/* $OpenBSD: bn_rand.c,v 1.31 2025/05/10 05:54:38 tb Exp $ */ /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com) * All rights reserved. * * This package is an SSL implementation written * by Eric Young (eay@cryptsoft.com). * The implementation was written so as to conform with Netscapes SSL. * * This library is free for commercial and non-commercial use as long as * the following conditions are aheared to. The following conditions * apply to all code found in this distribution, be it the RC4, RSA, * lhash, DES, etc., code; not just the SSL code. The SSL documentation * included with this distribution is covered by the same copyright terms * except that the holder is Tim Hudson (tjh@cryptsoft.com). * * Copyright remains Eric Young's, and as such any Copyright notices in * the code are not to be removed. * If this package is used in a product, Eric Young should be given attribution * as the author of the parts of the library used. * This can be in the form of a textual message at program startup or * in documentation (online or textual) provided with the package. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * 3. All advertising materials mentioning features or use of this software * must display the following acknowledgement: * "This product includes cryptographic software written by * Eric Young (eay@cryptsoft.com)" * The word 'cryptographic' can be left out if the rouines from the library * being used are not cryptographic related :-). * 4. If you include any Windows specific code (or a derivative thereof) from * the apps directory (application code) you must include an acknowledgement: * "This product includes software written by Tim Hudson (tjh@cryptsoft.com)" * * THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. * * The licence and distribution terms for any publically available version or * derivative of this code cannot be changed. i.e. this code cannot simply be * copied and put under another distribution licence * [including the GNU Public Licence.] */ /* ==================================================================== * Copyright (c) 1998-2001 The OpenSSL Project. All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in * the documentation and/or other materials provided with the * distribution. * * 3. All advertising materials mentioning features or use of this * software must display the following acknowledgment: * "This product includes software developed by the OpenSSL Project * for use in the OpenSSL Toolkit. (http://www.openssl.org/)" * * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to * endorse or promote products derived from this software without * prior written permission. For written permission, please contact * openssl-core@openssl.org. * * 5. Products derived from this software may not be called "OpenSSL" * nor may "OpenSSL" appear in their names without prior written * permission of the OpenSSL Project. * * 6. Redistributions of any form whatsoever must retain the following * acknowledgment: * "This product includes software developed by the OpenSSL Project * for use in the OpenSSL Toolkit (http://www.openssl.org/)" * * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE OpenSSL PROJECT OR * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED * OF THE POSSIBILITY OF SUCH DAMAGE. * ==================================================================== * * This product includes cryptographic software written by Eric Young * (eay@cryptsoft.com). This product includes software written by Tim * Hudson (tjh@cryptsoft.com). * */ #include <limits.h> #include <stdio.h> #include <stdlib.h> #include <string.h> #include <time.h> #include "bn_local.h" #include "err_local.h" static int bnrand(int pseudorand, BIGNUM *rnd, int bits, int top, int bottom) { unsigned char *buf = NULL; int ret = 0, bit, bytes, mask; if (rnd == NULL) { BNerror(ERR_R_PASSED_NULL_PARAMETER); return (0); } if (bits < 0 || (bits == 1 && top > 0)) { BNerror(BN_R_BITS_TOO_SMALL); return (0); } if (bits > INT_MAX - 7) { BNerror(BN_R_BIGNUM_TOO_LONG); return (0); } if (bits == 0) { BN_zero(rnd); return (1); } bytes = (bits + 7) / 8; bit = (bits - 1) % 8; mask = 0xff << (bit + 1); buf = malloc(bytes); if (buf == NULL) { BNerror(ERR_R_MALLOC_FAILURE); goto err; } /* make a random number and set the top and bottom bits */ arc4random_buf(buf, bytes); #if 1 if (pseudorand == 2) { /* generate patterns that are more likely to trigger BN library bugs */ int i; unsigned char c; for (i = 0; i < bytes; i++) { arc4random_buf(&c, 1); if (c >= 128 && i > 0) buf[i] = buf[i - 1]; else if (c < 42) buf[i] = 0; else if (c < 84) buf[i] = 255; } } #endif if (top > 0) { if (bit == 0) { buf[0] = 1; buf[1] |= 0x80; } else { buf[0] |= (3 << (bit - 1)); } } if (top == 0) buf[0] |= (1 << bit); buf[0] &= ~mask; if (bottom) /* set bottom bit if requested */ buf[bytes - 1] |= 1; if (BN_bin2bn(buf, bytes, rnd) == NULL) goto err; ret = 1; err: freezero(buf, bytes); return (ret); } int BN_rand(BIGNUM *rnd, int bits, int top, int bottom) { return bnrand(0, rnd, bits, top, bottom); } LCRYPTO_ALIAS(BN_rand); int BN_pseudo_rand(BIGNUM *rnd, int bits, int top, int bottom) { return bnrand(1, rnd, bits, top, bottom); } LCRYPTO_ALIAS(BN_pseudo_rand); #if 1 int BN_bntest_rand(BIGNUM *rnd, int bits, int top, int bottom) { return bnrand(2, rnd, bits, top, bottom); } #endif /* random number r: 0 <= r < range */ static int bn_rand_range(int pseudo, BIGNUM *r, const BIGNUM *range) { int (*bn_rand)(BIGNUM *, int, int, int) = pseudo ? BN_pseudo_rand : BN_rand; int n; int count = 100; if (range->neg || BN_is_zero(range)) { BNerror(BN_R_INVALID_RANGE); return 0; } n = BN_num_bits(range); /* n > 0 */ /* BN_is_bit_set(range, n - 1) always holds */ if (n == 1) BN_zero(r); else if (!BN_is_bit_set(range, n - 2) && !BN_is_bit_set(range, n - 3)) { /* range = 100..._2, * so 3*range (= 11..._2) is exactly one bit longer than range */ do { if (!bn_rand(r, n + 1, -1, 0)) return 0; /* If r < 3*range, use r := r MOD range * (which is either r, r - range, or r - 2*range). * Otherwise, iterate once more. * Since 3*range = 11..._2, each iteration succeeds with * probability >= .75. */ if (BN_cmp(r, range) >= 0) { if (!BN_sub(r, r, range)) return 0; if (BN_cmp(r, range) >= 0) if (!BN_sub(r, r, range)) return 0; } if (!--count) { BNerror(BN_R_TOO_MANY_ITERATIONS); return 0; } } while (BN_cmp(r, range) >= 0); } else { do { /* range = 11..._2 or range = 101..._2 */ if (!bn_rand(r, n, -1, 0)) return 0; if (!--count) { BNerror(BN_R_TOO_MANY_ITERATIONS); return 0; } } while (BN_cmp(r, range) >= 0); } return 1; } int BN_rand_range(BIGNUM *r, const BIGNUM *range) { return bn_rand_range(0, r, range); } LCRYPTO_ALIAS(BN_rand_range); int bn_rand_in_range(BIGNUM *rnd, const BIGNUM *lower_inc, const BIGNUM *upper_exc) { BIGNUM *len; int ret = 0; if ((len = BN_new()) == NULL) goto err; if (!BN_sub(len, upper_exc, lower_inc)) goto err; if (!BN_rand_range(rnd, len)) goto err; if (!BN_add(rnd, rnd, lower_inc)) goto err; ret = 1; err: BN_free(len); return ret; } int bn_rand_interval(BIGNUM *rnd, BN_ULONG lower_word, const BIGNUM *upper_exc) { BIGNUM *lower_inc = NULL; int ret = 0; if ((lower_inc = BN_new()) == NULL) goto err; if (!BN_set_word(lower_inc, lower_word)) goto err; if (!bn_rand_in_range(rnd, lower_inc, upper_exc)) goto err; ret = 1; err: BN_free(lower_inc); return ret; } int BN_pseudo_rand_range(BIGNUM *r, const BIGNUM *range) { return bn_rand_range(1, r, range); } LCRYPTO_ALIAS(BN_pseudo_rand_range);
