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Diffstat (limited to 'lib/libc/gen/arc4random.c')
-rw-r--r-- | lib/libc/gen/arc4random.c | 304 |
1 files changed, 0 insertions, 304 deletions
diff --git a/lib/libc/gen/arc4random.c b/lib/libc/gen/arc4random.c deleted file mode 100644 index 56dfba9..0000000 --- a/lib/libc/gen/arc4random.c +++ /dev/null @@ -1,304 +0,0 @@ -/* - * Copyright (c) 1996, David Mazieres <dm@uun.org> - * Copyright (c) 2008, Damien Miller <djm@openbsd.org> - * - * Permission to use, copy, modify, and distribute this software for any - * purpose with or without fee is hereby granted, provided that the above - * copyright notice and this permission notice appear in all copies. - * - * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES - * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF - * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR - * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES - * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN - * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF - * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. - */ - -/* - * Arc4 random number generator for OpenBSD. - * - * This code is derived from section 17.1 of Applied Cryptography, - * second edition, which describes a stream cipher allegedly - * compatible with RSA Labs "RC4" cipher (the actual description of - * which is a trade secret). The same algorithm is used as a stream - * cipher called "arcfour" in Tatu Ylonen's ssh package. - * - * Here the stream cipher has been modified always to include the time - * when initializing the state. That makes it impossible to - * regenerate the same random sequence twice, so this can't be used - * for encryption, but will generate good random numbers. - * - * RC4 is a registered trademark of RSA Laboratories. - */ - -#include <sys/cdefs.h> -__FBSDID("$FreeBSD$"); - -#include "namespace.h" -#include <sys/types.h> -#include <sys/time.h> -#include <stdlib.h> -#include <fcntl.h> -#include <unistd.h> -#include <pthread.h> - -#include "libc_private.h" -#include "un-namespace.h" - -struct arc4_stream { - u_int8_t i; - u_int8_t j; - u_int8_t s[256]; -}; - -static pthread_mutex_t arc4random_mtx = PTHREAD_MUTEX_INITIALIZER; - -#define RANDOMDEV "/dev/random" -#define KEYSIZE 128 -#define THREAD_LOCK() \ - do { \ - if (__isthreaded) \ - _pthread_mutex_lock(&arc4random_mtx); \ - } while (0) - -#define THREAD_UNLOCK() \ - do { \ - if (__isthreaded) \ - _pthread_mutex_unlock(&arc4random_mtx); \ - } while (0) - -static struct arc4_stream rs; -static int rs_initialized; -static int rs_stired; -static int arc4_count; - -static inline u_int8_t arc4_getbyte(void); -static void arc4_stir(void); - -static inline void -arc4_init(void) -{ - int n; - - for (n = 0; n < 256; n++) - rs.s[n] = n; - rs.i = 0; - rs.j = 0; -} - -static inline void -arc4_addrandom(u_char *dat, int datlen) -{ - int n; - u_int8_t si; - - rs.i--; - for (n = 0; n < 256; n++) { - rs.i = (rs.i + 1); - si = rs.s[rs.i]; - rs.j = (rs.j + si + dat[n % datlen]); - rs.s[rs.i] = rs.s[rs.j]; - rs.s[rs.j] = si; - } - rs.j = rs.i; -} - -static void -arc4_stir(void) -{ - int done, fd, n; - struct { - struct timeval tv; - pid_t pid; - u_int8_t rnd[KEYSIZE]; - } rdat; - - fd = _open(RANDOMDEV, O_RDONLY, 0); - done = 0; - if (fd >= 0) { - if (_read(fd, &rdat, KEYSIZE) == KEYSIZE) - done = 1; - (void)_close(fd); - } - if (!done) { - (void)gettimeofday(&rdat.tv, NULL); - rdat.pid = getpid(); - /* We'll just take whatever was on the stack too... */ - } - - arc4_addrandom((u_char *)&rdat, KEYSIZE); - - /* - * Throw away the first N bytes of output, as suggested in the - * paper "Weaknesses in the Key Scheduling Algorithm of RC4" - * by Fluher, Mantin, and Shamir. N=1024 is based on - * suggestions in the paper "(Not So) Random Shuffles of RC4" - * by Ilya Mironov. - */ - for (n = 0; n < 1024; n++) - (void) arc4_getbyte(); - arc4_count = 1600000; -} - -static inline u_int8_t -arc4_getbyte(void) -{ - u_int8_t si, sj; - - rs.i = (rs.i + 1); - si = rs.s[rs.i]; - rs.j = (rs.j + si); - sj = rs.s[rs.j]; - rs.s[rs.i] = sj; - rs.s[rs.j] = si; - - return (rs.s[(si + sj) & 0xff]); -} - -static inline u_int32_t -arc4_getword(void) -{ - u_int32_t val; - - val = arc4_getbyte() << 24; - val |= arc4_getbyte() << 16; - val |= arc4_getbyte() << 8; - val |= arc4_getbyte(); - - return (val); -} - -static void -arc4_check_init(void) -{ - if (!rs_initialized) { - arc4_init(); - rs_initialized = 1; - } -} - -static inline void -arc4_check_stir(void) -{ - if (!rs_stired || arc4_count <= 0) { - arc4_stir(); - rs_stired = 1; - } -} - -void -arc4random_stir(void) -{ - THREAD_LOCK(); - arc4_check_init(); - arc4_stir(); - rs_stired = 1; - THREAD_UNLOCK(); -} - -void -arc4random_addrandom(u_char *dat, int datlen) -{ - THREAD_LOCK(); - arc4_check_init(); - arc4_check_stir(); - arc4_addrandom(dat, datlen); - THREAD_UNLOCK(); -} - -u_int32_t -arc4random(void) -{ - u_int32_t rnd; - - THREAD_LOCK(); - arc4_check_init(); - arc4_check_stir(); - rnd = arc4_getword(); - arc4_count -= 4; - THREAD_UNLOCK(); - - return (rnd); -} - -void -arc4random_buf(void *_buf, size_t n) -{ - u_char *buf = (u_char *)_buf; - - THREAD_LOCK(); - arc4_check_init(); - while (n--) { - arc4_check_stir(); - buf[n] = arc4_getbyte(); - arc4_count--; - } - THREAD_UNLOCK(); -} - -/* - * Calculate a uniformly distributed random number less than upper_bound - * avoiding "modulo bias". - * - * Uniformity is achieved by generating new random numbers until the one - * returned is outside the range [0, 2**32 % upper_bound). This - * guarantees the selected random number will be inside - * [2**32 % upper_bound, 2**32) which maps back to [0, upper_bound) - * after reduction modulo upper_bound. - */ -u_int32_t -arc4random_uniform(u_int32_t upper_bound) -{ - u_int32_t r, min; - - if (upper_bound < 2) - return (0); - -#if (ULONG_MAX > 0xffffffffUL) - min = 0x100000000UL % upper_bound; -#else - /* Calculate (2**32 % upper_bound) avoiding 64-bit math */ - if (upper_bound > 0x80000000) - min = 1 + ~upper_bound; /* 2**32 - upper_bound */ - else { - /* (2**32 - (x * 2)) % x == 2**32 % x when x <= 2**31 */ - min = ((0xffffffff - (upper_bound * 2)) + 1) % upper_bound; - } -#endif - - /* - * This could theoretically loop forever but each retry has - * p > 0.5 (worst case, usually far better) of selecting a - * number inside the range we need, so it should rarely need - * to re-roll. - */ - for (;;) { - r = arc4random(); - if (r >= min) - break; - } - - return (r % upper_bound); -} - -#if 0 -/*-------- Test code for i386 --------*/ -#include <stdio.h> -#include <machine/pctr.h> -int -main(int argc, char **argv) -{ - const int iter = 1000000; - int i; - pctrval v; - - v = rdtsc(); - for (i = 0; i < iter; i++) - arc4random(); - v = rdtsc() - v; - v /= iter; - - printf("%qd cycles\n", v); -} -#endif |