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d02b48c6 | 1 | /* crypto/bn/bn_sqr.c */ |
58964a49 | 2 | /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com) |
d02b48c6 RE |
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. | |
ae5c8664 | 8 | * |
d02b48c6 RE |
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). | |
ae5c8664 | 15 | * |
d02b48c6 RE |
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. | |
ae5c8664 | 22 | * |
d02b48c6 RE |
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 :-). | |
ae5c8664 | 37 | * 4. If you include any Windows specific code (or a derivative thereof) from |
d02b48c6 RE |
38 | * the apps directory (application code) you must include an acknowledgement: |
39 | * "This product includes software written by Tim Hudson (tjh@cryptsoft.com)" | |
ae5c8664 | 40 | * |
d02b48c6 RE |
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. | |
ae5c8664 | 52 | * |
d02b48c6 RE |
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 "cryptlib.h" | |
61 | #include "bn_lcl.h" | |
62 | ||
63 | /* r must not be a */ | |
ae5c8664 MC |
64 | /* |
65 | * I've just gone over this and it is now %20 faster on x86 - eay - 27 Jun 96 | |
66 | */ | |
020fc820 | 67 | int BN_sqr(BIGNUM *r, const BIGNUM *a, BN_CTX *ctx) |
ae5c8664 MC |
68 | { |
69 | int max, al; | |
70 | int ret = 0; | |
71 | BIGNUM *tmp, *rr; | |
d02b48c6 | 72 | |
dfeab068 | 73 | #ifdef BN_COUNT |
ae5c8664 | 74 | fprintf(stderr, "BN_sqr %d * %d\n", a->top, a->top); |
dfeab068 | 75 | #endif |
ae5c8664 | 76 | bn_check_top(a); |
d02b48c6 | 77 | |
ae5c8664 MC |
78 | al = a->top; |
79 | if (al <= 0) { | |
80 | r->top = 0; | |
81 | r->neg = 0; | |
82 | return 1; | |
83 | } | |
d02b48c6 | 84 | |
ae5c8664 MC |
85 | BN_CTX_start(ctx); |
86 | rr = (a != r) ? r : BN_CTX_get(ctx); | |
87 | tmp = BN_CTX_get(ctx); | |
88 | if (!rr || !tmp) | |
89 | goto err; | |
9b141126 | 90 | |
ae5c8664 MC |
91 | max = 2 * al; /* Non-zero (from above) */ |
92 | if (bn_wexpand(rr, max) == NULL) | |
93 | goto err; | |
d02b48c6 | 94 | |
ae5c8664 | 95 | if (al == 4) { |
dfeab068 | 96 | #ifndef BN_SQR_COMBA |
ae5c8664 MC |
97 | BN_ULONG t[8]; |
98 | bn_sqr_normal(rr->d, a->d, 4, t); | |
dfeab068 | 99 | #else |
ae5c8664 | 100 | bn_sqr_comba4(rr->d, a->d); |
dfeab068 | 101 | #endif |
ae5c8664 | 102 | } else if (al == 8) { |
dfeab068 | 103 | #ifndef BN_SQR_COMBA |
ae5c8664 MC |
104 | BN_ULONG t[16]; |
105 | bn_sqr_normal(rr->d, a->d, 8, t); | |
dfeab068 | 106 | #else |
ae5c8664 | 107 | bn_sqr_comba8(rr->d, a->d); |
dfeab068 | 108 | #endif |
ae5c8664 | 109 | } else { |
dfeab068 | 110 | #if defined(BN_RECURSION) |
ae5c8664 MC |
111 | if (al < BN_SQR_RECURSIVE_SIZE_NORMAL) { |
112 | BN_ULONG t[BN_SQR_RECURSIVE_SIZE_NORMAL * 2]; | |
113 | bn_sqr_normal(rr->d, a->d, al, t); | |
114 | } else { | |
115 | int j, k; | |
a0a54079 | 116 | |
ae5c8664 MC |
117 | j = BN_num_bits_word((BN_ULONG)al); |
118 | j = 1 << (j - 1); | |
119 | k = j + j; | |
120 | if (al == j) { | |
121 | if (bn_wexpand(tmp, k * 2) == NULL) | |
122 | goto err; | |
123 | bn_sqr_recursive(rr->d, a->d, al, tmp->d); | |
124 | } else { | |
125 | if (bn_wexpand(tmp, max) == NULL) | |
126 | goto err; | |
127 | bn_sqr_normal(rr->d, a->d, al, tmp->d); | |
128 | } | |
129 | } | |
dfeab068 | 130 | #else |
ae5c8664 MC |
131 | if (bn_wexpand(tmp, max) == NULL) |
132 | goto err; | |
133 | bn_sqr_normal(rr->d, a->d, al, tmp->d); | |
dfeab068 | 134 | #endif |
ae5c8664 | 135 | } |
dfeab068 | 136 | |
ae5c8664 | 137 | rr->neg = 0; |
327b2c01 AP |
138 | rr->top = max; |
139 | bn_correct_top(rr); | |
8ac70bef RS |
140 | if (r != rr && BN_copy(r, rr) == NULL) |
141 | goto err; | |
142 | ||
ae5c8664 | 143 | ret = 1; |
9b141126 | 144 | err: |
ae5c8664 MC |
145 | bn_check_top(rr); |
146 | bn_check_top(tmp); | |
147 | BN_CTX_end(ctx); | |
148 | return (ret); | |
149 | } | |
dfeab068 RE |
150 | |
151 | /* tmp must have 2*n words */ | |
43fcc1b0 | 152 | void bn_sqr_normal(BN_ULONG *r, const BN_ULONG *a, int n, BN_ULONG *tmp) |
ae5c8664 MC |
153 | { |
154 | int i, j, max; | |
155 | const BN_ULONG *ap; | |
156 | BN_ULONG *rp; | |
d02b48c6 | 157 | |
ae5c8664 MC |
158 | max = n * 2; |
159 | ap = a; | |
160 | rp = r; | |
161 | rp[0] = rp[max - 1] = 0; | |
162 | rp++; | |
163 | j = n; | |
d02b48c6 | 164 | |
ae5c8664 MC |
165 | if (--j > 0) { |
166 | ap++; | |
167 | rp[j] = bn_mul_words(rp, ap, j, ap[-1]); | |
168 | rp += 2; | |
169 | } | |
d02b48c6 | 170 | |
ae5c8664 MC |
171 | for (i = n - 2; i > 0; i--) { |
172 | j--; | |
173 | ap++; | |
174 | rp[j] = bn_mul_add_words(rp, ap, j, ap[-1]); | |
175 | rp += 2; | |
176 | } | |
d02b48c6 | 177 | |
ae5c8664 | 178 | bn_add_words(r, r, r, max); |
d02b48c6 | 179 | |
ae5c8664 | 180 | /* There will not be a carry */ |
d02b48c6 | 181 | |
ae5c8664 | 182 | bn_sqr_words(tmp, a, n); |
d02b48c6 | 183 | |
ae5c8664 MC |
184 | bn_add_words(r, r, tmp, max); |
185 | } | |
d02b48c6 | 186 | |
dfeab068 | 187 | #ifdef BN_RECURSION |
6977c7e2 TH |
188 | /*- |
189 | * r is 2*n words in size, | |
fe035197 | 190 | * a and b are both n words in size. (There's not actually a 'b' here ...) |
dfeab068 RE |
191 | * n must be a power of 2. |
192 | * We multiply and return the result. | |
193 | * t must be 2*n words in size | |
657e60fa | 194 | * We calculate |
dfeab068 RE |
195 | * a[0]*b[0] |
196 | * a[0]*b[0]+a[1]*b[1]+(a[0]-a[1])*(b[1]-b[0]) | |
197 | * a[1]*b[1] | |
198 | */ | |
43fcc1b0 | 199 | void bn_sqr_recursive(BN_ULONG *r, const BN_ULONG *a, int n2, BN_ULONG *t) |
ae5c8664 MC |
200 | { |
201 | int n = n2 / 2; | |
202 | int zero, c1; | |
203 | BN_ULONG ln, lo, *p; | |
dfeab068 | 204 | |
ae5c8664 MC |
205 | # ifdef BN_COUNT |
206 | fprintf(stderr, " bn_sqr_recursive %d * %d\n", n2, n2); | |
207 | # endif | |
208 | if (n2 == 4) { | |
209 | # ifndef BN_SQR_COMBA | |
210 | bn_sqr_normal(r, a, 4, t); | |
211 | # else | |
212 | bn_sqr_comba4(r, a); | |
213 | # endif | |
214 | return; | |
215 | } else if (n2 == 8) { | |
216 | # ifndef BN_SQR_COMBA | |
217 | bn_sqr_normal(r, a, 8, t); | |
218 | # else | |
219 | bn_sqr_comba8(r, a); | |
220 | # endif | |
221 | return; | |
222 | } | |
223 | if (n2 < BN_SQR_RECURSIVE_SIZE_NORMAL) { | |
224 | bn_sqr_normal(r, a, n2, t); | |
225 | return; | |
226 | } | |
227 | /* r=(a[0]-a[1])*(a[1]-a[0]) */ | |
228 | c1 = bn_cmp_words(a, &(a[n]), n); | |
229 | zero = 0; | |
230 | if (c1 > 0) | |
231 | bn_sub_words(t, a, &(a[n]), n); | |
232 | else if (c1 < 0) | |
233 | bn_sub_words(t, &(a[n]), a, n); | |
234 | else | |
235 | zero = 1; | |
dfeab068 | 236 | |
ae5c8664 MC |
237 | /* The result will always be negative unless it is zero */ |
238 | p = &(t[n2 * 2]); | |
dfeab068 | 239 | |
ae5c8664 MC |
240 | if (!zero) |
241 | bn_sqr_recursive(&(t[n2]), t, n, p); | |
242 | else | |
243 | memset(&(t[n2]), 0, n2 * sizeof(BN_ULONG)); | |
244 | bn_sqr_recursive(r, a, n, p); | |
245 | bn_sqr_recursive(&(r[n2]), &(a[n]), n, p); | |
dfeab068 | 246 | |
83975c80 MC |
247 | /*- |
248 | * t[32] holds (a[0]-a[1])*(a[1]-a[0]), it is negative or zero | |
249 | * r[10] holds (a[0]*b[0]) | |
250 | * r[32] holds (b[1]*b[1]) | |
251 | */ | |
dfeab068 | 252 | |
ae5c8664 | 253 | c1 = (int)(bn_add_words(t, r, &(r[n2]), n2)); |
dfeab068 | 254 | |
ae5c8664 MC |
255 | /* t[32] is negative */ |
256 | c1 -= (int)(bn_sub_words(&(t[n2]), t, &(t[n2]), n2)); | |
dfeab068 | 257 | |
83975c80 MC |
258 | /*- |
259 | * t[32] holds (a[0]-a[1])*(a[1]-a[0])+(a[0]*a[0])+(a[1]*a[1]) | |
260 | * r[10] holds (a[0]*a[0]) | |
261 | * r[32] holds (a[1]*a[1]) | |
262 | * c1 holds the carry bits | |
263 | */ | |
ae5c8664 MC |
264 | c1 += (int)(bn_add_words(&(r[n]), &(r[n]), &(t[n2]), n2)); |
265 | if (c1) { | |
266 | p = &(r[n + n2]); | |
267 | lo = *p; | |
268 | ln = (lo + c1) & BN_MASK2; | |
269 | *p = ln; | |
dfeab068 | 270 | |
ae5c8664 MC |
271 | /* |
272 | * The overflow will stop before we over write words we should not | |
273 | * overwrite | |
274 | */ | |
275 | if (ln < (BN_ULONG)c1) { | |
276 | do { | |
277 | p++; | |
278 | lo = *p; | |
279 | ln = (lo + 1) & BN_MASK2; | |
280 | *p = ln; | |
281 | } while (ln == 0); | |
282 | } | |
283 | } | |
284 | } | |
dfeab068 | 285 | #endif |