/* crypto/bn/bn_sqr.c *//* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com) * All rights reserved. * * This package is an SSL implementation written * by Eric Young (eay@cryptsoft.com). * The implementation was written so as to conform with Netscapes SSL. *  * This library is free for commercial and non-commercial use as long as * the following conditions are aheared to.  The following conditions * apply to all code found in this distribution, be it the RC4, RSA, * lhash, DES, etc., code; not just the SSL code.  The SSL documentation * included with this distribution is covered by the same copyright terms * except that the holder is Tim Hudson (tjh@cryptsoft.com). *  * Copyright remains Eric Young's, and as such any Copyright notices in * the code are not to be removed. * If this package is used in a product, Eric Young should be given attribution * as the author of the parts of the library used. * This can be in the form of a textual message at program startup or * in documentation (online or textual) provided with the package. *  * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the copyright *    notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright *    notice, this list of conditions and the following disclaimer in the *    documentation and/or other materials provided with the distribution. * 3. All advertising materials mentioning features or use of this software *    must display the following acknowledgement: *    "This product includes cryptographic software written by *     Eric Young (eay@cryptsoft.com)" *    The word 'cryptographic' can be left out if the rouines from the library *    being used are not cryptographic related :-). * 4. If you include any Windows specific code (or a derivative thereof) from  *    the apps directory (application code) you must include an acknowledgement: *    "This product includes software written by Tim Hudson (tjh@cryptsoft.com)" *  * THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. *  * The licence and distribution terms for any publically available version or * derivative of this code cannot be changed.  i.e. this code cannot simply be * copied and put under another distribution licence * [including the GNU Public Licence.] */#include <stdio.h>#include "cryptlib.h"#include "bn_lcl.h"/* r must not be a *//* I've just gone over this and it is now %20 faster on x86 - eay - 27 Jun 96 */int BN_sqr(BIGNUM *r, const BIGNUM *a, BN_CTX *ctx)	{	int max,al;	int ret = 0;	BIGNUM *tmp,*rr;#ifdef BN_COUNT	fprintf(stderr,"BN_sqr %d * %d\n",a->top,a->top);#endif	bn_check_top(a);	al=a->top;	if (al <= 0)		{		r->top=0;		return(1);		}	BN_CTX_start(ctx);	rr=(a != r) ? r : BN_CTX_get(ctx);	tmp=BN_CTX_get(ctx);	if (tmp == NULL) goto err;	max=(al+al);	if (bn_wexpand(rr,max+1) == NULL) goto err;	if (al == 4)		{#ifndef BN_SQR_COMBA		BN_ULONG t[8];		bn_sqr_normal(rr->d,a->d,4,t);#else		bn_sqr_comba4(rr->d,a->d);#endif		}	else if (al == 8)		{#ifndef BN_SQR_COMBA		BN_ULONG t[16];		bn_sqr_normal(rr->d,a->d,8,t);#else		bn_sqr_comba8(rr->d,a->d);#endif		}	else 		{#if defined(BN_RECURSION)		if (al < BN_SQR_RECURSIVE_SIZE_NORMAL)			{			BN_ULONG t[BN_SQR_RECURSIVE_SIZE_NORMAL*2];			bn_sqr_normal(rr->d,a->d,al,t);			}		else			{			int j,k;			j=BN_num_bits_word((BN_ULONG)al);			j=1<<(j-1);			k=j+j;			if (al == j)				{				if (bn_wexpand(tmp,k*2) == NULL) goto err;				bn_sqr_recursive(rr->d,a->d,al,tmp->d);				}			else				{				if (bn_wexpand(tmp,max) == NULL) goto err;				bn_sqr_normal(rr->d,a->d,al,tmp->d);				}			}#else		if (bn_wexpand(tmp,max) == NULL) goto err;		bn_sqr_normal(rr->d,a->d,al,tmp->d);#endif		}	rr->top=max;	rr->neg=0;	if ((max > 0) && (rr->d[max-1] == 0)) rr->top--;	if (rr != r) BN_copy(r,rr);	ret = 1; err:	BN_CTX_end(ctx);	return(ret);	}/* tmp must have 2*n words */void bn_sqr_normal(BN_ULONG *r, const BN_ULONG *a, int n, BN_ULONG *tmp)	{	int i,j,max;	const BN_ULONG *ap;	BN_ULONG *rp;	max=n*2;	ap=a;	rp=r;	rp[0]=rp[max-1]=0;	rp++;	j=n;	if (--j > 0)		{		ap++;		rp[j]=bn_mul_words(rp,ap,j,ap[-1]);		rp+=2;		}	for (i=n-2; i>0; i--)		{		j--;		ap++;		rp[j]=bn_mul_add_words(rp,ap,j,ap[-1]);		rp+=2;		}	bn_add_words(r,r,r,max);	/* There will not be a carry */	bn_sqr_words(tmp,a,n);	bn_add_words(r,r,tmp,max);	}#ifdef BN_RECURSION/* r is 2*n words in size, * a and b are both n words in size.    (There's not actually a 'b' here ...) * n must be a power of 2. * We multiply and return the result. * t must be 2*n words in size * We calculate * a[0]*b[0] * a[0]*b[0]+a[1]*b[1]+(a[0]-a[1])*(b[1]-b[0]) * a[1]*b[1] */void bn_sqr_recursive(BN_ULONG *r, const BN_ULONG *a, int n2, BN_ULONG *t)	{	int n=n2/2;	int zero,c1;	BN_ULONG ln,lo,*p;#ifdef BN_COUNT	fprintf(stderr," bn_sqr_recursive %d * %d\n",n2,n2);#endif	if (n2 == 4)		{#ifndef BN_SQR_COMBA		bn_sqr_normal(r,a,4,t);#else		bn_sqr_comba4(r,a);#endif		return;		}	else if (n2 == 8)		{#ifndef BN_SQR_COMBA		bn_sqr_normal(r,a,8,t);#else		bn_sqr_comba8(r,a);#endif		return;		}	if (n2 < BN_SQR_RECURSIVE_SIZE_NORMAL)		{		bn_sqr_normal(r,a,n2,t);		return;		}	/* r=(a[0]-a[1])*(a[1]-a[0]) */	c1=bn_cmp_words(a,&(a[n]),n);	zero=0;	if (c1 > 0)		bn_sub_words(t,a,&(a[n]),n);	else if (c1 < 0)		bn_sub_words(t,&(a[n]),a,n);	else		zero=1;	/* The result will always be negative unless it is zero */	p= &(t[n2*2]);	if (!zero)		bn_sqr_recursive(&(t[n2]),t,n,p);	else		memset(&(t[n2]),0,n2*sizeof(BN_ULONG));	bn_sqr_recursive(r,a,n,p);	bn_sqr_recursive(&(r[n2]),&(a[n]),n,p);	/* t[32] holds (a[0]-a[1])*(a[1]-a[0]), it is negative or zero	 * r[10] holds (a[0]*b[0])	 * r[32] holds (b[1]*b[1])	 */	c1=(int)(bn_add_words(t,r,&(r[n2]),n2));	/* t[32] is negative */	c1-=(int)(bn_sub_words(&(t[n2]),t,&(t[n2]),n2));	/* t[32] holds (a[0]-a[1])*(a[1]-a[0])+(a[0]*a[0])+(a[1]*a[1])	 * r[10] holds (a[0]*a[0])	 * r[32] holds (a[1]*a[1])	 * c1 holds the carry bits	 */	c1+=(int)(bn_add_words(&(r[n]),&(r[n]),&(t[n2]),n2));	if (c1)		{		p= &(r[n+n2]);		lo= *p;		ln=(lo+c1)&BN_MASK2;		*p=ln;		/* The overflow will stop before we over write		 * words we should not overwrite */		if (ln < (BN_ULONG)c1)			{			do	{				p++;				lo= *p;				ln=(lo+1)&BN_MASK2;				*p=ln;				} while (ln == 0);			}		}	}#endif