| 1 | /* -*-c-*- |
| 2 | * |
| 3 | * $Id: rand.c,v 1.1 1999/09/03 08:41:12 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 1.1 1999/09/03 08:41:12 mdw |
| 34 | * Initial import. |
| 35 | * |
| 36 | */ |
| 37 | |
| 38 | /*----- Header files ------------------------------------------------------*/ |
| 39 | |
| 40 | #include <stdio.h> |
| 41 | #include <string.h> |
| 42 | |
| 43 | #include <mLib/bits.h> |
| 44 | |
| 45 | #include "blowfish-cbc.h" |
| 46 | #include "paranoia.h" |
| 47 | #include "rand.h" |
| 48 | #include "rmd160.h" |
| 49 | #include "rmd160-hmac.h" |
| 50 | |
| 51 | /*----- Static variables --------------------------------------------------*/ |
| 52 | |
| 53 | static rand_pool pool; /* Default random pool */ |
| 54 | |
| 55 | /*----- Macros ------------------------------------------------------------*/ |
| 56 | |
| 57 | #define RAND_RESOLVE(r) do { \ |
| 58 | if ((r) == RAND_GLOBAL) \ |
| 59 | (r) = &pool; \ |
| 60 | } while (0) |
| 61 | |
| 62 | #define TIMER(r) do { \ |
| 63 | if ((r)->s && (r)->s->timer) \ |
| 64 | (r)->s->timer(r); \ |
| 65 | } while (0) |
| 66 | |
| 67 | /*----- Main code ---------------------------------------------------------*/ |
| 68 | |
| 69 | /* --- @rand_init@ --- * |
| 70 | * |
| 71 | * Arguments: @rand_pool *r@ = pointer to a randomness pool |
| 72 | * |
| 73 | * Returns: --- |
| 74 | * |
| 75 | * Use: Initializes a randomness pool. The pool doesn't start out |
| 76 | * very random: that's your job to sort out. |
| 77 | */ |
| 78 | |
| 79 | void rand_init(rand_pool *r) |
| 80 | { |
| 81 | RAND_RESOLVE(r); |
| 82 | memset(r->pool, 0, sizeof(r->pool)); |
| 83 | memset(r->buf, 0, sizeof(r->buf)); |
| 84 | r->i = 0; |
| 85 | r->irot = 0; |
| 86 | r->ibits = r->obits = 0; |
| 87 | r->o = RAND_SECSZ; |
| 88 | r->s = 0; |
| 89 | rmd160_hmac(&r->k, 0, 0); |
| 90 | rand_gate(r); |
| 91 | } |
| 92 | |
| 93 | /* --- @rand_noisesrc@ --- * |
| 94 | * |
| 95 | * Arguments: @rand_pool *r@ = pointer to a randomness pool |
| 96 | * @const rand_source *s@ = pointer to source definition |
| 97 | * |
| 98 | * Returns: --- |
| 99 | * |
| 100 | * Use: Sets a noise source for a randomness pool. When the pool's |
| 101 | * estimate of good random bits falls to zero, the @getnoise@ |
| 102 | * function is called, passing the pool handle as an argument. |
| 103 | * It is expected to increase the number of good bits by at |
| 104 | * least one, because it'll be called over and over again until |
| 105 | * there are enough bits to satisfy the caller. The @timer@ |
| 106 | * function is called frequently throughout the generator's |
| 107 | * operation. |
| 108 | */ |
| 109 | |
| 110 | void rand_noisesrc(rand_pool *r, const rand_source *s) |
| 111 | { |
| 112 | RAND_RESOLVE(r); |
| 113 | r->s = s; |
| 114 | } |
| 115 | |
| 116 | /* --- @rand_key@ --- * |
| 117 | * |
| 118 | * Arguments: @rand_pool *r@ = pointer to a randomness pool |
| 119 | * @const void *k@ = pointer to key data |
| 120 | * @size_t sz@ = size of key data |
| 121 | * |
| 122 | * Returns: --- |
| 123 | * |
| 124 | * Use: Sets the secret key for a randomness pool. The key is used |
| 125 | * when mixing in new random bits. |
| 126 | */ |
| 127 | |
| 128 | void rand_key(rand_pool *r, const void *k, size_t sz) |
| 129 | { |
| 130 | RAND_RESOLVE(r); |
| 131 | rmd160_hmac(&r->k, k, sz); |
| 132 | } |
| 133 | |
| 134 | /* --- @rand_add@ --- * |
| 135 | * |
| 136 | * Arguments: @rand_pool *r@ = pointer to a randomness pool |
| 137 | * @const void *p@ = pointer a buffer of data to add |
| 138 | * @size_t sz@ = size of the data buffer |
| 139 | * @unsigned goodbits@ = number of good bits estimated in buffer |
| 140 | * |
| 141 | * Returns: --- |
| 142 | * |
| 143 | * Use: Mixes the data in the buffer with the contents of the |
| 144 | * pool. The estimate of the number of good bits is added to |
| 145 | * the pool's own count. The mixing operation is not |
| 146 | * cryptographically strong. However, data in the input pool |
| 147 | * isn't output directly, only through the one-way gating |
| 148 | * operation, so that shouldn't matter. |
| 149 | */ |
| 150 | |
| 151 | void rand_add(rand_pool *r, const void *p, size_t sz, unsigned goodbits) |
| 152 | { |
| 153 | const octet *c = p; |
| 154 | int i, rot, mid; |
| 155 | |
| 156 | #if RAND_POOLSZ != 1279 |
| 157 | # error Polynomial in rand_add is out of date. Fix it. |
| 158 | #endif |
| 159 | |
| 160 | RAND_RESOLVE(r); |
| 161 | |
| 162 | i = r->i; rot = r->irot; mid = i + 418; |
| 163 | if (mid >= RAND_POOLSZ) mid -= RAND_POOLSZ; |
| 164 | |
| 165 | while (sz) { |
| 166 | octet o = *c++; |
| 167 | r->pool[i] ^= (ROL8(o, rot) ^ r->pool[mid]); |
| 168 | rot = (rot + 5) & 7; |
| 169 | i++; if (i >= RAND_POOLSZ) i -= RAND_POOLSZ; |
| 170 | mid++; if (mid >= RAND_POOLSZ) mid -= RAND_POOLSZ; |
| 171 | sz--; |
| 172 | } |
| 173 | |
| 174 | r->i = i; |
| 175 | r->irot = rot; |
| 176 | r->ibits += goodbits; |
| 177 | if (r->ibits > RAND_IBITS) |
| 178 | r->ibits = RAND_IBITS; |
| 179 | } |
| 180 | |
| 181 | /* --- @rand_goodbits@ --- * |
| 182 | * |
| 183 | * Arguments: @rand_pool *r@ = pointer to a randomness pool |
| 184 | * |
| 185 | * Returns: Estimate of the number of good bits remaining in the pool. |
| 186 | */ |
| 187 | |
| 188 | unsigned rand_goodbits(rand_pool *r) |
| 189 | { |
| 190 | RAND_RESOLVE(r); |
| 191 | return (r->ibits + r->obits); |
| 192 | } |
| 193 | |
| 194 | /* --- @rand_gate@ --- * |
| 195 | * |
| 196 | * Arguments: @rand_pool *r@ = pointer to a randomness pool |
| 197 | * |
| 198 | * Returns: --- |
| 199 | * |
| 200 | * Use: Mixes up the entire state of the generator in a nonreversible |
| 201 | * way. |
| 202 | */ |
| 203 | |
| 204 | void rand_gate(rand_pool *r) |
| 205 | { |
| 206 | octet mac[RMD160_HASHSZ]; |
| 207 | |
| 208 | RAND_RESOLVE(r); |
| 209 | TIMER(r); |
| 210 | |
| 211 | /* --- Hash up all the data in the pool --- */ |
| 212 | |
| 213 | { |
| 214 | rmd160_macctx mc; |
| 215 | |
| 216 | rmd160_macinit(&mc, &r->k); |
| 217 | rmd160_mac(&mc, r->pool, sizeof(r->pool)); |
| 218 | rmd160_mac(&mc, r->buf, sizeof(r->buf)); |
| 219 | rmd160_macdone(&mc, mac); |
| 220 | BURN(mc); |
| 221 | } |
| 222 | |
| 223 | /* --- Now mangle all of the data based on the hash --- */ |
| 224 | |
| 225 | { |
| 226 | blowfish_cbcctx bc; |
| 227 | |
| 228 | blowfish_cbcinit(&bc, mac, sizeof(mac), 0); |
| 229 | blowfish_cbcencrypt(&bc, r->pool, r->pool, sizeof(r->pool)); |
| 230 | blowfish_cbcencrypt(&bc, r->buf, r->buf, sizeof(r->buf)); |
| 231 | BURN(bc); |
| 232 | } |
| 233 | |
| 234 | /* --- Reset the various state variables --- */ |
| 235 | |
| 236 | r->o = RAND_SECSZ; |
| 237 | r->obits += r->ibits; |
| 238 | if (r->obits > RAND_OBITS) { |
| 239 | r->ibits = r->obits - r->ibits; |
| 240 | r->obits = RAND_OBITS; |
| 241 | } else |
| 242 | r->ibits = 0; |
| 243 | TIMER(r); |
| 244 | } |
| 245 | |
| 246 | /* --- @rand_stretch@ --- * |
| 247 | * |
| 248 | * Arguments: @rand_pool *r@ = pointer to a randomness pool |
| 249 | * |
| 250 | * Returns: --- |
| 251 | * |
| 252 | * Use: Stretches the contents of the output buffer by transforming |
| 253 | * it in a nonreversible way. This doesn't add any entropy |
| 254 | * worth speaking about, but it works well enough when the |
| 255 | * caller doesn't care about that sort of thing. |
| 256 | */ |
| 257 | |
| 258 | void rand_stretch(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 buffer --- */ |
| 266 | |
| 267 | { |
| 268 | rmd160_macctx mc; |
| 269 | |
| 270 | rmd160_macinit(&mc, &r->k); |
| 271 | rmd160_mac(&mc, r->pool, sizeof(r->pool)); |
| 272 | rmd160_mac(&mc, r->buf, sizeof(r->buf)); |
| 273 | rmd160_macdone(&mc, mac); |
| 274 | BURN(mc); |
| 275 | } |
| 276 | |
| 277 | /* --- Now mangle the buffer based on that hash --- */ |
| 278 | |
| 279 | { |
| 280 | blowfish_cbcctx bc; |
| 281 | |
| 282 | blowfish_cbcinit(&bc, mac, sizeof(mac), 0); |
| 283 | blowfish_cbcencrypt(&bc, r->buf, r->buf, sizeof(r->buf)); |
| 284 | BURN(bc); |
| 285 | } |
| 286 | |
| 287 | /* --- Reset the various state variables --- */ |
| 288 | |
| 289 | r->o = RAND_SECSZ; |
| 290 | TIMER(r); |
| 291 | } |
| 292 | |
| 293 | /* --- @rand_get@ --- * |
| 294 | * |
| 295 | * Arguments: @rand_pool *r@ = pointer to a randomness pool |
| 296 | * @void *p@ = pointer to output buffer |
| 297 | * @size_t sz@ = size of output buffer |
| 298 | * |
| 299 | * Returns: --- |
| 300 | * |
| 301 | * Use: Gets random data from the pool. The pool's contents can't be |
| 302 | * determined from the output of this function; nor can the |
| 303 | * output data be determined from a knowledge of the data input |
| 304 | * to the pool wihtout also having knowledge of the secret key. |
| 305 | * The good bits counter is decremented, although no special |
| 306 | * action is taken if it reaches zero. |
| 307 | */ |
| 308 | |
| 309 | void rand_get(rand_pool *r, void *p, size_t sz) |
| 310 | { |
| 311 | octet *o = p; |
| 312 | |
| 313 | RAND_RESOLVE(r); |
| 314 | TIMER(r); |
| 315 | |
| 316 | if (!sz) |
| 317 | return; |
| 318 | for (;;) { |
| 319 | if (r->o + sz <= RAND_BUFSZ) { |
| 320 | memcpy(o, r->buf + r->o, sz); |
| 321 | r->o += sz; |
| 322 | break; |
| 323 | } else { |
| 324 | size_t chunk = RAND_BUFSZ - r->o; |
| 325 | if (chunk) { |
| 326 | memcpy(o, r->buf + r->o, chunk); |
| 327 | sz -= chunk; |
| 328 | o += chunk; |
| 329 | } |
| 330 | rand_stretch(r); |
| 331 | } |
| 332 | } |
| 333 | |
| 334 | if (r->obits > sz * 8) |
| 335 | r->obits -= sz * 8; |
| 336 | else |
| 337 | r->obits = 0; |
| 338 | } |
| 339 | |
| 340 | /* --- @rand_getgood@ --- * |
| 341 | * |
| 342 | * Arguments: @rand_pool *r@ = pointer to a randomness pool |
| 343 | * @void *p@ = pointer to output buffer |
| 344 | * @size_t sz@ = size of output buffer |
| 345 | * |
| 346 | * Returns: --- |
| 347 | * |
| 348 | * Use: Gets random data from the pool. The pool's contents can't be |
| 349 | * determined from the output of this function; nor can the |
| 350 | * output data be determined from a knowledge of the data input |
| 351 | * to the pool wihtout also having knowledge of the secret key. |
| 352 | * If a noise source is attached to the pool in question, it is |
| 353 | * called to replenish the supply of good bits in the pool; |
| 354 | * otherwise this call is equivalent to @rand_get@. |
| 355 | */ |
| 356 | |
| 357 | void rand_getgood(rand_pool *r, void *p, size_t sz) |
| 358 | { |
| 359 | octet *o = p; |
| 360 | |
| 361 | RAND_RESOLVE(r); |
| 362 | |
| 363 | if (!sz) |
| 364 | return; |
| 365 | if (!r->s || !r->s->getnoise) { |
| 366 | rand_get(r, p, sz); |
| 367 | return; |
| 368 | } |
| 369 | TIMER(r); |
| 370 | |
| 371 | while (sz) { |
| 372 | size_t chunk = sz; |
| 373 | |
| 374 | if (chunk * 8 > r->obits) { |
| 375 | if (chunk * 8 > r->ibits + r->obits) |
| 376 | do r->s->getnoise(r); while (r->ibits + r->obits < 128); |
| 377 | rand_gate(r); |
| 378 | if (chunk * 8 > r->obits) |
| 379 | chunk = r->obits / 8; |
| 380 | } |
| 381 | |
| 382 | if (chunk + r->o > RAND_BUFSZ) |
| 383 | chunk = RAND_BUFSZ - r->o; |
| 384 | |
| 385 | memcpy(o, r->buf + r->o, chunk); |
| 386 | r->obits -= chunk * 8; |
| 387 | o += chunk; |
| 388 | sz -= chunk; |
| 389 | } |
| 390 | } |
| 391 | |
| 392 | /*----- That's all, folks -------------------------------------------------*/ |