1 /* crypto/bn/bn_sqr.c */
2 /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
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.
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).
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.
23 * Redistribution and use in source and binary forms, with or without
24 * modification, are permitted provided that the following conditions
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)"
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
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.]
64 /* I've just gone over this and it is now %20 faster on x86 - eay - 27 Jun 96 */
65 int BN_sqr(BIGNUM *r, BIGNUM *a, BN_CTX *ctx)
71 printf("BN_sqr %d * %d\n",a->top,a->top);
74 tmp= &(ctx->bn[ctx->tos]);
75 rr=(a != r)?r: (&ctx->bn[ctx->tos+1]);
85 if (bn_wexpand(rr,max+1) == NULL) return(0);
92 bn_sqr_normal(rr->d,a->d,4,t);
94 bn_sqr_comba4(rr->d,a->d);
101 bn_sqr_normal(rr->d,a->d,8,t);
103 bn_sqr_comba8(rr->d,a->d);
108 #if defined(BN_RECURSION)
109 if (al < BN_SQR_RECURSIVE_SIZE_NORMAL)
111 BN_ULONG t[BN_SQR_RECURSIVE_SIZE_NORMAL*2];
112 bn_sqr_normal(rr->d,a->d,al,t);
118 j=BN_num_bits_word((BN_ULONG)al);
123 if (bn_wexpand(a,k*2) == NULL) return(0);
124 if (bn_wexpand(tmp,k*2) == NULL) return(0);
125 bn_sqr_recursive(rr->d,a->d,al,tmp->d);
129 if (bn_wexpand(tmp,max) == NULL) return(0);
130 bn_sqr_normal(rr->d,a->d,al,tmp->d);
134 if (bn_wexpand(tmp,max) == NULL) return(0);
135 bn_sqr_normal(rr->d,a->d,al,tmp->d);
140 if ((max > 0) && (rr->d[max-1] == 0)) rr->top--;
141 if (rr != r) BN_copy(r,rr);
145 /* tmp must have 2*n words */
146 void bn_sqr_normal(BN_ULONG *r, BN_ULONG *a, int n, BN_ULONG *tmp)
161 rp[j]=bn_mul_words(rp,ap,j,ap[-1]);
165 for (i=n-2; i>0; i--)
169 rp[j]=bn_mul_add_words(rp,ap,j,ap[-1]);
173 bn_add_words(r,r,r,max);
175 /* There will not be a carry */
177 bn_sqr_words(tmp,a,n);
179 bn_add_words(r,r,tmp,max);
183 /* r is 2*n words in size,
184 * a and b are both n words in size.
185 * n must be a power of 2.
186 * We multiply and return the result.
187 * t must be 2*n words in size
190 * a[0]*b[0]+a[1]*b[1]+(a[0]-a[1])*(b[1]-b[0])
193 void bn_sqr_recursive(BN_ULONG *r, BN_ULONG *a, int n2, BN_ULONG *t)
200 printf(" bn_sqr_recursive %d * %d\n",n2,n2);
205 bn_sqr_normal(r,a,4,t);
214 bn_sqr_normal(r,a,8,t);
220 if (n2 < BN_SQR_RECURSIVE_SIZE_NORMAL)
222 bn_sqr_normal(r,a,n2,t);
225 /* r=(a[0]-a[1])*(a[1]-a[0]) */
226 c1=bn_cmp_words(a,&(a[n]),n);
229 bn_sub_words(t,a,&(a[n]),n);
231 bn_sub_words(t,&(a[n]),a,n);
235 /* The result will always be negative unless it is zero */
239 bn_sqr_recursive(&(t[n2]),t,n,p);
241 memset(&(t[n2]),0,n*sizeof(BN_ULONG));
242 bn_sqr_recursive(r,a,n,p);
243 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));
255 /* t[32] holds (a[0]-a[1])*(a[1]-a[0])+(a[0]*a[0])+(a[1]*a[1])
256 * r[10] holds (a[0]*a[0])
257 * r[32] holds (a[1]*a[1])
258 * c1 holds the carry bits
260 c1+=(int)(bn_add_words(&(r[n]),&(r[n]),&(t[n2]),n2));
268 /* The overflow will stop before we over write
269 * words we should not overwrite */
270 if (ln < (BN_ULONG)c1)