diff options
Diffstat (limited to 'lib/libc/crypt/arc4random.c')
| -rw-r--r-- | lib/libc/crypt/arc4random.c | 38 |
1 files changed, 1 insertions, 37 deletions
diff --git a/lib/libc/crypt/arc4random.c b/lib/libc/crypt/arc4random.c index 13b94ed111e..9460af1e542 100644 --- a/lib/libc/crypt/arc4random.c +++ b/lib/libc/crypt/arc4random.c @@ -1,4 +1,4 @@ -/* $OpenBSD: arc4random.c,v 1.40 2014/07/09 16:52:09 bcook Exp $ */ +/* $OpenBSD: arc4random.c,v 1.41 2014/07/12 13:24:54 deraadt Exp $ */ /* * Copyright (c) 1996, David Mazieres <dm@uun.org> @@ -211,39 +211,3 @@ arc4random_buf(void *buf, size_t n) _rs_random_buf(buf, n); _ARC4_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. - */ -uint32_t -arc4random_uniform(uint32_t upper_bound) -{ - uint32_t r, min; - - if (upper_bound < 2) - return 0; - - /* 2**32 % x == (2**32 - x) % x */ - min = -upper_bound % upper_bound; - - /* - * 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; -} |