| 1 | /* -*-c-*- |
| 2 | * |
| 3 | * $Id: rand.c,v 1.2 1999/10/12 21:00:15 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 1.2 1999/10/12 21:00:15 mdw |
| 34 | * Make pool and buffer sizes more sensible. |
| 35 | * |
| 36 | * Revision 1.1 1999/09/03 08:41:12 mdw |
| 37 | * Initial import. |
| 38 | * |
| 39 | */ |
| 40 | |
| 41 | /*----- Header files ------------------------------------------------------*/ |
| 42 | |
| 43 | #include <stdio.h> |
| 44 | #include <string.h> |
| 45 | |
| 46 | #include <mLib/bits.h> |
| 47 | |
| 48 | #include "blowfish-cbc.h" |
| 49 | #include "paranoia.h" |
| 50 | #include "rand.h" |
| 51 | #include "rmd160.h" |
| 52 | #include "rmd160-hmac.h" |
| 53 | |
| 54 | /*----- Static variables --------------------------------------------------*/ |
| 55 | |
| 56 | static rand_pool pool; /* Default random pool */ |
| 57 | |
| 58 | /*----- Macros ------------------------------------------------------------*/ |
| 59 | |
| 60 | #define RAND_RESOLVE(r) do { \ |
| 61 | if ((r) == RAND_GLOBAL) \ |
| 62 | (r) = &pool; \ |
| 63 | } while (0) |
| 64 | |
| 65 | #define TIMER(r) do { \ |
| 66 | if ((r)->s && (r)->s->timer) \ |
| 67 | (r)->s->timer(r); \ |
| 68 | } while (0) |
| 69 | |
| 70 | /*----- Main code ---------------------------------------------------------*/ |
| 71 | |
| 72 | /* --- @rand_init@ --- * |
| 73 | * |
| 74 | * Arguments: @rand_pool *r@ = pointer to a randomness pool |
| 75 | * |
| 76 | * Returns: --- |
| 77 | * |
| 78 | * Use: Initializes a randomness pool. The pool doesn't start out |
| 79 | * very random: that's your job to sort out. |
| 80 | */ |
| 81 | |
| 82 | void rand_init(rand_pool *r) |
| 83 | { |
| 84 | RAND_RESOLVE(r); |
| 85 | memset(r->pool, 0, sizeof(r->pool)); |
| 86 | memset(r->buf, 0, sizeof(r->buf)); |
| 87 | r->i = 0; |
| 88 | r->irot = 0; |
| 89 | r->ibits = r->obits = 0; |
| 90 | r->o = RAND_SECSZ; |
| 91 | r->s = 0; |
| 92 | rmd160_hmac(&r->k, 0, 0); |
| 93 | rand_gate(r); |
| 94 | } |
| 95 | |
| 96 | /* --- @rand_noisesrc@ --- * |
| 97 | * |
| 98 | * Arguments: @rand_pool *r@ = pointer to a randomness pool |
| 99 | * @const rand_source *s@ = pointer to source definition |
| 100 | * |
| 101 | * Returns: --- |
| 102 | * |
| 103 | * Use: Sets a noise source for a randomness pool. When the pool's |
| 104 | * estimate of good random bits falls to zero, the @getnoise@ |
| 105 | * function is called, passing the pool handle as an argument. |
| 106 | * It is expected to increase the number of good bits by at |
| 107 | * least one, because it'll be called over and over again until |
| 108 | * there are enough bits to satisfy the caller. The @timer@ |
| 109 | * function is called frequently throughout the generator's |
| 110 | * operation. |
| 111 | */ |
| 112 | |
| 113 | void rand_noisesrc(rand_pool *r, const rand_source *s) |
| 114 | { |
| 115 | RAND_RESOLVE(r); |
| 116 | r->s = s; |
| 117 | } |
| 118 | |
| 119 | /* --- @rand_key@ --- * |
| 120 | * |
| 121 | * Arguments: @rand_pool *r@ = pointer to a randomness pool |
| 122 | * @const void *k@ = pointer to key data |
| 123 | * @size_t sz@ = size of key data |
| 124 | * |
| 125 | * Returns: --- |
| 126 | * |
| 127 | * Use: Sets the secret key for a randomness pool. The key is used |
| 128 | * when mixing in new random bits. |
| 129 | */ |
| 130 | |
| 131 | void rand_key(rand_pool *r, const void *k, size_t sz) |
| 132 | { |
| 133 | RAND_RESOLVE(r); |
| 134 | rmd160_hmac(&r->k, k, sz); |
| 135 | } |
| 136 | |
| 137 | /* --- @rand_add@ --- * |
| 138 | * |
| 139 | * Arguments: @rand_pool *r@ = pointer to a randomness pool |
| 140 | * @const void *p@ = pointer a buffer of data to add |
| 141 | * @size_t sz@ = size of the data buffer |
| 142 | * @unsigned goodbits@ = number of good bits estimated in buffer |
| 143 | * |
| 144 | * Returns: --- |
| 145 | * |
| 146 | * Use: Mixes the data in the buffer with the contents of the |
| 147 | * pool. The estimate of the number of good bits is added to |
| 148 | * the pool's own count. The mixing operation is not |
| 149 | * cryptographically strong. However, data in the input pool |
| 150 | * isn't output directly, only through the one-way gating |
| 151 | * operation, so that shouldn't matter. |
| 152 | */ |
| 153 | |
| 154 | void rand_add(rand_pool *r, const void *p, size_t sz, unsigned goodbits) |
| 155 | { |
| 156 | const octet *c = p; |
| 157 | int i, rot; |
| 158 | |
| 159 | #if RAND_POOLSZ != 128 |
| 160 | # error Polynomial in rand_add is out of date. Fix it. |
| 161 | #endif |
| 162 | |
| 163 | RAND_RESOLVE(r); |
| 164 | |
| 165 | i = r->i; rot = r->irot; |
| 166 | |
| 167 | while (sz) { |
| 168 | octet o = *c++; |
| 169 | r->pool[i] ^= (ROL8(o, rot) ^ |
| 170 | r->pool[(i + 1) % RAND_POOLSZ] ^ |
| 171 | r->pool[(i + 2) % RAND_POOLSZ] ^ |
| 172 | r->pool[(i + 7) % RAND_POOLSZ]); |
| 173 | rot = (rot + 5) & 7; |
| 174 | i++; if (i >= RAND_POOLSZ) i -= RAND_POOLSZ; |
| 175 | sz--; |
| 176 | } |
| 177 | |
| 178 | r->i = i; |
| 179 | r->irot = rot; |
| 180 | r->ibits += goodbits; |
| 181 | if (r->ibits > RAND_IBITS) |
| 182 | r->ibits = RAND_IBITS; |
| 183 | } |
| 184 | |
| 185 | /* --- @rand_goodbits@ --- * |
| 186 | * |
| 187 | * Arguments: @rand_pool *r@ = pointer to a randomness pool |
| 188 | * |
| 189 | * Returns: Estimate of the number of good bits remaining in the pool. |
| 190 | */ |
| 191 | |
| 192 | unsigned rand_goodbits(rand_pool *r) |
| 193 | { |
| 194 | RAND_RESOLVE(r); |
| 195 | return (r->ibits + r->obits); |
| 196 | } |
| 197 | |
| 198 | /* --- @rand_gate@ --- * |
| 199 | * |
| 200 | * Arguments: @rand_pool *r@ = pointer to a randomness pool |
| 201 | * |
| 202 | * Returns: --- |
| 203 | * |
| 204 | * Use: Mixes up the entire state of the generator in a nonreversible |
| 205 | * way. |
| 206 | */ |
| 207 | |
| 208 | void rand_gate(rand_pool *r) |
| 209 | { |
| 210 | octet mac[RMD160_HASHSZ]; |
| 211 | |
| 212 | RAND_RESOLVE(r); |
| 213 | TIMER(r); |
| 214 | |
| 215 | /* --- Hash up all the data in the pool --- */ |
| 216 | |
| 217 | { |
| 218 | rmd160_macctx mc; |
| 219 | |
| 220 | rmd160_macinit(&mc, &r->k); |
| 221 | rmd160_mac(&mc, r->pool, sizeof(r->pool)); |
| 222 | rmd160_mac(&mc, r->buf, sizeof(r->buf)); |
| 223 | rmd160_macdone(&mc, mac); |
| 224 | BURN(mc); |
| 225 | } |
| 226 | |
| 227 | /* --- Now mangle all of the data based on the hash --- */ |
| 228 | |
| 229 | { |
| 230 | blowfish_cbcctx bc; |
| 231 | |
| 232 | blowfish_cbcinit(&bc, mac, sizeof(mac), 0); |
| 233 | blowfish_cbcencrypt(&bc, r->pool, r->pool, sizeof(r->pool)); |
| 234 | blowfish_cbcencrypt(&bc, r->buf, r->buf, sizeof(r->buf)); |
| 235 | BURN(bc); |
| 236 | } |
| 237 | |
| 238 | /* --- Reset the various state variables --- */ |
| 239 | |
| 240 | r->o = RAND_SECSZ; |
| 241 | r->obits += r->ibits; |
| 242 | if (r->obits > RAND_OBITS) { |
| 243 | r->ibits = r->obits - r->ibits; |
| 244 | r->obits = RAND_OBITS; |
| 245 | } else |
| 246 | r->ibits = 0; |
| 247 | TIMER(r); |
| 248 | } |
| 249 | |
| 250 | /* --- @rand_stretch@ --- * |
| 251 | * |
| 252 | * Arguments: @rand_pool *r@ = pointer to a randomness pool |
| 253 | * |
| 254 | * Returns: --- |
| 255 | * |
| 256 | * Use: Stretches the contents of the output buffer by transforming |
| 257 | * it in a nonreversible way. This doesn't add any entropy |
| 258 | * worth speaking about, but it works well enough when the |
| 259 | * caller doesn't care about that sort of thing. |
| 260 | */ |
| 261 | |
| 262 | void rand_stretch(rand_pool *r) |
| 263 | { |
| 264 | octet mac[RMD160_HASHSZ]; |
| 265 | |
| 266 | RAND_RESOLVE(r); |
| 267 | TIMER(r); |
| 268 | |
| 269 | /* --- Hash up all the data in the buffer --- */ |
| 270 | |
| 271 | { |
| 272 | rmd160_macctx mc; |
| 273 | |
| 274 | rmd160_macinit(&mc, &r->k); |
| 275 | rmd160_mac(&mc, r->pool, sizeof(r->pool)); |
| 276 | rmd160_mac(&mc, r->buf, sizeof(r->buf)); |
| 277 | rmd160_macdone(&mc, mac); |
| 278 | BURN(mc); |
| 279 | } |
| 280 | |
| 281 | /* --- Now mangle the buffer based on that hash --- */ |
| 282 | |
| 283 | { |
| 284 | blowfish_cbcctx bc; |
| 285 | |
| 286 | blowfish_cbcinit(&bc, mac, sizeof(mac), 0); |
| 287 | blowfish_cbcencrypt(&bc, r->buf, r->buf, sizeof(r->buf)); |
| 288 | BURN(bc); |
| 289 | } |
| 290 | |
| 291 | /* --- Reset the various state variables --- */ |
| 292 | |
| 293 | r->o = RAND_SECSZ; |
| 294 | TIMER(r); |
| 295 | } |
| 296 | |
| 297 | /* --- @rand_get@ --- * |
| 298 | * |
| 299 | * Arguments: @rand_pool *r@ = pointer to a randomness pool |
| 300 | * @void *p@ = pointer to output buffer |
| 301 | * @size_t sz@ = size of output buffer |
| 302 | * |
| 303 | * Returns: --- |
| 304 | * |
| 305 | * Use: Gets random data from the pool. The pool's contents can't be |
| 306 | * determined from the output of this function; nor can the |
| 307 | * output data be determined from a knowledge of the data input |
| 308 | * to the pool wihtout also having knowledge of the secret key. |
| 309 | * The good bits counter is decremented, although no special |
| 310 | * action is taken if it reaches zero. |
| 311 | */ |
| 312 | |
| 313 | void rand_get(rand_pool *r, void *p, size_t sz) |
| 314 | { |
| 315 | octet *o = p; |
| 316 | |
| 317 | RAND_RESOLVE(r); |
| 318 | TIMER(r); |
| 319 | |
| 320 | if (!sz) |
| 321 | return; |
| 322 | for (;;) { |
| 323 | if (r->o + sz <= RAND_BUFSZ) { |
| 324 | memcpy(o, r->buf + r->o, sz); |
| 325 | r->o += sz; |
| 326 | break; |
| 327 | } else { |
| 328 | size_t chunk = RAND_BUFSZ - r->o; |
| 329 | if (chunk) { |
| 330 | memcpy(o, r->buf + r->o, chunk); |
| 331 | sz -= chunk; |
| 332 | o += chunk; |
| 333 | } |
| 334 | rand_stretch(r); |
| 335 | } |
| 336 | } |
| 337 | |
| 338 | if (r->obits > sz * 8) |
| 339 | r->obits -= sz * 8; |
| 340 | else |
| 341 | r->obits = 0; |
| 342 | } |
| 343 | |
| 344 | /* --- @rand_getgood@ --- * |
| 345 | * |
| 346 | * Arguments: @rand_pool *r@ = pointer to a randomness pool |
| 347 | * @void *p@ = pointer to output buffer |
| 348 | * @size_t sz@ = size of output buffer |
| 349 | * |
| 350 | * Returns: --- |
| 351 | * |
| 352 | * Use: Gets random data from the pool. The pool's contents can't be |
| 353 | * determined from the output of this function; nor can the |
| 354 | * output data be determined from a knowledge of the data input |
| 355 | * to the pool wihtout also having knowledge of the secret key. |
| 356 | * If a noise source is attached to the pool in question, it is |
| 357 | * called to replenish the supply of good bits in the pool; |
| 358 | * otherwise this call is equivalent to @rand_get@. |
| 359 | */ |
| 360 | |
| 361 | void rand_getgood(rand_pool *r, void *p, size_t sz) |
| 362 | { |
| 363 | octet *o = p; |
| 364 | |
| 365 | RAND_RESOLVE(r); |
| 366 | |
| 367 | if (!sz) |
| 368 | return; |
| 369 | if (!r->s || !r->s->getnoise) { |
| 370 | rand_get(r, p, sz); |
| 371 | return; |
| 372 | } |
| 373 | TIMER(r); |
| 374 | |
| 375 | while (sz) { |
| 376 | size_t chunk = sz; |
| 377 | |
| 378 | if (chunk * 8 > r->obits) { |
| 379 | if (chunk * 8 > r->ibits + r->obits) |
| 380 | do r->s->getnoise(r); while (r->ibits + r->obits < 128); |
| 381 | rand_gate(r); |
| 382 | if (chunk * 8 > r->obits) |
| 383 | chunk = r->obits / 8; |
| 384 | } |
| 385 | |
| 386 | if (chunk + r->o > RAND_BUFSZ) |
| 387 | chunk = RAND_BUFSZ - r->o; |
| 388 | |
| 389 | memcpy(o, r->buf + r->o, chunk); |
| 390 | r->obits -= chunk * 8; |
| 391 | o += chunk; |
| 392 | sz -= chunk; |
| 393 | } |
| 394 | } |
| 395 | |
| 396 | /*----- That's all, folks -------------------------------------------------*/ |