chiark - git - mdw - catacomb/blob - symm/cfb-def.h

   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 /*----- Macros ------------------------------------------------------------*/
  63
  64 /* --- @CFB_DEF@ --- *
  65  *
  66  * Arguments:   @PRE@, @pre@ = prefixes for the underlying block cipher
  67  *
  68  * Use:         Creates an implementation for CFB mode.
  69  */
  70
  71 #define CFB_DEF(PRE, pre) CFB_DEFX(PRE, pre, #pre, #pre)
  72
  73 #define CFB_DEFX(PRE, pre, name, fname)                                 \
  74                                                                         \
  75 /* --- @pre_cfbgetiv@ --- *                                             \
  76  *                                                                      \
  77  * Arguments:   @const pre_cfbctx *ctx@ = pointer to CFB context block  \
  78  *              @void *iv@ = pointer to output data block               \
  79  *                                                                      \
  80  * Returns:     ---                                                     \
  81  *                                                                      \
  82  * Use:         Reads the currently set IV.  Reading and setting an IV  \
  83  *              is not transparent to the cipher.  It will add a `step' \
  84  *              which must be matched by a similar operation during     \
  85  *              decryption.                                             \
  86  */                                                                     \
  87                                                                         \
  88 void pre##_cfbgetiv(const pre##_cfbctx *ctx, void *iv)                  \
  89 {                                                                       \
  90   octet *p = iv;                                                        \
  91   unsigned off = ctx->off;                                              \
  92   unsigned rest = PRE##_BLKSZ - off;                                    \
  93   memcpy(p, ctx->iv + off, rest);                                       \
  94   memcpy(p + rest, ctx->iv, off);                                       \
  95 }                                                                       \
  96                                                                         \
  97 /* --- @pre_cfbsetiv@ --- *                                             \
  98  *                                                                      \
  99  * Arguments:   @pre_cfbctx *ctx@ = pointer to CFB context block        \
 100  *              @cnost void *iv@ = pointer to IV to set                 \
 101  *                                                                      \
 102  * Returns:     ---                                                     \
 103  *                                                                      \
 104  * Use:         Sets the IV to use for subsequent encryption.           \
 105  */                                                                     \
 106                                                                         \
 107 void pre##_cfbsetiv(pre##_cfbctx *ctx, const void *iv)                  \
 108 {                                                                       \
 109   memcpy(ctx->iv, iv, PRE##_BLKSZ);                                     \
 110   ctx->off = PRE##_BLKSZ;                                               \
 111 }                                                                       \
 112                                                                         \
 113 /* --- @pre_cfbbdry@ --- *                                              \
 114  *                                                                      \
 115  * Arguments:   @pre_cfbctx *ctx@ = pointer to CFB context block        \
 116  *                                                                      \
 117  * Returns:     ---                                                     \
 118  *                                                                      \
 119  * Use:         Inserts a boundary during encryption.  Successful       \
 120  *              decryption must place a similar boundary.               \
 121  */                                                                     \
 122                                                                         \
 123 void pre##_cfbbdry(pre##_cfbctx *ctx)                                   \
 124 {                                                                       \
 125   uint32 niv[PRE##_BLKSZ / 4];                                          \
 126   BLKC_LOAD(PRE, niv, ctx->iv);                                         \
 127   pre##_eblk(&ctx->ctx, niv, niv);                                      \
 128   BLKC_STORE(PRE, ctx->iv, niv);                                        \
 129   ctx->off = PRE##_BLKSZ;                                               \
 130   BURN(niv);                                                            \
 131 }                                                                       \
 132                                                                         \
 133 /* --- @pre_cfbsetkey@ --- *                                            \
 134  *                                                                      \
 135  * Arguments:   @pre_cfbctx *ctx@ = pointer to CFB context block        \
 136  *              @const pre_ctx *k@ = pointer to cipher context          \
 137  *                                                                      \
 138  * Returns:     ---                                                     \
 139  *                                                                      \
 140  * Use:         Sets the CFB context to use a different cipher key.     \
 141  */                                                                     \
 142                                                                         \
 143 void pre##_cfbsetkey(pre##_cfbctx *ctx, const pre##_ctx *k)             \
 144 {                                                                       \
 145   ctx->ctx = *k;                                                        \
 146   ctx->off = PRE##_BLKSZ;                                               \
 147 }                                                                       \
 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   pre##_init(&ctx->ctx, key, sz);                                       \
 171   pre##_cfbsetiv(ctx, iv ? iv : zero);                                  \
 172 }                                                                       \
 173                                                                         \
 174 /* --- @pre_cfbencrypt@ --- *                                           \
 175  *                                                                      \
 176  * Arguments:   @pre_cfbctx *ctx@ = pointer to CFB context block        \
 177  *              @const void *src@ = pointer to source data              \
 178  *              @void *dest@ = pointer to destination data              \
 179  *              @size_t sz@ = size of block to be encrypted             \
 180  *                                                                      \
 181  * Returns:     ---                                                     \
 182  *                                                                      \
 183  * Use:         Encrypts a block with a block cipher in CFB mode.  The  \
 184  *              input block may be arbitrary in size.  CFB mode is not  \
 185  *              sensitive to block boundaries.                          \
 186  */                                                                     \
 187                                                                         \
 188 void pre##_cfbencrypt(pre##_cfbctx *ctx,                                \
 189                         const void *src, void *dest,                    \
 190                         size_t sz)                                      \
 191 {                                                                       \
 192   const octet *s = src;                                                 \
 193   octet *d = dest;                                                      \
 194   unsigned off = ctx->off;                                              \
 195                                                                         \
 196   /* --- Empty blocks are trivial --- */                                \
 197                                                                         \
 198   if (!sz)                                                              \
 199     return;                                                             \
 200                                                                         \
 201   /* --- If I can deal with the block from my buffer, do that --- */    \
 202                                                                         \
 203   if (sz < PRE##_BLKSZ - off)                                           \
 204     goto small;                                                         \
 205                                                                         \
 206   /* --- Finish off what's left in my buffer --- */                     \
 207                                                                         \
 208   while (off < PRE##_BLKSZ) {                                           \
 209     register octet x = *s++;                                            \
 210     ctx->iv[off] ^= x;                                                  \
 211     if (d) *d++ = ctx->iv[off];                                         \
 212     off++;                                                              \
 213     sz--;                                                               \
 214   }                                                                     \
 215                                                                         \
 216   /* --- Main encryption loop --- */                                    \
 217                                                                         \
 218   {                                                                     \
 219     uint32 iv[PRE##_BLKSZ / 4];                                         \
 220     BLKC_LOAD(PRE, iv, ctx->iv);                                        \
 221                                                                         \
 222     for (;;) {                                                          \
 223       pre##_eblk(&ctx->ctx, iv, iv);                                    \
 224       if (sz < PRE##_BLKSZ)                                             \
 225         break;                                                          \
 226       if (s) {                                                          \
 227         BLKC_XLOAD(PRE, iv, s);                                         \
 228         s += PRE##_BLKSZ;                                               \
 229       }                                                                 \
 230       if (d) {                                                          \
 231         BLKC_STORE(PRE, d, iv);                                         \
 232         d += PRE##_BLKSZ;                                               \
 233       }                                                                 \
 234       sz -= PRE##_BLKSZ;                                                \
 235     }                                                                   \
 236     off = 0;                                                            \
 237     BLKC_STORE(PRE, ctx->iv, iv);                                       \
 238   }                                                                     \
 239                                                                         \
 240   /* --- Tidying up the tail end --- */                                 \
 241                                                                         \
 242   if (sz) {                                                             \
 243   small:                                                                \
 244     do {                                                                \
 245       register octet x = *s++;                                          \
 246       ctx->iv[off] ^= x;                                                \
 247       if (d) *d++ = ctx->iv[off];                                       \
 248       off++;                                                            \
 249       sz--;                                                             \
 250     } while (sz);                                                       \
 251   }                                                                     \
 252                                                                         \
 253   /* --- Done --- */                                                    \
 254                                                                         \
 255   ctx->off = off;                                                       \
 256   return;                                                               \
 257 }                                                                       \
 258                                                                         \
 259 /* --- @pre_cfbdecrypt@ --- *                                           \
 260  *                                                                      \
 261  * Arguments:   @pre_cfbctx *ctx@ = pointer to CFB context block        \
 262  *              @const void *src@ = pointer to source data              \
 263  *              @void *dest@ = pointer to destination data              \
 264  *              @size_t sz@ = size of block to be encrypted             \
 265  *                                                                      \
 266  * Returns:     ---                                                     \
 267  *                                                                      \
 268  * Use:         Decrypts a block with a block cipher in CFB mode.  The  \
 269  *              input block may be arbitrary in size.  CFB mode is not  \
 270  *              sensitive to block boundaries.                          \
 271  */                                                                     \
 272                                                                         \
 273 void pre##_cfbdecrypt(pre##_cfbctx *ctx,                                \
 274                         const void *src, void *dest,                    \
 275                         size_t sz)                                      \
 276 {                                                                       \
 277   const octet *s = src;                                                 \
 278   octet *d = dest;                                                      \
 279   unsigned off = ctx->off;                                              \
 280                                                                         \
 281   /* --- Empty blocks are trivial --- */                                \
 282                                                                         \
 283   if (!sz)                                                              \
 284     return;                                                             \
 285                                                                         \
 286   /* --- If I can deal with the block from my buffer, do that --- */    \
 287                                                                         \
 288   if (sz < PRE##_BLKSZ - off)                                           \
 289     goto small;                                                         \
 290                                                                         \
 291   /* --- Finish off what's left in my buffer --- */                     \
 292                                                                         \
 293   while (off < PRE##_BLKSZ) {                                           \
 294     register octet x = *s++;                                            \
 295     *d++ = ctx->iv[off] ^ x;                                            \
 296     ctx->iv[off++] = x;                                                 \
 297     sz--;                                                               \
 298   }                                                                     \
 299                                                                         \
 300   /* --- Main encryption loop --- */                                    \
 301                                                                         \
 302   {                                                                     \
 303     uint32 iv[PRE##_BLKSZ / 4];                                         \
 304     BLKC_LOAD(PRE, iv, ctx->iv);                                        \
 305                                                                         \
 306     for (;;) {                                                          \
 307       uint32 x[PRE##_BLKSZ / 4];                                        \
 308       pre##_eblk(&ctx->ctx, iv, iv);                                    \
 309       if (sz < PRE##_BLKSZ)                                             \
 310         break;                                                          \
 311       BLKC_LOAD(PRE, x, s);                                             \
 312       BLKC_XSTORE(PRE, d, iv, x);                                       \
 313       BLKC_MOVE(PRE, iv, x);                                            \
 314       s += PRE##_BLKSZ;                                                 \
 315       d += PRE##_BLKSZ;                                                 \
 316       sz -= PRE##_BLKSZ;                                                \
 317     }                                                                   \
 318     off = 0;                                                            \
 319     BLKC_STORE(PRE, ctx->iv, iv);                                       \
 320   }                                                                     \
 321                                                                         \
 322   /* --- Tidying up the tail end --- */                                 \
 323                                                                         \
 324   if (sz) {                                                             \
 325   small:                                                                \
 326     do {                                                                \
 327       register octet x = *s++;                                          \
 328       *d++ = ctx->iv[off] ^ x;                                          \
 329       ctx->iv[off++] = x;                                               \
 330       sz--;                                                             \
 331     } while (sz);                                                       \
 332   }                                                                     \
 333                                                                         \
 334   /* --- Done --- */                                                    \
 335                                                                         \
 336   ctx->off = off;                                                       \
 337   return;                                                               \
 338 }                                                                       \
 339                                                                         \
 340 /* --- Generic cipher interface --- */                                  \
 341                                                                         \
 342 static const gcipher_ops gops;                                          \
 343                                                                         \
 344 typedef struct gctx {                                                   \
 345   gcipher c;                                                            \
 346   pre##_cfbctx k;                                                       \
 347 } gctx;                                                                 \
 348                                                                         \
 349 static gcipher *ginit(const void *k, size_t sz)                         \
 350 {                                                                       \
 351   gctx *g = S_CREATE(gctx);                                             \
 352   g->c.ops = &gops;                                                     \
 353   pre##_cfbinit(&g->k, k, sz, 0);                                       \
 354   return (&g->c);                                                       \
 355 }                                                                       \
 356                                                                         \
 357 static void gencrypt(gcipher *c, const void *s, void *t, size_t sz)     \
 358 {                                                                       \
 359   gctx *g = (gctx *)c;                                                  \
 360   pre##_cfbencrypt(&g->k, s, t, sz);                                    \
 361 }                                                                       \
 362                                                                         \
 363 static void gdecrypt(gcipher *c, const void *s, void *t, size_t sz)     \
 364 {                                                                       \
 365   gctx *g = (gctx *)c;                                                  \
 366   pre##_cfbdecrypt(&g->k, s, t, sz);                                    \
 367 }                                                                       \
 368                                                                         \
 369 static void gdestroy(gcipher *c)                                        \
 370 {                                                                       \
 371   gctx *g = (gctx *)c;                                                  \
 372   BURN(*g);                                                             \
 373   S_DESTROY(g);                                                         \
 374 }                                                                       \
 375                                                                         \
 376 static void gsetiv(gcipher *c, const void *iv)                          \
 377 {                                                                       \
 378   gctx *g = (gctx *)c;                                                  \
 379   pre##_cfbsetiv(&g->k, iv);                                            \
 380 }                                                                       \
 381                                                                         \
 382 static void gbdry(gcipher *c)                                           \
 383 {                                                                       \
 384   gctx *g = (gctx *)c;                                                  \
 385   pre##_cfbbdry(&g->k);                                                 \
 386 }                                                                       \
 387                                                                         \
 388 static const gcipher_ops gops = {                                       \
 389   &pre##_cfb,                                                           \
 390   gencrypt, gdecrypt, gdestroy, gsetiv, gbdry                           \
 391 };                                                                      \
 392                                                                         \
 393 const gccipher pre##_cfb = {                                            \
 394   name "-cfb", pre##_keysz, PRE##_BLKSZ,                                \
 395   ginit                                                                 \
 396 };                                                                      \
 397                                                                         \
 398 CFB_TESTX(PRE, pre, name, fname)
 399
 400 /*----- Test rig ----------------------------------------------------------*/
 401
 402 #define CFB_TEST(PRE, pre) CFB_TESTX(PRE, pre, #pre, #pre)
 403
 404 #ifdef TEST_RIG
 405
 406 #include <stdio.h>
 407
 408 #include "daftstory.h"
 409
 410 /* --- @CFB_TEST@ --- *
 411  *
 412  * Arguments:   @PRE@, @pre@ = prefixes for block cipher definitions
 413  *
 414  * Use:         Standard test rig for CFB functions.
 415  */
 416
 417 #define CFB_TESTX(PRE, pre, name, fname)                                \
 418                                                                         \
 419 /* --- Initial plaintext for the test --- */                            \
 420                                                                         \
 421 static const octet text[] = TEXT;                                       \
 422                                                                         \
 423 /* --- Key and IV to use --- */                                         \
 424                                                                         \
 425 static const octet key[] = KEY;                                         \
 426 static const octet iv[] = IV;                                           \
 427                                                                         \
 428 /* --- Buffers for encryption and decryption output --- */              \
 429                                                                         \
 430 static octet ct[sizeof(text)];                                          \
 431 static octet pt[sizeof(text)];                                          \
 432                                                                         \
 433 static void hexdump(const octet *p, size_t sz, size_t off)              \
 434 {                                                                       \
 435   const octet *q = p + sz;                                              \
 436   for (sz = 0; p < q; p++, sz++) {                                      \
 437     printf("%02x", *p);                                                 \
 438     if ((off + sz + 1) % PRE##_BLKSZ == 0)                              \
 439       putchar(':');                                                     \
 440   }                                                                     \
 441 }                                                                       \
 442                                                                         \
 443 int main(void)                                                          \
 444 {                                                                       \
 445   size_t sz = 0, rest;                                                  \
 446   pre##_cfbctx ctx;                                                     \
 447   int status = 0;                                                       \
 448   int done = 0;                                                         \
 449   pre##_ctx k;                                                          \
 450                                                                         \
 451   size_t keysz = PRE##_KEYSZ ?                                          \
 452     PRE##_KEYSZ : strlen((const char *)key);                            \
 453                                                                         \
 454   fputs(name "-cfb: ", stdout);                                         \
 455                                                                         \
 456   pre##_init(&k, key, keysz);                                           \
 457   pre##_cfbsetkey(&ctx, &k);                                            \
 458                                                                         \
 459   while (sz <= sizeof(text)) {                                          \
 460     rest = sizeof(text) - sz;                                           \
 461     memcpy(ct, text, sizeof(text));                                     \
 462     pre##_cfbsetiv(&ctx, iv);                                           \
 463     pre##_cfbencrypt(&ctx, ct, ct, sz);                                 \
 464     pre##_cfbencrypt(&ctx, ct + sz, ct + sz, rest);                     \
 465     memcpy(pt, ct, sizeof(text));                                       \
 466     pre##_cfbsetiv(&ctx, iv);                                           \
 467     pre##_cfbdecrypt(&ctx, pt, pt, rest);                               \
 468     pre##_cfbdecrypt(&ctx, pt + rest, pt + rest, sz);                   \
 469     if (memcmp(pt, text, sizeof(text)) == 0) {                          \
 470       done++;                                                           \
 471       if (sizeof(text) < 40 || done % 8 == 0)                           \
 472         fputc('.', stdout);                                             \
 473       if (done % 480 == 0)                                              \
 474         fputs("\n\t", stdout);                                          \
 475       fflush(stdout);                                                   \
 476     } else {                                                            \
 477       printf("\nError (sz = %lu)\n", (unsigned long)sz);                \
 478       status = 1;                                                       \
 479       printf("\tplaintext      = "); hexdump(text, sz, 0);              \
 480         printf(", "); hexdump(text + sz, rest, sz);                     \
 481         fputc('\n', stdout);                                            \
 482       printf("\tciphertext     = "); hexdump(ct, sz, 0);                \
 483         printf(", "); hexdump(ct + sz, rest, sz);                       \
 484         fputc('\n', stdout);                                            \
 485       printf("\trecovered text = "); hexdump(pt, sz, 0);                \
 486         printf(", "); hexdump(pt + sz, rest, sz);                       \
 487         fputc('\n', stdout);                                            \
 488       fputc('\n', stdout);                                              \
 489     }                                                                   \
 490     if (sz < 63)                                                        \
 491       sz++;                                                             \
 492     else                                                                \
 493       sz += 9;                                                          \
 494   }                                                                     \
 495                                                                         \
 496   fputs(status ? " failed\n" : " ok\n", stdout);                        \
 497   return (status);                                                      \
 498 }
 499
 500 #else
 501 #  define CFB_TESTX(PRE, pre, name, fname)
 502 #endif
 503
 504 /*----- That's all, folks -------------------------------------------------*/
 505
 506 #ifdef __cplusplus
 507   }
 508 #endif
 509
 510 #endif