GCC Code Coverage Report
Directory: ./ Exec Total Coverage
File: lib/libcrypto/bn/bn_exp2.c Lines: 67 84 79.8 %
Date: 2017-11-07 Branches: 71 114 62.3 %

Line Branch Exec Source
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/* $OpenBSD: bn_exp2.c,v 1.12 2017/01/29 17:49:22 beck Exp $ */
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
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 * 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
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 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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 * SUCH DAMAGE.
52
 *
53
 * The licence and distribution terms for any publically available version or
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 * derivative of this code cannot be changed.  i.e. this code cannot simply be
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 * copied and put under another distribution licence
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 * [including the GNU Public Licence.]
57
 */
58
/* ====================================================================
59
 * Copyright (c) 1998-2000 The OpenSSL Project.  All rights reserved.
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 *
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"
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 *    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
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 * 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;
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 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
100
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
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 * 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
#include <stdio.h>
113
114
#include <openssl/err.h>
115
116
#include "bn_lcl.h"
117
118
#define TABLE_SIZE	32
119
120
int
121
BN_mod_exp2_mont(BIGNUM *rr, const BIGNUM *a1, const BIGNUM *p1,
122
    const BIGNUM *a2, const BIGNUM *p2, const BIGNUM *m, BN_CTX *ctx,
123
    BN_MONT_CTX *in_mont)
124
{
125
	int i, j, bits, b, bits1, bits2, ret = 0, wpos1, wpos2, window1, window2, wvalue1, wvalue2;
126
	int r_is_one = 1;
127
	BIGNUM *d, *r;
128
	const BIGNUM *a_mod_m;
129
	/* Tables of variables obtained from 'ctx' */
130
28
	BIGNUM *val1[TABLE_SIZE], *val2[TABLE_SIZE];
131
	BN_MONT_CTX *mont = NULL;
132
133
	bn_check_top(a1);
134
	bn_check_top(p1);
135
	bn_check_top(a2);
136
	bn_check_top(p2);
137
	bn_check_top(m);
138
139
14
	if (!(m->d[0] & 1)) {
140
		BNerror(BN_R_CALLED_WITH_EVEN_MODULUS);
141
		return (0);
142
	}
143
14
	bits1 = BN_num_bits(p1);
144
14
	bits2 = BN_num_bits(p2);
145
14
	if ((bits1 == 0) && (bits2 == 0)) {
146
		ret = BN_one(rr);
147
		return ret;
148
	}
149
150
14
	bits = (bits1 > bits2) ? bits1 : bits2;
151
152
14
	BN_CTX_start(ctx);
153
14
	if ((d = BN_CTX_get(ctx)) == NULL)
154
		goto err;
155
14
	if ((r = BN_CTX_get(ctx)) == NULL)
156
		goto err;
157
14
	if ((val1[0] = BN_CTX_get(ctx)) == NULL)
158
		goto err;
159
14
	if ((val2[0] = BN_CTX_get(ctx)) == NULL)
160
		goto err;
161
162
14
	if (in_mont != NULL)
163
14
		mont = in_mont;
164
	else {
165
		if ((mont = BN_MONT_CTX_new()) == NULL)
166
			goto err;
167
		if (!BN_MONT_CTX_set(mont, m, ctx))
168
			goto err;
169
	}
170
171

56
	window1 = BN_window_bits_for_exponent_size(bits1);
172

56
	window2 = BN_window_bits_for_exponent_size(bits2);
173
174
	/*
175
	 * Build table for a1:   val1[i] := a1^(2*i + 1) mod m  for i = 0 .. 2^(window1-1)
176
	 */
177

28
	if (a1->neg || BN_ucmp(a1, m) >= 0) {
178
		if (!BN_mod_ct(val1[0], a1, m, ctx))
179
			goto err;
180
		a_mod_m = val1[0];
181
	} else
182
		a_mod_m = a1;
183
14
	if (BN_is_zero(a_mod_m)) {
184
		BN_zero(rr);
185
		ret = 1;
186
		goto err;
187
	}
188
189
14
	if (!BN_to_montgomery(val1[0], a_mod_m, mont, ctx))
190
		goto err;
191
14
	if (window1 > 1) {
192
14
		if (!BN_mod_mul_montgomery(d, val1[0], val1[0], mont, ctx))
193
			goto err;
194
195
14
		j = 1 << (window1 - 1);
196
224
		for (i = 1; i < j; i++) {
197

196
			if (((val1[i] = BN_CTX_get(ctx)) == NULL) ||
198
98
			    !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

28
	if (a2->neg || BN_ucmp(a2, m) >= 0) {
209
		if (!BN_mod_ct(val2[0], a2, m, ctx))
210
			goto err;
211
		a_mod_m = val2[0];
212
	} else
213
		a_mod_m = a2;
214
14
	if (BN_is_zero(a_mod_m)) {
215
		BN_zero(rr);
216
		ret = 1;
217
		goto err;
218
	}
219
14
	if (!BN_to_montgomery(val2[0], a_mod_m, mont, ctx))
220
		goto err;
221
14
	if (window2 > 1) {
222
14
		if (!BN_mod_mul_montgomery(d, val2[0], val2[0], mont, ctx))
223
			goto err;
224
225
14
		j = 1 << (window2 - 1);
226
224
		for (i = 1; i < j; i++) {
227

196
			if (((val2[i] = BN_CTX_get(ctx)) == NULL) ||
228
98
			    !BN_mod_mul_montgomery(val2[i], val2[i - 1],
229
			    d, mont, ctx))
230
				goto err;
231
		}
232
	}
233
234
235
	/* Now compute the power product, using independent windows. */
236
	r_is_one = 1;
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 */
241
242
14
	if (!BN_to_montgomery(r, BN_value_one(), mont, ctx))
243
		goto err;
244
4500
	for (b = bits - 1; b >= 0; b--) {
245
2236
		if (!r_is_one) {
246
2203
			if (!BN_mod_mul_montgomery(r, r,r, mont, ctx))
247
				goto err;
248
		}
249
250
2236
		if (!wvalue1)
251
1294
			if (BN_is_bit_set(p1, b)) {
252
			/* consider bits b-window1+1 .. b for this window */
253
456
			i = b - window1 + 1;
254
1764
			while (!BN_is_bit_set(p1, i)) /* works for i<0 */
255
426
				i++;
256
			wpos1 = i;
257
			wvalue1 = 1;
258
2796
			for (i = b - 1; i >= wpos1; i--) {
259
942
				wvalue1 <<= 1;
260
942
				if (BN_is_bit_set(p1, i))
261
651
					wvalue1++;
262
			}
263
		}
264
265
2236
		if (!wvalue2)
266
1302
			if (BN_is_bit_set(p2, b)) {
267
			/* consider bits b-window2+1 .. b for this window */
268
457
			i = b - window2 + 1;
269
1788
			while (!BN_is_bit_set(p2, i))
270
437
				i++;
271
			wpos2 = i;
272
			wvalue2 = 1;
273
2782
			for (i = b - 1; i >= wpos2; i--) {
274
934
				wvalue2 <<= 1;
275
934
				if (BN_is_bit_set(p2, i))
276
638
					wvalue2++;
277
			}
278
		}
279
280

3634
		if (wvalue1 && b == wpos1) {
281
			/* wvalue1 is odd and < 2^window1 */
282
456
			if (!BN_mod_mul_montgomery(r, r, val1[wvalue1 >> 1],
283
			    mont, ctx))
284
				goto err;
285
			wvalue1 = 0;
286
			r_is_one = 0;
287
456
		}
288
289

3627
		if (wvalue2 && b == wpos2) {
290
			/* wvalue2 is odd and < 2^window2 */
291
457
			if (!BN_mod_mul_montgomery(r, r, val2[wvalue2 >> 1],
292
			    mont, ctx))
293
				goto err;
294
			wvalue2 = 0;
295
			r_is_one = 0;
296
457
		}
297
	}
298
14
	if (!BN_from_montgomery(rr, r,mont, ctx))
299
		goto err;
300
14
	ret = 1;
301
302
err:
303
14
	if ((in_mont == NULL) && (mont != NULL))
304
		BN_MONT_CTX_free(mont);
305
14
	BN_CTX_end(ctx);
306
	bn_check_top(rr);
307
14
	return (ret);
308
14
}