[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, 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);
	bn_check_top(r);
	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
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 */
020fc820	65	int BN_sqr(BIGNUM r, const BIGNUM a, BN_CTX *ctx)
d02b48c6	66	{
dfeab068	67	int max,al;
9b141126	68	int ret = 0;
afb83c45	69	BIGNUM tmp,rr;
d02b48c6	70
dfeab068	71	#ifdef BN_COUNT
43fcc1b0	72	fprintf(stderr,"BN_sqr %d * %d\n",a->top,a->top);
dfeab068 RE	73	#endif
dfeab068 RE	74	bn_check_top(a);
d02b48c6 RE	75
d02b48c6 RE	76	al=a->top;
dfeab068	77	if (al <= 0)
d02b48c6 RE	78	{
	79	r->top=0;
	80	return(1);
	81	}
	82
9b141126 UM	83	BN_CTX_start(ctx);
	84	rr=(a != r) ? r : BN_CTX_get(ctx);
	85	tmp=BN_CTX_get(ctx);
	86	if (tmp == NULL) goto err;
	87
dfeab068	88	max=(al+al);
9b141126	89	if (bn_wexpand(rr,max+1) == NULL) goto err;
d02b48c6	90
dfeab068 RE	91	if (al == 4)
	92	{
	93	#ifndef BN_SQR_COMBA
	94	BN_ULONG t[8];
a0a54079	95	bn_sqr_normal(rr->d,a->d,4,t);
dfeab068	96	#else
a0a54079	97	bn_sqr_comba4(rr->d,a->d);
dfeab068 RE	98	#endif
	99	}
	100	else if (al == 8)
	101	{
	102	#ifndef BN_SQR_COMBA
	103	BN_ULONG t[16];
a0a54079	104	bn_sqr_normal(rr->d,a->d,8,t);
dfeab068	105	#else
a0a54079	106	bn_sqr_comba8(rr->d,a->d);
dfeab068 RE	107	#endif
	108	}
	109	else
	110	{
	111	#if defined(BN_RECURSION)
	112	if (al < BN_SQR_RECURSIVE_SIZE_NORMAL)
	113	{
	114	BN_ULONG t[BN_SQR_RECURSIVE_SIZE_NORMAL*2];
a0a54079	115	bn_sqr_normal(rr->d,a->d,al,t);
dfeab068 RE	116	}
	117	else
	118	{
a0a54079 MC	119	int j,k;
	120
	121	j=BN_num_bits_word((BN_ULONG)al);
	122	j=1<<(j-1);
	123	k=j+j;
	124	if (al == j)
	125	{
9b141126	126	if (bn_wexpand(tmp,k*2) == NULL) goto err;
a0a54079 MC	127	bn_sqr_recursive(rr->d,a->d,al,tmp->d);
	128	}
	129	else
	130	{
9b141126	131	if (bn_wexpand(tmp,max) == NULL) goto err;
a0a54079 MC	132	bn_sqr_normal(rr->d,a->d,al,tmp->d);
a0a54079 MC	133	}
dfeab068 RE	134	}
dfeab068 RE	135	#else
9b141126	136	if (bn_wexpand(tmp,max) == NULL) goto err;
a0a54079	137	bn_sqr_normal(rr->d,a->d,al,tmp->d);
dfeab068 RE	138	#endif
	139	}
	140
a0a54079	141	rr->top=max;
78a0c1f1	142	rr->neg=0;
a0a54079 MC	143	if ((max > 0) && (rr->d[max-1] == 0)) rr->top--;
a0a54079 MC	144	if (rr != r) BN_copy(r,rr);
9b141126 UM	145	ret = 1;
	146	err:
	147	BN_CTX_end(ctx);
d870740c	148	bn_check_top(r);
9b141126	149	return(ret);
dfeab068 RE	150	}
	151
	152	/* tmp must have 2n words /
43fcc1b0	153	void bn_sqr_normal(BN_ULONG r, const BN_ULONG a, int n, BN_ULONG *tmp)
dfeab068 RE	154	{
dfeab068 RE	155	int i,j,max;
43fcc1b0 RL	156	const BN_ULONG *ap;
43fcc1b0 RL	157	BN_ULONG *rp;
d02b48c6	158
dfeab068 RE	159	max=n*2;
	160	ap=a;
	161	rp=r;
d02b48c6 RE	162	rp[0]=rp[max-1]=0;
d02b48c6 RE	163	rp++;
dfeab068	164	j=n;
d02b48c6 RE	165
	166	if (--j > 0)
	167	{
	168	ap++;
58964a49	169	rp[j]=bn_mul_words(rp,ap,j,ap[-1]);
d02b48c6 RE	170	rp+=2;
	171	}
	172
dfeab068	173	for (i=n-2; i>0; i--)
d02b48c6 RE	174	{
	175	j--;
	176	ap++;
58964a49	177	rp[j]=bn_mul_add_words(rp,ap,j,ap[-1]);
d02b48c6 RE	178	rp+=2;
	179	}
	180
dfeab068	181	bn_add_words(r,r,r,max);
d02b48c6	182
58964a49	183	/* There will not be a carry */
d02b48c6	184
dfeab068	185	bn_sqr_words(tmp,a,n);
d02b48c6	186
dfeab068	187	bn_add_words(r,r,tmp,max);
d02b48c6 RE	188	}
d02b48c6 RE	189
dfeab068 RE	190	#ifdef BN_RECURSION
dfeab068 RE	191	/* r is 2*n words in size,
fe035197	192	* a and b are both n words in size. (There's not actually a 'b' here ...)
dfeab068 RE	193	* n must be a power of 2.
	194	* We multiply and return the result.
	195	* t must be 2*n words in size
657e60fa	196	* We calculate
dfeab068 RE	197	* a[0]*b[0]
	198	* a[0]b[0]+a[1]b[1]+(a[0]-a[1])*(b[1]-b[0])
	199	* a[1]*b[1]
	200	*/
43fcc1b0	201	void bn_sqr_recursive(BN_ULONG r, const BN_ULONG a, int n2, BN_ULONG *t)
dfeab068 RE	202	{
	203	int n=n2/2;
	204	int zero,c1;
	205	BN_ULONG ln,lo,*p;
	206
	207	#ifdef BN_COUNT
43fcc1b0	208	fprintf(stderr," bn_sqr_recursive %d * %d\n",n2,n2);
dfeab068 RE	209	#endif
	210	if (n2 == 4)
	211	{
	212	#ifndef BN_SQR_COMBA
	213	bn_sqr_normal(r,a,4,t);
	214	#else
	215	bn_sqr_comba4(r,a);
	216	#endif
	217	return;
	218	}
	219	else if (n2 == 8)
	220	{
	221	#ifndef BN_SQR_COMBA
	222	bn_sqr_normal(r,a,8,t);
	223	#else
	224	bn_sqr_comba8(r,a);
	225	#endif
	226	return;
	227	}
	228	if (n2 < BN_SQR_RECURSIVE_SIZE_NORMAL)
	229	{
	230	bn_sqr_normal(r,a,n2,t);
	231	return;
	232	}
	233	/* r=(a[0]-a[1])(a[1]-a[0]) /
	234	c1=bn_cmp_words(a,&(a[n]),n);
	235	zero=0;
	236	if (c1 > 0)
	237	bn_sub_words(t,a,&(a[n]),n);
	238	else if (c1 < 0)
	239	bn_sub_words(t,&(a[n]),a,n);
	240	else
	241	zero=1;
	242
	243	/* The result will always be negative unless it is zero */
	244	p= &(t[n2*2]);
	245
	246	if (!zero)
	247	bn_sqr_recursive(&(t[n2]),t,n,p);
	248	else
d98a4b73	249	memset(&(t[n2]),0,n2*sizeof(BN_ULONG));
dfeab068 RE	250	bn_sqr_recursive(r,a,n,p);
	251	bn_sqr_recursive(&(r[n2]),&(a[n]),n,p);
	252
	253	/* t[32] holds (a[0]-a[1])*(a[1]-a[0]), it is negative or zero
	254	* r[10] holds (a[0]*b[0])
	255	* r[32] holds (b[1]*b[1])
	256	*/
	257
651d0aff	258	c1=(int)(bn_add_words(t,r,&(r[n2]),n2));
dfeab068 RE	259
dfeab068 RE	260	/* t[32] is negative */
651d0aff	261	c1-=(int)(bn_sub_words(&(t[n2]),t,&(t[n2]),n2));
dfeab068 RE	262
	263	/* t[32] holds (a[0]-a[1])(a[1]-a[0])+(a[0]a[0])+(a[1]*a[1])
	264	* r[10] holds (a[0]*a[0])
	265	* r[32] holds (a[1]*a[1])
	266	* c1 holds the carry bits
	267	*/
651d0aff	268	c1+=(int)(bn_add_words(&(r[n]),&(r[n]),&(t[n2]),n2));
dfeab068 RE	269	if (c1)
	270	{
	271	p= &(r[n+n2]);
	272	lo= *p;
	273	ln=(lo+c1)&BN_MASK2;
	274	*p=ln;
	275
	276	/* The overflow will stop before we over write
	277	* words we should not overwrite */
	278	if (ln < (BN_ULONG)c1)
	279	{
	280	do {
	281	p++;
	282	lo= *p;
	283	ln=(lo+1)&BN_MASK2;
	284	*p=ln;
	285	} while (ln == 0);
	286	}
	287	}
	288	}
	289	#endif