chiark - git - mdw - catacomb/blob - ofb-def.h

   1 /* -*-c-*-
   2  *
   3  * $Id: ofb-def.h,v 1.3 2000/06/17 11:48:02 mdw Exp $
   4  *
   5  * Definitions for output feedback mode
   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-def.h,v $
  33  * Revision 1.3  2000/06/17 11:48:02  mdw
  34  * Use secure arena for memory allocation.  Rearrange setiv slightly.
  35  *
  36  * Revision 1.2  1999/12/13 15:34:01  mdw
  37  * Add support for seeding from a generic pseudorandom source.
  38  *
  39  * Revision 1.1  1999/12/10 23:16:40  mdw
  40  * Split mode macros into interface and implementation.
  41  *
  42  */
  43
  44 #ifndef CATACOMB_OFB_DEF_H
  45 #define CATACOMB_OFB_DEF_H
  46
  47 #ifdef __cplusplus
  48   extern "C" {
  49 #endif
  50
  51 /*----- Header files ------------------------------------------------------*/
  52
  53 #include <stdarg.h>
  54 #include <string.h>
  55
  56 #include <mLib/bits.h>
  57 #include <mLib/sub.h>
  58
  59 #ifndef CATACOMB_ARENA_H
  60 #  include "arena.h"
  61 #endif
  62
  63 #ifndef CATACOMB_BLKC_H
  64 #  include "blkc.h"
  65 #endif
  66
  67 #ifndef CATACOMB_GCIPHER_H
  68 #  include "gcipher.h"
  69 #endif
  70
  71 #ifndef CATACOMB_PARANOIA_H
  72 #  include "paranoia.h"
  73 #endif
  74
  75 /*----- Macros ------------------------------------------------------------*/
  76
  77 /* --- @OFB_DEF@ --- *
  78  *
  79  * Arguments:   @PRE@, @pre@ = prefixes for the underlying block cipher
  80  *
  81  * Use:         Creates definitions for output feedback mode.
  82  */
  83
  84 #define OFB_DEF(PRE, pre)                                               \
  85                                                                         \
  86 /* --- @pre_ofbgetiv@ --- *                                             \
  87  *                                                                      \
  88  * Arguments:   @const pre_ofbctx *ctx@ = pointer to OFB context block  \
  89  *              @void *iv#@ = pointer to output data block              \
  90  *                                                                      \
  91  * Returns:     ---                                                     \
  92  *                                                                      \
  93  * Use:         Reads the currently set IV.  Reading and setting an IV  \
  94  *              is not transparent to the cipher.  It will add a `step' \
  95  *              which must be matched by a similar operation during     \
  96  *              decryption.                                             \
  97  */                                                                     \
  98                                                                         \
  99 void pre##_ofbgetiv(const pre##_ofbctx *ctx, void *iv)                  \
 100 {                                                                       \
 101   octet *p = iv;                                                        \
 102   unsigned off = ctx->off;                                              \
 103   unsigned rest = PRE##_BLKSZ - off;                                    \
 104   memcpy(p, ctx->iv + off, rest);                                       \
 105   memcpy(p + rest, ctx->iv, off);                                       \
 106 }                                                                       \
 107                                                                         \
 108 /* --- @pre_ofbsetiv@ --- *                                             \
 109  *                                                                      \
 110  * Arguments:   @pre_ofbctx *ctx@ = pointer to OFB context block        \
 111  *              @cnost void *iv@ = pointer to IV to set                 \
 112  *                                                                      \
 113  * Returns:     ---                                                     \
 114  *                                                                      \
 115  * Use:         Sets the IV to use for subsequent encryption.           \
 116  */                                                                     \
 117                                                                         \
 118 void pre##_ofbsetiv(pre##_ofbctx *ctx, const void *iv)                  \
 119 {                                                                       \
 120   memcpy(ctx->iv, iv, PRE##_BLKSZ);                                     \
 121   ctx->off = PRE##_BLKSZ;                                               \
 122 }                                                                       \
 123                                                                         \
 124 /* --- @pre_ofbbdry@ --- *                                              \
 125  *                                                                      \
 126  * Arguments:   @pre_ofbctx *ctx@ = pointer to OFB context block        \
 127  *                                                                      \
 128  * Returns:     ---                                                     \
 129  *                                                                      \
 130  * Use:         Inserts a boundary during encryption.  Successful       \
 131  *              decryption must place a similar boundary.               \
 132  */                                                                     \
 133                                                                         \
 134 void pre##_ofbbdry(pre##_ofbctx *ctx)                                   \
 135 {                                                                       \
 136   uint32 niv[PRE##_BLKSZ / 4];                                          \
 137   BLKC_LOAD(PRE, niv, ctx->iv);                                         \
 138   pre##_eblk(&ctx->ctx, niv, niv);                                      \
 139   BLKC_STORE(PRE, ctx->iv, niv);                                        \
 140   ctx->off = PRE##_BLKSZ;                                               \
 141   BURN(niv);                                                            \
 142 }                                                                       \
 143                                                                         \
 144 /* --- @pre_ofbsetkey@ --- *                                            \
 145  *                                                                      \
 146  * Arguments:   @pre_ofbctx *ctx@ = pointer to OFB context block        \
 147  *              @const pre_ctx *k@ = pointer to cipher context          \
 148  *                                                                      \
 149  * Returns:     ---                                                     \
 150  *                                                                      \
 151  * Use:         Sets the OFB context to use a different cipher key.     \
 152  */                                                                     \
 153                                                                         \
 154 void pre##_ofbsetkey(pre##_ofbctx *ctx, const pre##_ctx *k)             \
 155 {                                                                       \
 156   ctx->ctx = *k;                                                        \
 157 }                                                                       \
 158                                                                         \
 159 /* --- @pre_ofbinit@ --- *                                              \
 160  *                                                                      \
 161  * Arguments:   @pre_ofbctx *ctx@ = pointer to cipher context           \
 162  *              @const void *key@ = pointer to the key buffer           \
 163  *              @size_t sz@ = size of the key                           \
 164  *              @const void *iv@ = pointer to initialization vector     \
 165  *                                                                      \
 166  * Returns:     ---                                                     \
 167  *                                                                      \
 168  * Use:         Initializes a OFB context ready for use.  You should    \
 169  *              ensure that the IV chosen is unique: reusing an IV will \
 170  *              compromise the security of the entire plaintext.  This  \
 171  *              is equivalent to calls to @pre_init@, @pre_ofbsetkey@   \
 172  *              and @pre_ofbsetiv@.                                     \
 173  */                                                                     \
 174                                                                         \
 175 void pre##_ofbinit(pre##_ofbctx *ctx,                                   \
 176                      const void *key, size_t sz,                        \
 177                      const void *iv)                                    \
 178 {                                                                       \
 179   static octet zero[PRE##_BLKSZ] = { 0 };                               \
 180   pre##_init(&ctx->ctx, key, sz);                                       \
 181   pre##_ofbsetiv(ctx, iv ? iv : zero);                                  \
 182 }                                                                       \
 183                                                                         \
 184 /* --- @pre_ofbencrypt@ --- *                                           \
 185  *                                                                      \
 186  * Arguments:   @pre_ofbctx *ctx@ = pointer to OFB context block        \
 187  *              @const void *src@ = pointer to source data              \
 188  *              @void *dest@ = pointer to destination data              \
 189  *              @size_t sz@ = size of block to be encrypted             \
 190  *                                                                      \
 191  * Returns:     ---                                                     \
 192  *                                                                      \
 193  * Use:         Encrypts or decrypts a block with a block cipher in OFB \
 194  *              mode: encryption and decryption are the same in OFB.    \
 195  *              The destination may be null to just churn the feedback  \
 196  *              round for a bit.  The source may be null to use the     \
 197  *              cipher as a random data generator.                      \
 198  */                                                                     \
 199                                                                         \
 200 void pre##_ofbencrypt(pre##_ofbctx *ctx,                                \
 201                         const void *src, void *dest,                    \
 202                         size_t sz)                                      \
 203 {                                                                       \
 204   const octet *s = src;                                                 \
 205   octet *d = dest;                                                      \
 206   unsigned off = ctx->off;                                              \
 207                                                                         \
 208   /* --- Empty blocks are trivial --- */                                \
 209                                                                         \
 210   if (!sz)                                                              \
 211     return;                                                             \
 212                                                                         \
 213   /* --- If I can deal with the block from my buffer, do that --- */    \
 214                                                                         \
 215   if (sz < PRE##_BLKSZ - off)                                           \
 216     goto small;                                                         \
 217                                                                         \
 218   /* --- Finish off what's left in my buffer --- */                     \
 219                                                                         \
 220   if (!d)                                                               \
 221     sz -= PRE##_BLKSZ - off;                                            \
 222   else {                                                                \
 223     while (off < PRE##_BLKSZ) {                                         \
 224       register octet x = s ? *s++ : 0;                                  \
 225       *d++ = ctx->iv[off++] ^ x;                                        \
 226       sz--;                                                             \
 227     }                                                                   \
 228   }                                                                     \
 229                                                                         \
 230   /* --- Main encryption loop --- */                                    \
 231                                                                         \
 232   {                                                                     \
 233     uint32 iv[PRE##_BLKSZ / 4];                                         \
 234     BLKC_LOAD(PRE, iv, ctx->iv);                                        \
 235                                                                         \
 236     for (;;) {                                                          \
 237       pre##_eblk(&ctx->ctx, iv, iv);                                    \
 238       if (sz < PRE##_BLKSZ)                                             \
 239         break;                                                          \
 240       if (d) {                                                          \
 241         if (!s)                                                         \
 242           BLKC_STORE(PRE, d, iv);                                       \
 243         else {                                                          \
 244           uint32 x[PRE##_BLKSZ / 4];                                    \
 245           BLKC_LOAD(PRE, x, s);                                         \
 246           BLKC_XSTORE(PRE, d, iv, x);                                   \
 247           s += PRE##_BLKSZ;                                             \
 248         }                                                               \
 249         d += PRE##_BLKSZ;                                               \
 250       }                                                                 \
 251       sz -= PRE##_BLKSZ;                                                \
 252     }                                                                   \
 253                                                                         \
 254     BLKC_STORE(PRE, ctx->iv, iv);                                       \
 255     off = 0;                                                            \
 256   }                                                                     \
 257                                                                         \
 258   /* --- Tidying up the tail end --- */                                 \
 259                                                                         \
 260   if (sz) {                                                             \
 261   small:                                                                \
 262     if (!d)                                                             \
 263       off += sz;                                                        \
 264     else do {                                                           \
 265       register octet x = s ? *s++ : 0;                                  \
 266       *d++ = ctx->iv[off++] ^ x;                                        \
 267       sz--;                                                             \
 268     } while (sz);                                                       \
 269   }                                                                     \
 270                                                                         \
 271   /* --- Done --- */                                                    \
 272                                                                         \
 273   ctx->off = off;                                                       \
 274   return;                                                               \
 275 }                                                                       \
 276                                                                         \
 277 /* --- Generic cipher interface --- */                                  \
 278                                                                         \
 279 static const gcipher_ops gops;                                          \
 280                                                                         \
 281 typedef struct gctx {                                                   \
 282   gcipher c;                                                            \
 283   pre##_ofbctx k;                                                       \
 284 } gctx;                                                                 \
 285                                                                         \
 286 static gcipher *ginit(const void *k, size_t sz)                         \
 287 {                                                                       \
 288   gctx *g = S_CREATE(gctx);                                             \
 289   g->c.ops = &gops;                                                     \
 290   pre##_ofbinit(&g->k, k, sz, 0);                                       \
 291   return (&g->c);                                                       \
 292 }                                                                       \
 293                                                                         \
 294 static void gencrypt(gcipher *c, const void *s, void *t, size_t sz)     \
 295 {                                                                       \
 296   gctx *g = (gctx *)c;                                                  \
 297   pre##_ofbencrypt(&g->k, s, t, sz);                                    \
 298 }                                                                       \
 299                                                                         \
 300 static void gdestroy(gcipher *c)                                        \
 301 {                                                                       \
 302   gctx *g = (gctx *)c;                                                  \
 303   BURN(*g);                                                             \
 304   S_DESTROY(g);                                                         \
 305 }                                                                       \
 306                                                                         \
 307 static void gsetiv(gcipher *c, const void *iv)                          \
 308 {                                                                       \
 309   gctx *g = (gctx *)c;                                                  \
 310   pre##_ofbsetiv(&g->k, iv);                                            \
 311 }                                                                       \
 312                                                                         \
 313 static void gbdry(gcipher *c)                                           \
 314 {                                                                       \
 315   gctx *g = (gctx *)c;                                                  \
 316   pre##_ofbbdry(&g->k);                                                 \
 317 }                                                                       \
 318                                                                         \
 319 static const gcipher_ops gops = {                                       \
 320   &pre##_ofb,                                                           \
 321   gencrypt, gencrypt, gdestroy, gsetiv, gbdry                           \
 322 };                                                                      \
 323                                                                         \
 324 const gccipher pre##_ofb = {                                            \
 325   #pre "-ofb", pre##_keysz, PRE##_BLKSZ,                                \
 326   ginit                                                                 \
 327 };                                                                      \
 328                                                                         \
 329 /* --- Generic random number generator interface --- */                 \
 330                                                                         \
 331 typedef struct grctx {                                                  \
 332   grand r;                                                              \
 333   pre##_ofbctx k;                                                       \
 334 } grctx;                                                                \
 335                                                                         \
 336 static void grdestroy(grand *r)                                         \
 337 {                                                                       \
 338   grctx *g = (grctx *)r;                                                \
 339   BURN(*g);                                                             \
 340   S_DESTROY(g);                                                         \
 341 }                                                                       \
 342                                                                         \
 343 static int grmisc(grand *r, unsigned op, ...)                           \
 344 {                                                                       \
 345   grctx *g = (grctx *)r;                                                \
 346   va_list ap;                                                           \
 347   int rc = 0;                                                           \
 348   octet buf[PRE##_BLKSZ];                                               \
 349   va_start(ap, op);                                                     \
 350                                                                         \
 351   switch (op) {                                                         \
 352     case GRAND_CHECK:                                                   \
 353       switch (va_arg(ap, unsigned)) {                                   \
 354         case GRAND_CHECK:                                               \
 355         case GRAND_SEEDINT:                                             \
 356         case GRAND_SEEDUINT32:                                          \
 357         case GRAND_SEEDBLOCK:                                           \
 358         case GRAND_SEEDRAND:                                            \
 359           rc = 1;                                                       \
 360           break;                                                        \
 361         default:                                                        \
 362           rc = 0;                                                       \
 363           break;                                                        \
 364       }                                                                 \
 365       break;                                                            \
 366     case GRAND_SEEDINT:                                                 \
 367       memset(buf, 0, sizeof(buf));                                      \
 368       STORE32(buf, va_arg(ap, unsigned));                               \
 369       pre##_ofbsetiv(&g->k, buf);                                       \
 370       break;                                                            \
 371     case GRAND_SEEDUINT32:                                              \
 372       memset(buf, 0, sizeof(buf));                                      \
 373       STORE32(buf, va_arg(ap, uint32));                                 \
 374       pre##_ofbsetiv(&g->k, buf);                                       \
 375       break;                                                            \
 376     case GRAND_SEEDBLOCK: {                                             \
 377       const void *p = va_arg(ap, const void *);                         \
 378       size_t sz = va_arg(ap, size_t);                                   \
 379       if (sz < sizeof(buf)) {                                           \
 380         memset(buf, 0, sizeof(buf));                                    \
 381         memcpy(buf, p, sz);                                             \
 382         p = buf;                                                        \
 383       }                                                                 \
 384       pre##_ofbsetiv(&g->k, p);                                         \
 385     } break;                                                            \
 386     case GRAND_SEEDRAND: {                                              \
 387       grand *rr = va_arg(ap, grand *);                                  \
 388       rr->ops->fill(rr, buf, sizeof(buf));                              \
 389       pre##_ofbsetiv(&g->k, buf);                                       \
 390     } break;                                                            \
 391     default:                                                            \
 392       GRAND_BADOP;                                                      \
 393       break;                                                            \
 394   }                                                                     \
 395                                                                         \
 396   va_end(ap);                                                           \
 397   return (rc);                                                          \
 398 }                                                                       \
 399                                                                         \
 400 static octet grbyte(grand *r)                                           \
 401 {                                                                       \
 402   grctx *g = (grctx *)r;                                                \
 403   octet o;                                                              \
 404   pre##_ofbencrypt(&g->k, 0, &o, 1);                                    \
 405   return (o);                                                           \
 406 }                                                                       \
 407                                                                         \
 408 static uint32 grword(grand *r)                                          \
 409 {                                                                       \
 410   grctx *g = (grctx *)r;                                                \
 411   octet b[4];                                                           \
 412   pre##_ofbencrypt(&g->k, 0, b, sizeof(b));                             \
 413   return (LOAD32(b));                                                   \
 414 }                                                                       \
 415                                                                         \
 416 static void grfill(grand *r, void *p, size_t sz)                        \
 417 {                                                                       \
 418   grctx *g = (grctx *)r;                                                \
 419   pre##_ofbencrypt(&g->k, 0, p, sz);                                    \
 420 }                                                                       \
 421                                                                         \
 422 static const grand_ops grops = {                                        \
 423   #pre "-ofb",                                                          \
 424   GRAND_CRYPTO, 0,                                                      \
 425   grmisc, grdestroy,                                                    \
 426   grword, grbyte, grword, grand_range, grfill                           \
 427 };                                                                      \
 428                                                                         \
 429 /* --- @pre_ofbrand@ --- *                                              \
 430  *                                                                      \
 431  * Arguments:   @const void *k@ = pointer to key material               \
 432  *              @size_t sz@ = size of key material                      \
 433  *                                                                      \
 434  * Returns:     Pointer to generic random number generator interface.   \
 435  *                                                                      \
 436  * Use:         Creates a random number interface wrapper around an     \
 437  *              OFB-mode block cipher.                                  \
 438  */                                                                     \
 439                                                                         \
 440 grand *pre##_ofbrand(const void *k, size_t sz)                          \
 441 {                                                                       \
 442   grctx *g = S_CREATE(grctx);                                           \
 443   g->r.ops = &grops;                                                    \
 444   pre##_ofbinit(&g->k, k, sz, 0);                                       \
 445   return (&g->r);                                                       \
 446 }                                                                       \
 447                                                                         \
 448 OFB_TEST(PRE, pre)
 449
 450 /*----- Test rig ----------------------------------------------------------*/
 451
 452 #ifdef TEST_RIG
 453
 454 #include <stdio.h>
 455
 456 #include "daftstory.h"
 457
 458 /* --- @OFB_TEST@ --- *
 459  *
 460  * Arguments:   @PRE@, @pre@ = prefixes for block cipher definitions
 461  *
 462  * Use:         Standard test rig for OFB functions.
 463  */
 464
 465 #define OFB_TEST(PRE, pre)                                              \
 466                                                                         \
 467 /* --- Initial plaintext for the test --- */                            \
 468                                                                         \
 469 static const octet text[] = TEXT;                                       \
 470                                                                         \
 471 /* --- Key and IV to use --- */                                         \
 472                                                                         \
 473 static const octet key[] = KEY;                                         \
 474 static const octet iv[] = IV;                                           \
 475                                                                         \
 476 /* --- Buffers for encryption and decryption output --- */              \
 477                                                                         \
 478 static octet ct[sizeof(text)];                                          \
 479 static octet pt[sizeof(text)];                                          \
 480                                                                         \
 481 static void hexdump(const octet *p, size_t sz)                          \
 482 {                                                                       \
 483   const octet *q = p + sz;                                              \
 484   for (sz = 0; p < q; p++, sz++) {                                      \
 485     printf("%02x", *p);                                                 \
 486     if ((sz + 1) % PRE##_BLKSZ == 0)                                    \
 487       putchar(':');                                                     \
 488   }                                                                     \
 489 }                                                                       \
 490                                                                         \
 491 int main(void)                                                          \
 492 {                                                                       \
 493   size_t sz = 0, rest;                                                  \
 494   pre##_ofbctx ctx;                                                     \
 495   int status = 0;                                                       \
 496   int done = 0;                                                         \
 497   pre##_ctx k;                                                          \
 498                                                                         \
 499   size_t keysz = PRE##_KEYSZ ?                                          \
 500     PRE##_KEYSZ : strlen((const char *)key);                            \
 501                                                                         \
 502   fputs(#pre "-ofb: ", stdout);                                         \
 503                                                                         \
 504   pre##_init(&k, key, keysz);                                           \
 505   pre##_ofbsetkey(&ctx, &k);                                            \
 506                                                                         \
 507   while (sz <= sizeof(text)) {                                          \
 508     rest = sizeof(text) - sz;                                           \
 509     memcpy(ct, text, sizeof(text));                                     \
 510     pre##_ofbsetiv(&ctx, iv);                                           \
 511     pre##_ofbencrypt(&ctx, ct, ct, sz);                                 \
 512     pre##_ofbencrypt(&ctx, ct + sz, ct + sz, rest);                     \
 513     memcpy(pt, ct, sizeof(text));                                       \
 514     pre##_ofbsetiv(&ctx, iv);                                           \
 515     pre##_ofbencrypt(&ctx, pt, pt, rest);                               \
 516     pre##_ofbencrypt(&ctx, pt + rest, pt + rest, sz);                   \
 517     if (memcmp(pt, text, sizeof(text)) == 0) {                          \
 518       done++;                                                           \
 519       if (sizeof(text) < 40 || done % 8 == 0)                           \
 520         fputc('.', stdout);                                             \
 521       if (done % 480 == 0)                                              \
 522         fputs("\n\t", stdout);                                          \
 523       fflush(stdout);                                                   \
 524     } else {                                                            \
 525       printf("\nError (sz = %lu)\n", (unsigned long)sz);                \
 526       status = 1;                                                       \
 527       printf("\tplaintext      = "); hexdump(text, sz);                 \
 528         printf(", "); hexdump(text + sz, rest);                         \
 529         fputc('\n', stdout);                                            \
 530       printf("\tciphertext     = "); hexdump(ct, sz);                   \
 531         printf(", "); hexdump(ct + sz, rest);                           \
 532         fputc('\n', stdout);                                            \
 533       printf("\trecovered text = "); hexdump(pt, sz);                   \
 534         printf(", "); hexdump(pt + sz, rest);                           \
 535         fputc('\n', stdout);                                            \
 536       fputc('\n', stdout);                                              \
 537     }                                                                   \
 538     if (sz < 63)                                                        \
 539       sz++;                                                             \
 540     else                                                                \
 541       sz += 9;                                                          \
 542   }                                                                     \
 543                                                                         \
 544   fputs(status ? " failed\n" : " ok\n", stdout);                        \
 545   return (status);                                                      \
 546 }
 547
 548 #else
 549 #  define OFB_TEST(PRE, pre)
 550 #endif
 551
 552 /*----- That's all, folks -------------------------------------------------*/
 553
 554 #ifdef __cplusplus
 555   }
 556 #endif
 557
 558 #endif