224 lines
6 KiB
C
224 lines
6 KiB
C
/* crypto/bn/bn_rand.c */
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/* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
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* All rights reserved.
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*
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* This package is an SSL implementation written
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* by Eric Young (eay@cryptsoft.com).
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* The implementation was written so as to conform with Netscapes SSL.
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*
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* This library is free for commercial and non-commercial use as long as
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* the following conditions are aheared to. The following conditions
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* apply to all code found in this distribution, be it the RC4, RSA,
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* lhash, DES, etc., code; not just the SSL code. The SSL documentation
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* included with this distribution is covered by the same copyright terms
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* except that the holder is Tim Hudson (tjh@cryptsoft.com).
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*
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* Copyright remains Eric Young's, and as such any Copyright notices in
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* the code are not to be removed.
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* If this package is used in a product, Eric Young should be given attribution
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* as the author of the parts of the library used.
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* This can be in the form of a textual message at program startup or
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* in documentation (online or textual) provided with the package.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* "This product includes cryptographic software written by
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* Eric Young (eay@cryptsoft.com)"
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* The word 'cryptographic' can be left out if the rouines from the library
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* being used are not cryptographic related :-).
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* 4. If you include any Windows specific code (or a derivative thereof) from
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* the apps directory (application code) you must include an acknowledgement:
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* "This product includes software written by Tim Hudson (tjh@cryptsoft.com)"
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*
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* THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* The licence and distribution terms for any publically available version or
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* derivative of this code cannot be changed. i.e. this code cannot simply be
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* copied and put under another distribution licence
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* [including the GNU Public Licence.]
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*/
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#include <stdio.h>
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#include <time.h>
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#include "cryptlib.h"
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#include "bn_lcl.h"
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#include <openssl/rand.h>
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static int bnrand(int pseudorand, BIGNUM *rnd, int bits, int top, int bottom)
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{
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unsigned char *buf=NULL;
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int ret=0,bit,bytes,mask;
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time_t tim;
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if (bits == 0)
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{
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BN_zero(rnd);
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return 1;
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}
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bytes=(bits+7)/8;
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bit=(bits-1)%8;
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mask=0xff<<(bit+1);
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buf=(unsigned char *)OPENSSL_malloc(bytes);
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if (buf == NULL)
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{
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BNerr(BN_F_BN_RAND,ERR_R_MALLOC_FAILURE);
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goto err;
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}
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/* make a random number and set the top and bottom bits */
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time(&tim);
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RAND_add(&tim,sizeof(tim),0);
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if (pseudorand)
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{
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if (RAND_pseudo_bytes(buf, bytes) == -1)
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goto err;
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}
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else
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{
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if (RAND_bytes(buf, bytes) <= 0)
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goto err;
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}
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#if 1
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if (pseudorand == 2)
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{
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/* generate patterns that are more likely to trigger BN
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library bugs */
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int i;
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unsigned char c;
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for (i = 0; i < bytes; i++)
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{
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RAND_pseudo_bytes(&c, 1);
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if (c >= 128 && i > 0)
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buf[i] = buf[i-1];
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else if (c < 42)
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buf[i] = 0;
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else if (c < 84)
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buf[i] = 255;
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}
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}
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#endif
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if (top != -1)
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{
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if (top)
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{
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if (bit == 0)
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{
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buf[0]=1;
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buf[1]|=0x80;
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}
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else
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{
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buf[0]|=(3<<(bit-1));
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}
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}
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else
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{
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buf[0]|=(1<<bit);
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}
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}
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buf[0] &= ~mask;
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if (bottom) /* set bottom bit if requested */
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buf[bytes-1]|=1;
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if (!BN_bin2bn(buf,bytes,rnd)) goto err;
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ret=1;
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err:
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if (buf != NULL)
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{
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memset(buf,0,bytes);
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OPENSSL_free(buf);
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}
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return(ret);
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}
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int BN_rand(BIGNUM *rnd, int bits, int top, int bottom)
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{
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return bnrand(0, rnd, bits, top, bottom);
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}
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int BN_pseudo_rand(BIGNUM *rnd, int bits, int top, int bottom)
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{
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return bnrand(1, rnd, bits, top, bottom);
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}
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#if 1
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int BN_bntest_rand(BIGNUM *rnd, int bits, int top, int bottom)
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{
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return bnrand(2, rnd, bits, top, bottom);
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}
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#endif
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/* random number r: 0 <= r < range */
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int BN_rand_range(BIGNUM *r, BIGNUM *range)
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{
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int n;
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if (range->neg || BN_is_zero(range))
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{
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BNerr(BN_F_BN_RAND_RANGE, BN_R_INVALID_RANGE);
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return 0;
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}
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n = BN_num_bits(range); /* n > 0 */
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if (n == 1)
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{
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if (!BN_zero(r)) return 0;
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}
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else if (BN_is_bit_set(range, n - 2))
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{
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do
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{
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/* range = 11..._2, so each iteration succeeds with probability >= .75 */
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if (!BN_rand(r, n, -1, 0)) return 0;
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}
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while (BN_cmp(r, range) >= 0);
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}
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else
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{
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/* range = 10..._2,
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* so 3*range (= 11..._2) is exactly one bit longer than range */
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do
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{
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if (!BN_rand(r, n + 1, -1, 0)) return 0;
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/* If r < 3*range, use r := r MOD range
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* (which is either r, r - range, or r - 2*range).
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* Otherwise, iterate once more.
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* Since 3*range = 11..._2, each iteration succeeds with
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* probability >= .75. */
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if (BN_cmp(r ,range) >= 0)
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{
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if (!BN_sub(r, r, range)) return 0;
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if (BN_cmp(r, range) >= 0)
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if (!BN_sub(r, r, range)) return 0;
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}
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}
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while (BN_cmp(r, range) >= 0);
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}
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return 1;
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}
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