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1 : : /* crypto/bn/bn_exp2.c */
2 : : /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
3 : : * All rights reserved.
4 : : *
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.
8 : : *
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).
15 : : *
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.
22 : : *
23 : : * Redistribution and use in source and binary forms, with or without
24 : : * modification, are permitted provided that the following conditions
25 : : * are met:
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)"
40 : : *
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
51 : : * SUCH DAMAGE.
52 : : *
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.]
57 : : */
58 : : /* ====================================================================
59 : : * Copyright (c) 1998-2000 The OpenSSL Project. All rights reserved.
60 : : *
61 : : * Redistribution and use in source and binary forms, with or without
62 : : * modification, are permitted provided that the following conditions
63 : : * are met:
64 : : *
65 : : * 1. Redistributions of source code must retain the above copyright
66 : : * notice, this list of conditions and the following disclaimer.
67 : : *
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
71 : : * distribution.
72 : : *
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/)"
77 : : *
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.
82 : : *
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.
86 : : *
87 : : * 6. Redistributions of any form whatsoever must retain the following
88 : : * acknowledgment:
89 : : * "This product includes software developed by the OpenSSL Project
90 : : * for use in the OpenSSL Toolkit (http://www.openssl.org/)"
91 : : *
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 : : * ====================================================================
105 : : *
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).
109 : : *
110 : : */
111 : :
112 : : #define OPENSSL_FIPSAPI
113 : :
114 : : #include <stdio.h>
115 : : #include "cryptlib.h"
116 : : #include "bn_lcl.h"
117 : :
118 : : #define TABLE_SIZE 32
119 : :
120 : 45 : int BN_mod_exp2_mont(BIGNUM *rr, const BIGNUM *a1, const BIGNUM *p1,
121 : : const BIGNUM *a2, const BIGNUM *p2, const BIGNUM *m,
122 : : BN_CTX *ctx, BN_MONT_CTX *in_mont)
123 : : {
124 : 45 : int i,j,bits,b,bits1,bits2,ret=0,wpos1,wpos2,window1,window2,wvalue1,wvalue2;
125 : 45 : int r_is_one=1;
126 : : BIGNUM *d,*r;
127 : : const BIGNUM *a_mod_m;
128 : : /* Tables of variables obtained from 'ctx' */
129 : : BIGNUM *val1[TABLE_SIZE], *val2[TABLE_SIZE];
130 : 45 : BN_MONT_CTX *mont=NULL;
131 : :
132 : : bn_check_top(a1);
133 : : bn_check_top(p1);
134 : : bn_check_top(a2);
135 : : bn_check_top(p2);
136 : : bn_check_top(m);
137 : :
138 [ - + ]: 45 : if (!(m->d[0] & 1))
139 : : {
140 : 0 : BNerr(BN_F_BN_MOD_EXP2_MONT,BN_R_CALLED_WITH_EVEN_MODULUS);
141 : 0 : return(0);
142 : : }
143 : 45 : bits1=BN_num_bits(p1);
144 : 45 : bits2=BN_num_bits(p2);
145 [ - + ]: 45 : if ((bits1 == 0) && (bits2 == 0))
146 : : {
147 : 0 : ret = BN_one(rr);
148 : 0 : return ret;
149 : : }
150 : :
151 : 45 : bits=(bits1 > bits2)?bits1:bits2;
152 : :
153 : 45 : BN_CTX_start(ctx);
154 : 45 : d = BN_CTX_get(ctx);
155 : 45 : r = BN_CTX_get(ctx);
156 : 45 : val1[0] = BN_CTX_get(ctx);
157 : 45 : val2[0] = BN_CTX_get(ctx);
158 [ + - ][ + - ]: 45 : if(!d || !r || !val1[0] || !val2[0]) goto err;
[ + - ]
159 : :
160 [ - + ]: 45 : if (in_mont != NULL)
161 : : mont=in_mont;
162 : : else
163 : : {
164 [ # # ]: 0 : if ((mont=BN_MONT_CTX_new()) == NULL) goto err;
165 [ # # ]: 0 : if (!BN_MONT_CTX_set(mont,m,ctx)) goto err;
166 : : }
167 : :
168 [ + - ][ + + ]: 45 : window1 = BN_window_bits_for_exponent_size(bits1);
[ - + ][ # # ]
169 [ + - ][ + + ]: 45 : window2 = BN_window_bits_for_exponent_size(bits2);
[ - + ][ # # ]
170 : :
171 : : /*
172 : : * Build table for a1: val1[i] := a1^(2*i + 1) mod m for i = 0 .. 2^(window1-1)
173 : : */
174 [ + - ][ - + ]: 45 : if (a1->neg || BN_ucmp(a1,m) >= 0)
175 : : {
176 [ # # ]: 0 : if (!BN_mod(val1[0],a1,m,ctx))
177 : : goto err;
178 : : a_mod_m = val1[0];
179 : : }
180 : : else
181 : : a_mod_m = a1;
182 [ - + ]: 45 : if (BN_is_zero(a_mod_m))
183 : : {
184 : 0 : BN_zero(rr);
185 : 0 : ret = 1;
186 : 0 : goto err;
187 : : }
188 : :
189 [ + - ]: 45 : if (!BN_to_montgomery(val1[0],a_mod_m,mont,ctx)) goto err;
190 [ + - ]: 45 : if (window1 > 1)
191 : : {
192 [ + - ]: 45 : if (!BN_mod_mul_montgomery(d,val1[0],val1[0],mont,ctx)) goto err;
193 : :
194 : 45 : j=1<<(window1-1);
195 [ + + ]: 680 : for (i=1; i<j; i++)
196 : : {
197 [ + - + - ]: 1270 : if(((val1[i] = BN_CTX_get(ctx)) == NULL) ||
198 : 635 : !BN_mod_mul_montgomery(val1[i],val1[i-1],
199 : : d,mont,ctx))
200 : : goto err;
201 : : }
202 : : }
203 : :
204 : :
205 : : /*
206 : : * Build table for a2: val2[i] := a2^(2*i + 1) mod m for i = 0 .. 2^(window2-1)
207 : : */
208 [ + - ][ - + ]: 45 : if (a2->neg || BN_ucmp(a2,m) >= 0)
209 : : {
210 [ # # ]: 0 : if (!BN_mod(val2[0],a2,m,ctx))
211 : : goto err;
212 : : a_mod_m = val2[0];
213 : : }
214 : : else
215 : : a_mod_m = a2;
216 [ - + ]: 45 : if (BN_is_zero(a_mod_m))
217 : : {
218 : 0 : BN_zero(rr);
219 : 0 : ret = 1;
220 : 0 : goto err;
221 : : }
222 [ + - ]: 45 : if (!BN_to_montgomery(val2[0],a_mod_m,mont,ctx)) goto err;
223 [ + - ]: 45 : if (window2 > 1)
224 : : {
225 [ + - ]: 45 : if (!BN_mod_mul_montgomery(d,val2[0],val2[0],mont,ctx)) goto err;
226 : :
227 : 45 : j=1<<(window2-1);
228 [ + + ]: 680 : for (i=1; i<j; i++)
229 : : {
230 [ + - + - ]: 1270 : if(((val2[i] = BN_CTX_get(ctx)) == NULL) ||
231 : 635 : !BN_mod_mul_montgomery(val2[i],val2[i-1],
232 : : d,mont,ctx))
233 : : goto err;
234 : : }
235 : : }
236 : :
237 : :
238 : : /* Now compute the power product, using independent windows. */
239 : 45 : r_is_one=1;
240 : 45 : wvalue1=0; /* The 'value' of the first window */
241 : 45 : wvalue2=0; /* The 'value' of the second window */
242 : 45 : wpos1=0; /* If wvalue1 > 0, the bottom bit of the first window */
243 : 45 : wpos2=0; /* If wvalue2 > 0, the bottom bit of the second window */
244 : :
245 [ + - ]: 45 : if (!BN_to_montgomery(r,BN_value_one(),mont,ctx)) goto err;
246 [ + + ]: 11057 : for (b=bits-1; b>=0; b--)
247 : : {
248 [ + + ]: 11012 : if (!r_is_one)
249 : : {
250 [ + - ]: 10845 : if (!BN_mod_mul_montgomery(r,r,r,mont,ctx))
251 : : goto err;
252 : : }
253 : :
254 [ + + ]: 11012 : if (!wvalue1)
255 [ + + ]: 5434 : if (BN_is_bit_set(p1, b))
256 : : {
257 : : /* consider bits b-window1+1 .. b for this window */
258 : 1898 : i = b-window1+1;
259 [ + + ]: 3745 : while (!BN_is_bit_set(p1, i)) /* works for i<0 */
260 : 1847 : i++;
261 : 1898 : wpos1 = i;
262 : 1898 : wvalue1 = 1;
263 [ + + ]: 7476 : for (i = b-1; i >= wpos1; i--)
264 : : {
265 : 5578 : wvalue1 <<= 1;
266 [ + + ]: 5578 : if (BN_is_bit_set(p1, i))
267 : 3616 : wvalue1++;
268 : : }
269 : : }
270 : :
271 [ + + ]: 11012 : if (!wvalue2)
272 [ + + ]: 5416 : if (BN_is_bit_set(p2, b))
273 : : {
274 : : /* consider bits b-window2+1 .. b for this window */
275 : 1886 : i = b-window2+1;
276 [ + + ]: 3675 : while (!BN_is_bit_set(p2, i))
277 : 1789 : i++;
278 : 1886 : wpos2 = i;
279 : 1886 : wvalue2 = 1;
280 [ + + ]: 7482 : for (i = b-1; i >= wpos2; i--)
281 : : {
282 : 5596 : wvalue2 <<= 1;
283 [ + + ]: 5596 : if (BN_is_bit_set(p2, i))
284 : 3747 : wvalue2++;
285 : : }
286 : : }
287 : :
288 [ + + ]: 11012 : if (wvalue1 && b == wpos1)
289 : : {
290 : : /* wvalue1 is odd and < 2^window1 */
291 [ + - ]: 1898 : if (!BN_mod_mul_montgomery(r,r,val1[wvalue1>>1],mont,ctx))
292 : : goto err;
293 : : wvalue1 = 0;
294 : : r_is_one = 0;
295 : : }
296 : :
297 [ + + ]: 11012 : if (wvalue2 && b == wpos2)
298 : : {
299 : : /* wvalue2 is odd and < 2^window2 */
300 [ + - ]: 1886 : if (!BN_mod_mul_montgomery(r,r,val2[wvalue2>>1],mont,ctx))
301 : : goto err;
302 : : wvalue2 = 0;
303 : : r_is_one = 0;
304 : : }
305 : : }
306 [ + - ]: 45 : if (!BN_from_montgomery(rr,r,mont,ctx))
307 : : goto err;
308 : 45 : ret=1;
309 : : err:
310 [ - + ]: 45 : if ((in_mont == NULL) && (mont != NULL)) BN_MONT_CTX_free(mont);
311 : 45 : BN_CTX_end(ctx);
312 : : bn_check_top(rr);
313 : 45 : return(ret);
314 : : }
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