1 /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
4 * This package is an SSL implementation written
5 * by Eric Young (eay@cryptsoft.com).
6 * The implementation was written so as to conform with Netscapes SSL.
8 * This library is free for commercial and non-commercial use as long as
9 * the following conditions are aheared to. The following conditions
10 * apply to all code found in this distribution, be it the RC4, RSA,
11 * lhash, DES, etc., code; not just the SSL code. The SSL documentation
12 * included with this distribution is covered by the same copyright terms
13 * except that the holder is Tim Hudson (tjh@cryptsoft.com).
15 * Copyright remains Eric Young's, and as such any Copyright notices in
16 * the code are not to be removed.
17 * If this package is used in a product, Eric Young should be given attribution
18 * as the author of the parts of the library used.
19 * This can be in the form of a textual message at program startup or
20 * in documentation (online or textual) provided with the package.
22 * Redistribution and use in source and binary forms, with or without
23 * modification, are permitted provided that the following conditions
25 * 1. Redistributions of source code must retain the copyright
26 * notice, this list of conditions and the following disclaimer.
27 * 2. Redistributions in binary form must reproduce the above copyright
28 * notice, this list of conditions and the following disclaimer in the
29 * documentation and/or other materials provided with the distribution.
30 * 3. All advertising materials mentioning features or use of this software
31 * must display the following acknowledgement:
32 * "This product includes cryptographic software written by
33 * Eric Young (eay@cryptsoft.com)"
34 * The word 'cryptographic' can be left out if the rouines from the library
35 * being used are not cryptographic related :-).
36 * 4. If you include any Windows specific code (or a derivative thereof) from
37 * the apps directory (application code) you must include an acknowledgement:
38 * "This product includes software written by Tim Hudson (tjh@cryptsoft.com)"
40 * THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND
41 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
42 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
43 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
44 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
45 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
46 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
47 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
48 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
49 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
52 * The licence and distribution terms for any publically available version or
53 * derivative of this code cannot be changed. i.e. this code cannot simply be
54 * copied and put under another distribution licence
55 * [including the GNU Public Licence.]
58 #include "internal/cryptlib.h"
63 * I've just gone over this and it is now %20 faster on x86 - eay - 27 Jun 96
65 int BN_sqr(BIGNUM *r, const BIGNUM *a, BN_CTX *ctx)
81 rr = (a != r) ? r : BN_CTX_get(ctx);
82 tmp = BN_CTX_get(ctx);
86 max = 2 * al; /* Non-zero (from above) */
87 if (bn_wexpand(rr, max) == NULL)
93 bn_sqr_normal(rr->d, a->d, 4, t);
95 bn_sqr_comba4(rr->d, a->d);
100 bn_sqr_normal(rr->d, a->d, 8, t);
102 bn_sqr_comba8(rr->d, a->d);
105 #if defined(BN_RECURSION)
106 if (al < BN_SQR_RECURSIVE_SIZE_NORMAL) {
107 BN_ULONG t[BN_SQR_RECURSIVE_SIZE_NORMAL * 2];
108 bn_sqr_normal(rr->d, a->d, al, t);
112 j = BN_num_bits_word((BN_ULONG)al);
116 if (bn_wexpand(tmp, k * 2) == NULL)
118 bn_sqr_recursive(rr->d, a->d, al, tmp->d);
120 if (bn_wexpand(tmp, max) == NULL)
122 bn_sqr_normal(rr->d, a->d, al, tmp->d);
126 if (bn_wexpand(tmp, max) == NULL)
128 bn_sqr_normal(rr->d, a->d, al, tmp->d);
134 * If the most-significant half of the top word of 'a' is zero, then the
135 * square of 'a' will max-1 words.
137 if (a->d[al - 1] == (a->d[al - 1] & BN_MASK2l))
151 /* tmp must have 2*n words */
152 void bn_sqr_normal(BN_ULONG *r, const BN_ULONG *a, int n, BN_ULONG *tmp)
161 rp[0] = rp[max - 1] = 0;
167 rp[j] = bn_mul_words(rp, ap, j, ap[-1]);
171 for (i = n - 2; i > 0; i--) {
174 rp[j] = bn_mul_add_words(rp, ap, j, ap[-1]);
178 bn_add_words(r, r, r, max);
180 /* There will not be a carry */
182 bn_sqr_words(tmp, a, n);
184 bn_add_words(r, r, tmp, max);
189 * r is 2*n words in size,
190 * a and b are both n words in size. (There's not actually a 'b' here ...)
191 * n must be a power of 2.
192 * We multiply and return the result.
193 * t must be 2*n words in size
196 * a[0]*b[0]+a[1]*b[1]+(a[0]-a[1])*(b[1]-b[0])
199 void bn_sqr_recursive(BN_ULONG *r, const BN_ULONG *a, int n2, BN_ULONG *t)
206 # ifndef BN_SQR_COMBA
207 bn_sqr_normal(r, a, 4, t);
212 } else if (n2 == 8) {
213 # ifndef BN_SQR_COMBA
214 bn_sqr_normal(r, a, 8, t);
220 if (n2 < BN_SQR_RECURSIVE_SIZE_NORMAL) {
221 bn_sqr_normal(r, a, n2, t);
224 /* r=(a[0]-a[1])*(a[1]-a[0]) */
225 c1 = bn_cmp_words(a, &(a[n]), n);
228 bn_sub_words(t, a, &(a[n]), n);
230 bn_sub_words(t, &(a[n]), a, n);
234 /* The result will always be negative unless it is zero */
238 bn_sqr_recursive(&(t[n2]), t, n, p);
240 memset(&t[n2], 0, sizeof(*t) * n2);
241 bn_sqr_recursive(r, a, n, p);
242 bn_sqr_recursive(&(r[n2]), &(a[n]), n, p);
245 * t[32] holds (a[0]-a[1])*(a[1]-a[0]), it is negative or zero
246 * r[10] holds (a[0]*b[0])
247 * r[32] holds (b[1]*b[1])
250 c1 = (int)(bn_add_words(t, r, &(r[n2]), n2));
252 /* t[32] is negative */
253 c1 -= (int)(bn_sub_words(&(t[n2]), t, &(t[n2]), n2));
256 * t[32] holds (a[0]-a[1])*(a[1]-a[0])+(a[0]*a[0])+(a[1]*a[1])
257 * r[10] holds (a[0]*a[0])
258 * r[32] holds (a[1]*a[1])
259 * c1 holds the carry bits
261 c1 += (int)(bn_add_words(&(r[n]), &(r[n]), &(t[n2]), n2));
265 ln = (lo + c1) & BN_MASK2;
269 * The overflow will stop before we over write words we should not
272 if (ln < (BN_ULONG)c1) {
276 ln = (lo + 1) & BN_MASK2;