src/parsec/disk-image/parsec/parsec-benchmark/pkgs/libs/ssl/src/crypto/bn/bn_mont.c - public/gem5-resources - Git at Google

 /* crypto/bn/bn_mont.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.]
  */
 /* ====================================================================
  * Copyright (c) 1998-2006 The OpenSSL Project.  All rights reserved.
  *
  * 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 above 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 acknowledgment:
  *    "This product includes software developed by the OpenSSL Project
  *    for use in the OpenSSL Toolkit. (http://www.openssl.org/)"
  *
  * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
  *    endorse or promote products derived from this software without
  *    prior written permission. For written permission, please contact
  *    openssl-core@openssl.org.
  *
  * 5. Products derived from this software may not be called "OpenSSL"
  *    nor may "OpenSSL" appear in their names without prior written
  *    permission of the OpenSSL Project.
  *
  * 6. Redistributions of any form whatsoever must retain the following
  *    acknowledgment:
  *    "This product includes software developed by the OpenSSL Project
  *    for use in the OpenSSL Toolkit (http://www.openssl.org/)"
  *
  * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
  * EXPRESSED 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 OpenSSL PROJECT OR
  * ITS 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.
  * ====================================================================
  *
  * This product includes cryptographic software written by Eric Young
  * (eay@cryptsoft.com).  This product includes software written by Tim
  * Hudson (tjh@cryptsoft.com).
  *
  */

 /*
  * Details about Montgomery multiplication algorithms can be found at
  * http://security.ece.orst.edu/publications.html, e.g.
  * http://security.ece.orst.edu/koc/papers/j37acmon.pdf and
  * sections 3.8 and 4.2 in http://security.ece.orst.edu/koc/papers/r01rsasw.pdf
  */

 #include <stdio.h>
 #include "cryptlib.h"
 #include "bn_lcl.h"

 #define MONT_WORD /* use the faster word-based algorithm */

 #if defined(MONT_WORD) && defined(OPENSSL_BN_ASM_MONT) && (BN_BITS2<=32)
 /* This condition means we have a specific non-default build:
  * In the 0.9.8 branch, OPENSSL_BN_ASM_MONT is normally not set for any
  * BN_BITS2<=32 platform; an explicit "enable-montasm" is required.
  * I.e., if we are here, the user intentionally deviates from the
  * normal stable build to get better Montgomery performance from
  * the 0.9.9-dev backport.
  *
  * In this case only, we also enable BN_from_montgomery_word()
  * (another non-stable feature from 0.9.9-dev).
  */
 #define MONT_FROM_WORD___NON_DEFAULT_0_9_8_BUILD
 #endif

 #ifdef MONT_FROM_WORD___NON_DEFAULT_0_9_8_BUILD
 static int BN_from_montgomery_word(BIGNUM *ret, BIGNUM *r, BN_MONT_CTX *mont);
 #endif


 int BN_mod_mul_montgomery(BIGNUM *r, const BIGNUM *a, const BIGNUM *b,
 			  BN_MONT_CTX *mont, BN_CTX *ctx)
 	{
 	BIGNUM *tmp;
 	int ret=0;
 #if defined(OPENSSL_BN_ASM_MONT) && defined(MONT_WORD)
 	int num = mont->N.top;

 	if (num>1 && a->top==num && b->top==num)
 		{
 		if (bn_wexpand(r,num) == NULL) return(0);
 #if 0 /* for OpenSSL 0.9.9 mont->n0 */
 		if (bn_mul_mont(r->d,a->d,b->d,mont->N.d,mont->n0,num))
 #else
 		if (bn_mul_mont(r->d,a->d,b->d,mont->N.d,&mont->n0,num))
 #endif
 			{
 			r->neg = a->neg^b->neg;
 			r->top = num;
 			bn_correct_top(r);
 			return(1);
 			}
 		}
 #endif

 	BN_CTX_start(ctx);
 	tmp = BN_CTX_get(ctx);
 	if (tmp == NULL) goto err;

 	bn_check_top(tmp);
 	if (a == b)
 		{
 		if (!BN_sqr(tmp,a,ctx)) goto err;
 		}
 	else
 		{
 		if (!BN_mul(tmp,a,b,ctx)) goto err;
 		}
 	/* reduce from aRR to aR */
 #ifdef MONT_FROM_WORD___NON_DEFAULT_0_9_8_BUILD
 	if (!BN_from_montgomery_word(r,tmp,mont)) goto err;
 #else
 	if (!BN_from_montgomery(r,tmp,mont,ctx)) goto err;
 #endif
 	bn_check_top(r);
 	ret=1;
 err:
 	BN_CTX_end(ctx);
 	return(ret);
 	}

 #ifdef MONT_FROM_WORD___NON_DEFAULT_0_9_8_BUILD
 static int BN_from_montgomery_word(BIGNUM *ret, BIGNUM *r, BN_MONT_CTX *mont)
 	{
 	BIGNUM *n;
 	BN_ULONG *ap,*np,*rp,n0,v,*nrp;
 	int al,nl,max,i,x,ri;

 	n= &(mont->N);
 	/* mont->ri is the size of mont->N in bits (rounded up
 	   to the word size) */
 	al=ri=mont->ri/BN_BITS2;

 	nl=n->top;
 	if ((al == 0) || (nl == 0)) { ret->top=0; return(1); }

 	max=(nl+al+1); /* allow for overflow (no?) XXX */
 	if (bn_wexpand(r,max) == NULL) return(0);

 	r->neg^=n->neg;
 	np=n->d;
 	rp=r->d;
 	nrp= &(r->d[nl]);

 	/* clear the top words of T */
 	for (i=r->top; i<max; i++) /* memset? XXX */
 		r->d[i]=0;

 	r->top=max;
 #if 0 /* for OpenSSL 0.9.9 mont->n0 */
 	n0=mont->n0[0];
 #else
 	n0=mont->n0;
 #endif

 #ifdef BN_COUNT
 	fprintf(stderr,"word BN_from_montgomery_word %d * %d\n",nl,nl);
 #endif
 	for (i=0; i<nl; i++)
 		{
 #ifdef __TANDEM
                 {
                    long long t1;
                    long long t2;
                    long long t3;
                    t1 = rp[0] * (n0 & 0177777);
                    t2 = 037777600000l;
                    t2 = n0 & t2;
                    t3 = rp[0] & 0177777;
                    t2 = (t3 * t2) & BN_MASK2;
                    t1 = t1 + t2;
                    v=bn_mul_add_words(rp,np,nl,(BN_ULONG) t1);
                 }
 #else
 		v=bn_mul_add_words(rp,np,nl,(rp[0]*n0)&BN_MASK2);
 #endif
 		nrp++;
 		rp++;
 		if (((nrp[-1]+=v)&BN_MASK2) >= v)
 			continue;
 		else
 			{
 			if (((++nrp[0])&BN_MASK2) != 0) continue;
 			if (((++nrp[1])&BN_MASK2) != 0) continue;
 			for (x=2; (((++nrp[x])&BN_MASK2) == 0); x++) ;
 			}
 		}
 	bn_correct_top(r);

 	/* mont->ri will be a multiple of the word size and below code
 	 * is kind of BN_rshift(ret,r,mont->ri) equivalent */
 	if (r->top <= ri)
 		{
 		ret->top=0;
 		return(1);
 		}
 	al=r->top-ri;

 	if (bn_wexpand(ret,ri) == NULL) return(0);
 	x=0-(((al-ri)>>(sizeof(al)*8-1))&1);
 	ret->top=x=(ri&~x)|(al&x);	/* min(ri,al) */
 	ret->neg=r->neg;

 	rp=ret->d;
 	ap=&(r->d[ri]);

 	{
 	size_t m1,m2;

 	v=bn_sub_words(rp,ap,np,ri);
 	/* this ----------------^^ works even in al<ri case
 	 * thanks to zealous zeroing of top of the vector in the
 	 * beginning. */

 	/* if (al==ri && !v) || al>ri) nrp=rp; else nrp=ap; */
 	/* in other words if subtraction result is real, then
 	 * trick unconditional memcpy below to perform in-place
 	 * "refresh" instead of actual copy. */
 	m1=0-(size_t)(((al-ri)>>(sizeof(al)*8-1))&1);	/* al<ri */
 	m2=0-(size_t)(((ri-al)>>(sizeof(al)*8-1))&1);	/* al>ri */
 	m1|=m2;			/* (al!=ri) */
 	m1|=(0-(size_t)v);	/* (al!=ri || v) */
 	m1&=~m2;		/* (al!=ri || v) && !al>ri */
 	nrp=(BN_ULONG *)(((size_t)rp&~m1)|((size_t)ap&m1));
 	}

 	/* 'i<ri' is chosen to eliminate dependency on input data, even
 	 * though it results in redundant copy in al<ri case. */
 	for (i=0,ri-=4; i<ri; i+=4)
 		{
 		BN_ULONG t1,t2,t3,t4;

 		t1=nrp[i+0];
 		t2=nrp[i+1];
 		t3=nrp[i+2];	ap[i+0]=0;
 		t4=nrp[i+3];	ap[i+1]=0;
 		rp[i+0]=t1;	ap[i+2]=0;
 		rp[i+1]=t2;	ap[i+3]=0;
 		rp[i+2]=t3;
 		rp[i+3]=t4;
 		}
 	for (ri+=4; i<ri; i++)
 		rp[i]=nrp[i], ap[i]=0;
 	bn_correct_top(r);
 	bn_correct_top(ret);
 	bn_check_top(ret);

 	return(1);
 	}

 int BN_from_montgomery(BIGNUM *ret, const BIGNUM *a, BN_MONT_CTX *mont,
 	     BN_CTX *ctx)
 	{
 	int retn=0;
 	BIGNUM *t;

 	BN_CTX_start(ctx);
 	if ((t = BN_CTX_get(ctx)) && BN_copy(t,a))
 		retn = BN_from_montgomery_word(ret,t,mont);
 	BN_CTX_end(ctx);
 	return retn;
 	}

 #else /* !MONT_FROM_WORD___NON_DEFAULT_0_9_8_BUILD */

 int BN_from_montgomery(BIGNUM *ret, const BIGNUM *a, BN_MONT_CTX *mont,
 	     BN_CTX *ctx)
 	{
 	int retn=0;

 #ifdef MONT_WORD
 	BIGNUM *n,*r;
 	BN_ULONG *ap,*np,*rp,n0,v,*nrp;
 	int al,nl,max,i,x,ri;

 	BN_CTX_start(ctx);
 	if ((r = BN_CTX_get(ctx)) == NULL) goto err;

 	if (!BN_copy(r,a)) goto err;
 	n= &(mont->N);

 	ap=a->d;
 	/* mont->ri is the size of mont->N in bits (rounded up
 	   to the word size) */
 	al=ri=mont->ri/BN_BITS2;

 	nl=n->top;
 	if ((al == 0) || (nl == 0)) { r->top=0; return(1); }

 	max=(nl+al+1); /* allow for overflow (no?) XXX */
 	if (bn_wexpand(r,max) == NULL) goto err;

 	r->neg=a->neg^n->neg;
 	np=n->d;
 	rp=r->d;
 	nrp= &(r->d[nl]);

 	/* clear the top words of T */
 #if 1
 	for (i=r->top; i<max; i++) /* memset? XXX */
 		r->d[i]=0;
 #else
 	memset(&(r->d[r->top]),0,(max-r->top)*sizeof(BN_ULONG));
 #endif

 	r->top=max;
 	n0=mont->n0;

 #ifdef BN_COUNT
 	fprintf(stderr,"word BN_from_montgomery %d * %d\n",nl,nl);
 #endif
 	for (i=0; i<nl; i++)
 		{
 #ifdef __TANDEM
                 {
                    long long t1;
                    long long t2;
                    long long t3;
                    t1 = rp[0] * (n0 & 0177777);
                    t2 = 037777600000l;
                    t2 = n0 & t2;
                    t3 = rp[0] & 0177777;
                    t2 = (t3 * t2) & BN_MASK2;
                    t1 = t1 + t2;
                    v=bn_mul_add_words(rp,np,nl,(BN_ULONG) t1);
                 }
 #else
 		v=bn_mul_add_words(rp,np,nl,(rp[0]*n0)&BN_MASK2);
 #endif
 		nrp++;
 		rp++;
 		if (((nrp[-1]+=v)&BN_MASK2) >= v)
 			continue;
 		else
 			{
 			if (((++nrp[0])&BN_MASK2) != 0) continue;
 			if (((++nrp[1])&BN_MASK2) != 0) continue;
 			for (x=2; (((++nrp[x])&BN_MASK2) == 0); x++) ;
 			}
 		}
 	bn_correct_top(r);

 	/* mont->ri will be a multiple of the word size and below code
 	 * is kind of BN_rshift(ret,r,mont->ri) equivalent */
 	if (r->top <= ri)
 		{
 		ret->top=0;
 		retn=1;
 		goto err;
 		}
 	al=r->top-ri;

 # define BRANCH_FREE 1
 # if BRANCH_FREE
 	if (bn_wexpand(ret,ri) == NULL) goto err;
 	x=0-(((al-ri)>>(sizeof(al)*8-1))&1);
 	ret->top=x=(ri&~x)|(al&x);	/* min(ri,al) */
 	ret->neg=r->neg;

 	rp=ret->d;
 	ap=&(r->d[ri]);

 	{
 	size_t m1,m2;

 	v=bn_sub_words(rp,ap,np,ri);
 	/* this ----------------^^ works even in al<ri case
 	 * thanks to zealous zeroing of top of the vector in the
 	 * beginning. */

 	/* if (al==ri && !v) || al>ri) nrp=rp; else nrp=ap; */
 	/* in other words if subtraction result is real, then
 	 * trick unconditional memcpy below to perform in-place
 	 * "refresh" instead of actual copy. */
 	m1=0-(size_t)(((al-ri)>>(sizeof(al)*8-1))&1);	/* al<ri */
 	m2=0-(size_t)(((ri-al)>>(sizeof(al)*8-1))&1);	/* al>ri */
 	m1|=m2;			/* (al!=ri) */
 	m1|=(0-(size_t)v);	/* (al!=ri || v) */
 	m1&=~m2;		/* (al!=ri || v) && !al>ri */
 	nrp=(BN_ULONG *)(((size_t)rp&~m1)|((size_t)ap&m1));
 	}

 	/* 'i<ri' is chosen to eliminate dependency on input data, even
 	 * though it results in redundant copy in al<ri case. */
 	for (i=0,ri-=4; i<ri; i+=4)
 		{
 		BN_ULONG t1,t2,t3,t4;

 		t1=nrp[i+0];
 		t2=nrp[i+1];
 		t3=nrp[i+2];	ap[i+0]=0;
 		t4=nrp[i+3];	ap[i+1]=0;
 		rp[i+0]=t1;	ap[i+2]=0;
 		rp[i+1]=t2;	ap[i+3]=0;
 		rp[i+2]=t3;
 		rp[i+3]=t4;
 		}
 	for (ri+=4; i<ri; i++)
 		rp[i]=nrp[i], ap[i]=0;
 	bn_correct_top(r);
 	bn_correct_top(ret);
 # else
 	if (bn_wexpand(ret,al) == NULL) goto err;
 	ret->top=al;
 	ret->neg=r->neg;

 	rp=ret->d;
 	ap=&(r->d[ri]);
 	al-=4;
 	for (i=0; i<al; i+=4)
 		{
 		BN_ULONG t1,t2,t3,t4;

 		t1=ap[i+0];
 		t2=ap[i+1];
 		t3=ap[i+2];
 		t4=ap[i+3];
 		rp[i+0]=t1;
 		rp[i+1]=t2;
 		rp[i+2]=t3;
 		rp[i+3]=t4;
 		}
 	al+=4;
 	for (; i<al; i++)
 		rp[i]=ap[i];
 # endif
 #else /* !MONT_WORD */
 	BIGNUM *t1,*t2;

 	BN_CTX_start(ctx);
 	t1 = BN_CTX_get(ctx);
 	t2 = BN_CTX_get(ctx);
 	if (t1 == NULL || t2 == NULL) goto err;

 	if (!BN_copy(t1,a)) goto err;
 	BN_mask_bits(t1,mont->ri);

 	if (!BN_mul(t2,t1,&mont->Ni,ctx)) goto err;
 	BN_mask_bits(t2,mont->ri);

 	if (!BN_mul(t1,t2,&mont->N,ctx)) goto err;
 	if (!BN_add(t2,a,t1)) goto err;
 	if (!BN_rshift(ret,t2,mont->ri)) goto err;
 #endif /* MONT_WORD */

 #if !defined(BRANCH_FREE) || BRANCH_FREE==0
 	if (BN_ucmp(ret, &(mont->N)) >= 0)
 		{
 		if (!BN_usub(ret,ret,&(mont->N))) goto err;
 		}
 #endif
 	retn=1;
 	bn_check_top(ret);
  err:
 	BN_CTX_end(ctx);
 	return(retn);
 	}
 #endif /* MONT_FROM_WORD___NON_DEFAULT_0_9_8_BUILD */

 BN_MONT_CTX *BN_MONT_CTX_new(void)
 	{
 	BN_MONT_CTX *ret;

 	if ((ret=(BN_MONT_CTX *)OPENSSL_malloc(sizeof(BN_MONT_CTX))) == NULL)
 		return(NULL);

 	BN_MONT_CTX_init(ret);
 	ret->flags=BN_FLG_MALLOCED;
 	return(ret);
 	}

 void BN_MONT_CTX_init(BN_MONT_CTX *ctx)
 	{
 	ctx->ri=0;
 	BN_init(&(ctx->RR));
 	BN_init(&(ctx->N));
 	BN_init(&(ctx->Ni));
 #if 0 /* for OpenSSL 0.9.9 mont->n0 */
 	ctx->n0[0] = ctx->n0[1] = 0;
 #else
 	ctx->n0 = 0;
 #endif
 	ctx->flags=0;
 	}

 void BN_MONT_CTX_free(BN_MONT_CTX *mont)
 	{
 	if(mont == NULL)
 	    return;

 	BN_free(&(mont->RR));
 	BN_free(&(mont->N));
 	BN_free(&(mont->Ni));
 	if (mont->flags & BN_FLG_MALLOCED)
 		OPENSSL_free(mont);
 	}

 int BN_MONT_CTX_set(BN_MONT_CTX *mont, const BIGNUM *mod, BN_CTX *ctx)
 	{
 	int ret = 0;
 	BIGNUM *Ri,*R;

 	BN_CTX_start(ctx);
 	if((Ri = BN_CTX_get(ctx)) == NULL) goto err;
 	R= &(mont->RR);					/* grab RR as a temp */
 	if (!BN_copy(&(mont->N),mod)) goto err;		/* Set N */
 	mont->N.neg = 0;

 #ifdef MONT_WORD
 		{
 		BIGNUM tmod;
 		BN_ULONG buf[2];

 		mont->ri=(BN_num_bits(mod)+(BN_BITS2-1))/BN_BITS2*BN_BITS2;
 		BN_zero(R);
 #if 0 /* for OpenSSL 0.9.9 mont->n0, would be "#if defined(OPENSSL_BN_ASM_MONT) && (BN_BITS2<=32)",
          only certain BN_BITS2<=32 platforms actually need this */
 		if (!(BN_set_bit(R,2*BN_BITS2))) goto err;	/* R */
 #else
 		if (!(BN_set_bit(R,BN_BITS2))) goto err;	/* R */
 #endif

 		buf[0]=mod->d[0]; /* tmod = N mod word size */
 		buf[1]=0;

 		BN_init(&tmod);
 		tmod.d=buf;
 		tmod.top = buf[0] != 0 ? 1 : 0;
 		tmod.dmax=2;
 		tmod.neg=0;

 #if 0 /* for OpenSSL 0.9.9 mont->n0, would be "#if defined(OPENSSL_BN_ASM_MONT) && (BN_BITS2<=32)";
          only certain BN_BITS2<=32 platforms actually need this */
 								tmod.top=0;
 		if ((buf[0] = mod->d[0]))			tmod.top=1;
 		if ((buf[1] = mod->top>1 ? mod->d[1] : 0))	tmod.top=2;

 		if ((BN_mod_inverse(Ri,R,&tmod,ctx)) == NULL)
 			goto err;
 		if (!BN_lshift(Ri,Ri,2*BN_BITS2)) goto err; /* R*Ri */
 		if (!BN_is_zero(Ri))
 			{
 			if (!BN_sub_word(Ri,1)) goto err;
 			}
 		else /* if N mod word size == 1 */
 			{
 			if (bn_expand(Ri,(int)sizeof(BN_ULONG)*2) == NULL)
 				goto err;
 			/* Ri-- (mod double word size) */
 			Ri->neg=0;
 			Ri->d[0]=BN_MASK2;
 			Ri->d[1]=BN_MASK2;
 			Ri->top=2;
 			}
 		if (!BN_div(Ri,NULL,Ri,&tmod,ctx)) goto err;
 		/* Ni = (R*Ri-1)/N,
 		 * keep only couple of least significant words: */
 		mont->n0[0] = (Ri->top > 0) ? Ri->d[0] : 0;
 		mont->n0[1] = (Ri->top > 1) ? Ri->d[1] : 0;
 #else
 							/* Ri = R^-1 mod N*/
 		if ((BN_mod_inverse(Ri,R,&tmod,ctx)) == NULL)
 			goto err;
 		if (!BN_lshift(Ri,Ri,BN_BITS2)) goto err; /* R*Ri */
 		if (!BN_is_zero(Ri))
 			{
 			if (!BN_sub_word(Ri,1)) goto err;
 			}
 		else /* if N mod word size == 1 */
 			{
 			if (!BN_set_word(Ri,BN_MASK2)) goto err;  /* Ri-- (mod word size) */
 			}
 		if (!BN_div(Ri,NULL,Ri,&tmod,ctx)) goto err;
 		/* Ni = (R*Ri-1)/N,
 		 * keep only least significant word: */
 # if 0 /* for OpenSSL 0.9.9 mont->n0 */
 		mont->n0[0] = (Ri->top > 0) ? Ri->d[0] : 0;
 		mont->n0[1] = 0;
 # else
 		mont->n0 = (Ri->top > 0) ? Ri->d[0] : 0;
 # endif
 #endif
 		}
 #else /* !MONT_WORD */
 		{ /* bignum version */
 		mont->ri=BN_num_bits(&mont->N);
 		BN_zero(R);
 		if (!BN_set_bit(R,mont->ri)) goto err;  /* R = 2^ri */
 		                                        /* Ri = R^-1 mod N*/
 		if ((BN_mod_inverse(Ri,R,&mont->N,ctx)) == NULL)
 			goto err;
 		if (!BN_lshift(Ri,Ri,mont->ri)) goto err; /* R*Ri */
 		if (!BN_sub_word(Ri,1)) goto err;
 							/* Ni = (R*Ri-1) / N */
 		if (!BN_div(&(mont->Ni),NULL,Ri,&mont->N,ctx)) goto err;
 		}
 #endif

 	/* setup RR for conversions */
 	BN_zero(&(mont->RR));
 	if (!BN_set_bit(&(mont->RR),mont->ri*2)) goto err;
 	if (!BN_mod(&(mont->RR),&(mont->RR),&(mont->N),ctx)) goto err;

 	ret = 1;
 err:
 	BN_CTX_end(ctx);
 	return ret;
 	}

 BN_MONT_CTX *BN_MONT_CTX_copy(BN_MONT_CTX *to, BN_MONT_CTX *from)
 	{
 	if (to == from) return(to);

 	if (!BN_copy(&(to->RR),&(from->RR))) return NULL;
 	if (!BN_copy(&(to->N),&(from->N))) return NULL;
 	if (!BN_copy(&(to->Ni),&(from->Ni))) return NULL;
 	to->ri=from->ri;
 #if 0 /* for OpenSSL 0.9.9 mont->n0 */
 	to->n0[0]=from->n0[0];
 	to->n0[1]=from->n0[1];
 #else
 	to->n0=from->n0;
 #endif
 	return(to);
 	}

 BN_MONT_CTX *BN_MONT_CTX_set_locked(BN_MONT_CTX **pmont, int lock,
 					const BIGNUM *mod, BN_CTX *ctx)
 	{
 	int got_write_lock = 0;
 	BN_MONT_CTX *ret;

 	CRYPTO_r_lock(lock);
 	if (!*pmont)
 		{
 		CRYPTO_r_unlock(lock);
 		CRYPTO_w_lock(lock);
 		got_write_lock = 1;

 		if (!*pmont)
 			{
 			ret = BN_MONT_CTX_new();
 			if (ret && !BN_MONT_CTX_set(ret, mod, ctx))
 				BN_MONT_CTX_free(ret);
 			else
 				*pmont = ret;
 			}
 		}

 	ret = *pmont;

 	if (got_write_lock)
 		CRYPTO_w_unlock(lock);
 	else
 		CRYPTO_r_unlock(lock);

 	return ret;
 	}
	/* crypto/bn/bn_mont.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.]
	*/
	/* ====================================================================
	* Copyright (c) 1998-2006 The OpenSSL Project. All rights reserved.
	*
	* 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 above 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 acknowledgment:
	* "This product includes software developed by the OpenSSL Project
	* for use in the OpenSSL Toolkit. (http://www.openssl.org/)"
	*
	* 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
	* endorse or promote products derived from this software without
	* prior written permission. For written permission, please contact
	* openssl-core@openssl.org.
	*
	* 5. Products derived from this software may not be called "OpenSSL"
	* nor may "OpenSSL" appear in their names without prior written
	* permission of the OpenSSL Project.
	*
	* 6. Redistributions of any form whatsoever must retain the following
	* acknowledgment:
	* "This product includes software developed by the OpenSSL Project
	* for use in the OpenSSL Toolkit (http://www.openssl.org/)"
	*
	* THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
	* EXPRESSED 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 OpenSSL PROJECT OR
	* ITS 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.
	* ====================================================================
	*
	* This product includes cryptographic software written by Eric Young
	* (eay@cryptsoft.com). This product includes software written by Tim
	* Hudson (tjh@cryptsoft.com).
	*
	*/

	/*
	* Details about Montgomery multiplication algorithms can be found at
	* http://security.ece.orst.edu/publications.html, e.g.
	* http://security.ece.orst.edu/koc/papers/j37acmon.pdf and
	* sections 3.8 and 4.2 in http://security.ece.orst.edu/koc/papers/r01rsasw.pdf
	*/

	#include <stdio.h>
	#include "cryptlib.h"
	#include "bn_lcl.h"

	#define MONT_WORD /* use the faster word-based algorithm */

	#if defined(MONT_WORD) && defined(OPENSSL_BN_ASM_MONT) && (BN_BITS2<=32)
	/* This condition means we have a specific non-default build:
	* In the 0.9.8 branch, OPENSSL_BN_ASM_MONT is normally not set for any
	* BN_BITS2<=32 platform; an explicit "enable-montasm" is required.
	* I.e., if we are here, the user intentionally deviates from the
	* normal stable build to get better Montgomery performance from
	* the 0.9.9-dev backport.
	*
	* In this case only, we also enable BN_from_montgomery_word()
	* (another non-stable feature from 0.9.9-dev).
	*/
	#define MONT_FROM_WORD___NON_DEFAULT_0_9_8_BUILD
	#endif

	#ifdef MONT_FROM_WORD___NON_DEFAULT_0_9_8_BUILD
	static int BN_from_montgomery_word(BIGNUM ret, BIGNUM r, BN_MONT_CTX *mont);
	#endif



	int BN_mod_mul_montgomery(BIGNUM r, const BIGNUM a, const BIGNUM *b,
	BN_MONT_CTX mont, BN_CTX ctx)
	{
	BIGNUM *tmp;
	int ret=0;
	#if defined(OPENSSL_BN_ASM_MONT) && defined(MONT_WORD)
	int num = mont->N.top;

	if (num>1 && a->top==num && b->top==num)
	{
	if (bn_wexpand(r,num) == NULL) return(0);
	#if 0 /* for OpenSSL 0.9.9 mont->n0 */
	if (bn_mul_mont(r->d,a->d,b->d,mont->N.d,mont->n0,num))
	#else
	if (bn_mul_mont(r->d,a->d,b->d,mont->N.d,&mont->n0,num))
	#endif
	{
	r->neg = a->neg^b->neg;
	r->top = num;
	bn_correct_top(r);
	return(1);
	}
	}
	#endif

	BN_CTX_start(ctx);
	tmp = BN_CTX_get(ctx);
	if (tmp == NULL) goto err;

	bn_check_top(tmp);
	if (a == b)
	{
	if (!BN_sqr(tmp,a,ctx)) goto err;
	}
	else
	{
	if (!BN_mul(tmp,a,b,ctx)) goto err;
	}
	/* reduce from aRR to aR */
	#ifdef MONT_FROM_WORD___NON_DEFAULT_0_9_8_BUILD
	if (!BN_from_montgomery_word(r,tmp,mont)) goto err;
	#else
	if (!BN_from_montgomery(r,tmp,mont,ctx)) goto err;
	#endif
	bn_check_top(r);
	ret=1;
	err:
	BN_CTX_end(ctx);
	return(ret);
	}

	#ifdef MONT_FROM_WORD___NON_DEFAULT_0_9_8_BUILD
	static int BN_from_montgomery_word(BIGNUM ret, BIGNUM r, BN_MONT_CTX *mont)
	{
	BIGNUM *n;
	BN_ULONG ap,np,rp,n0,v,nrp;
	int al,nl,max,i,x,ri;

	n= &(mont->N);
	/* mont->ri is the size of mont->N in bits (rounded up
	to the word size) */
	al=ri=mont->ri/BN_BITS2;

	nl=n->top;
	if ((al == 0) \|\| (nl == 0)) { ret->top=0; return(1); }

	max=(nl+al+1); /* allow for overflow (no?) XXX */
	if (bn_wexpand(r,max) == NULL) return(0);

	r->neg^=n->neg;
	np=n->d;
	rp=r->d;
	nrp= &(r->d[nl]);

	/* clear the top words of T */
	for (i=r->top; i<max; i++) /* memset? XXX */
	r->d[i]=0;

	r->top=max;
	#if 0 /* for OpenSSL 0.9.9 mont->n0 */
	n0=mont->n0[0];
	#else
	n0=mont->n0;
	#endif

	#ifdef BN_COUNT
	fprintf(stderr,"word BN_from_montgomery_word %d * %d\n",nl,nl);
	#endif
	for (i=0; i<nl; i++)
	{
	#ifdef __TANDEM
	{
	long long t1;
	long long t2;
	long long t3;
	t1 = rp[0] * (n0 & 0177777);
	t2 = 037777600000l;
	t2 = n0 & t2;
	t3 = rp[0] & 0177777;
	t2 = (t3 * t2) & BN_MASK2;
	t1 = t1 + t2;
	v=bn_mul_add_words(rp,np,nl,(BN_ULONG) t1);
	}
	#else
	v=bn_mul_add_words(rp,np,nl,(rp[0]*n0)&BN_MASK2);
	#endif
	nrp++;
	rp++;
	if (((nrp[-1]+=v)&BN_MASK2) >= v)
	continue;
	else
	{
	if (((++nrp[0])&BN_MASK2) != 0) continue;
	if (((++nrp[1])&BN_MASK2) != 0) continue;
	for (x=2; (((++nrp[x])&BN_MASK2) == 0); x++) ;
	}
	}
	bn_correct_top(r);

	/* mont->ri will be a multiple of the word size and below code
	* is kind of BN_rshift(ret,r,mont->ri) equivalent */
	if (r->top <= ri)
	{
	ret->top=0;
	return(1);
	}
	al=r->top-ri;

	if (bn_wexpand(ret,ri) == NULL) return(0);
	x=0-(((al-ri)>>(sizeof(al)*8-1))&1);
	ret->top=x=(ri&~x)\|(al&x); /* min(ri,al) */
	ret->neg=r->neg;

	rp=ret->d;
	ap=&(r->d[ri]);

	{
	size_t m1,m2;

	v=bn_sub_words(rp,ap,np,ri);
	/* this ----------------^^ works even in al<ri case
	* thanks to zealous zeroing of top of the vector in the
	* beginning. */

	/* if (al==ri && !v) \|\| al>ri) nrp=rp; else nrp=ap; */
	/* in other words if subtraction result is real, then
	* trick unconditional memcpy below to perform in-place
	* "refresh" instead of actual copy. */
	m1=0-(size_t)(((al-ri)>>(sizeof(al)8-1))&1); / al<ri */
	m2=0-(size_t)(((ri-al)>>(sizeof(al)8-1))&1); / al>ri */
	m1\|=m2; /* (al!=ri) */
	m1\|=(0-(size_t)v); /* (al!=ri \|\| v) */
	m1&=~m2; /* (al!=ri \|\| v) && !al>ri */
	nrp=(BN_ULONG *)(((size_t)rp&~m1)\|((size_t)ap&m1));
	}

	/* 'i<ri' is chosen to eliminate dependency on input data, even
	* though it results in redundant copy in al<ri case. */
	for (i=0,ri-=4; i<ri; i+=4)
	{
	BN_ULONG t1,t2,t3,t4;

	t1=nrp[i+0];
	t2=nrp[i+1];
	t3=nrp[i+2]; ap[i+0]=0;
	t4=nrp[i+3]; ap[i+1]=0;
	rp[i+0]=t1; ap[i+2]=0;
	rp[i+1]=t2; ap[i+3]=0;
	rp[i+2]=t3;
	rp[i+3]=t4;
	}
	for (ri+=4; i<ri; i++)
	rp[i]=nrp[i], ap[i]=0;
	bn_correct_top(r);
	bn_correct_top(ret);
	bn_check_top(ret);

	return(1);
	}

	int BN_from_montgomery(BIGNUM ret, const BIGNUM a, BN_MONT_CTX *mont,
	BN_CTX *ctx)
	{
	int retn=0;
	BIGNUM *t;

	BN_CTX_start(ctx);
	if ((t = BN_CTX_get(ctx)) && BN_copy(t,a))
	retn = BN_from_montgomery_word(ret,t,mont);
	BN_CTX_end(ctx);
	return retn;
	}

	#else /* !MONT_FROM_WORD___NON_DEFAULT_0_9_8_BUILD */

	int BN_from_montgomery(BIGNUM ret, const BIGNUM a, BN_MONT_CTX *mont,
	BN_CTX *ctx)
	{
	int retn=0;

	#ifdef MONT_WORD
	BIGNUM n,r;
	BN_ULONG ap,np,rp,n0,v,nrp;
	int al,nl,max,i,x,ri;

	BN_CTX_start(ctx);
	if ((r = BN_CTX_get(ctx)) == NULL) goto err;

	if (!BN_copy(r,a)) goto err;
	n= &(mont->N);

	ap=a->d;
	/* mont->ri is the size of mont->N in bits (rounded up
	to the word size) */
	al=ri=mont->ri/BN_BITS2;

	nl=n->top;
	if ((al == 0) \|\| (nl == 0)) { r->top=0; return(1); }

	max=(nl+al+1); /* allow for overflow (no?) XXX */
	if (bn_wexpand(r,max) == NULL) goto err;

	r->neg=a->neg^n->neg;
	np=n->d;
	rp=r->d;
	nrp= &(r->d[nl]);

	/* clear the top words of T */
	#if 1
	for (i=r->top; i<max; i++) /* memset? XXX */
	r->d[i]=0;
	#else
	memset(&(r->d[r->top]),0,(max-r->top)*sizeof(BN_ULONG));
	#endif

	r->top=max;
	n0=mont->n0;

	#ifdef BN_COUNT
	fprintf(stderr,"word BN_from_montgomery %d * %d\n",nl,nl);
	#endif
	for (i=0; i<nl; i++)
	{
	#ifdef __TANDEM
	{
	long long t1;
	long long t2;
	long long t3;
	t1 = rp[0] * (n0 & 0177777);
	t2 = 037777600000l;
	t2 = n0 & t2;
	t3 = rp[0] & 0177777;
	t2 = (t3 * t2) & BN_MASK2;
	t1 = t1 + t2;
	v=bn_mul_add_words(rp,np,nl,(BN_ULONG) t1);
	}
	#else
	v=bn_mul_add_words(rp,np,nl,(rp[0]*n0)&BN_MASK2);
	#endif
	nrp++;
	rp++;
	if (((nrp[-1]+=v)&BN_MASK2) >= v)
	continue;
	else
	{
	if (((++nrp[0])&BN_MASK2) != 0) continue;
	if (((++nrp[1])&BN_MASK2) != 0) continue;
	for (x=2; (((++nrp[x])&BN_MASK2) == 0); x++) ;
	}
	}
	bn_correct_top(r);

	/* mont->ri will be a multiple of the word size and below code
	* is kind of BN_rshift(ret,r,mont->ri) equivalent */
	if (r->top <= ri)
	{
	ret->top=0;
	retn=1;
	goto err;
	}
	al=r->top-ri;

	# define BRANCH_FREE 1
	# if BRANCH_FREE
	if (bn_wexpand(ret,ri) == NULL) goto err;
	x=0-(((al-ri)>>(sizeof(al)*8-1))&1);
	ret->top=x=(ri&~x)\|(al&x); /* min(ri,al) */
	ret->neg=r->neg;

	rp=ret->d;
	ap=&(r->d[ri]);

	{
	size_t m1,m2;

	v=bn_sub_words(rp,ap,np,ri);
	/* this ----------------^^ works even in al<ri case
	* thanks to zealous zeroing of top of the vector in the
	* beginning. */

	/* if (al==ri && !v) \|\| al>ri) nrp=rp; else nrp=ap; */
	/* in other words if subtraction result is real, then
	* trick unconditional memcpy below to perform in-place
	* "refresh" instead of actual copy. */
	m1=0-(size_t)(((al-ri)>>(sizeof(al)8-1))&1); / al<ri */
	m2=0-(size_t)(((ri-al)>>(sizeof(al)8-1))&1); / al>ri */
	m1\|=m2; /* (al!=ri) */
	m1\|=(0-(size_t)v); /* (al!=ri \|\| v) */
	m1&=~m2; /* (al!=ri \|\| v) && !al>ri */
	nrp=(BN_ULONG *)(((size_t)rp&~m1)\|((size_t)ap&m1));
	}

	/* 'i<ri' is chosen to eliminate dependency on input data, even
	* though it results in redundant copy in al<ri case. */
	for (i=0,ri-=4; i<ri; i+=4)
	{
	BN_ULONG t1,t2,t3,t4;

	t1=nrp[i+0];
	t2=nrp[i+1];
	t3=nrp[i+2]; ap[i+0]=0;
	t4=nrp[i+3]; ap[i+1]=0;
	rp[i+0]=t1; ap[i+2]=0;
	rp[i+1]=t2; ap[i+3]=0;
	rp[i+2]=t3;
	rp[i+3]=t4;
	}
	for (ri+=4; i<ri; i++)
	rp[i]=nrp[i], ap[i]=0;
	bn_correct_top(r);
	bn_correct_top(ret);
	# else
	if (bn_wexpand(ret,al) == NULL) goto err;
	ret->top=al;
	ret->neg=r->neg;

	rp=ret->d;
	ap=&(r->d[ri]);
	al-=4;
	for (i=0; i<al; i+=4)
	{
	BN_ULONG t1,t2,t3,t4;

	t1=ap[i+0];
	t2=ap[i+1];
	t3=ap[i+2];
	t4=ap[i+3];
	rp[i+0]=t1;
	rp[i+1]=t2;
	rp[i+2]=t3;
	rp[i+3]=t4;
	}
	al+=4;
	for (; i<al; i++)
	rp[i]=ap[i];
	# endif
	#else /* !MONT_WORD */
	BIGNUM t1,t2;

	BN_CTX_start(ctx);
	t1 = BN_CTX_get(ctx);
	t2 = BN_CTX_get(ctx);
	if (t1 == NULL \|\| t2 == NULL) goto err;

	if (!BN_copy(t1,a)) goto err;
	BN_mask_bits(t1,mont->ri);

	if (!BN_mul(t2,t1,&mont->Ni,ctx)) goto err;
	BN_mask_bits(t2,mont->ri);

	if (!BN_mul(t1,t2,&mont->N,ctx)) goto err;
	if (!BN_add(t2,a,t1)) goto err;
	if (!BN_rshift(ret,t2,mont->ri)) goto err;
	#endif /* MONT_WORD */

	#if !defined(BRANCH_FREE) \|\| BRANCH_FREE==0
	if (BN_ucmp(ret, &(mont->N)) >= 0)
	{
	if (!BN_usub(ret,ret,&(mont->N))) goto err;
	}
	#endif
	retn=1;
	bn_check_top(ret);
	err:
	BN_CTX_end(ctx);
	return(retn);
	}
	#endif /* MONT_FROM_WORD___NON_DEFAULT_0_9_8_BUILD */

	BN_MONT_CTX *BN_MONT_CTX_new(void)
	{
	BN_MONT_CTX *ret;

	if ((ret=(BN_MONT_CTX *)OPENSSL_malloc(sizeof(BN_MONT_CTX))) == NULL)
	return(NULL);

	BN_MONT_CTX_init(ret);
	ret->flags=BN_FLG_MALLOCED;
	return(ret);
	}

	void BN_MONT_CTX_init(BN_MONT_CTX *ctx)
	{
	ctx->ri=0;
	BN_init(&(ctx->RR));
	BN_init(&(ctx->N));
	BN_init(&(ctx->Ni));
	#if 0 /* for OpenSSL 0.9.9 mont->n0 */
	ctx->n0[0] = ctx->n0[1] = 0;
	#else
	ctx->n0 = 0;
	#endif
	ctx->flags=0;
	}

	void BN_MONT_CTX_free(BN_MONT_CTX *mont)
	{
	if(mont == NULL)
	return;

	BN_free(&(mont->RR));
	BN_free(&(mont->N));
	BN_free(&(mont->Ni));
	if (mont->flags & BN_FLG_MALLOCED)
	OPENSSL_free(mont);
	}

	int BN_MONT_CTX_set(BN_MONT_CTX mont, const BIGNUM mod, BN_CTX *ctx)
	{
	int ret = 0;
	BIGNUM Ri,R;

	BN_CTX_start(ctx);
	if((Ri = BN_CTX_get(ctx)) == NULL) goto err;
	R= &(mont->RR); /* grab RR as a temp */
	if (!BN_copy(&(mont->N),mod)) goto err; /* Set N */
	mont->N.neg = 0;

	#ifdef MONT_WORD
	{
	BIGNUM tmod;
	BN_ULONG buf[2];

	mont->ri=(BN_num_bits(mod)+(BN_BITS2-1))/BN_BITS2*BN_BITS2;
	BN_zero(R);
	#if 0 /* for OpenSSL 0.9.9 mont->n0, would be "#if defined(OPENSSL_BN_ASM_MONT) && (BN_BITS2<=32)",
	only certain BN_BITS2<=32 platforms actually need this */
	if (!(BN_set_bit(R,2BN_BITS2))) goto err; / R */
	#else
	if (!(BN_set_bit(R,BN_BITS2))) goto err; /* R */
	#endif

	buf[0]=mod->d[0]; /* tmod = N mod word size */
	buf[1]=0;

	BN_init(&tmod);
	tmod.d=buf;
	tmod.top = buf[0] != 0 ? 1 : 0;
	tmod.dmax=2;
	tmod.neg=0;

	#if 0 /* for OpenSSL 0.9.9 mont->n0, would be "#if defined(OPENSSL_BN_ASM_MONT) && (BN_BITS2<=32)";
	only certain BN_BITS2<=32 platforms actually need this */
	tmod.top=0;
	if ((buf[0] = mod->d[0])) tmod.top=1;
	if ((buf[1] = mod->top>1 ? mod->d[1] : 0)) tmod.top=2;

	if ((BN_mod_inverse(Ri,R,&tmod,ctx)) == NULL)
	goto err;
	if (!BN_lshift(Ri,Ri,2BN_BITS2)) goto err; / RRi /
	if (!BN_is_zero(Ri))
	{
	if (!BN_sub_word(Ri,1)) goto err;
	}
	else /* if N mod word size == 1 */
	{
	if (bn_expand(Ri,(int)sizeof(BN_ULONG)*2) == NULL)
	goto err;
	/* Ri-- (mod double word size) */
	Ri->neg=0;
	Ri->d[0]=BN_MASK2;
	Ri->d[1]=BN_MASK2;
	Ri->top=2;
	}
	if (!BN_div(Ri,NULL,Ri,&tmod,ctx)) goto err;
	/* Ni = (R*Ri-1)/N,
	* keep only couple of least significant words: */
	mont->n0[0] = (Ri->top > 0) ? Ri->d[0] : 0;
	mont->n0[1] = (Ri->top > 1) ? Ri->d[1] : 0;
	#else
	/* Ri = R^-1 mod N*/
	if ((BN_mod_inverse(Ri,R,&tmod,ctx)) == NULL)
	goto err;
	if (!BN_lshift(Ri,Ri,BN_BITS2)) goto err; /* RRi /
	if (!BN_is_zero(Ri))
	{
	if (!BN_sub_word(Ri,1)) goto err;
	}
	else /* if N mod word size == 1 */
	{
	if (!BN_set_word(Ri,BN_MASK2)) goto err; /* Ri-- (mod word size) */
	}
	if (!BN_div(Ri,NULL,Ri,&tmod,ctx)) goto err;
	/* Ni = (R*Ri-1)/N,
	* keep only least significant word: */
	# if 0 /* for OpenSSL 0.9.9 mont->n0 */
	mont->n0[0] = (Ri->top > 0) ? Ri->d[0] : 0;
	mont->n0[1] = 0;
	# else
	mont->n0 = (Ri->top > 0) ? Ri->d[0] : 0;
	# endif
	#endif
	}
	#else /* !MONT_WORD */
	{ /* bignum version */
	mont->ri=BN_num_bits(&mont->N);
	BN_zero(R);
	if (!BN_set_bit(R,mont->ri)) goto err; /* R = 2^ri */
	/* Ri = R^-1 mod N*/
	if ((BN_mod_inverse(Ri,R,&mont->N,ctx)) == NULL)
	goto err;
	if (!BN_lshift(Ri,Ri,mont->ri)) goto err; /* RRi /
	if (!BN_sub_word(Ri,1)) goto err;
	/* Ni = (RRi-1) / N /
	if (!BN_div(&(mont->Ni),NULL,Ri,&mont->N,ctx)) goto err;
	}
	#endif

	/* setup RR for conversions */
	BN_zero(&(mont->RR));
	if (!BN_set_bit(&(mont->RR),mont->ri*2)) goto err;
	if (!BN_mod(&(mont->RR),&(mont->RR),&(mont->N),ctx)) goto err;

	ret = 1;
	err:
	BN_CTX_end(ctx);
	return ret;
	}

	BN_MONT_CTX BN_MONT_CTX_copy(BN_MONT_CTX to, BN_MONT_CTX *from)
	{
	if (to == from) return(to);

	if (!BN_copy(&(to->RR),&(from->RR))) return NULL;
	if (!BN_copy(&(to->N),&(from->N))) return NULL;
	if (!BN_copy(&(to->Ni),&(from->Ni))) return NULL;
	to->ri=from->ri;
	#if 0 /* for OpenSSL 0.9.9 mont->n0 */
	to->n0[0]=from->n0[0];
	to->n0[1]=from->n0[1];
	#else
	to->n0=from->n0;
	#endif
	return(to);
	}

	BN_MONT_CTX BN_MONT_CTX_set_locked(BN_MONT_CTX *pmont, int lock,
	const BIGNUM mod, BN_CTX ctx)
	{
	int got_write_lock = 0;
	BN_MONT_CTX *ret;

	CRYPTO_r_lock(lock);
	if (!*pmont)
	{
	CRYPTO_r_unlock(lock);
	CRYPTO_w_lock(lock);
	got_write_lock = 1;

	if (!*pmont)
	{
	ret = BN_MONT_CTX_new();
	if (ret && !BN_MONT_CTX_set(ret, mod, ctx))
	BN_MONT_CTX_free(ret);
	else
	*pmont = ret;
	}
	}

	ret = *pmont;

	if (got_write_lock)
	CRYPTO_w_unlock(lock);
	else
	CRYPTO_r_unlock(lock);

	return ret;
	}