bn_mod.c
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- /* crypto/bn/bn_mod.c */
- /* Includes code written by Lenka Fibikova <fibikova@exp-math.uni-essen.de>
- * for the OpenSSL project. */
- /* ====================================================================
- * Copyright (c) 1998-2000 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).
- *
- */
- /* 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.]
- */
- #include "cryptlib.h"
- #include "bn_lcl.h"
- #if 0 /* now just a #define */
- int BN_mod(BIGNUM *rem, const BIGNUM *m, const BIGNUM *d, BN_CTX *ctx)
- {
- return(BN_div(NULL,rem,m,d,ctx));
- /* note that rem->neg == m->neg (unless the remainder is zero) */
- }
- #endif
- int BN_nnmod(BIGNUM *r, const BIGNUM *m, const BIGNUM *d, BN_CTX *ctx)
- {
- /* like BN_mod, but returns non-negative remainder
- * (i.e., 0 <= r < |d| always holds) */
- if (!(BN_mod(r,m,d,ctx)))
- return 0;
- if (!r->neg)
- return 1;
- /* now -|d| < r < 0, so we have to set r := r + |d| */
- return (d->neg ? BN_sub : BN_add)(r, r, d);
- }
- int BN_mod_add(BIGNUM *r, const BIGNUM *a, const BIGNUM *b, const BIGNUM *m, BN_CTX *ctx)
- {
- if (!BN_add(r, a, b)) return 0;
- return BN_nnmod(r, r, m, ctx);
- }
- /* BN_mod_add variant that may be used if both a and b are non-negative
- * and less than m */
- int BN_mod_add_quick(BIGNUM *r, const BIGNUM *a, const BIGNUM *b, const BIGNUM *m)
- {
- if (!BN_uadd(r, a, b)) return 0;
- if (BN_ucmp(r, m) >= 0)
- return BN_usub(r, r, m);
- return 1;
- }
- int BN_mod_sub(BIGNUM *r, const BIGNUM *a, const BIGNUM *b, const BIGNUM *m, BN_CTX *ctx)
- {
- if (!BN_sub(r, a, b)) return 0;
- return BN_nnmod(r, r, m, ctx);
- }
- /* BN_mod_sub variant that may be used if both a and b are non-negative
- * and less than m */
- int BN_mod_sub_quick(BIGNUM *r, const BIGNUM *a, const BIGNUM *b, const BIGNUM *m)
- {
- if (!BN_sub(r, a, b)) return 0;
- if (r->neg)
- return BN_add(r, r, m);
- return 1;
- }
- /* slow but works */
- int BN_mod_mul(BIGNUM *r, const BIGNUM *a, const BIGNUM *b, const BIGNUM *m,
- BN_CTX *ctx)
- {
- BIGNUM *t;
- int ret=0;
- bn_check_top(a);
- bn_check_top(b);
- bn_check_top(m);
- BN_CTX_start(ctx);
- if ((t = BN_CTX_get(ctx)) == NULL) goto err;
- if (a == b)
- { if (!BN_sqr(t,a,ctx)) goto err; }
- else
- { if (!BN_mul(t,a,b,ctx)) goto err; }
- if (!BN_nnmod(r,t,m,ctx)) goto err;
- bn_check_top(r);
- ret=1;
- err:
- BN_CTX_end(ctx);
- return(ret);
- }
- int BN_mod_sqr(BIGNUM *r, const BIGNUM *a, const BIGNUM *m, BN_CTX *ctx)
- {
- if (!BN_sqr(r, a, ctx)) return 0;
- /* r->neg == 0, thus we don't need BN_nnmod */
- return BN_mod(r, r, m, ctx);
- }
- int BN_mod_lshift1(BIGNUM *r, const BIGNUM *a, const BIGNUM *m, BN_CTX *ctx)
- {
- if (!BN_lshift1(r, a)) return 0;
- bn_check_top(r);
- return BN_nnmod(r, r, m, ctx);
- }
- /* BN_mod_lshift1 variant that may be used if a is non-negative
- * and less than m */
- int BN_mod_lshift1_quick(BIGNUM *r, const BIGNUM *a, const BIGNUM *m)
- {
- if (!BN_lshift1(r, a)) return 0;
- bn_check_top(r);
- if (BN_cmp(r, m) >= 0)
- return BN_sub(r, r, m);
- return 1;
- }
- int BN_mod_lshift(BIGNUM *r, const BIGNUM *a, int n, const BIGNUM *m, BN_CTX *ctx)
- {
- BIGNUM *abs_m = NULL;
- int ret;
- if (!BN_nnmod(r, a, m, ctx)) return 0;
- if (m->neg)
- {
- abs_m = BN_dup(m);
- if (abs_m == NULL) return 0;
- abs_m->neg = 0;
- }
-
- ret = BN_mod_lshift_quick(r, r, n, (abs_m ? abs_m : m));
- bn_check_top(r);
- if (abs_m)
- BN_free(abs_m);
- return ret;
- }
- /* BN_mod_lshift variant that may be used if a is non-negative
- * and less than m */
- int BN_mod_lshift_quick(BIGNUM *r, const BIGNUM *a, int n, const BIGNUM *m)
- {
- if (r != a)
- {
- if (BN_copy(r, a) == NULL) return 0;
- }
- while (n > 0)
- {
- int max_shift;
-
- /* 0 < r < m */
- max_shift = BN_num_bits(m) - BN_num_bits(r);
- /* max_shift >= 0 */
- if (max_shift < 0)
- {
- BNerr(BN_F_BN_MOD_LSHIFT_QUICK, BN_R_INPUT_NOT_REDUCED);
- return 0;
- }
- if (max_shift > n)
- max_shift = n;
- if (max_shift)
- {
- if (!BN_lshift(r, r, max_shift)) return 0;
- n -= max_shift;
- }
- else
- {
- if (!BN_lshift1(r, r)) return 0;
- --n;
- }
- /* BN_num_bits(r) <= BN_num_bits(m) */
- if (BN_cmp(r, m) >= 0)
- {
- if (!BN_sub(r, r, m)) return 0;
- }
- }
- bn_check_top(r);
-
- return 1;
- }