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

   1 /* -*-c-*-
   2  *
   3  * Definitions for output feedback mode
   4  *
   5  * (c) 1999 Straylight/Edgeware
   6  */
   7
   8 /*----- Licensing notice --------------------------------------------------*
   9  *
  10  * This file is part of Catacomb.
  11  *
  12  * Catacomb is free software; you can redistribute it and/or modify
  13  * it under the terms of the GNU Library General Public License as
  14  * published by the Free Software Foundation; either version 2 of the
  15  * License, or (at your option) any later version.
  16  *
  17  * Catacomb is distributed in the hope that it will be useful,
  18  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  19  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  20  * GNU Library General Public License for more details.
  21  *
  22  * You should have received a copy of the GNU Library General Public
  23  * License along with Catacomb; if not, write to the Free
  24  * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
  25  * MA 02111-1307, USA.
  26  */
  27
  28 #ifndef CATACOMB_OFB_DEF_H
  29 #define CATACOMB_OFB_DEF_H
  30
  31 #ifdef __cplusplus
  32   extern "C" {
  33 #endif
  34
  35 /*----- Header files ------------------------------------------------------*/
  36
  37 #include <stdarg.h>
  38 #include <string.h>
  39
  40 #include <mLib/bits.h>
  41 #include <mLib/sub.h>
  42
  43 #ifndef CATACOMB_ARENA_H
  44 #  include "arena.h"
  45 #endif
  46
  47 #ifndef CATACOMB_BLKC_H
  48 #  include "blkc.h"
  49 #endif
  50
  51 #ifndef CATACOMB_GCIPHER_H
  52 #  include "gcipher.h"
  53 #endif
  54
  55 #ifndef CATACOMB_PARANOIA_H
  56 #  include "paranoia.h"
  57 #endif
  58
  59 /*----- Macros ------------------------------------------------------------*/
  60
  61 /* --- @OFB_DEF@ --- *
  62  *
  63  * Arguments:   @PRE@, @pre@ = prefixes for the underlying block cipher
  64  *
  65  * Use:         Creates definitions for output feedback mode.
  66  */
  67
  68 #define OFB_DEF(PRE, pre)                                               \
  69                                                                         \
  70 /* --- @pre_ofbgetiv@ --- *                                             \
  71  *                                                                      \
  72  * Arguments:   @const pre_ofbctx *ctx@ = pointer to OFB context block  \
  73  *              @void *iv@ = pointer to output data block               \
  74  *                                                                      \
  75  * Returns:     ---                                                     \
  76  *                                                                      \
  77  * Use:         Reads the currently set IV.  Reading and setting an IV  \
  78  *              is not transparent to the cipher.  It will add a `step' \
  79  *              which must be matched by a similar operation during     \
  80  *              decryption.                                             \
  81  */                                                                     \
  82                                                                         \
  83 void pre##_ofbgetiv(const pre##_ofbctx *ctx, void *iv)                  \
  84 {                                                                       \
  85   octet *p = iv;                                                        \
  86   unsigned off = ctx->off;                                              \
  87   unsigned rest = PRE##_BLKSZ - off;                                    \
  88   memcpy(p, ctx->iv + off, rest);                                       \
  89   memcpy(p + rest, ctx->iv, off);                                       \
  90 }                                                                       \
  91                                                                         \
  92 /* --- @pre_ofbsetiv@ --- *                                             \
  93  *                                                                      \
  94  * Arguments:   @pre_ofbctx *ctx@ = pointer to OFB context block        \
  95  *              @cnost void *iv@ = pointer to IV to set                 \
  96  *                                                                      \
  97  * Returns:     ---                                                     \
  98  *                                                                      \
  99  * Use:         Sets the IV to use for subsequent encryption.           \
 100  */                                                                     \
 101                                                                         \
 102 void pre##_ofbsetiv(pre##_ofbctx *ctx, const void *iv)                  \
 103 {                                                                       \
 104   memcpy(ctx->iv, iv, PRE##_BLKSZ);                                     \
 105   ctx->off = PRE##_BLKSZ;                                               \
 106 }                                                                       \
 107                                                                         \
 108 /* --- @pre_ofbbdry@ --- *                                              \
 109  *                                                                      \
 110  * Arguments:   @pre_ofbctx *ctx@ = pointer to OFB context block        \
 111  *                                                                      \
 112  * Returns:     ---                                                     \
 113  *                                                                      \
 114  * Use:         Inserts a boundary during encryption.  Successful       \
 115  *              decryption must place a similar boundary.               \
 116  */                                                                     \
 117                                                                         \
 118 void pre##_ofbbdry(pre##_ofbctx *ctx)                                   \
 119 {                                                                       \
 120   uint32 niv[PRE##_BLKSZ / 4];                                          \
 121   BLKC_LOAD(PRE, niv, ctx->iv);                                         \
 122   pre##_eblk(&ctx->ctx, niv, niv);                                      \
 123   BLKC_STORE(PRE, ctx->iv, niv);                                        \
 124   ctx->off = PRE##_BLKSZ;                                               \
 125   BURN(niv);                                                            \
 126 }                                                                       \
 127                                                                         \
 128 /* --- @pre_ofbsetkey@ --- *                                            \
 129  *                                                                      \
 130  * Arguments:   @pre_ofbctx *ctx@ = pointer to OFB context block        \
 131  *              @const pre_ctx *k@ = pointer to cipher context          \
 132  *                                                                      \
 133  * Returns:     ---                                                     \
 134  *                                                                      \
 135  * Use:         Sets the OFB context to use a different cipher key.     \
 136  */                                                                     \
 137                                                                         \
 138 void pre##_ofbsetkey(pre##_ofbctx *ctx, const pre##_ctx *k)             \
 139 {                                                                       \
 140   ctx->ctx = *k;                                                        \
 141 }                                                                       \
 142                                                                         \
 143 /* --- @pre_ofbinit@ --- *                                              \
 144  *                                                                      \
 145  * Arguments:   @pre_ofbctx *ctx@ = pointer to cipher context           \
 146  *              @const void *key@ = pointer to the key buffer           \
 147  *              @size_t sz@ = size of the key                           \
 148  *              @const void *iv@ = pointer to initialization vector     \
 149  *                                                                      \
 150  * Returns:     ---                                                     \
 151  *                                                                      \
 152  * Use:         Initializes a OFB context ready for use.  You should    \
 153  *              ensure that the IV chosen is unique: reusing an IV will \
 154  *              compromise the security of the entire plaintext.  This  \
 155  *              is equivalent to calls to @pre_init@, @pre_ofbsetkey@   \
 156  *              and @pre_ofbsetiv@.                                     \
 157  */                                                                     \
 158                                                                         \
 159 void pre##_ofbinit(pre##_ofbctx *ctx,                                   \
 160                      const void *key, size_t sz,                        \
 161                      const void *iv)                                    \
 162 {                                                                       \
 163   static const octet zero[PRE##_BLKSZ] = { 0 };                         \
 164   pre##_init(&ctx->ctx, key, sz);                                       \
 165   pre##_ofbsetiv(ctx, iv ? iv : zero);                                  \
 166 }                                                                       \
 167                                                                         \
 168 /* --- @pre_ofbencrypt@ --- *                                           \
 169  *                                                                      \
 170  * Arguments:   @pre_ofbctx *ctx@ = pointer to OFB context block        \
 171  *              @const void *src@ = pointer to source data              \
 172  *              @void *dest@ = pointer to destination data              \
 173  *              @size_t sz@ = size of block to be encrypted             \
 174  *                                                                      \
 175  * Returns:     ---                                                     \
 176  *                                                                      \
 177  * Use:         Encrypts or decrypts a block with a block cipher in OFB \
 178  *              mode: encryption and decryption are the same in OFB.    \
 179  *              The destination may be null to just churn the feedback  \
 180  *              round for a bit.  The source may be null to use the     \
 181  *              cipher as a random data generator.                      \
 182  */                                                                     \
 183                                                                         \
 184 void pre##_ofbencrypt(pre##_ofbctx *ctx,                                \
 185                         const void *src, void *dest,                    \
 186                         size_t sz)                                      \
 187 {                                                                       \
 188   const octet *s = src;                                                 \
 189   octet *d = dest;                                                      \
 190   unsigned off = ctx->off;                                              \
 191                                                                         \
 192   /* --- Empty blocks are trivial --- */                                \
 193                                                                         \
 194   if (!sz)                                                              \
 195     return;                                                             \
 196                                                                         \
 197   /* --- If I can deal with the block from my buffer, do that --- */    \
 198                                                                         \
 199   if (sz < PRE##_BLKSZ - off)                                           \
 200     goto small;                                                         \
 201                                                                         \
 202   /* --- Finish off what's left in my buffer --- */                     \
 203                                                                         \
 204   if (!d)                                                               \
 205     sz -= PRE##_BLKSZ - off;                                            \
 206   else {                                                                \
 207     while (off < PRE##_BLKSZ) {                                         \
 208       register octet x = s ? *s++ : 0;                                  \
 209       *d++ = ctx->iv[off++] ^ x;                                        \
 210       sz--;                                                             \
 211     }                                                                   \
 212   }                                                                     \
 213                                                                         \
 214   /* --- Main encryption loop --- */                                    \
 215                                                                         \
 216   {                                                                     \
 217     uint32 iv[PRE##_BLKSZ / 4];                                         \
 218     BLKC_LOAD(PRE, iv, ctx->iv);                                        \
 219                                                                         \
 220     for (;;) {                                                          \
 221       pre##_eblk(&ctx->ctx, iv, iv);                                    \
 222       if (sz < PRE##_BLKSZ)                                             \
 223         break;                                                          \
 224       if (d) {                                                          \
 225         if (!s)                                                         \
 226           BLKC_STORE(PRE, d, iv);                                       \
 227         else {                                                          \
 228           uint32 x[PRE##_BLKSZ / 4];                                    \
 229           BLKC_LOAD(PRE, x, s);                                         \
 230           BLKC_XSTORE(PRE, d, iv, x);                                   \
 231           s += PRE##_BLKSZ;                                             \
 232         }                                                               \
 233         d += PRE##_BLKSZ;                                               \
 234       }                                                                 \
 235       sz -= PRE##_BLKSZ;                                                \
 236     }                                                                   \
 237                                                                         \
 238     BLKC_STORE(PRE, ctx->iv, iv);                                       \
 239     off = 0;                                                            \
 240   }                                                                     \
 241                                                                         \
 242   /* --- Tidying up the tail end --- */                                 \
 243                                                                         \
 244   if (sz) {                                                             \
 245   small:                                                                \
 246     if (!d)                                                             \
 247       off += sz;                                                        \
 248     else do {                                                           \
 249       register octet x = s ? *s++ : 0;                                  \
 250       *d++ = ctx->iv[off++] ^ x;                                        \
 251       sz--;                                                             \
 252     } while (sz);                                                       \
 253   }                                                                     \
 254                                                                         \
 255   /* --- Done --- */                                                    \
 256                                                                         \
 257   ctx->off = off;                                                       \
 258   return;                                                               \
 259 }                                                                       \
 260                                                                         \
 261 /* --- Generic cipher interface --- */                                  \
 262                                                                         \
 263 static const gcipher_ops gops;                                          \
 264                                                                         \
 265 typedef struct gctx {                                                   \
 266   gcipher c;                                                            \
 267   pre##_ofbctx k;                                                       \
 268 } gctx;                                                                 \
 269                                                                         \
 270 static gcipher *ginit(const void *k, size_t sz)                         \
 271 {                                                                       \
 272   gctx *g = S_CREATE(gctx);                                             \
 273   g->c.ops = &gops;                                                     \
 274   pre##_ofbinit(&g->k, k, sz, 0);                                       \
 275   return (&g->c);                                                       \
 276 }                                                                       \
 277                                                                         \
 278 static void gencrypt(gcipher *c, const void *s, void *t, size_t sz)     \
 279 {                                                                       \
 280   gctx *g = (gctx *)c;                                                  \
 281   pre##_ofbencrypt(&g->k, s, t, sz);                                    \
 282 }                                                                       \
 283                                                                         \
 284 static void gdestroy(gcipher *c)                                        \
 285 {                                                                       \
 286   gctx *g = (gctx *)c;                                                  \
 287   BURN(*g);                                                             \
 288   S_DESTROY(g);                                                         \
 289 }                                                                       \
 290                                                                         \
 291 static void gsetiv(gcipher *c, const void *iv)                          \
 292 {                                                                       \
 293   gctx *g = (gctx *)c;                                                  \
 294   pre##_ofbsetiv(&g->k, iv);                                            \
 295 }                                                                       \
 296                                                                         \
 297 static void gbdry(gcipher *c)                                           \
 298 {                                                                       \
 299   gctx *g = (gctx *)c;                                                  \
 300   pre##_ofbbdry(&g->k);                                                 \
 301 }                                                                       \
 302                                                                         \
 303 static const gcipher_ops gops = {                                       \
 304   &pre##_ofb,                                                           \
 305   gencrypt, gencrypt, gdestroy, gsetiv, gbdry                           \
 306 };                                                                      \
 307                                                                         \
 308 const gccipher pre##_ofb = {                                            \
 309   #pre "-ofb", pre##_keysz, PRE##_BLKSZ,                                \
 310   ginit                                                                 \
 311 };                                                                      \
 312                                                                         \
 313 /* --- Generic random number generator interface --- */                 \
 314                                                                         \
 315 typedef struct grctx {                                                  \
 316   grand r;                                                              \
 317   pre##_ofbctx k;                                                       \
 318 } grctx;                                                                \
 319                                                                         \
 320 static void grdestroy(grand *r)                                         \
 321 {                                                                       \
 322   grctx *g = (grctx *)r;                                                \
 323   BURN(*g);                                                             \
 324   S_DESTROY(g);                                                         \
 325 }                                                                       \
 326                                                                         \
 327 static int grmisc(grand *r, unsigned op, ...)                           \
 328 {                                                                       \
 329   grctx *g = (grctx *)r;                                                \
 330   va_list ap;                                                           \
 331   int rc = 0;                                                           \
 332   uint32 i;                                                             \
 333   octet buf[PRE##_BLKSZ];                                               \
 334   va_start(ap, op);                                                     \
 335                                                                         \
 336   switch (op) {                                                         \
 337     case GRAND_CHECK:                                                   \
 338       switch (va_arg(ap, unsigned)) {                                   \
 339         case GRAND_CHECK:                                               \
 340         case GRAND_SEEDINT:                                             \
 341         case GRAND_SEEDUINT32:                                          \
 342         case GRAND_SEEDBLOCK:                                           \
 343         case GRAND_SEEDRAND:                                            \
 344           rc = 1;                                                       \
 345           break;                                                        \
 346         default:                                                        \
 347           rc = 0;                                                       \
 348           break;                                                        \
 349       }                                                                 \
 350       break;                                                            \
 351     case GRAND_SEEDINT:                                                 \
 352       memset(buf, 0, sizeof(buf));                                      \
 353       i = va_arg(ap, unsigned);                                         \
 354       STORE32(buf, i);                                                  \
 355       pre##_ofbsetiv(&g->k, buf);                                       \
 356       break;                                                            \
 357     case GRAND_SEEDUINT32:                                              \
 358       memset(buf, 0, sizeof(buf));                                      \
 359       i = va_arg(ap, uint32);                                           \
 360       STORE32(buf, i);                                                  \
 361       pre##_ofbsetiv(&g->k, buf);                                       \
 362       break;                                                            \
 363     case GRAND_SEEDBLOCK: {                                             \
 364       const void *p = va_arg(ap, const void *);                         \
 365       size_t sz = va_arg(ap, size_t);                                   \
 366       if (sz < sizeof(buf)) {                                           \
 367         memset(buf, 0, sizeof(buf));                                    \
 368         memcpy(buf, p, sz);                                             \
 369         p = buf;                                                        \
 370       }                                                                 \
 371       pre##_ofbsetiv(&g->k, p);                                         \
 372     } break;                                                            \
 373     case GRAND_SEEDRAND: {                                              \
 374       grand *rr = va_arg(ap, grand *);                                  \
 375       rr->ops->fill(rr, buf, sizeof(buf));                              \
 376       pre##_ofbsetiv(&g->k, buf);                                       \
 377     } break;                                                            \
 378     default:                                                            \
 379       GRAND_BADOP;                                                      \
 380       break;                                                            \
 381   }                                                                     \
 382                                                                         \
 383   va_end(ap);                                                           \
 384   return (rc);                                                          \
 385 }                                                                       \
 386                                                                         \
 387 static octet grbyte(grand *r)                                           \
 388 {                                                                       \
 389   grctx *g = (grctx *)r;                                                \
 390   octet o;                                                              \
 391   pre##_ofbencrypt(&g->k, 0, &o, 1);                                    \
 392   return (o);                                                           \
 393 }                                                                       \
 394                                                                         \
 395 static uint32 grword(grand *r)                                          \
 396 {                                                                       \
 397   grctx *g = (grctx *)r;                                                \
 398   octet b[4];                                                           \
 399   pre##_ofbencrypt(&g->k, 0, b, sizeof(b));                             \
 400   return (LOAD32(b));                                                   \
 401 }                                                                       \
 402                                                                         \
 403 static void grfill(grand *r, void *p, size_t sz)                        \
 404 {                                                                       \
 405   grctx *g = (grctx *)r;                                                \
 406   pre##_ofbencrypt(&g->k, 0, p, sz);                                    \
 407 }                                                                       \
 408                                                                         \
 409 static const grand_ops grops = {                                        \
 410   #pre "-ofb",                                                          \
 411   GRAND_CRYPTO, 0,                                                      \
 412   grmisc, grdestroy,                                                    \
 413   grword, grbyte, grword, grand_range, grfill                           \
 414 };                                                                      \
 415                                                                         \
 416 /* --- @pre_ofbrand@ --- *                                              \
 417  *                                                                      \
 418  * Arguments:   @const void *k@ = pointer to key material               \
 419  *              @size_t sz@ = size of key material                      \
 420  *                                                                      \
 421  * Returns:     Pointer to generic random number generator interface.   \
 422  *                                                                      \
 423  * Use:         Creates a random number interface wrapper around an     \
 424  *              OFB-mode block cipher.                                  \
 425  */                                                                     \
 426                                                                         \
 427 grand *pre##_ofbrand(const void *k, size_t sz)                          \
 428 {                                                                       \
 429   grctx *g = S_CREATE(grctx);                                           \
 430   g->r.ops = &grops;                                                    \
 431   pre##_ofbinit(&g->k, k, sz, 0);                                       \
 432   return (&g->r);                                                       \
 433 }                                                                       \
 434                                                                         \
 435 OFB_TEST(PRE, pre)
 436
 437 /*----- Test rig ----------------------------------------------------------*/
 438
 439 #ifdef TEST_RIG
 440
 441 #include <stdio.h>
 442
 443 #include "daftstory.h"
 444
 445 /* --- @OFB_TEST@ --- *
 446  *
 447  * Arguments:   @PRE@, @pre@ = prefixes for block cipher definitions
 448  *
 449  * Use:         Standard test rig for OFB functions.
 450  */
 451
 452 #define OFB_TEST(PRE, pre)                                              \
 453                                                                         \
 454 /* --- Initial plaintext for the test --- */                            \
 455                                                                         \
 456 static const octet text[] = TEXT;                                       \
 457                                                                         \
 458 /* --- Key and IV to use --- */                                         \
 459                                                                         \
 460 static const octet key[] = KEY;                                         \
 461 static const octet iv[] = IV;                                           \
 462                                                                         \
 463 /* --- Buffers for encryption and decryption output --- */              \
 464                                                                         \
 465 static octet ct[sizeof(text)];                                          \
 466 static octet pt[sizeof(text)];                                          \
 467                                                                         \
 468 static void hexdump(const octet *p, size_t sz)                          \
 469 {                                                                       \
 470   const octet *q = p + sz;                                              \
 471   for (sz = 0; p < q; p++, sz++) {                                      \
 472     printf("%02x", *p);                                                 \
 473     if ((sz + 1) % PRE##_BLKSZ == 0)                                    \
 474       putchar(':');                                                     \
 475   }                                                                     \
 476 }                                                                       \
 477                                                                         \
 478 int main(void)                                                          \
 479 {                                                                       \
 480   size_t sz = 0, rest;                                                  \
 481   pre##_ofbctx ctx;                                                     \
 482   int status = 0;                                                       \
 483   int done = 0;                                                         \
 484   pre##_ctx k;                                                          \
 485                                                                         \
 486   size_t keysz = PRE##_KEYSZ ?                                          \
 487     PRE##_KEYSZ : strlen((const char *)key);                            \
 488                                                                         \
 489   fputs(#pre "-ofb: ", stdout);                                         \
 490                                                                         \
 491   pre##_init(&k, key, keysz);                                           \
 492   pre##_ofbsetkey(&ctx, &k);                                            \
 493                                                                         \
 494   while (sz <= sizeof(text)) {                                          \
 495     rest = sizeof(text) - sz;                                           \
 496     memcpy(ct, text, sizeof(text));                                     \
 497     pre##_ofbsetiv(&ctx, iv);                                           \
 498     pre##_ofbencrypt(&ctx, ct, ct, sz);                                 \
 499     pre##_ofbencrypt(&ctx, ct + sz, ct + sz, rest);                     \
 500     memcpy(pt, ct, sizeof(text));                                       \
 501     pre##_ofbsetiv(&ctx, iv);                                           \
 502     pre##_ofbencrypt(&ctx, pt, pt, rest);                               \
 503     pre##_ofbencrypt(&ctx, pt + rest, pt + rest, sz);                   \
 504     if (memcmp(pt, text, sizeof(text)) == 0) {                          \
 505       done++;                                                           \
 506       if (sizeof(text) < 40 || done % 8 == 0)                           \
 507         fputc('.', stdout);                                             \
 508       if (done % 480 == 0)                                              \
 509         fputs("\n\t", stdout);                                          \
 510       fflush(stdout);                                                   \
 511     } else {                                                            \
 512       printf("\nError (sz = %lu)\n", (unsigned long)sz);                \
 513       status = 1;                                                       \
 514       printf("\tplaintext      = "); hexdump(text, sz);                 \
 515         printf(", "); hexdump(text + sz, rest);                         \
 516         fputc('\n', stdout);                                            \
 517       printf("\tciphertext     = "); hexdump(ct, sz);                   \
 518         printf(", "); hexdump(ct + sz, rest);                           \
 519         fputc('\n', stdout);                                            \
 520       printf("\trecovered text = "); hexdump(pt, sz);                   \
 521         printf(", "); hexdump(pt + sz, rest);                           \
 522         fputc('\n', stdout);                                            \
 523       fputc('\n', stdout);                                              \
 524     }                                                                   \
 525     if (sz < 63)                                                        \
 526       sz++;                                                             \
 527     else                                                                \
 528       sz += 9;                                                          \
 529   }                                                                     \
 530                                                                         \
 531   fputs(status ? " failed\n" : " ok\n", stdout);                        \
 532   return (status);                                                      \
 533 }
 534
 535 #else
 536 #  define OFB_TEST(PRE, pre)
 537 #endif
 538
 539 /*----- That's all, folks -------------------------------------------------*/
 540
 541 #ifdef __cplusplus
 542   }
 543 #endif
 544
 545 #endif