| 1 | /* -*-c-*- |
| 2 | * |
| 3 | * $Id: rand.c,v 1.5 2000/06/17 11:53:55 mdw Exp $ |
| 4 | * |
| 5 | * Secure random number generator |
| 6 | * |
| 7 | * (c) 1998 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: rand.c,v $ |
| 33 | * Revision 1.5 2000/06/17 11:53:55 mdw |
| 34 | * Deprecate `rand_getgood'. Provide a new interface to ensure that a pool |
| 35 | * is well seeded. Use secure arena for memory allocation. |
| 36 | * |
| 37 | * Revision 1.4 1999/12/13 15:34:28 mdw |
| 38 | * Increase the entropy threshhold in rand_getgood. |
| 39 | * |
| 40 | * Revision 1.3 1999/12/10 23:28:07 mdw |
| 41 | * Bug fix: rand_getgood didn't update buffer pointer. |
| 42 | * |
| 43 | * Revision 1.2 1999/10/12 21:00:15 mdw |
| 44 | * Make pool and buffer sizes more sensible. |
| 45 | * |
| 46 | * Revision 1.1 1999/09/03 08:41:12 mdw |
| 47 | * Initial import. |
| 48 | * |
| 49 | */ |
| 50 | |
| 51 | /*----- Header files ------------------------------------------------------*/ |
| 52 | |
| 53 | #include <stdarg.h> |
| 54 | #include <stdio.h> |
| 55 | #include <string.h> |
| 56 | |
| 57 | #include <mLib/bits.h> |
| 58 | #include <mLib/sub.h> |
| 59 | |
| 60 | #include "arena.h" |
| 61 | #include "blowfish-cbc.h" |
| 62 | #include "paranoia.h" |
| 63 | #include "rand.h" |
| 64 | #include "rmd160.h" |
| 65 | #include "rmd160-hmac.h" |
| 66 | |
| 67 | /*----- Static variables --------------------------------------------------*/ |
| 68 | |
| 69 | static const grand_ops gops; |
| 70 | |
| 71 | typedef struct gctx { |
| 72 | grand r; |
| 73 | rand_pool p; |
| 74 | } gctx; |
| 75 | |
| 76 | static gctx *pool = 0; /* Default random pool */ |
| 77 | |
| 78 | /*----- Macros ------------------------------------------------------------*/ |
| 79 | |
| 80 | #define RAND_RESOLVE(r) do { \ |
| 81 | if ((r) == RAND_GLOBAL) { \ |
| 82 | if (!pool) \ |
| 83 | pool = (gctx *)rand_create(); \ |
| 84 | (r) = &pool->p; \ |
| 85 | } \ |
| 86 | } while (0) |
| 87 | |
| 88 | #define TIMER(r) do { \ |
| 89 | if ((r)->s && (r)->s->timer) \ |
| 90 | (r)->s->timer(r); \ |
| 91 | } while (0) |
| 92 | |
| 93 | /*----- Main code ---------------------------------------------------------*/ |
| 94 | |
| 95 | /* --- @rand_init@ --- * |
| 96 | * |
| 97 | * Arguments: @rand_pool *r@ = pointer to a randomness pool |
| 98 | * |
| 99 | * Returns: --- |
| 100 | * |
| 101 | * Use: Initializes a randomness pool. The pool doesn't start out |
| 102 | * very random: that's your job to sort out. A good suggestion |
| 103 | * would be to attach an appropriate noise source and call |
| 104 | * @rand_seed@. |
| 105 | */ |
| 106 | |
| 107 | void rand_init(rand_pool *r) |
| 108 | { |
| 109 | RAND_RESOLVE(r); |
| 110 | memset(r->pool, 0, sizeof(r->pool)); |
| 111 | memset(r->buf, 0, sizeof(r->buf)); |
| 112 | r->i = 0; |
| 113 | r->irot = 0; |
| 114 | r->ibits = r->obits = 0; |
| 115 | r->o = RAND_SECSZ; |
| 116 | r->s = 0; |
| 117 | rmd160_hmacinit(&r->k, 0, 0); |
| 118 | rand_gate(r); |
| 119 | } |
| 120 | |
| 121 | /* --- @rand_noisesrc@ --- * |
| 122 | * |
| 123 | * Arguments: @rand_pool *r@ = pointer to a randomness pool |
| 124 | * @const rand_source *s@ = pointer to source definition |
| 125 | * |
| 126 | * Returns: --- |
| 127 | * |
| 128 | * Use: Sets a noise source for a randomness pool. When the pool's |
| 129 | * estimate of good random bits falls to zero, the @getnoise@ |
| 130 | * function is called, passing the pool handle as an argument. |
| 131 | * It is expected to increase the number of good bits by at |
| 132 | * least one, because it'll be called over and over again until |
| 133 | * there are enough bits to satisfy the caller. The @timer@ |
| 134 | * function is called frequently throughout the generator's |
| 135 | * operation. |
| 136 | */ |
| 137 | |
| 138 | void rand_noisesrc(rand_pool *r, const rand_source *s) |
| 139 | { |
| 140 | RAND_RESOLVE(r); |
| 141 | r->s = s; |
| 142 | } |
| 143 | |
| 144 | /* --- @rand_seed@ --- * |
| 145 | * |
| 146 | * Arguments: @rand_pool *r@ = pointer to a randomness pool |
| 147 | * @unsigned bits@ = number of bits to ensure |
| 148 | * |
| 149 | * Returns: --- |
| 150 | * |
| 151 | * Use: Ensures that there are at least @bits@ good bits of entropy |
| 152 | * in the pool. It is recommended that you call this after |
| 153 | * initializing a new pool. Requesting @bits > RAND_IBITS@ is |
| 154 | * doomed to failure (and is an error). |
| 155 | */ |
| 156 | |
| 157 | void rand_seed(rand_pool *r, unsigned bits) |
| 158 | { |
| 159 | RAND_RESOLVE(r); |
| 160 | |
| 161 | assert(((void)"bits pointlessly large in rand_seed", bits <= RAND_IBITS)); |
| 162 | assert(((void)"no noise source in rand_seed", r->s)); |
| 163 | |
| 164 | while (r->ibits < bits) |
| 165 | r->s->getnoise(r); |
| 166 | rand_gate(r); |
| 167 | } |
| 168 | |
| 169 | /* --- @rand_key@ --- * |
| 170 | * |
| 171 | * Arguments: @rand_pool *r@ = pointer to a randomness pool |
| 172 | * @const void *k@ = pointer to key data |
| 173 | * @size_t sz@ = size of key data |
| 174 | * |
| 175 | * Returns: --- |
| 176 | * |
| 177 | * Use: Sets the secret key for a randomness pool. The key is used |
| 178 | * when mixing in new random bits. |
| 179 | */ |
| 180 | |
| 181 | void rand_key(rand_pool *r, const void *k, size_t sz) |
| 182 | { |
| 183 | RAND_RESOLVE(r); |
| 184 | rmd160_hmacinit(&r->k, k, sz); |
| 185 | } |
| 186 | |
| 187 | /* --- @rand_add@ --- * |
| 188 | * |
| 189 | * Arguments: @rand_pool *r@ = pointer to a randomness pool |
| 190 | * @const void *p@ = pointer a buffer of data to add |
| 191 | * @size_t sz@ = size of the data buffer |
| 192 | * @unsigned goodbits@ = number of good bits estimated in buffer |
| 193 | * |
| 194 | * Returns: --- |
| 195 | * |
| 196 | * Use: Mixes the data in the buffer with the contents of the |
| 197 | * pool. The estimate of the number of good bits is added to |
| 198 | * the pool's own count. The mixing operation is not |
| 199 | * cryptographically strong. However, data in the input pool |
| 200 | * isn't output directly, only through the one-way gating |
| 201 | * operation, so that shouldn't matter. |
| 202 | */ |
| 203 | |
| 204 | void rand_add(rand_pool *r, const void *p, size_t sz, unsigned goodbits) |
| 205 | { |
| 206 | const octet *c = p; |
| 207 | int i, rot; |
| 208 | |
| 209 | #if RAND_POOLSZ != 128 |
| 210 | # error Polynomial in rand_add is out of date. Fix it. |
| 211 | #endif |
| 212 | |
| 213 | RAND_RESOLVE(r); |
| 214 | |
| 215 | i = r->i; rot = r->irot; |
| 216 | |
| 217 | while (sz) { |
| 218 | octet o = *c++; |
| 219 | r->pool[i] ^= (ROL8(o, rot) ^ |
| 220 | r->pool[(i + 1) % RAND_POOLSZ] ^ |
| 221 | r->pool[(i + 2) % RAND_POOLSZ] ^ |
| 222 | r->pool[(i + 7) % RAND_POOLSZ]); |
| 223 | rot = (rot + 5) & 7; |
| 224 | i++; if (i >= RAND_POOLSZ) i -= RAND_POOLSZ; |
| 225 | sz--; |
| 226 | } |
| 227 | |
| 228 | r->i = i; |
| 229 | r->irot = rot; |
| 230 | r->ibits += goodbits; |
| 231 | if (r->ibits > RAND_IBITS) |
| 232 | r->ibits = RAND_IBITS; |
| 233 | } |
| 234 | |
| 235 | /* --- @rand_goodbits@ --- * |
| 236 | * |
| 237 | * Arguments: @rand_pool *r@ = pointer to a randomness pool |
| 238 | * |
| 239 | * Returns: Estimate of the number of good bits remaining in the pool. |
| 240 | */ |
| 241 | |
| 242 | unsigned rand_goodbits(rand_pool *r) |
| 243 | { |
| 244 | RAND_RESOLVE(r); |
| 245 | return (r->ibits + r->obits); |
| 246 | } |
| 247 | |
| 248 | /* --- @rand_gate@ --- * |
| 249 | * |
| 250 | * Arguments: @rand_pool *r@ = pointer to a randomness pool |
| 251 | * |
| 252 | * Returns: --- |
| 253 | * |
| 254 | * Use: Mixes up the entire state of the generator in a nonreversible |
| 255 | * way. |
| 256 | */ |
| 257 | |
| 258 | void rand_gate(rand_pool *r) |
| 259 | { |
| 260 | octet mac[RMD160_HASHSZ]; |
| 261 | |
| 262 | RAND_RESOLVE(r); |
| 263 | TIMER(r); |
| 264 | |
| 265 | /* --- Hash up all the data in the pool --- */ |
| 266 | |
| 267 | { |
| 268 | rmd160_macctx mc; |
| 269 | |
| 270 | rmd160_macinit(&mc, &r->k); |
| 271 | rmd160_machash(&mc, r->pool, sizeof(r->pool)); |
| 272 | rmd160_machash(&mc, r->buf, sizeof(r->buf)); |
| 273 | rmd160_macdone(&mc, mac); |
| 274 | BURN(mc); |
| 275 | } |
| 276 | |
| 277 | /* --- Now mangle all of the data based on the hash --- */ |
| 278 | |
| 279 | { |
| 280 | blowfish_cbcctx bc; |
| 281 | |
| 282 | blowfish_cbcinit(&bc, mac, sizeof(mac), 0); |
| 283 | blowfish_cbcencrypt(&bc, r->pool, r->pool, sizeof(r->pool)); |
| 284 | blowfish_cbcencrypt(&bc, r->buf, r->buf, sizeof(r->buf)); |
| 285 | BURN(bc); |
| 286 | } |
| 287 | |
| 288 | /* --- Reset the various state variables --- */ |
| 289 | |
| 290 | r->o = RAND_SECSZ; |
| 291 | r->obits += r->ibits; |
| 292 | if (r->obits > RAND_OBITS) { |
| 293 | r->ibits = r->obits - r->ibits; |
| 294 | r->obits = RAND_OBITS; |
| 295 | } else |
| 296 | r->ibits = 0; |
| 297 | TIMER(r); |
| 298 | } |
| 299 | |
| 300 | /* --- @rand_stretch@ --- * |
| 301 | * |
| 302 | * Arguments: @rand_pool *r@ = pointer to a randomness pool |
| 303 | * |
| 304 | * Returns: --- |
| 305 | * |
| 306 | * Use: Stretches the contents of the output buffer by transforming |
| 307 | * it in a nonreversible way. This doesn't add any entropy |
| 308 | * worth speaking about, but it works well enough when the |
| 309 | * caller doesn't care about that sort of thing. |
| 310 | */ |
| 311 | |
| 312 | void rand_stretch(rand_pool *r) |
| 313 | { |
| 314 | octet mac[RMD160_HASHSZ]; |
| 315 | |
| 316 | RAND_RESOLVE(r); |
| 317 | TIMER(r); |
| 318 | |
| 319 | /* --- Hash up all the data in the buffer --- */ |
| 320 | |
| 321 | { |
| 322 | rmd160_macctx mc; |
| 323 | |
| 324 | rmd160_macinit(&mc, &r->k); |
| 325 | rmd160_machash(&mc, r->pool, sizeof(r->pool)); |
| 326 | rmd160_machash(&mc, r->buf, sizeof(r->buf)); |
| 327 | rmd160_macdone(&mc, mac); |
| 328 | BURN(mc); |
| 329 | } |
| 330 | |
| 331 | /* --- Now mangle the buffer based on that hash --- */ |
| 332 | |
| 333 | { |
| 334 | blowfish_cbcctx bc; |
| 335 | |
| 336 | blowfish_cbcinit(&bc, mac, sizeof(mac), 0); |
| 337 | blowfish_cbcencrypt(&bc, r->buf, r->buf, sizeof(r->buf)); |
| 338 | BURN(bc); |
| 339 | } |
| 340 | |
| 341 | /* --- Reset the various state variables --- */ |
| 342 | |
| 343 | r->o = RAND_SECSZ; |
| 344 | TIMER(r); |
| 345 | } |
| 346 | |
| 347 | /* --- @rand_get@ --- * |
| 348 | * |
| 349 | * Arguments: @rand_pool *r@ = pointer to a randomness pool |
| 350 | * @void *p@ = pointer to output buffer |
| 351 | * @size_t sz@ = size of output buffer |
| 352 | * |
| 353 | * Returns: --- |
| 354 | * |
| 355 | * Use: Gets random data from the pool. The pool's contents can't be |
| 356 | * determined from the output of this function; nor can the |
| 357 | * output data be determined from a knowledge of the data input |
| 358 | * to the pool wihtout also having knowledge of the secret key. |
| 359 | * The good bits counter is decremented, although no special |
| 360 | * action is taken if it reaches zero. |
| 361 | */ |
| 362 | |
| 363 | void rand_get(rand_pool *r, void *p, size_t sz) |
| 364 | { |
| 365 | octet *o = p; |
| 366 | |
| 367 | RAND_RESOLVE(r); |
| 368 | TIMER(r); |
| 369 | |
| 370 | if (!sz) |
| 371 | return; |
| 372 | for (;;) { |
| 373 | if (r->o + sz <= RAND_BUFSZ) { |
| 374 | memcpy(o, r->buf + r->o, sz); |
| 375 | r->o += sz; |
| 376 | break; |
| 377 | } else { |
| 378 | size_t chunk = RAND_BUFSZ - r->o; |
| 379 | if (chunk) { |
| 380 | memcpy(o, r->buf + r->o, chunk); |
| 381 | sz -= chunk; |
| 382 | o += chunk; |
| 383 | } |
| 384 | rand_stretch(r); |
| 385 | } |
| 386 | } |
| 387 | |
| 388 | if (r->obits > sz * 8) |
| 389 | r->obits -= sz * 8; |
| 390 | else |
| 391 | r->obits = 0; |
| 392 | } |
| 393 | |
| 394 | /* --- @rand_getgood@ --- * |
| 395 | * |
| 396 | * Arguments: @rand_pool *r@ = pointer to a randomness pool |
| 397 | * @void *p@ = pointer to output buffer |
| 398 | * @size_t sz@ = size of output buffer |
| 399 | * |
| 400 | * Returns: --- |
| 401 | * |
| 402 | * Use: Gets random data from the pool, ensuring that there are |
| 403 | * enough good bits. This interface isn't recommended: it makes |
| 404 | * the generator slow, and doesn't provide much more security |
| 405 | * than @rand_get@, assuming you've previously done a |
| 406 | * @rand_seed@. |
| 407 | */ |
| 408 | |
| 409 | void rand_getgood(rand_pool *r, void *p, size_t sz) |
| 410 | { |
| 411 | octet *o = p; |
| 412 | |
| 413 | RAND_RESOLVE(r); |
| 414 | |
| 415 | if (!sz) |
| 416 | return; |
| 417 | if (!r->s || !r->s->getnoise) { |
| 418 | rand_get(r, p, sz); |
| 419 | return; |
| 420 | } |
| 421 | TIMER(r); |
| 422 | |
| 423 | while (sz) { |
| 424 | size_t chunk = sz; |
| 425 | |
| 426 | if (chunk * 8 > r->obits) { |
| 427 | if (chunk * 8 > r->ibits + r->obits) |
| 428 | do r->s->getnoise(r); while (r->ibits + r->obits < 256); |
| 429 | rand_gate(r); |
| 430 | if (chunk * 8 > r->obits) |
| 431 | chunk = r->obits / 8; |
| 432 | } |
| 433 | |
| 434 | if (chunk + r->o > RAND_BUFSZ) |
| 435 | chunk = RAND_BUFSZ - r->o; |
| 436 | |
| 437 | memcpy(o, r->buf + r->o, chunk); |
| 438 | r->o += chunk; |
| 439 | r->obits -= chunk * 8; |
| 440 | o += chunk; |
| 441 | sz -= chunk; |
| 442 | } |
| 443 | } |
| 444 | |
| 445 | /*----- Generic random number generator interface -------------------------*/ |
| 446 | |
| 447 | #define GRESOLVE(g, r) do { \ |
| 448 | if (r != &rand_global) \ |
| 449 | g = (gctx *)r; \ |
| 450 | else { \ |
| 451 | if (!pool) \ |
| 452 | pool = (gctx *)rand_create(); \ |
| 453 | g = pool; \ |
| 454 | } \ |
| 455 | } while (0) |
| 456 | |
| 457 | static void gdestroy(grand *r) |
| 458 | { |
| 459 | gctx *g; |
| 460 | GRESOLVE(g, r); |
| 461 | if (g != pool) { |
| 462 | BURN(*g); |
| 463 | S_DESTROY(g); |
| 464 | } |
| 465 | } |
| 466 | |
| 467 | static int gmisc(grand *r, unsigned op, ...) |
| 468 | { |
| 469 | gctx *g; |
| 470 | va_list ap; |
| 471 | int rc = 0; |
| 472 | va_start(ap, op); |
| 473 | |
| 474 | GRESOLVE(g, r); |
| 475 | switch (op) { |
| 476 | case GRAND_CHECK: |
| 477 | switch (va_arg(ap, unsigned)) { |
| 478 | case GRAND_CHECK: |
| 479 | case GRAND_SEEDINT: |
| 480 | case GRAND_SEEDUINT32: |
| 481 | case GRAND_SEEDBLOCK: |
| 482 | case GRAND_SEEDRAND: |
| 483 | case RAND_GATE: |
| 484 | case RAND_STRETCH: |
| 485 | case RAND_KEY: |
| 486 | case RAND_NOISESRC: |
| 487 | case RAND_SEED: |
| 488 | rc = 1; |
| 489 | break; |
| 490 | default: |
| 491 | rc = 0; |
| 492 | break; |
| 493 | } |
| 494 | break; |
| 495 | case GRAND_SEEDINT: { |
| 496 | unsigned u = va_arg(ap, unsigned); |
| 497 | rand_add(&g->p, &u, sizeof(u), sizeof(u)); |
| 498 | } break; |
| 499 | case GRAND_SEEDUINT32: { |
| 500 | uint32 i = va_arg(ap, uint32); |
| 501 | rand_add(&g->p, &i, sizeof(i), 4); |
| 502 | } break; |
| 503 | case GRAND_SEEDBLOCK: { |
| 504 | const void *p = va_arg(ap, const void *); |
| 505 | size_t sz = va_arg(ap, size_t); |
| 506 | rand_add(&g->p, p, sz, sz); |
| 507 | } break; |
| 508 | case GRAND_SEEDRAND: { |
| 509 | grand *rr = va_arg(ap, grand *); |
| 510 | octet buf[16]; |
| 511 | rr->ops->fill(rr, buf, sizeof(buf)); |
| 512 | rand_add(&g->p, buf, sizeof(buf), 8); |
| 513 | } break; |
| 514 | case RAND_GATE: |
| 515 | rand_gate(&g->p); |
| 516 | break; |
| 517 | case RAND_STRETCH: |
| 518 | rand_stretch(&g->p); |
| 519 | break; |
| 520 | case RAND_KEY: { |
| 521 | const void *k = va_arg(ap, const void *); |
| 522 | size_t sz = va_arg(ap, size_t); |
| 523 | rand_key(&g->p, k, sz); |
| 524 | } break; |
| 525 | case RAND_NOISESRC: |
| 526 | rand_noisesrc(&g->p, va_arg(ap, const rand_source *)); |
| 527 | break; |
| 528 | case RAND_SEED: |
| 529 | rand_seed(&g->p, va_arg(ap, unsigned)); |
| 530 | break; |
| 531 | default: |
| 532 | GRAND_BADOP; |
| 533 | break; |
| 534 | } |
| 535 | |
| 536 | va_end(ap); |
| 537 | return (rc); |
| 538 | } |
| 539 | |
| 540 | static octet gbyte(grand *r) |
| 541 | { |
| 542 | gctx *g; |
| 543 | octet o; |
| 544 | GRESOLVE(g, r); |
| 545 | rand_getgood(&g->p, &o, 1); |
| 546 | return (o); |
| 547 | } |
| 548 | |
| 549 | static uint32 gword(grand *r) |
| 550 | { |
| 551 | gctx *g; |
| 552 | octet b[4]; |
| 553 | GRESOLVE(g, r); |
| 554 | rand_getgood(&g->p, &b, sizeof(b)); |
| 555 | return (LOAD32(b)); |
| 556 | } |
| 557 | |
| 558 | static void gfill(grand *r, void *p, size_t sz) |
| 559 | { |
| 560 | gctx *g; |
| 561 | GRESOLVE(g, r); |
| 562 | rand_get(&g->p, p, sz); |
| 563 | } |
| 564 | |
| 565 | static const grand_ops gops = { |
| 566 | "rand", |
| 567 | GRAND_CRYPTO, 0, |
| 568 | gmisc, gdestroy, |
| 569 | gword, gbyte, gword, grand_range, gfill |
| 570 | }; |
| 571 | |
| 572 | grand rand_global = { &gops }; |
| 573 | |
| 574 | /* --- @rand_create@ --- * |
| 575 | * |
| 576 | * Arguments: --- |
| 577 | * |
| 578 | * Returns: Pointer to a generic generator. |
| 579 | * |
| 580 | * Use: Constructs a generic generator interface over a Catacomb |
| 581 | * entropy pool generator. |
| 582 | */ |
| 583 | |
| 584 | grand *rand_create(void) |
| 585 | { |
| 586 | gctx *g = S_CREATE(gctx); |
| 587 | g->r.ops = &gops; |
| 588 | rand_init(&g->p); |
| 589 | return (&g->r); |
| 590 | } |
| 591 | |
| 592 | /*----- That's all, folks -------------------------------------------------*/ |