[thirdparty/openssl.git] / crypto / bn / bn_sqr.c

/* 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, BIGNUM *a, BN_CTX *ctx)
	{
	int max,al;
	BIGNUM *tmp,*rr;

#ifdef BN_COUNT
printf("BN_sqr %d * %d\n",a->top,a->top);
#endif
	bn_check_top(a);
	tmp= &(ctx->bn[ctx->tos]);
	rr=(a != r)?r: (&ctx->bn[ctx->tos+1]);

	al=a->top;
	if (al <= 0)
		{
		r->top=0;
		return(1);
		}

	max=(al+al);
	if (bn_wexpand(rr,max+1) == NULL) return(0);

	r->neg=0;
	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(a,k*2) == NULL) return(0);
				if (bn_wexpand(tmp,k*2) == NULL) return(0);
				bn_sqr_recursive(rr->d,a->d,al,tmp->d);
				}
			else
				{
				if (bn_wexpand(tmp,max) == NULL) return(0);
				bn_sqr_normal(rr->d,a->d,al,tmp->d);
				}
			}
#else
		if (bn_wexpand(tmp,max) == NULL) return(0);
		bn_sqr_normal(rr->d,a->d,al,tmp->d);
#endif
		}

	rr->top=max;
	if ((max > 0) && (rr->d[max-1] == 0)) rr->top--;
	if (rr != r) BN_copy(r,rr);
	return(1);
	}

/* tmp must have 2*n words */
void bn_sqr_normal(BN_ULONG *r, BN_ULONG *a, int n, BN_ULONG *tmp)
	{
	int i,j,max;
	BN_ULONG *ap,*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.
 * n must be a power of 2.
 * We multiply and return the result.
 * t must be 2*n words in size
 * We calulate
 * 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, BN_ULONG *a, int n2, BN_ULONG *t)
	{
	int n=n2/2;
	int zero,c1;
	BN_ULONG ln,lo,*p;

#ifdef BN_COUNT
printf(" 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,n*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
Commit	Line	Data
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.
	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 "cryptlib.h"
	61	#include "bn_lcl.h"
	62
	63	/* r must not be a */
	64	/* I've just gone over this and it is now %20 faster on x86 - eay - 27 Jun 96 */
6b691a5c	65	int BN_sqr(BIGNUM r, BIGNUM a, BN_CTX *ctx)
d02b48c6	66	{
dfeab068	67	int max,al;
a0a54079	68	BIGNUM tmp,rr;
d02b48c6	69
dfeab068 RE	70	#ifdef BN_COUNT
	71	printf("BN_sqr %d * %d\n",a->top,a->top);
	72	#endif
	73	bn_check_top(a);
	74	tmp= &(ctx->bn[ctx->tos]);
a0a54079	75	rr=(a != r)?r: (&ctx->bn[ctx->tos+1]);
d02b48c6 RE	76
d02b48c6 RE	77	al=a->top;
dfeab068	78	if (al <= 0)
d02b48c6 RE	79	{
	80	r->top=0;
	81	return(1);
	82	}
	83
dfeab068	84	max=(al+al);
a0a54079	85	if (bn_wexpand(rr,max+1) == NULL) return(0);
d02b48c6 RE	86
d02b48c6 RE	87	r->neg=0;
dfeab068 RE	88	if (al == 4)
	89	{
	90	#ifndef BN_SQR_COMBA
	91	BN_ULONG t[8];
a0a54079	92	bn_sqr_normal(rr->d,a->d,4,t);
dfeab068	93	#else
a0a54079	94	bn_sqr_comba4(rr->d,a->d);
dfeab068 RE	95	#endif
	96	}
	97	else if (al == 8)
	98	{
	99	#ifndef BN_SQR_COMBA
	100	BN_ULONG t[16];
a0a54079	101	bn_sqr_normal(rr->d,a->d,8,t);
dfeab068	102	#else
a0a54079	103	bn_sqr_comba8(rr->d,a->d);
dfeab068 RE	104	#endif
	105	}
	106	else
	107	{
	108	#if defined(BN_RECURSION)
	109	if (al < BN_SQR_RECURSIVE_SIZE_NORMAL)
	110	{
	111	BN_ULONG t[BN_SQR_RECURSIVE_SIZE_NORMAL*2];
a0a54079	112	bn_sqr_normal(rr->d,a->d,al,t);
dfeab068 RE	113	}
	114	else
	115	{
a0a54079 MC	116	int j,k;
	117
	118	j=BN_num_bits_word((BN_ULONG)al);
	119	j=1<<(j-1);
	120	k=j+j;
	121	if (al == j)
	122	{
	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);
	126	}
	127	else
	128	{
	129	if (bn_wexpand(tmp,max) == NULL) return(0);
	130	bn_sqr_normal(rr->d,a->d,al,tmp->d);
	131	}
dfeab068 RE	132	}
	133	#else
	134	if (bn_wexpand(tmp,max) == NULL) return(0);
a0a54079	135	bn_sqr_normal(rr->d,a->d,al,tmp->d);
dfeab068 RE	136	#endif
	137	}
	138
a0a54079 MC	139	rr->top=max;
	140	if ((max > 0) && (rr->d[max-1] == 0)) rr->top--;
	141	if (rr != r) BN_copy(r,rr);
dfeab068 RE	142	return(1);
	143	}
	144
	145	/* tmp must have 2n words /
6b691a5c	146	void bn_sqr_normal(BN_ULONG r, BN_ULONG a, int n, BN_ULONG *tmp)
dfeab068 RE	147	{
	148	int i,j,max;
	149	BN_ULONG ap,rp;
d02b48c6	150
dfeab068 RE	151	max=n*2;
	152	ap=a;
	153	rp=r;
d02b48c6 RE	154	rp[0]=rp[max-1]=0;
d02b48c6 RE	155	rp++;
dfeab068	156	j=n;
d02b48c6 RE	157
	158	if (--j > 0)
	159	{
	160	ap++;
58964a49	161	rp[j]=bn_mul_words(rp,ap,j,ap[-1]);
d02b48c6 RE	162	rp+=2;
	163	}
	164
dfeab068	165	for (i=n-2; i>0; i--)
d02b48c6 RE	166	{
	167	j--;
	168	ap++;
58964a49	169	rp[j]=bn_mul_add_words(rp,ap,j,ap[-1]);
d02b48c6 RE	170	rp+=2;
	171	}
	172
dfeab068	173	bn_add_words(r,r,r,max);
d02b48c6	174
58964a49	175	/* There will not be a carry */
d02b48c6	176
dfeab068	177	bn_sqr_words(tmp,a,n);
d02b48c6	178
dfeab068	179	bn_add_words(r,r,tmp,max);
d02b48c6 RE	180	}
d02b48c6 RE	181
dfeab068 RE	182	#ifdef BN_RECURSION
	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
	188	* We calulate
	189	* a[0]*b[0]
	190	* a[0]b[0]+a[1]b[1]+(a[0]-a[1])*(b[1]-b[0])
	191	* a[1]*b[1]
	192	*/
6b691a5c	193	void bn_sqr_recursive(BN_ULONG r, BN_ULONG a, int n2, BN_ULONG *t)
dfeab068 RE	194	{
	195	int n=n2/2;
	196	int zero,c1;
	197	BN_ULONG ln,lo,*p;
	198
	199	#ifdef BN_COUNT
	200	printf(" bn_sqr_recursive %d * %d\n",n2,n2);
	201	#endif
	202	if (n2 == 4)
	203	{
	204	#ifndef BN_SQR_COMBA
	205	bn_sqr_normal(r,a,4,t);
	206	#else
	207	bn_sqr_comba4(r,a);
	208	#endif
	209	return;
	210	}
	211	else if (n2 == 8)
	212	{
	213	#ifndef BN_SQR_COMBA
	214	bn_sqr_normal(r,a,8,t);
	215	#else
	216	bn_sqr_comba8(r,a);
	217	#endif
	218	return;
	219	}
	220	if (n2 < BN_SQR_RECURSIVE_SIZE_NORMAL)
	221	{
	222	bn_sqr_normal(r,a,n2,t);
	223	return;
	224	}
	225	/* r=(a[0]-a[1])(a[1]-a[0]) /
	226	c1=bn_cmp_words(a,&(a[n]),n);
	227	zero=0;
	228	if (c1 > 0)
	229	bn_sub_words(t,a,&(a[n]),n);
	230	else if (c1 < 0)
	231	bn_sub_words(t,&(a[n]),a,n);
	232	else
	233	zero=1;
	234
	235	/* The result will always be negative unless it is zero */
	236	p= &(t[n2*2]);
	237
	238	if (!zero)
	239	bn_sqr_recursive(&(t[n2]),t,n,p);
	240	else
	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);
	244
	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])
	248	*/
	249
651d0aff	250	c1=(int)(bn_add_words(t,r,&(r[n2]),n2));
dfeab068 RE	251
dfeab068 RE	252	/* t[32] is negative */
651d0aff	253	c1-=(int)(bn_sub_words(&(t[n2]),t,&(t[n2]),n2));
dfeab068 RE	254
	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
	259	*/
651d0aff	260	c1+=(int)(bn_add_words(&(r[n]),&(r[n]),&(t[n2]),n2));
dfeab068 RE	261	if (c1)
	262	{
	263	p= &(r[n+n2]);
	264	lo= *p;
	265	ln=(lo+c1)&BN_MASK2;
	266	*p=ln;
	267
	268	/* The overflow will stop before we over write
	269	* words we should not overwrite */
	270	if (ln < (BN_ULONG)c1)
	271	{
	272	do {
	273	p++;
	274	lo= *p;
	275	ln=(lo+1)&BN_MASK2;
	276	*p=ln;
	277	} while (ln == 0);
	278	}
	279	}
	280	}
	281	#endif