1 /* crypto/bn/bn_mod.c */
3 * Includes code written by Lenka Fibikova <fibikova@exp-math.uni-essen.de>
4 * for the OpenSSL project.
6 /* ====================================================================
7 * Copyright (c) 1998-2000 The OpenSSL Project. All rights reserved.
9 * Redistribution and use in source and binary forms, with or without
10 * modification, are permitted provided that the following conditions
13 * 1. Redistributions of source code must retain the above copyright
14 * notice, this list of conditions and the following disclaimer.
16 * 2. Redistributions in binary form must reproduce the above copyright
17 * notice, this list of conditions and the following disclaimer in
18 * the documentation and/or other materials provided with the
21 * 3. All advertising materials mentioning features or use of this
22 * software must display the following acknowledgment:
23 * "This product includes software developed by the OpenSSL Project
24 * for use in the OpenSSL Toolkit. (http://www.openssl.org/)"
26 * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
27 * endorse or promote products derived from this software without
28 * prior written permission. For written permission, please contact
29 * openssl-core@openssl.org.
31 * 5. Products derived from this software may not be called "OpenSSL"
32 * nor may "OpenSSL" appear in their names without prior written
33 * permission of the OpenSSL Project.
35 * 6. Redistributions of any form whatsoever must retain the following
37 * "This product includes software developed by the OpenSSL Project
38 * for use in the OpenSSL Toolkit (http://www.openssl.org/)"
40 * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
41 * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
42 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
43 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE OpenSSL PROJECT OR
44 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
45 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
46 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
47 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
48 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
49 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
50 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
51 * OF THE POSSIBILITY OF SUCH DAMAGE.
52 * ====================================================================
54 * This product includes cryptographic software written by Eric Young
55 * (eay@cryptsoft.com). This product includes software written by Tim
56 * Hudson (tjh@cryptsoft.com).
59 /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
60 * All rights reserved.
62 * This package is an SSL implementation written
63 * by Eric Young (eay@cryptsoft.com).
64 * The implementation was written so as to conform with Netscapes SSL.
66 * This library is free for commercial and non-commercial use as long as
67 * the following conditions are aheared to. The following conditions
68 * apply to all code found in this distribution, be it the RC4, RSA,
69 * lhash, DES, etc., code; not just the SSL code. The SSL documentation
70 * included with this distribution is covered by the same copyright terms
71 * except that the holder is Tim Hudson (tjh@cryptsoft.com).
73 * Copyright remains Eric Young's, and as such any Copyright notices in
74 * the code are not to be removed.
75 * If this package is used in a product, Eric Young should be given attribution
76 * as the author of the parts of the library used.
77 * This can be in the form of a textual message at program startup or
78 * in documentation (online or textual) provided with the package.
80 * Redistribution and use in source and binary forms, with or without
81 * modification, are permitted provided that the following conditions
83 * 1. Redistributions of source code must retain the copyright
84 * notice, this list of conditions and the following disclaimer.
85 * 2. Redistributions in binary form must reproduce the above copyright
86 * notice, this list of conditions and the following disclaimer in the
87 * documentation and/or other materials provided with the distribution.
88 * 3. All advertising materials mentioning features or use of this software
89 * must display the following acknowledgement:
90 * "This product includes cryptographic software written by
91 * Eric Young (eay@cryptsoft.com)"
92 * The word 'cryptographic' can be left out if the rouines from the library
93 * being used are not cryptographic related :-).
94 * 4. If you include any Windows specific code (or a derivative thereof) from
95 * the apps directory (application code) you must include an acknowledgement:
96 * "This product includes software written by Tim Hudson (tjh@cryptsoft.com)"
98 * THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND
99 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
100 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
101 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
102 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
103 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
104 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
105 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
106 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
107 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
110 * The licence and distribution terms for any publically available version or
111 * derivative of this code cannot be changed. i.e. this code cannot simply be
112 * copied and put under another distribution licence
113 * [including the GNU Public Licence.]
116 #include "cryptlib.h"
119 #if 0 /* now just a #define */
120 int BN_mod(BIGNUM *rem, const BIGNUM *m, const BIGNUM *d, BN_CTX *ctx)
122 return (BN_div(NULL, rem, m, d, ctx));
123 /* 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)
130 * like BN_mod, but returns non-negative remainder (i.e., 0 <= r < |d|
134 if (!(BN_mod(r, m, d, ctx)))
138 /* now -|d| < r < 0, so we have to set r := r + |d| */
139 return (d->neg ? BN_sub : BN_add) (r, r, d);
142 int BN_mod_add(BIGNUM *r, const BIGNUM *a, const BIGNUM *b, const BIGNUM *m,
145 if (!BN_add(r, a, b))
147 return BN_nnmod(r, r, m, ctx);
151 * BN_mod_add variant that may be used if both a and b are non-negative and
152 * less than m. The original algorithm was
154 * if (!BN_uadd(r, a, b))
156 * if (BN_ucmp(r, m) >= 0)
157 * return BN_usub(r, r, m);
159 * which is replaced with addition, subtracting modulus, and conditional
160 * move depending on whether or not subtraction borrowed.
162 int bn_mod_add_fixed_top(BIGNUM *r, const BIGNUM *a, const BIGNUM *b,
165 size_t i, ai, bi, mtop = m->top;
166 BN_ULONG storage[1024 / BN_BITS2];
167 BN_ULONG carry, temp, mask, *rp, *tp = storage;
168 const BN_ULONG *ap, *bp;
170 if (bn_wexpand(r, m->top) == NULL)
173 if (mtop > sizeof(storage) / sizeof(storage[0])
174 && (tp = OPENSSL_malloc(mtop * sizeof(BN_ULONG))) == NULL)
177 ap = a->d != NULL ? a->d : tp;
178 bp = b->d != NULL ? b->d : tp;
180 for (i = 0, ai = 0, bi = 0, carry = 0; i < mtop;) {
181 mask = (BN_ULONG)0 - ((i - a->top) >> (8 * sizeof(i) - 1));
182 temp = ((ap[ai] & mask) + carry) & BN_MASK2;
183 carry = (temp < carry);
185 mask = (BN_ULONG)0 - ((i - b->top) >> (8 * sizeof(i) - 1));
186 tp[i] = ((bp[bi] & mask) + temp) & BN_MASK2;
187 carry += (tp[i] < temp);
190 ai += (i - a->dmax) >> (8 * sizeof(i) - 1);
191 bi += (i - b->dmax) >> (8 * sizeof(i) - 1);
194 carry -= bn_sub_words(rp, tp, m->d, mtop);
195 for (i = 0; i < mtop; i++) {
196 rp[i] = (carry & tp[i]) | (~carry & rp[i]);
197 ((volatile BN_ULONG *)tp)[i] = 0;
207 int BN_mod_add_quick(BIGNUM *r, const BIGNUM *a, const BIGNUM *b,
210 int ret = bn_mod_add_fixed_top(r, a, b, m);
218 int BN_mod_sub(BIGNUM *r, const BIGNUM *a, const BIGNUM *b, const BIGNUM *m,
221 if (!BN_sub(r, a, b))
223 return BN_nnmod(r, r, m, ctx);
227 * BN_mod_sub variant that may be used if both a and b are non-negative and
230 int BN_mod_sub_quick(BIGNUM *r, const BIGNUM *a, const BIGNUM *b,
233 if (!BN_sub(r, a, b))
236 return BN_add(r, r, m);
241 int BN_mod_mul(BIGNUM *r, const BIGNUM *a, const BIGNUM *b, const BIGNUM *m,
252 if ((t = BN_CTX_get(ctx)) == NULL)
255 if (!BN_sqr(t, a, ctx))
258 if (!BN_mul(t, a, b, ctx))
261 if (!BN_nnmod(r, t, m, ctx))
270 int BN_mod_sqr(BIGNUM *r, const BIGNUM *a, const BIGNUM *m, BN_CTX *ctx)
272 if (!BN_sqr(r, a, ctx))
274 /* r->neg == 0, thus we don't need BN_nnmod */
275 return BN_mod(r, r, m, ctx);
278 int BN_mod_lshift1(BIGNUM *r, const BIGNUM *a, const BIGNUM *m, BN_CTX *ctx)
280 if (!BN_lshift1(r, a))
283 return BN_nnmod(r, r, m, ctx);
287 * BN_mod_lshift1 variant that may be used if a is non-negative and less than
290 int BN_mod_lshift1_quick(BIGNUM *r, const BIGNUM *a, const BIGNUM *m)
292 if (!BN_lshift1(r, a))
295 if (BN_cmp(r, m) >= 0)
296 return BN_sub(r, r, m);
300 int BN_mod_lshift(BIGNUM *r, const BIGNUM *a, int n, const BIGNUM *m,
303 BIGNUM *abs_m = NULL;
306 if (!BN_nnmod(r, a, m, ctx))
316 ret = BN_mod_lshift_quick(r, r, n, (abs_m ? abs_m : m));
325 * BN_mod_lshift variant that may be used if a is non-negative and less than
328 int BN_mod_lshift_quick(BIGNUM *r, const BIGNUM *a, int n, const BIGNUM *m)
331 if (BN_copy(r, a) == NULL)
339 max_shift = BN_num_bits(m) - BN_num_bits(r);
343 BNerr(BN_F_BN_MOD_LSHIFT_QUICK, BN_R_INPUT_NOT_REDUCED);
351 if (!BN_lshift(r, r, max_shift))
355 if (!BN_lshift1(r, r))
360 /* BN_num_bits(r) <= BN_num_bits(m) */
362 if (BN_cmp(r, m) >= 0) {
363 if (!BN_sub(r, r, m))