cprng_fast.c revision 1.14
1 1.14 riastrad /* $NetBSD: cprng_fast.c,v 1.14 2020/04/30 03:29:35 riastradh Exp $ */ 2 1.2 tls 3 1.2 tls /*- 4 1.2 tls * Copyright (c) 2014 The NetBSD Foundation, Inc. 5 1.2 tls * All rights reserved. 6 1.2 tls * 7 1.2 tls * This code is derived from software contributed to The NetBSD Foundation 8 1.2 tls * by Taylor R. Campbell. 9 1.2 tls * 10 1.2 tls * Redistribution and use in source and binary forms, with or without 11 1.2 tls * modification, are permitted provided that the following conditions 12 1.2 tls * are met: 13 1.2 tls * 1. Redistributions of source code must retain the above copyright 14 1.2 tls * notice, this list of conditions and the following disclaimer. 15 1.2 tls * 2. Redistributions in binary form must reproduce the above copyright 16 1.2 tls * notice, this list of conditions and the following disclaimer in the 17 1.2 tls * documentation and/or other materials provided with the distribution. 18 1.2 tls * 19 1.2 tls * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 20 1.2 tls * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 21 1.2 tls * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 22 1.2 tls * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 23 1.2 tls * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 24 1.2 tls * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 25 1.2 tls * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 26 1.2 tls * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 27 1.2 tls * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 28 1.2 tls * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 29 1.2 tls * POSSIBILITY OF SUCH DAMAGE. 30 1.2 tls */ 31 1.2 tls 32 1.2 tls #include <sys/cdefs.h> 33 1.14 riastrad __KERNEL_RCSID(0, "$NetBSD: cprng_fast.c,v 1.14 2020/04/30 03:29:35 riastradh Exp $"); 34 1.2 tls 35 1.2 tls #include <sys/types.h> 36 1.4 riastrad #include <sys/param.h> 37 1.2 tls #include <sys/bitops.h> 38 1.4 riastrad #include <sys/cprng.h> 39 1.2 tls #include <sys/cpu.h> 40 1.14 riastrad #include <sys/entropy.h> 41 1.2 tls #include <sys/intr.h> 42 1.2 tls #include <sys/percpu.h> 43 1.2 tls 44 1.2 tls /* ChaCha core */ 46 1.2 tls 47 1.2 tls #define crypto_core_OUTPUTWORDS 16 48 1.2 tls #define crypto_core_INPUTWORDS 4 49 1.2 tls #define crypto_core_KEYWORDS 8 50 1.2 tls #define crypto_core_CONSTWORDS 4 51 1.2 tls 52 1.2 tls #define crypto_core_ROUNDS 8 53 1.2 tls 54 1.2 tls static uint32_t 55 1.2 tls rotate(uint32_t u, unsigned c) 56 1.2 tls { 57 1.2 tls 58 1.2 tls return (u << c) | (u >> (32 - c)); 59 1.2 tls } 60 1.2 tls 61 1.2 tls #define QUARTERROUND(a, b, c, d) do { \ 62 1.2 tls (a) += (b); (d) ^= (a); (d) = rotate((d), 16); \ 63 1.2 tls (c) += (d); (b) ^= (c); (b) = rotate((b), 12); \ 64 1.2 tls (a) += (b); (d) ^= (a); (d) = rotate((d), 8); \ 65 1.2 tls (c) += (d); (b) ^= (c); (b) = rotate((b), 7); \ 66 1.2 tls } while (0) 67 1.2 tls 68 1.2 tls static void 69 1.2 tls crypto_core(uint32_t *out, const uint32_t *in, const uint32_t *k, 70 1.2 tls const uint32_t *c) 71 1.2 tls { 72 1.2 tls uint32_t x0,x1,x2,x3,x4,x5,x6,x7,x8,x9,x10,x11,x12,x13,x14,x15; 73 1.2 tls int i; 74 1.2 tls 75 1.2 tls x0 = c[0]; 76 1.2 tls x1 = c[1]; 77 1.2 tls x2 = c[2]; 78 1.2 tls x3 = c[3]; 79 1.2 tls x4 = k[0]; 80 1.2 tls x5 = k[1]; 81 1.2 tls x6 = k[2]; 82 1.2 tls x7 = k[3]; 83 1.2 tls x8 = k[4]; 84 1.2 tls x9 = k[5]; 85 1.2 tls x10 = k[6]; 86 1.2 tls x11 = k[7]; 87 1.2 tls x12 = in[0]; 88 1.2 tls x13 = in[1]; 89 1.2 tls x14 = in[2]; 90 1.2 tls x15 = in[3]; 91 1.2 tls 92 1.2 tls for (i = crypto_core_ROUNDS; i > 0; i -= 2) { 93 1.2 tls QUARTERROUND( x0, x4, x8,x12); 94 1.2 tls QUARTERROUND( x1, x5, x9,x13); 95 1.2 tls QUARTERROUND( x2, x6,x10,x14); 96 1.2 tls QUARTERROUND( x3, x7,x11,x15); 97 1.2 tls QUARTERROUND( x0, x5,x10,x15); 98 1.2 tls QUARTERROUND( x1, x6,x11,x12); 99 1.2 tls QUARTERROUND( x2, x7, x8,x13); 100 1.2 tls QUARTERROUND( x3, x4, x9,x14); 101 1.2 tls } 102 1.2 tls 103 1.2 tls out[0] = x0 + c[0]; 104 1.2 tls out[1] = x1 + c[1]; 105 1.2 tls out[2] = x2 + c[2]; 106 1.2 tls out[3] = x3 + c[3]; 107 1.2 tls out[4] = x4 + k[0]; 108 1.2 tls out[5] = x5 + k[1]; 109 1.2 tls out[6] = x6 + k[2]; 110 1.2 tls out[7] = x7 + k[3]; 111 1.2 tls out[8] = x8 + k[4]; 112 1.2 tls out[9] = x9 + k[5]; 113 1.2 tls out[10] = x10 + k[6]; 114 1.2 tls out[11] = x11 + k[7]; 115 1.2 tls out[12] = x12 + in[0]; 116 1.2 tls out[13] = x13 + in[1]; 117 1.2 tls out[14] = x14 + in[2]; 118 1.2 tls out[15] = x15 + in[3]; 119 1.2 tls } 120 1.2 tls 121 1.2 tls /* `expand 32-byte k' */ 123 1.2 tls static const uint32_t crypto_core_constant32[4] = { 124 1.2 tls 0x61707865U, 0x3320646eU, 0x79622d32U, 0x6b206574U, 125 1.2 tls }; 126 1.2 tls 127 1.2 tls /* 128 1.2 tls * Test vector for ChaCha20 from 129 1.2 tls * <http://tools.ietf.org/html/draft-strombergson-chacha-test-vectors-00>, 130 1.2 tls * test vectors for ChaCha12 and ChaCha8 generated by the same 131 1.2 tls * crypto_core code with crypto_core_ROUNDS varied. 132 1.2 tls */ 133 1.2 tls 134 1.2 tls #define check(E) do \ 135 1.2 tls { \ 136 1.2 tls if (!(E)) \ 137 1.2 tls panic("crypto self-test failed: %s", #E); \ 138 1.2 tls } while (0) 139 1.2 tls 140 1.2 tls static void 141 1.2 tls crypto_core_selftest(void) 142 1.2 tls { 143 1.2 tls const uint32_t zero32[8] = {0}; 144 1.2 tls const uint8_t sigma[] = "expand 32-byte k"; 145 1.2 tls uint32_t block[16]; 146 1.2 tls unsigned i; 147 1.2 tls 148 1.2 tls #if crypto_core_ROUNDS == 8 149 1.2 tls static const uint8_t out[64] = { 150 1.2 tls 0x3e,0x00,0xef,0x2f,0x89,0x5f,0x40,0xd6, 151 1.2 tls 0x7f,0x5b,0xb8,0xe8,0x1f,0x09,0xa5,0xa1, 152 1.2 tls 0x2c,0x84,0x0e,0xc3,0xce,0x9a,0x7f,0x3b, 153 1.2 tls 0x18,0x1b,0xe1,0x88,0xef,0x71,0x1a,0x1e, 154 1.2 tls 0x98,0x4c,0xe1,0x72,0xb9,0x21,0x6f,0x41, 155 1.2 tls 0x9f,0x44,0x53,0x67,0x45,0x6d,0x56,0x19, 156 1.2 tls 0x31,0x4a,0x42,0xa3,0xda,0x86,0xb0,0x01, 157 1.2 tls 0x38,0x7b,0xfd,0xb8,0x0e,0x0c,0xfe,0x42, 158 1.2 tls }; 159 1.2 tls #elif crypto_core_ROUNDS == 12 160 1.2 tls static const uint8_t out[64] = { 161 1.2 tls 0x9b,0xf4,0x9a,0x6a,0x07,0x55,0xf9,0x53, 162 1.2 tls 0x81,0x1f,0xce,0x12,0x5f,0x26,0x83,0xd5, 163 1.2 tls 0x04,0x29,0xc3,0xbb,0x49,0xe0,0x74,0x14, 164 1.2 tls 0x7e,0x00,0x89,0xa5,0x2e,0xae,0x15,0x5f, 165 1.2 tls 0x05,0x64,0xf8,0x79,0xd2,0x7a,0xe3,0xc0, 166 1.2 tls 0x2c,0xe8,0x28,0x34,0xac,0xfa,0x8c,0x79, 167 1.2 tls 0x3a,0x62,0x9f,0x2c,0xa0,0xde,0x69,0x19, 168 1.2 tls 0x61,0x0b,0xe8,0x2f,0x41,0x13,0x26,0xbe, 169 1.2 tls }; 170 1.2 tls #elif crypto_core_ROUNDS == 20 171 1.2 tls static const uint8_t out[64] = { 172 1.2 tls 0x76,0xb8,0xe0,0xad,0xa0,0xf1,0x3d,0x90, 173 1.2 tls 0x40,0x5d,0x6a,0xe5,0x53,0x86,0xbd,0x28, 174 1.2 tls 0xbd,0xd2,0x19,0xb8,0xa0,0x8d,0xed,0x1a, 175 1.2 tls 0xa8,0x36,0xef,0xcc,0x8b,0x77,0x0d,0xc7, 176 1.2 tls 0xda,0x41,0x59,0x7c,0x51,0x57,0x48,0x8d, 177 1.2 tls 0x77,0x24,0xe0,0x3f,0xb8,0xd8,0x4a,0x37, 178 1.2 tls 0x6a,0x43,0xb8,0xf4,0x15,0x18,0xa1,0x1c, 179 1.2 tls 0xc3,0x87,0xb6,0x69,0xb2,0xee,0x65,0x86, 180 1.2 tls }; 181 1.2 tls #else 182 1.2 tls #error crypto_core_ROUNDS must be 8, 12, or 20. 183 1.2 tls #endif 184 1.2 tls 185 1.2 tls check(crypto_core_constant32[0] == le32dec(&sigma[0])); 186 1.2 tls check(crypto_core_constant32[1] == le32dec(&sigma[4])); 187 1.2 tls check(crypto_core_constant32[2] == le32dec(&sigma[8])); 188 1.2 tls check(crypto_core_constant32[3] == le32dec(&sigma[12])); 189 1.2 tls 190 1.2 tls crypto_core(block, zero32, zero32, crypto_core_constant32); 191 1.2 tls for (i = 0; i < 16; i++) 192 1.2 tls check(block[i] == le32dec(&out[i*4])); 193 1.2 tls } 194 1.2 tls 195 1.2 tls #undef check 196 1.2 tls 197 1.2 tls #define CPRNG_FAST_SEED_BYTES (crypto_core_KEYWORDS * sizeof(uint32_t)) 199 1.2 tls 200 1.2 tls struct cprng_fast { 201 1.14 riastrad uint32_t buffer[crypto_core_OUTPUTWORDS]; 202 1.2 tls uint32_t key[crypto_core_KEYWORDS]; 203 1.2 tls uint32_t nonce[crypto_core_INPUTWORDS]; 204 1.2 tls unsigned epoch; 205 1.2 tls }; 206 1.8 riastrad 207 1.2 tls __CTASSERT(sizeof ((struct cprng_fast *)0)->key == CPRNG_FAST_SEED_BYTES); 208 1.2 tls 209 1.2 tls static void cprng_fast_init_cpu(void *, void *, struct cpu_info *); 210 1.6 riastrad static void cprng_fast_schedule_reseed(struct cprng_fast *); 211 1.2 tls static void cprng_fast_intr(void *); 212 1.2 tls 213 1.2 tls static void cprng_fast_seed(struct cprng_fast *, const void *); 214 1.2 tls static void cprng_fast_buf(struct cprng_fast *, void *, unsigned); 215 1.2 tls 216 1.2 tls static void cprng_fast_buf_short(void *, size_t); 217 1.2 tls static void cprng_fast_buf_long(void *, size_t); 218 1.2 tls 219 1.2 tls static percpu_t *cprng_fast_percpu __read_mostly; 220 1.2 tls static void *cprng_fast_softint __read_mostly; 221 1.2 tls 222 1.2 tls void 223 1.2 tls cprng_fast_init(void) 224 1.2 tls { 225 1.8 riastrad 226 1.2 tls crypto_core_selftest(); 227 1.2 tls cprng_fast_percpu = percpu_alloc(sizeof(struct cprng_fast)); 228 1.2 tls percpu_foreach(cprng_fast_percpu, &cprng_fast_init_cpu, NULL); 229 1.2 tls cprng_fast_softint = softint_establish(SOFTINT_SERIAL|SOFTINT_MPSAFE, 230 1.8 riastrad &cprng_fast_intr, NULL); 231 1.8 riastrad } 232 1.8 riastrad 233 1.8 riastrad static void 234 1.8 riastrad cprng_fast_init_cpu(void *p, void *arg __unused, struct cpu_info *ci __unused) 235 1.8 riastrad { 236 1.14 riastrad struct cprng_fast *const cprng = p; 237 1.12 riastrad uint8_t seed[CPRNG_FAST_SEED_BYTES]; 238 1.8 riastrad 239 1.8 riastrad cprng->epoch = entropy_epoch(); 240 1.8 riastrad cprng_strong(kern_cprng, seed, sizeof seed, 0); 241 1.9 riastrad cprng_fast_seed(cprng, seed); 242 1.2 tls (void)explicit_memset(seed, 0, sizeof seed); 243 1.2 tls } 244 1.2 tls 245 1.9 riastrad static inline int 247 1.9 riastrad cprng_fast_get(struct cprng_fast **cprngp) 248 1.9 riastrad { 249 1.9 riastrad struct cprng_fast *cprng; 250 1.2 tls int s; 251 1.14 riastrad 252 1.9 riastrad *cprngp = cprng = percpu_getref(cprng_fast_percpu); 253 1.9 riastrad s = splvm(); 254 1.9 riastrad 255 1.2 tls if (__predict_false(cprng->epoch != entropy_epoch())) 256 1.2 tls cprng_fast_schedule_reseed(cprng); 257 1.2 tls 258 1.2 tls return s; 259 1.2 tls } 260 1.2 tls 261 1.2 tls static inline void 262 1.2 tls cprng_fast_put(struct cprng_fast *cprng, int s) 263 1.2 tls { 264 1.2 tls 265 1.2 tls KASSERT((cprng == percpu_getref(cprng_fast_percpu)) && 266 1.9 riastrad (percpu_putref(cprng_fast_percpu), true)); 267 1.11 justin splx(s); 268 1.2 tls percpu_putref(cprng_fast_percpu); 269 1.2 tls } 270 1.2 tls 271 1.2 tls static void 272 1.2 tls cprng_fast_schedule_reseed(struct cprng_fast *cprng __unused) 273 1.2 tls { 274 1.2 tls 275 1.2 tls softint_schedule(cprng_fast_softint); 276 1.2 tls } 277 1.14 riastrad 278 1.2 tls static void 279 1.2 tls cprng_fast_intr(void *cookie __unused) 280 1.7 riastrad { 281 1.2 tls unsigned epoch = entropy_epoch(); 282 1.12 riastrad struct cprng_fast *cprng; 283 1.2 tls uint8_t seed[CPRNG_FAST_SEED_BYTES]; 284 1.2 tls int s; 285 1.7 riastrad 286 1.2 tls cprng_strong(kern_cprng, seed, sizeof(seed), 0); 287 1.14 riastrad 288 1.7 riastrad cprng = percpu_getref(cprng_fast_percpu); 289 1.2 tls s = splvm(); 290 1.2 tls cprng_fast_seed(cprng, seed); 291 1.2 tls cprng->epoch = epoch; 292 1.2 tls splx(s); 293 1.2 tls percpu_putref(cprng_fast_percpu); 294 1.2 tls 295 1.2 tls explicit_memset(seed, 0, sizeof(seed)); 296 1.2 tls } 297 1.2 tls 298 1.2 tls /* CPRNG algorithm */ 300 1.2 tls 301 1.2 tls /* 302 1.2 tls * The state consists of a key, the current nonce, and a 64-byte buffer 303 1.2 tls * of output. Since we fill the buffer only when we need output, and 304 1.2 tls * eat a 32-bit word at a time, one 32-bit word of the buffer would be 305 1.2 tls * wasted. Instead, we repurpose it to count the number of entries in 306 1.6 riastrad * the buffer remaining, counting from high to low in order to allow 307 1.2 tls * comparison to zero to detect when we need to refill it. 308 1.2 tls */ 309 1.2 tls #define CPRNG_FAST_BUFIDX (crypto_core_OUTPUTWORDS - 1) 310 1.2 tls 311 1.2 tls static void 312 1.2 tls cprng_fast_seed(struct cprng_fast *cprng, const void *seed) 313 1.2 tls { 314 1.2 tls 315 1.2 tls (void)memset(cprng->buffer, 0, sizeof cprng->buffer); 316 1.2 tls (void)memcpy(cprng->key, seed, sizeof cprng->key); 317 1.2 tls (void)memset(cprng->nonce, 0, sizeof cprng->nonce); 318 1.2 tls } 319 1.2 tls 320 1.2 tls static inline uint32_t 321 1.2 tls cprng_fast_word(struct cprng_fast *cprng) 322 1.2 tls { 323 1.2 tls uint32_t v; 324 1.2 tls 325 1.2 tls if (__predict_true(0 < cprng->buffer[CPRNG_FAST_BUFIDX])) { 326 1.2 tls v = cprng->buffer[--cprng->buffer[CPRNG_FAST_BUFIDX]]; 327 1.2 tls } else { 328 1.2 tls /* If we don't have enough words, refill the buffer. */ 329 1.2 tls crypto_core(cprng->buffer, cprng->nonce, cprng->key, 330 1.2 tls crypto_core_constant32); 331 1.2 tls if (__predict_false(++cprng->nonce[0] == 0)) { 332 1.2 tls cprng->nonce[1]++; 333 1.2 tls cprng_fast_schedule_reseed(cprng); 334 1.2 tls } 335 1.2 tls v = cprng->buffer[CPRNG_FAST_BUFIDX]; 336 1.2 tls cprng->buffer[CPRNG_FAST_BUFIDX] = CPRNG_FAST_BUFIDX; 337 1.2 tls } 338 1.2 tls 339 1.2 tls return v; 340 1.2 tls } 341 1.2 tls 342 1.10 riastrad static inline void 343 1.2 tls cprng_fast_buf(struct cprng_fast *cprng, void *buf, unsigned n) 344 1.10 riastrad { 345 1.10 riastrad uint8_t *p = buf; 346 1.10 riastrad uint32_t v; 347 1.10 riastrad unsigned w, r; 348 1.10 riastrad 349 1.10 riastrad w = n / sizeof(uint32_t); 350 1.10 riastrad while (w--) { 351 1.10 riastrad v = cprng_fast_word(cprng); 352 1.10 riastrad (void)memcpy(p, &v, 4); 353 1.2 tls p += 4; 354 1.2 tls } 355 1.2 tls 356 1.2 tls r = n % sizeof(uint32_t); 357 1.2 tls if (r) { 358 1.2 tls v = cprng_fast_word(cprng); 359 1.2 tls while (r--) { 360 1.2 tls *p++ = (v & 0xff); 361 1.2 tls v >>= 8; 362 1.2 tls } 363 1.2 tls } 364 1.2 tls } 365 1.2 tls 366 1.2 tls /* 368 1.2 tls * crypto_onetimestream: Expand a short unpredictable one-time seed 369 1.2 tls * into a long unpredictable output. 370 1.2 tls */ 371 1.2 tls static void 372 1.2 tls crypto_onetimestream(const uint32_t seed[crypto_core_KEYWORDS], void *buf, 373 1.2 tls size_t n) 374 1.2 tls { 375 1.2 tls uint32_t block[crypto_core_OUTPUTWORDS]; 376 1.2 tls uint32_t nonce[crypto_core_INPUTWORDS] = {0}; 377 1.2 tls uint8_t *p8; 378 1.2 tls uint32_t *p32; 379 1.2 tls size_t ni, nb, nf; 380 1.2 tls 381 1.2 tls /* 382 1.2 tls * Guarantee we can generate up to n bytes. We have 383 1.2 tls * 2^(32*INPUTWORDS) possible inputs yielding output of 384 1.2 tls * 4*OUTPUTWORDS*2^(32*INPUTWORDS) bytes. It suffices to 385 1.2 tls * require that sizeof n > (1/CHAR_BIT) log_2 n be less than 386 1.2 tls * (1/CHAR_BIT) log_2 of the total output stream length. We 387 1.2 tls * have 388 1.2 tls * 389 1.2 tls * log_2 (4 o 2^(32 i)) = log_2 (4 o) + log_2 2^(32 i) 390 1.2 tls * = 2 + log_2 o + 32 i. 391 1.2 tls */ 392 1.2 tls __CTASSERT(CHAR_BIT*sizeof n <= 393 1.2 tls (2 + ilog2(crypto_core_OUTPUTWORDS) + 32*crypto_core_INPUTWORDS)); 394 1.2 tls 395 1.2 tls p8 = buf; 396 1.2 tls p32 = (uint32_t *)roundup2((uintptr_t)p8, sizeof(uint32_t)); 397 1.2 tls ni = (uint8_t *)p32 - p8; 398 1.2 tls if (n < ni) 399 1.2 tls ni = n; 400 1.2 tls nb = (n - ni) / sizeof block; 401 1.2 tls nf = (n - ni) % sizeof block; 402 1.2 tls 403 1.2 tls KASSERT(((uintptr_t)p32 & 3) == 0); 404 1.2 tls KASSERT(ni <= n); 405 1.2 tls KASSERT(nb <= (n / sizeof block)); 406 1.2 tls KASSERT(nf <= n); 407 1.2 tls KASSERT(n == (ni + (nb * sizeof block) + nf)); 408 1.2 tls KASSERT(ni < sizeof(uint32_t)); 409 1.2 tls KASSERT(nf < sizeof block); 410 1.2 tls 411 1.2 tls if (ni) { 412 1.2 tls crypto_core(block, nonce, seed, crypto_core_constant32); 413 1.2 tls nonce[0]++; 414 1.2 tls (void)memcpy(p8, block, ni); 415 1.2 tls } 416 1.2 tls while (nb--) { 417 1.2 tls crypto_core(p32, nonce, seed, crypto_core_constant32); 418 1.2 tls if (++nonce[0] == 0) 419 1.2 tls nonce[1]++; 420 1.2 tls p32 += crypto_core_OUTPUTWORDS; 421 1.2 tls } 422 1.2 tls if (nf) { 423 1.2 tls crypto_core(block, nonce, seed, crypto_core_constant32); 424 1.2 tls if (++nonce[0] == 0) 425 1.2 tls nonce[1]++; 426 1.2 tls (void)memcpy(p32, block, nf); 427 1.2 tls } 428 1.2 tls 429 1.2 tls if (ni | nf) 430 1.2 tls (void)explicit_memset(block, 0, sizeof block); 431 1.2 tls } 432 1.2 tls 433 1.2 tls /* Public API */ 435 1.2 tls 436 1.2 tls uint32_t 437 1.2 tls cprng_fast32(void) 438 1.2 tls { 439 1.2 tls struct cprng_fast *cprng; 440 1.2 tls uint32_t v; 441 1.2 tls int s; 442 1.2 tls 443 1.2 tls s = cprng_fast_get(&cprng); 444 1.2 tls v = cprng_fast_word(cprng); 445 1.2 tls cprng_fast_put(cprng, s); 446 1.2 tls 447 1.2 tls return v; 448 1.2 tls } 449 1.2 tls 450 1.2 tls uint64_t 451 1.2 tls cprng_fast64(void) 452 1.2 tls { 453 1.2 tls struct cprng_fast *cprng; 454 1.2 tls uint32_t hi, lo; 455 1.2 tls int s; 456 1.2 tls 457 1.2 tls s = cprng_fast_get(&cprng); 458 1.2 tls hi = cprng_fast_word(cprng); 459 1.2 tls lo = cprng_fast_word(cprng); 460 1.2 tls cprng_fast_put(cprng, s); 461 1.2 tls 462 1.2 tls return ((uint64_t)hi << 32) | lo; 463 1.2 tls } 464 1.2 tls 465 1.2 tls static void 466 1.2 tls cprng_fast_buf_short(void *buf, size_t len) 467 1.2 tls { 468 1.2 tls struct cprng_fast *cprng; 469 1.2 tls int s; 470 1.2 tls 471 1.2 tls s = cprng_fast_get(&cprng); 472 1.2 tls cprng_fast_buf(cprng, buf, len); 473 1.2 tls cprng_fast_put(cprng, s); 474 1.2 tls } 475 1.2 tls 476 1.2 tls static __noinline void 477 1.2 tls cprng_fast_buf_long(void *buf, size_t len) 478 1.2 tls { 479 1.2 tls uint32_t seed[crypto_core_KEYWORDS]; 480 1.2 tls struct cprng_fast *cprng; 481 1.2 tls int s; 482 1.2 tls 483 1.2 tls s = cprng_fast_get(&cprng); 484 1.2 tls cprng_fast_buf(cprng, seed, sizeof seed); 485 1.2 tls cprng_fast_put(cprng, s); 486 1.2 tls 487 1.2 tls crypto_onetimestream(seed, buf, len); 488 1.2 tls 489 1.2 tls (void)explicit_memset(seed, 0, sizeof seed); 490 1.2 tls } 491 1.2 tls 492 1.2 tls size_t 493 1.2 tls cprng_fast(void *buf, size_t len) 494 1.2 tls { 495 1.2 tls 496 1.2 tls /* 497 1.2 tls * We don't want to hog the CPU, so we use the short version, 498 1.2 tls * to generate output without preemption, only if we can do it 499 1.2 tls * with at most one crypto_core. 500 1.2 tls */ 501 if (len <= (sizeof(uint32_t) * crypto_core_OUTPUTWORDS)) 502 cprng_fast_buf_short(buf, len); 503 else 504 cprng_fast_buf_long(buf, len); 505 506 return len; 507 } 508
Indexes created Tue Sep 30 11:09:46 GMT 2025