1
/* crypto/bn/bn_mod.c */
2
/* Includes code written by Lenka Fibikova <fibikova@exp-math.uni-essen.de>
3
* for the OpenSSL project. */
4
/* ====================================================================
5
* Copyright (c) 1998-2000 The OpenSSL Project. All rights reserved.
7
* Redistribution and use in source and binary forms, with or without
8
* modification, are permitted provided that the following conditions
11
* 1. Redistributions of source code must retain the above copyright
12
* notice, this list of conditions and the following disclaimer.
14
* 2. Redistributions in binary form must reproduce the above copyright
15
* notice, this list of conditions and the following disclaimer in
16
* the documentation and/or other materials provided with the
19
* 3. All advertising materials mentioning features or use of this
20
* software must display the following acknowledgment:
21
* "This product includes software developed by the OpenSSL Project
22
* for use in the OpenSSL Toolkit. (http://www.openssl.org/)"
24
* 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
25
* endorse or promote products derived from this software without
26
* prior written permission. For written permission, please contact
27
* openssl-core@openssl.org.
29
* 5. Products derived from this software may not be called "OpenSSL"
30
* nor may "OpenSSL" appear in their names without prior written
31
* permission of the OpenSSL Project.
33
* 6. Redistributions of any form whatsoever must retain the following
35
* "This product includes software developed by the OpenSSL Project
36
* for use in the OpenSSL Toolkit (http://www.openssl.org/)"
38
* THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
39
* EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
40
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
41
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE OpenSSL PROJECT OR
42
* ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
43
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
44
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
45
* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
46
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
47
* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
48
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
49
* OF THE POSSIBILITY OF SUCH DAMAGE.
50
* ====================================================================
52
* This product includes cryptographic software written by Eric Young
53
* (eay@cryptsoft.com). This product includes software written by Tim
54
* Hudson (tjh@cryptsoft.com).
57
/* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
58
* All rights reserved.
60
* This package is an SSL implementation written
61
* by Eric Young (eay@cryptsoft.com).
62
* The implementation was written so as to conform with Netscapes SSL.
64
* This library is free for commercial and non-commercial use as long as
65
* the following conditions are aheared to. The following conditions
66
* apply to all code found in this distribution, be it the RC4, RSA,
67
* lhash, DES, etc., code; not just the SSL code. The SSL documentation
68
* included with this distribution is covered by the same copyright terms
69
* except that the holder is Tim Hudson (tjh@cryptsoft.com).
71
* Copyright remains Eric Young's, and as such any Copyright notices in
72
* the code are not to be removed.
73
* If this package is used in a product, Eric Young should be given attribution
74
* as the author of the parts of the library used.
75
* This can be in the form of a textual message at program startup or
76
* in documentation (online or textual) provided with the package.
78
* Redistribution and use in source and binary forms, with or without
79
* modification, are permitted provided that the following conditions
81
* 1. Redistributions of source code must retain the copyright
82
* notice, this list of conditions and the following disclaimer.
83
* 2. Redistributions in binary form must reproduce the above copyright
84
* notice, this list of conditions and the following disclaimer in the
85
* documentation and/or other materials provided with the distribution.
86
* 3. All advertising materials mentioning features or use of this software
87
* must display the following acknowledgement:
88
* "This product includes cryptographic software written by
89
* Eric Young (eay@cryptsoft.com)"
90
* The word 'cryptographic' can be left out if the rouines from the library
91
* being used are not cryptographic related :-).
92
* 4. If you include any Windows specific code (or a derivative thereof) from
93
* the apps directory (application code) you must include an acknowledgement:
94
* "This product includes software written by Tim Hudson (tjh@cryptsoft.com)"
96
* THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND
97
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
98
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
99
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
100
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
101
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
102
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
103
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
104
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
105
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
108
* The licence and distribution terms for any publically available version or
109
* derivative of this code cannot be changed. i.e. this code cannot simply be
110
* copied and put under another distribution licence
111
* [including the GNU Public Licence.]
114
#include "cryptlib.h"
118
#if 0 /* now just a #define */
119
int BN_mod(BIGNUM *rem, const BIGNUM *m, const BIGNUM *d, BN_CTX *ctx)
121
return(BN_div(NULL,rem,m,d,ctx));
122
/* note that rem->neg == m->neg (unless the remainder is zero) */
127
int BN_nnmod(BIGNUM *r, const BIGNUM *m, const BIGNUM *d, BN_CTX *ctx)
129
/* like BN_mod, but returns non-negative remainder
130
* (i.e., 0 <= r < |d| always holds) */
132
if (!(BN_mod(r,m,d,ctx)))
136
/* now -|d| < r < 0, so we have to set r := r + |d| */
137
return (d->neg ? BN_sub : BN_add)(r, r, d);
141
int BN_mod_add(BIGNUM *r, const BIGNUM *a, const BIGNUM *b, const BIGNUM *m, BN_CTX *ctx)
143
if (!BN_add(r, a, b)) return 0;
144
return BN_nnmod(r, r, m, ctx);
148
/* BN_mod_add variant that may be used if both a and b are non-negative
150
int BN_mod_add_quick(BIGNUM *r, const BIGNUM *a, const BIGNUM *b, const BIGNUM *m)
152
if (!BN_add(r, a, b)) return 0;
153
if (BN_ucmp(r, m) >= 0)
154
return BN_usub(r, r, m);
159
int BN_mod_sub(BIGNUM *r, const BIGNUM *a, const BIGNUM *b, const BIGNUM *m, BN_CTX *ctx)
161
if (!BN_sub(r, a, b)) return 0;
162
return BN_nnmod(r, r, m, ctx);
166
/* BN_mod_sub variant that may be used if both a and b are non-negative
168
int BN_mod_sub_quick(BIGNUM *r, const BIGNUM *a, const BIGNUM *b, const BIGNUM *m)
170
if (!BN_sub(r, a, b)) return 0;
172
return BN_add(r, r, m);
178
int BN_mod_mul(BIGNUM *r, const BIGNUM *a, const BIGNUM *b, const BIGNUM *m,
189
if ((t = BN_CTX_get(ctx)) == NULL) goto err;
191
{ if (!BN_sqr(t,a,ctx)) goto err; }
193
{ if (!BN_mul(t,a,b,ctx)) goto err; }
194
if (!BN_nnmod(r,t,m,ctx)) goto err;
202
int BN_mod_sqr(BIGNUM *r, const BIGNUM *a, const BIGNUM *m, BN_CTX *ctx)
204
if (!BN_sqr(r, a, ctx)) return 0;
205
/* r->neg == 0, thus we don't need BN_nnmod */
206
return BN_mod(r, r, m, ctx);
210
int BN_mod_lshift1(BIGNUM *r, const BIGNUM *a, const BIGNUM *m, BN_CTX *ctx)
212
if (!BN_lshift1(r, a)) return 0;
213
return BN_nnmod(r, r, m, ctx);
217
/* BN_mod_lshift1 variant that may be used if a is non-negative
219
int BN_mod_lshift1_quick(BIGNUM *r, const BIGNUM *a, const BIGNUM *m)
221
if (!BN_lshift1(r, a)) return 0;
222
if (BN_cmp(r, m) >= 0)
223
return BN_sub(r, r, m);
228
int BN_mod_lshift(BIGNUM *r, const BIGNUM *a, int n, const BIGNUM *m, BN_CTX *ctx)
230
BIGNUM *abs_m = NULL;
233
if (!BN_nnmod(r, a, m, ctx)) return 0;
238
if (abs_m == NULL) return 0;
242
ret = BN_mod_lshift_quick(r, r, n, (abs_m ? abs_m : m));
250
/* BN_mod_lshift variant that may be used if a is non-negative
252
int BN_mod_lshift_quick(BIGNUM *r, const BIGNUM *a, int n, const BIGNUM *m)
256
if (BN_copy(r, a) == NULL) return 0;
264
max_shift = BN_num_bits(m) - BN_num_bits(r);
269
BNerr(BN_F_BN_MOD_LSHIFT_QUICK, BN_R_INPUT_NOT_REDUCED);
278
if (!BN_lshift(r, r, max_shift)) return 0;
283
if (!BN_lshift1(r, r)) return 0;
287
/* BN_num_bits(r) <= BN_num_bits(m) */
289
if (BN_cmp(r, m) >= 0)
291
if (!BN_sub(r, r, m)) return 0;