1 /* crypto/bn/bn_exp2.c */
2 /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
5 * This package is an SSL implementation written
6 * by Eric Young (eay@cryptsoft.com).
7 * The implementation was written so as to conform with Netscapes SSL.
9 * This library is free for commercial and non-commercial use as long as
10 * the following conditions are aheared to. The following conditions
11 * apply to all code found in this distribution, be it the RC4, RSA,
12 * lhash, DES, etc., code; not just the SSL code. The SSL documentation
13 * included with this distribution is covered by the same copyright terms
14 * except that the holder is Tim Hudson (tjh@cryptsoft.com).
16 * Copyright remains Eric Young's, and as such any Copyright notices in
17 * the code are not to be removed.
18 * If this package is used in a product, Eric Young should be given attribution
19 * as the author of the parts of the library used.
20 * This can be in the form of a textual message at program startup or
21 * in documentation (online or textual) provided with the package.
23 * Redistribution and use in source and binary forms, with or without
24 * modification, are permitted provided that the following conditions
26 * 1. Redistributions of source code must retain the copyright
27 * notice, this list of conditions and the following disclaimer.
28 * 2. Redistributions in binary form must reproduce the above copyright
29 * notice, this list of conditions and the following disclaimer in the
30 * documentation and/or other materials provided with the distribution.
31 * 3. All advertising materials mentioning features or use of this software
32 * must display the following acknowledgement:
33 * "This product includes cryptographic software written by
34 * Eric Young (eay@cryptsoft.com)"
35 * The word 'cryptographic' can be left out if the rouines from the library
36 * being used are not cryptographic related :-).
37 * 4. If you include any Windows specific code (or a derivative thereof) from
38 * the apps directory (application code) you must include an acknowledgement:
39 * "This product includes software written by Tim Hudson (tjh@cryptsoft.com)"
41 * THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND
42 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
43 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
44 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
45 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
46 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
47 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
48 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
49 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
50 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
53 * The licence and distribution terms for any publically available version or
54 * derivative of this code cannot be changed. i.e. this code cannot simply be
55 * copied and put under another distribution licence
56 * [including the GNU Public Licence.]
58 /* ====================================================================
59 * Copyright (c) 1998-2000 The OpenSSL Project. All rights reserved.
61 * Redistribution and use in source and binary forms, with or without
62 * modification, are permitted provided that the following conditions
65 * 1. Redistributions of source code must retain the above copyright
66 * notice, this list of conditions and the following disclaimer.
68 * 2. Redistributions in binary form must reproduce the above copyright
69 * notice, this list of conditions and the following disclaimer in
70 * the documentation and/or other materials provided with the
73 * 3. All advertising materials mentioning features or use of this
74 * software must display the following acknowledgment:
75 * "This product includes software developed by the OpenSSL Project
76 * for use in the OpenSSL Toolkit. (http://www.openssl.org/)"
78 * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
79 * endorse or promote products derived from this software without
80 * prior written permission. For written permission, please contact
81 * openssl-core@openssl.org.
83 * 5. Products derived from this software may not be called "OpenSSL"
84 * nor may "OpenSSL" appear in their names without prior written
85 * permission of the OpenSSL Project.
87 * 6. Redistributions of any form whatsoever must retain the following
89 * "This product includes software developed by the OpenSSL Project
90 * for use in the OpenSSL Toolkit (http://www.openssl.org/)"
92 * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
93 * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
94 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
95 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE OpenSSL PROJECT OR
96 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
97 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
98 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
99 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
100 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
101 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
102 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
103 * OF THE POSSIBILITY OF SUCH DAMAGE.
104 * ====================================================================
106 * This product includes cryptographic software written by Eric Young
107 * (eay@cryptsoft.com). This product includes software written by Tim
108 * Hudson (tjh@cryptsoft.com).
113 #include "cryptlib.h"
116 #define TABLE_SIZE 32
118 int BN_mod_exp2_mont(BIGNUM *rr, const BIGNUM *a1, const BIGNUM *p1,
119 const BIGNUM *a2, const BIGNUM *p2, const BIGNUM *m,
120 BN_CTX *ctx, BN_MONT_CTX *in_mont)
122 int i,j,bits,b,bits1,bits2,ret=0,wpos1,wpos2,window1,window2,wvalue1,wvalue2;
123 int r_is_one=1,ts1=0,ts2=0;
125 const BIGNUM *a_mod_m;
126 BIGNUM val1[TABLE_SIZE], val2[TABLE_SIZE];
127 BN_MONT_CTX *mont=NULL;
137 BNerr(BN_F_BN_MOD_EXP2_MONT,BN_R_CALLED_WITH_EVEN_MODULUS);
140 bits1=BN_num_bits(p1);
141 bits2=BN_num_bits(p2);
142 if ((bits1 == 0) && (bits2 == 0))
148 bits=(bits1 > bits2)?bits1:bits2;
153 if (d == NULL || r == NULL) goto err;
159 if ((mont=BN_MONT_CTX_new()) == NULL) goto err;
160 if (!BN_MONT_CTX_set(mont,m,ctx)) goto err;
163 window1 = BN_window_bits_for_exponent_size(bits1);
164 window2 = BN_window_bits_for_exponent_size(bits2);
167 * Build table for a1: val1[i] := a1^(2*i + 1) mod m for i = 0 .. 2^(window1-1)
171 if (a1->neg || BN_ucmp(a1,m) >= 0)
173 if (!BN_mod(&(val1[0]),a1,m,ctx))
175 a_mod_m = &(val1[0]);
179 if (BN_is_zero(a_mod_m))
185 if (!BN_to_montgomery(&(val1[0]),a_mod_m,mont,ctx)) goto err;
188 if (!BN_mod_mul_montgomery(d,&(val1[0]),&(val1[0]),mont,ctx)) goto err;
194 if (!BN_mod_mul_montgomery(&(val1[i]),&(val1[i-1]),d,mont,ctx))
202 * Build table for a2: val2[i] := a2^(2*i + 1) mod m for i = 0 .. 2^(window2-1)
206 if (a2->neg || BN_ucmp(a2,m) >= 0)
208 if (!BN_mod(&(val2[0]),a2,m,ctx))
210 a_mod_m = &(val2[0]);
214 if (BN_is_zero(a_mod_m))
219 if (!BN_to_montgomery(&(val2[0]),a_mod_m,mont,ctx)) goto err;
222 if (!BN_mod_mul_montgomery(d,&(val2[0]),&(val2[0]),mont,ctx)) goto err;
228 if (!BN_mod_mul_montgomery(&(val2[i]),&(val2[i-1]),d,mont,ctx))
235 /* Now compute the power product, using independent windows. */
237 wvalue1=0; /* The 'value' of the first window */
238 wvalue2=0; /* The 'value' of the second window */
239 wpos1=0; /* If wvalue1 > 0, the bottom bit of the first window */
240 wpos2=0; /* If wvalue2 > 0, the bottom bit of the second window */
242 if (!BN_to_montgomery(r,BN_value_one(),mont,ctx)) goto err;
243 for (b=bits-1; b>=0; b--)
247 if (!BN_mod_mul_montgomery(r,r,r,mont,ctx))
252 if (BN_is_bit_set(p1, b))
254 /* consider bits b-window1+1 .. b for this window */
256 while (!BN_is_bit_set(p1, i)) /* works for i<0 */
260 for (i = b-1; i >= wpos1; i--)
263 if (BN_is_bit_set(p1, i))
269 if (BN_is_bit_set(p2, b))
271 /* consider bits b-window2+1 .. b for this window */
273 while (!BN_is_bit_set(p2, i))
277 for (i = b-1; i >= wpos2; i--)
280 if (BN_is_bit_set(p2, i))
285 if (wvalue1 && b == wpos1)
287 /* wvalue1 is odd and < 2^window1 */
288 if (!BN_mod_mul_montgomery(r,r,&(val1[wvalue1>>1]),mont,ctx))
294 if (wvalue2 && b == wpos2)
296 /* wvalue2 is odd and < 2^window2 */
297 if (!BN_mod_mul_montgomery(r,r,&(val2[wvalue2>>1]),mont,ctx))
303 BN_from_montgomery(rr,r,mont,ctx);
306 if ((in_mont == NULL) && (mont != NULL)) BN_MONT_CTX_free(mont);
308 for (i=0; i<ts1; i++)
309 BN_clear_free(&(val1[i]));
310 for (i=0; i<ts2; i++)
311 BN_clear_free(&(val2[i]));