/* $OpenBSD: bn_rand.c,v 1.24 2020/09/12 17:16:36 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 <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>
#include <openssl/err.h>
#include "bn_lcl.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 == 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);
bn_check_top(rnd);
return (ret);
}
int
BN_rand(BIGNUM *rnd, int bits, int top, int bottom)
{
return bnrand(0, rnd, bits, top, bottom);
}
int
BN_pseudo_rand(BIGNUM *rnd, int bits, int top, int bottom)
{
return bnrand(1, rnd, bits, top, bottom);
}
#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);
}
bn_check_top(r);
return 1;
}
int
BN_rand_range(BIGNUM *r, const BIGNUM *range)
{
return bn_rand_range(0, r, range);
}
int
bn_rand_interval(BIGNUM *rnd, const BIGNUM *lower_inc, const BIGNUM *upper_exc)
{
BIGNUM *len = NULL;
int ret = 0;
if (BN_cmp(lower_inc, upper_exc) >= 0)
goto err;
if ((len = BN_new()) == NULL)
goto err;
if (!BN_sub(len, upper_exc, lower_inc))
goto err;
if (!bn_rand_range(0, rnd, len))
goto err;
if (!BN_add(rnd, rnd, lower_inc))
goto err;
ret = 1;
err:
BN_free(len);
return ret;
}
int
BN_pseudo_rand_range(BIGNUM *r, const BIGNUM *range)
{
return bn_rand_range(1, r, range);
}