
| 418 | |
| 419 | #ifdef __cplusplus |
| 420 | } |
| 421 | #endif |
| 422 | |
| 423 | #endif |