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

   1 /* -*-c-*-
   2  *
   3  * $Id: ofb-def.h,v 1.4 2001/04/03 19:36:36 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 1.4  2001/04/03 19:36:36  mdw
  34  * Don't use @va_arg@ as an argument to @STORE32@!
  35  *
  36  * Revision 1.3  2000/06/17 11:48:02  mdw
  37  * Use secure arena for memory allocation.  Rearrange setiv slightly.
  38  *
  39  * Revision 1.2  1999/12/13 15:34:01  mdw
  40  * Add support for seeding from a generic pseudorandom source.
  41  *
  42  * Revision 1.1  1999/12/10 23:16:40  mdw
  43  * Split mode macros into interface and implementation.
  44  *
  45  */
  46
  47 #ifndef CATACOMB_OFB_DEF_H
  48 #define CATACOMB_OFB_DEF_H
  49
  50 #ifdef __cplusplus
  51   extern "C" {
  52 #endif
  53
  54 /*----- Header files ------------------------------------------------------*/
  55
  56 #include <stdarg.h>
  57 #include <string.h>
  58
  59 #include <mLib/bits.h>
  60 #include <mLib/sub.h>
  61
  62 #ifndef CATACOMB_ARENA_H
  63 #  include "arena.h"
  64 #endif
  65
  66 #ifndef CATACOMB_BLKC_H
  67 #  include "blkc.h"
  68 #endif
  69
  70 #ifndef CATACOMB_GCIPHER_H
  71 #  include "gcipher.h"
  72 #endif
  73
  74 #ifndef CATACOMB_PARANOIA_H
  75 #  include "paranoia.h"
  76 #endif
  77
  78 /*----- Macros ------------------------------------------------------------*/
  79
  80 /* --- @OFB_DEF@ --- *
  81  *
  82  * Arguments:   @PRE@, @pre@ = prefixes for the underlying block cipher
  83  *
  84  * Use:         Creates definitions for output feedback mode.
  85  */
  86
  87 #define OFB_DEF(PRE, pre)                                               \
  88                                                                         \
  89 /* --- @pre_ofbgetiv@ --- *                                             \
  90  *                                                                      \
  91  * Arguments:   @const pre_ofbctx *ctx@ = pointer to OFB context block  \
  92  *              @void *iv#@ = pointer to output data block              \
  93  *                                                                      \
  94  * Returns:     ---                                                     \
  95  *                                                                      \
  96  * Use:         Reads the currently set IV.  Reading and setting an IV  \
  97  *              is not transparent to the cipher.  It will add a `step' \
  98  *              which must be matched by a similar operation during     \
  99  *              decryption.                                             \
 100  */                                                                     \
 101                                                                         \
 102 void pre##_ofbgetiv(const pre##_ofbctx *ctx, void *iv)                  \
 103 {                                                                       \
 104   octet *p = iv;                                                        \
 105   unsigned off = ctx->off;                                              \
 106   unsigned rest = PRE##_BLKSZ - off;                                    \
 107   memcpy(p, ctx->iv + off, rest);                                       \
 108   memcpy(p + rest, ctx->iv, off);                                       \
 109 }                                                                       \
 110                                                                         \
 111 /* --- @pre_ofbsetiv@ --- *                                             \
 112  *                                                                      \
 113  * Arguments:   @pre_ofbctx *ctx@ = pointer to OFB context block        \
 114  *              @cnost void *iv@ = pointer to IV to set                 \
 115  *                                                                      \
 116  * Returns:     ---                                                     \
 117  *                                                                      \
 118  * Use:         Sets the IV to use for subsequent encryption.           \
 119  */                                                                     \
 120                                                                         \
 121 void pre##_ofbsetiv(pre##_ofbctx *ctx, const void *iv)                  \
 122 {                                                                       \
 123   memcpy(ctx->iv, iv, PRE##_BLKSZ);                                     \
 124   ctx->off = PRE##_BLKSZ;                                               \
 125 }                                                                       \
 126                                                                         \
 127 /* --- @pre_ofbbdry@ --- *                                              \
 128  *                                                                      \
 129  * Arguments:   @pre_ofbctx *ctx@ = pointer to OFB context block        \
 130  *                                                                      \
 131  * Returns:     ---                                                     \
 132  *                                                                      \
 133  * Use:         Inserts a boundary during encryption.  Successful       \
 134  *              decryption must place a similar boundary.               \
 135  */                                                                     \
 136                                                                         \
 137 void pre##_ofbbdry(pre##_ofbctx *ctx)                                   \
 138 {                                                                       \
 139   uint32 niv[PRE##_BLKSZ / 4];                                          \
 140   BLKC_LOAD(PRE, niv, ctx->iv);                                         \
 141   pre##_eblk(&ctx->ctx, niv, niv);                                      \
 142   BLKC_STORE(PRE, ctx->iv, niv);                                        \
 143   ctx->off = PRE##_BLKSZ;                                               \
 144   BURN(niv);                                                            \
 145 }                                                                       \
 146                                                                         \
 147 /* --- @pre_ofbsetkey@ --- *                                            \
 148  *                                                                      \
 149  * Arguments:   @pre_ofbctx *ctx@ = pointer to OFB context block        \
 150  *              @const pre_ctx *k@ = pointer to cipher context          \
 151  *                                                                      \
 152  * Returns:     ---                                                     \
 153  *                                                                      \
 154  * Use:         Sets the OFB context to use a different cipher key.     \
 155  */                                                                     \
 156                                                                         \
 157 void pre##_ofbsetkey(pre##_ofbctx *ctx, const pre##_ctx *k)             \
 158 {                                                                       \
 159   ctx->ctx = *k;                                                        \
 160 }                                                                       \
 161                                                                         \
 162 /* --- @pre_ofbinit@ --- *                                              \
 163  *                                                                      \
 164  * Arguments:   @pre_ofbctx *ctx@ = pointer to cipher context           \
 165  *              @const void *key@ = pointer to the key buffer           \
 166  *              @size_t sz@ = size of the key                           \
 167  *              @const void *iv@ = pointer to initialization vector     \
 168  *                                                                      \
 169  * Returns:     ---                                                     \
 170  *                                                                      \
 171  * Use:         Initializes a OFB context ready for use.  You should    \
 172  *              ensure that the IV chosen is unique: reusing an IV will \
 173  *              compromise the security of the entire plaintext.  This  \
 174  *              is equivalent to calls to @pre_init@, @pre_ofbsetkey@   \
 175  *              and @pre_ofbsetiv@.                                     \
 176  */                                                                     \
 177                                                                         \
 178 void pre##_ofbinit(pre##_ofbctx *ctx,                                   \
 179                      const void *key, size_t sz,                        \
 180                      const void *iv)                                    \
 181 {                                                                       \
 182   static octet zero[PRE##_BLKSZ] = { 0 };                               \
 183   pre##_init(&ctx->ctx, key, sz);                                       \
 184   pre##_ofbsetiv(ctx, iv ? iv : zero);                                  \
 185 }                                                                       \
 186                                                                         \
 187 /* --- @pre_ofbencrypt@ --- *                                           \
 188  *                                                                      \
 189  * Arguments:   @pre_ofbctx *ctx@ = pointer to OFB context block        \
 190  *              @const void *src@ = pointer to source data              \
 191  *              @void *dest@ = pointer to destination data              \
 192  *              @size_t sz@ = size of block to be encrypted             \
 193  *                                                                      \
 194  * Returns:     ---                                                     \
 195  *                                                                      \
 196  * Use:         Encrypts or decrypts a block with a block cipher in OFB \
 197  *              mode: encryption and decryption are the same in OFB.    \
 198  *              The destination may be null to just churn the feedback  \
 199  *              round for a bit.  The source may be null to use the     \
 200  *              cipher as a random data generator.                      \
 201  */                                                                     \
 202                                                                         \
 203 void pre##_ofbencrypt(pre##_ofbctx *ctx,                                \
 204                         const void *src, void *dest,                    \
 205                         size_t sz)                                      \
 206 {                                                                       \
 207   const octet *s = src;                                                 \
 208   octet *d = dest;                                                      \
 209   unsigned off = ctx->off;                                              \
 210                                                                         \
 211   /* --- Empty blocks are trivial --- */                                \
 212                                                                         \
 213   if (!sz)                                                              \
 214     return;                                                             \
 215                                                                         \
 216   /* --- If I can deal with the block from my buffer, do that --- */    \
 217                                                                         \
 218   if (sz < PRE##_BLKSZ - off)                                           \
 219     goto small;                                                         \
 220                                                                         \
 221   /* --- Finish off what's left in my buffer --- */                     \
 222                                                                         \
 223   if (!d)                                                               \
 224     sz -= PRE##_BLKSZ - off;                                            \
 225   else {                                                                \
 226     while (off < PRE##_BLKSZ) {                                         \
 227       register octet x = s ? *s++ : 0;                                  \
 228       *d++ = ctx->iv[off++] ^ x;                                        \
 229       sz--;                                                             \
 230     }                                                                   \
 231   }                                                                     \
 232                                                                         \
 233   /* --- Main encryption loop --- */                                    \
 234                                                                         \
 235   {                                                                     \
 236     uint32 iv[PRE##_BLKSZ / 4];                                         \
 237     BLKC_LOAD(PRE, iv, ctx->iv);                                        \
 238                                                                         \
 239     for (;;) {                                                          \
 240       pre##_eblk(&ctx->ctx, iv, iv);                                    \
 241       if (sz < PRE##_BLKSZ)                                             \
 242         break;                                                          \
 243       if (d) {                                                          \
 244         if (!s)                                                         \
 245           BLKC_STORE(PRE, d, iv);                                       \
 246         else {                                                          \
 247           uint32 x[PRE##_BLKSZ / 4];                                    \
 248           BLKC_LOAD(PRE, x, s);                                         \
 249           BLKC_XSTORE(PRE, d, iv, x);                                   \
 250           s += PRE##_BLKSZ;                                             \
 251         }                                                               \
 252         d += PRE##_BLKSZ;                                               \
 253       }                                                                 \
 254       sz -= PRE##_BLKSZ;                                                \
 255     }                                                                   \
 256                                                                         \
 257     BLKC_STORE(PRE, ctx->iv, iv);                                       \
 258     off = 0;                                                            \
 259   }                                                                     \
 260                                                                         \
 261   /* --- Tidying up the tail end --- */                                 \
 262                                                                         \
 263   if (sz) {                                                             \
 264   small:                                                                \
 265     if (!d)                                                             \
 266       off += sz;                                                        \
 267     else do {                                                           \
 268       register octet x = s ? *s++ : 0;                                  \
 269       *d++ = ctx->iv[off++] ^ x;                                        \
 270       sz--;                                                             \
 271     } while (sz);                                                       \
 272   }                                                                     \
 273                                                                         \
 274   /* --- Done --- */                                                    \
 275                                                                         \
 276   ctx->off = off;                                                       \
 277   return;                                                               \
 278 }                                                                       \
 279                                                                         \
 280 /* --- Generic cipher interface --- */                                  \
 281                                                                         \
 282 static const gcipher_ops gops;                                          \
 283                                                                         \
 284 typedef struct gctx {                                                   \
 285   gcipher c;                                                            \
 286   pre##_ofbctx k;                                                       \
 287 } gctx;                                                                 \
 288                                                                         \
 289 static gcipher *ginit(const void *k, size_t sz)                         \
 290 {                                                                       \
 291   gctx *g = S_CREATE(gctx);                                             \
 292   g->c.ops = &gops;                                                     \
 293   pre##_ofbinit(&g->k, k, sz, 0);                                       \
 294   return (&g->c);                                                       \
 295 }                                                                       \
 296                                                                         \
 297 static void gencrypt(gcipher *c, const void *s, void *t, size_t sz)     \
 298 {                                                                       \
 299   gctx *g = (gctx *)c;                                                  \
 300   pre##_ofbencrypt(&g->k, s, t, sz);                                    \
 301 }                                                                       \
 302                                                                         \
 303 static void gdestroy(gcipher *c)                                        \
 304 {                                                                       \
 305   gctx *g = (gctx *)c;                                                  \
 306   BURN(*g);                                                             \
 307   S_DESTROY(g);                                                         \
 308 }                                                                       \
 309                                                                         \
 310 static void gsetiv(gcipher *c, const void *iv)                          \
 311 {                                                                       \
 312   gctx *g = (gctx *)c;                                                  \
 313   pre##_ofbsetiv(&g->k, iv);                                            \
 314 }                                                                       \
 315                                                                         \
 316 static void gbdry(gcipher *c)                                           \
 317 {                                                                       \
 318   gctx *g = (gctx *)c;                                                  \
 319   pre##_ofbbdry(&g->k);                                                 \
 320 }                                                                       \
 321                                                                         \
 322 static const gcipher_ops gops = {                                       \
 323   &pre##_ofb,                                                           \
 324   gencrypt, gencrypt, gdestroy, gsetiv, gbdry                           \
 325 };                                                                      \
 326                                                                         \
 327 const gccipher pre##_ofb = {                                            \
 328   #pre "-ofb", pre##_keysz, PRE##_BLKSZ,                                \
 329   ginit                                                                 \
 330 };                                                                      \
 331                                                                         \
 332 /* --- Generic random number generator interface --- */                 \
 333                                                                         \
 334 typedef struct grctx {                                                  \
 335   grand r;                                                              \
 336   pre##_ofbctx k;                                                       \
 337 } grctx;                                                                \
 338                                                                         \
 339 static void grdestroy(grand *r)                                         \
 340 {                                                                       \
 341   grctx *g = (grctx *)r;                                                \
 342   BURN(*g);                                                             \
 343   S_DESTROY(g);                                                         \
 344 }                                                                       \
 345                                                                         \
 346 static int grmisc(grand *r, unsigned op, ...)                           \
 347 {                                                                       \
 348   grctx *g = (grctx *)r;                                                \
 349   va_list ap;                                                           \
 350   int rc = 0;                                                           \
 351   uint32 i;                                                             \
 352   octet buf[PRE##_BLKSZ];                                               \
 353   va_start(ap, op);                                                     \
 354                                                                         \
 355   switch (op) {                                                         \
 356     case GRAND_CHECK:                                                   \
 357       switch (va_arg(ap, unsigned)) {                                   \
 358         case GRAND_CHECK:                                               \
 359         case GRAND_SEEDINT:                                             \
 360         case GRAND_SEEDUINT32:                                          \
 361         case GRAND_SEEDBLOCK:                                           \
 362         case GRAND_SEEDRAND:                                            \
 363           rc = 1;                                                       \
 364           break;                                                        \
 365         default:                                                        \
 366           rc = 0;                                                       \
 367           break;                                                        \
 368       }                                                                 \
 369       break;                                                            \
 370     case GRAND_SEEDINT:                                                 \
 371       memset(buf, 0, sizeof(buf));                                      \
 372       i = va_arg(ap, unsigned);                                         \
 373       STORE32(buf, i);                                                  \
 374       pre##_ofbsetiv(&g->k, buf);                                       \
 375       break;                                                            \
 376     case GRAND_SEEDUINT32:                                              \
 377       memset(buf, 0, sizeof(buf));                                      \
 378       i = va_arg(ap, uint32);                                           \
 379       STORE32(buf, i);                                                  \
 380       pre##_ofbsetiv(&g->k, buf);                                       \
 381       break;                                                            \
 382     case GRAND_SEEDBLOCK: {                                             \
 383       const void *p = va_arg(ap, const void *);                         \
 384       size_t sz = va_arg(ap, size_t);                                   \
 385       if (sz < sizeof(buf)) {                                           \
 386         memset(buf, 0, sizeof(buf));                                    \
 387         memcpy(buf, p, sz);                                             \
 388         p = buf;                                                        \
 389       }                                                                 \
 390       pre##_ofbsetiv(&g->k, p);                                         \
 391     } break;                                                            \
 392     case GRAND_SEEDRAND: {                                              \
 393       grand *rr = va_arg(ap, grand *);                                  \
 394       rr->ops->fill(rr, buf, sizeof(buf));                              \
 395       pre##_ofbsetiv(&g->k, buf);                                       \
 396     } break;                                                            \
 397     default:                                                            \
 398       GRAND_BADOP;                                                      \
 399       break;                                                            \
 400   }                                                                     \
 401                                                                         \
 402   va_end(ap);                                                           \
 403   return (rc);                                                          \
 404 }                                                                       \
 405                                                                         \
 406 static octet grbyte(grand *r)                                           \
 407 {                                                                       \
 408   grctx *g = (grctx *)r;                                                \
 409   octet o;                                                              \
 410   pre##_ofbencrypt(&g->k, 0, &o, 1);                                    \
 411   return (o);                                                           \
 412 }                                                                       \
 413                                                                         \
 414 static uint32 grword(grand *r)                                          \
 415 {                                                                       \
 416   grctx *g = (grctx *)r;                                                \
 417   octet b[4];                                                           \
 418   pre##_ofbencrypt(&g->k, 0, b, sizeof(b));                             \
 419   return (LOAD32(b));                                                   \
 420 }                                                                       \
 421                                                                         \
 422 static void grfill(grand *r, void *p, size_t sz)                        \
 423 {                                                                       \
 424   grctx *g = (grctx *)r;                                                \
 425   pre##_ofbencrypt(&g->k, 0, p, sz);                                    \
 426 }                                                                       \
 427                                                                         \
 428 static const grand_ops grops = {                                        \
 429   #pre "-ofb",                                                          \
 430   GRAND_CRYPTO, 0,                                                      \
 431   grmisc, grdestroy,                                                    \
 432   grword, grbyte, grword, grand_range, grfill                           \
 433 };                                                                      \
 434                                                                         \
 435 /* --- @pre_ofbrand@ --- *                                              \
 436  *                                                                      \
 437  * Arguments:   @const void *k@ = pointer to key material               \
 438  *              @size_t sz@ = size of key material                      \
 439  *                                                                      \
 440  * Returns:     Pointer to generic random number generator interface.   \
 441  *                                                                      \
 442  * Use:         Creates a random number interface wrapper around an     \
 443  *              OFB-mode block cipher.                                  \
 444  */                                                                     \
 445                                                                         \
 446 grand *pre##_ofbrand(const void *k, size_t sz)                          \
 447 {                                                                       \
 448   grctx *g = S_CREATE(grctx);                                           \
 449   g->r.ops = &grops;                                                    \
 450   pre##_ofbinit(&g->k, k, sz, 0);                                       \
 451   return (&g->r);                                                       \
 452 }                                                                       \
 453                                                                         \
 454 OFB_TEST(PRE, pre)
 455
 456 /*----- Test rig ----------------------------------------------------------*/
 457
 458 #ifdef TEST_RIG
 459
 460 #include <stdio.h>
 461
 462 #include "daftstory.h"
 463
 464 /* --- @OFB_TEST@ --- *
 465  *
 466  * Arguments:   @PRE@, @pre@ = prefixes for block cipher definitions
 467  *
 468  * Use:         Standard test rig for OFB functions.
 469  */
 470
 471 #define OFB_TEST(PRE, pre)                                              \
 472                                                                         \
 473 /* --- Initial plaintext for the test --- */                            \
 474                                                                         \
 475 static const octet text[] = TEXT;                                       \
 476                                                                         \
 477 /* --- Key and IV to use --- */                                         \
 478                                                                         \
 479 static const octet key[] = KEY;                                         \
 480 static const octet iv[] = IV;                                           \
 481                                                                         \
 482 /* --- Buffers for encryption and decryption output --- */              \
 483                                                                         \
 484 static octet ct[sizeof(text)];                                          \
 485 static octet pt[sizeof(text)];                                          \
 486                                                                         \
 487 static void hexdump(const octet *p, size_t sz)                          \
 488 {                                                                       \
 489   const octet *q = p + sz;                                              \
 490   for (sz = 0; p < q; p++, sz++) {                                      \
 491     printf("%02x", *p);                                                 \
 492     if ((sz + 1) % PRE##_BLKSZ == 0)                                    \
 493       putchar(':');                                                     \
 494   }                                                                     \
 495 }                                                                       \
 496                                                                         \
 497 int main(void)                                                          \
 498 {                                                                       \
 499   size_t sz = 0, rest;                                                  \
 500   pre##_ofbctx ctx;                                                     \
 501   int status = 0;                                                       \
 502   int done = 0;                                                         \
 503   pre##_ctx k;                                                          \
 504                                                                         \
 505   size_t keysz = PRE##_KEYSZ ?                                          \
 506     PRE##_KEYSZ : strlen((const char *)key);                            \
 507                                                                         \
 508   fputs(#pre "-ofb: ", stdout);                                         \
 509                                                                         \
 510   pre##_init(&k, key, keysz);                                           \
 511   pre##_ofbsetkey(&ctx, &k);                                            \
 512                                                                         \
 513   while (sz <= sizeof(text)) {                                          \
 514     rest = sizeof(text) - sz;                                           \
 515     memcpy(ct, text, sizeof(text));                                     \
 516     pre##_ofbsetiv(&ctx, iv);                                           \
 517     pre##_ofbencrypt(&ctx, ct, ct, sz);                                 \
 518     pre##_ofbencrypt(&ctx, ct + sz, ct + sz, rest);                     \
 519     memcpy(pt, ct, sizeof(text));                                       \
 520     pre##_ofbsetiv(&ctx, iv);                                           \
 521     pre##_ofbencrypt(&ctx, pt, pt, rest);                               \
 522     pre##_ofbencrypt(&ctx, pt + rest, pt + rest, sz);                   \
 523     if (memcmp(pt, text, sizeof(text)) == 0) {                          \
 524       done++;                                                           \
 525       if (sizeof(text) < 40 || done % 8 == 0)                           \
 526         fputc('.', stdout);                                             \
 527       if (done % 480 == 0)                                              \
 528         fputs("\n\t", stdout);                                          \
 529       fflush(stdout);                                                   \
 530     } else {                                                            \
 531       printf("\nError (sz = %lu)\n", (unsigned long)sz);                \
 532       status = 1;                                                       \
 533       printf("\tplaintext      = "); hexdump(text, sz);                 \
 534         printf(", "); hexdump(text + sz, rest);                         \
 535         fputc('\n', stdout);                                            \
 536       printf("\tciphertext     = "); hexdump(ct, sz);                   \
 537         printf(", "); hexdump(ct + sz, rest);                           \
 538         fputc('\n', stdout);                                            \
 539       printf("\trecovered text = "); hexdump(pt, sz);                   \
 540         printf(", "); hexdump(pt + sz, rest);                           \
 541         fputc('\n', stdout);                                            \
 542       fputc('\n', stdout);                                              \
 543     }                                                                   \
 544     if (sz < 63)                                                        \
 545       sz++;                                                             \
 546     else                                                                \
 547       sz += 9;                                                          \
 548   }                                                                     \
 549                                                                         \
 550   fputs(status ? " failed\n" : " ok\n", stdout);                        \
 551   return (status);                                                      \
 552 }
 553
 554 #else
 555 #  define OFB_TEST(PRE, pre)
 556 #endif
 557
 558 /*----- That's all, folks -------------------------------------------------*/
 559
 560 #ifdef __cplusplus
 561   }
 562 #endif
 563
 564 #endif