GCC Code Coverage Report
Directory: ./ Exec Total Coverage
File: lib/libcrypto/bn/bn_sqr.c Lines: 82 94 87.2 %
Date: 2017-11-07 Branches: 42 53 79.2 %

Line Branch Exec Source
1
/* $OpenBSD: bn_sqr.c,v 1.12 2015/02/09 15:49:22 jsing 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
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
#include <stdio.h>
60
#include <string.h>
61
62
#include "bn_lcl.h"
63
64
/* r must not be a */
65
/* I've just gone over this and it is now %20 faster on x86 - eay - 27 Jun 96 */
66
int
67
BN_sqr(BIGNUM *r, const BIGNUM *a, BN_CTX *ctx)
68
{
69
	int max, al;
70
	int ret = 0;
71
	BIGNUM *tmp, *rr;
72
73
#ifdef BN_COUNT
74
	fprintf(stderr, "BN_sqr %d * %d\n", a->top, a->top);
75
#endif
76
	bn_check_top(a);
77
78
4871654
	al = a->top;
79
2435827
	if (al <= 0) {
80
11551
		r->top = 0;
81
11551
		r->neg = 0;
82
11551
		return 1;
83
	}
84
85
2424276
	BN_CTX_start(ctx);
86
7272828
	rr = (a != r) ? r : BN_CTX_get(ctx);
87
2424276
	tmp = BN_CTX_get(ctx);
88
2424276
	if (rr == NULL || tmp == NULL)
89
		goto err;
90
91
2424276
	max = 2 * al; /* Non-zero (from above) */
92

4890101
	if (bn_wexpand(rr, max) == NULL)
93
		goto err;
94
95
2424276
	if (al == 4) {
96
#ifndef BN_SQR_COMBA
97
		BN_ULONG t[8];
98
		bn_sqr_normal(rr->d, a->d, 4, t);
99
#else
100
58881
		bn_sqr_comba4(rr->d, a->d);
101
#endif
102
2424276
	} else if (al == 8) {
103
#ifndef BN_SQR_COMBA
104
		BN_ULONG t[16];
105
		bn_sqr_normal(rr->d, a->d, 8, t);
106
#else
107
729405
		bn_sqr_comba8(rr->d, a->d);
108
#endif
109
729405
	} else {
110
#if defined(BN_RECURSION)
111
1635990
		if (al < BN_SQR_RECURSIVE_SIZE_NORMAL) {
112
1574889
			BN_ULONG t[BN_SQR_RECURSIVE_SIZE_NORMAL*2];
113
1574889
			bn_sqr_normal(rr->d, a->d, al, t);
114
1574889
		} else {
115
			int j, k;
116
117
61101
			j = BN_num_bits_word((BN_ULONG)al);
118
61101
			j = 1 << (j - 1);
119
61101
			k = j + j;
120
61101
			if (al == j) {
121

144315
				if (bn_wexpand(tmp, k * 2) == NULL)
122
					goto err;
123
60971
				bn_sqr_recursive(rr->d, a->d, al, tmp->d);
124
60971
			} else {
125

328
				if (bn_wexpand(tmp, max) == NULL)
126
					goto err;
127
130
				bn_sqr_normal(rr->d, a->d, al, tmp->d);
128
			}
129
61101
		}
130
#else
131
		if (bn_wexpand(tmp, max) == NULL)
132
			goto err;
133
		bn_sqr_normal(rr->d, a->d, al, tmp->d);
134
#endif
135
	}
136
137
2424276
	rr->neg = 0;
138
	/* If the most-significant half of the top word of 'a' is zero, then
139
	 * the square of 'a' will max-1 words. */
140
4848552
	if (a->d[al - 1] == (a->d[al - 1] & BN_MASK2l))
141
2424276
		rr->top = max - 1;
142
	else
143
		rr->top = max;
144
2424276
	if (rr != r)
145
54132
		BN_copy(r, rr);
146
2424276
	ret = 1;
147
148
err:
149
	bn_check_top(rr);
150
	bn_check_top(tmp);
151
2424276
	BN_CTX_end(ctx);
152
2424276
	return (ret);
153
2435827
}
154
155
/* tmp must have 2*n words */
156
void
157
bn_sqr_normal(BN_ULONG *r, const BN_ULONG *a, int n, BN_ULONG *tmp)
158
{
159
	int i, j, max;
160
	const BN_ULONG *ap;
161
	BN_ULONG *rp;
162
163
3150038
	max = n * 2;
164
	ap = a;
165
	rp = r;
166
1575019
	rp[0] = rp[max - 1] = 0;
167
1575019
	rp++;
168
	j = n;
169
170
1575019
	if (--j > 0) {
171
383811
		ap++;
172
383811
		rp[j] = bn_mul_words(rp, ap, j, ap[-1]);
173
383811
		rp += 2;
174
383811
	}
175
176
5571998
	for (i = n - 2; i > 0; i--) {
177
1210980
		j--;
178
1210980
		ap++;
179
1210980
		rp[j] = bn_mul_add_words(rp, ap, j, ap[-1]);
180
1210980
		rp += 2;
181
	}
182
183
1575019
	bn_add_words(r, r, r, max);
184
185
	/* There will not be a carry */
186
187
1575019
	bn_sqr_words(tmp, a, n);
188
189
1575019
	bn_add_words(r, r, tmp, max);
190
1575019
}
191
192
#ifdef BN_RECURSION
193
/* r is 2*n words in size,
194
 * a and b are both n words in size.    (There's not actually a 'b' here ...)
195
 * n must be a power of 2.
196
 * We multiply and return the result.
197
 * t must be 2*n words in size
198
 * We calculate
199
 * a[0]*b[0]
200
 * a[0]*b[0]+a[1]*b[1]+(a[0]-a[1])*(b[1]-b[0])
201
 * a[1]*b[1]
202
 */
203
void
204
bn_sqr_recursive(BN_ULONG *r, const BN_ULONG *a, int n2, BN_ULONG *t)
205
{
206
1185664
	int n = n2 / 2;
207
	int zero, c1;
208
	BN_ULONG ln, lo, *p;
209
210
#ifdef BN_COUNT
211
	fprintf(stderr, " bn_sqr_recursive %d * %d\n", n2, n2);
212
#endif
213
592832
	if (n2 == 4) {
214
#ifndef BN_SQR_COMBA
215
		bn_sqr_normal(r, a, 4, t);
216
#else
217
		bn_sqr_comba4(r, a);
218
#endif
219
		return;
220
592832
	} else if (n2 == 8) {
221
#ifndef BN_SQR_COMBA
222
		bn_sqr_normal(r, a, 8, t);
223
#else
224
415545
		bn_sqr_comba8(r, a);
225
#endif
226
415545
		return;
227
	}
228
177287
	if (n2 < BN_SQR_RECURSIVE_SIZE_NORMAL) {
229
		bn_sqr_normal(r, a, n2, t);
230
		return;
231
	}
232
	/* r=(a[0]-a[1])*(a[1]-a[0]) */
233
177287
	c1 = bn_cmp_words(a, &(a[n]), n);
234
	zero = 0;
235
177287
	if (c1 > 0)
236
108583
		bn_sub_words(t, a, &(a[n]), n);
237
68704
	else if (c1 < 0)
238
68704
		bn_sub_words(t, &(a[n]), a, n);
239
	else
240
		zero = 1;
241
242
	/* The result will always be negative unless it is zero */
243
177287
	p = &(t[n2*2]);
244
245
177287
	if (!zero)
246
177287
		bn_sqr_recursive(&(t[n2]), t, n, p);
247
	else
248
		memset(&(t[n2]), 0, n2 * sizeof(BN_ULONG));
249
177287
	bn_sqr_recursive(r, a, n, p);
250
177287
	bn_sqr_recursive(&(r[n2]), &(a[n]), n, p);
251
252
	/* t[32] holds (a[0]-a[1])*(a[1]-a[0]), it is negative or zero
253
	 * r[10] holds (a[0]*b[0])
254
	 * r[32] holds (b[1]*b[1])
255
	 */
256
257
177287
	c1 = (int)(bn_add_words(t, r, &(r[n2]), n2));
258
259
	/* t[32] is negative */
260
177287
	c1 -= (int)(bn_sub_words(&(t[n2]), t, &(t[n2]), n2));
261
262
	/* t[32] holds (a[0]-a[1])*(a[1]-a[0])+(a[0]*a[0])+(a[1]*a[1])
263
	 * r[10] holds (a[0]*a[0])
264
	 * r[32] holds (a[1]*a[1])
265
	 * c1 holds the carry bits
266
	 */
267
177287
	c1 += (int)(bn_add_words(&(r[n]), &(r[n]), &(t[n2]), n2));
268
177287
	if (c1) {
269
65404
		p = &(r[n + n2]);
270
65404
		lo= *p;
271
65404
		ln = (lo + c1) & BN_MASK2;
272
65404
		*p = ln;
273
274
		/* The overflow will stop before we over write
275
		 * words we should not overwrite */
276
65404
		if (ln < (BN_ULONG)c1) {
277
			do {
278
				p++;
279
				lo= *p;
280
				ln = (lo + 1) & BN_MASK2;
281
				*p = ln;
282
			} while (ln == 0);
283
		}
284
	}
285
770119
}
286
#endif