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Diffstat (limited to 'code/crypto/compat/arc4random_uniform.c')
-rw-r--r-- | code/crypto/compat/arc4random_uniform.c | 56 |
1 files changed, 0 insertions, 56 deletions
diff --git a/code/crypto/compat/arc4random_uniform.c b/code/crypto/compat/arc4random_uniform.c deleted file mode 100644 index 2d22434..0000000 --- a/code/crypto/compat/arc4random_uniform.c +++ /dev/null @@ -1,56 +0,0 @@ -/* $OpenBSD: arc4random_uniform.c,v 1.2 2015/09/13 08:31:47 guenther Exp $ */ - -/* - * 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. - */ - -#include <sys/types.h> -#include <stdlib.h> - -/* - * 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; -} |