From: Andy Polyakov <appro@openssl.org>
Date: Mon, 14 Nov 2011 21:05:42 +0000 (+0000)
Subject: BN update from HEAD.
X-Git-Tag: OpenSSL_1_0_1-beta1~79
X-Git-Url: https://git.openssl.org/?p=openssl.git;a=commitdiff_plain;h=9f1c5491d27465adf2c26fb94e309355da7cbc95

BN update from HEAD.
---

diff --git a/crypto/bn/bn_div.c b/crypto/bn/bn_div.c
index 802a43d642..52b3304293 100644
--- a/crypto/bn/bn_div.c
+++ b/crypto/bn/bn_div.c
@@ -169,15 +169,13 @@ int BN_div(BIGNUM *dv, BIGNUM *rem, const BIGNUM *m, const BIGNUM *d,
 #endif /* OPENSSL_NO_ASM */
 
 
-/* BN_div[_no_branch] computes  dv := num / divisor,  rounding towards
+/* BN_div computes  dv := num / divisor,  rounding towards
  * zero, and sets up rm  such that  dv*divisor + rm = num  holds.
  * Thus:
  *     dv->neg == num->neg ^ divisor->neg  (unless the result is zero)
  *     rm->neg == num->neg                 (unless the remainder is zero)
  * If 'dv' or 'rm' is NULL, the respective value is not returned.
  */
-static int BN_div_no_branch(BIGNUM *dv, BIGNUM *rm, const BIGNUM *num,
-        const BIGNUM *divisor, BN_CTX *ctx);
 int BN_div(BIGNUM *dv, BIGNUM *rm, const BIGNUM *num, const BIGNUM *divisor,
 	   BN_CTX *ctx)
 	{
@@ -186,6 +184,7 @@ int BN_div(BIGNUM *dv, BIGNUM *rm, const BIGNUM *num, const BIGNUM *divisor,
 	BN_ULONG *resp,*wnump;
 	BN_ULONG d0,d1;
 	int num_n,div_n;
+	int no_branch=0;
 
 	/* Invalid zero-padding would have particularly bad consequences
 	 * in the case of 'num', so don't just rely on bn_check_top() for this one
@@ -200,7 +199,7 @@ int BN_div(BIGNUM *dv, BIGNUM *rm, const BIGNUM *num, const BIGNUM *divisor,
 
 	if ((BN_get_flags(num, BN_FLG_CONSTTIME) != 0) || (BN_get_flags(divisor, BN_FLG_CONSTTIME) != 0))
 		{
-		return BN_div_no_branch(dv, rm, num, divisor, ctx);
+		no_branch=1;
 		}
 
 	bn_check_top(dv);
@@ -214,7 +213,7 @@ int BN_div(BIGNUM *dv, BIGNUM *rm, const BIGNUM *num, const BIGNUM *divisor,
 		return(0);
 		}
 
-	if (BN_ucmp(num,divisor) < 0)
+	if (!no_branch && BN_ucmp(num,divisor) < 0)
 		{
 		if (rm != NULL)
 			{ if (BN_copy(rm,num) == NULL) return(0); }
@@ -239,242 +238,25 @@ int BN_div(BIGNUM *dv, BIGNUM *rm, const BIGNUM *num, const BIGNUM *divisor,
 	norm_shift+=BN_BITS2;
 	if (!(BN_lshift(snum,num,norm_shift))) goto err;
 	snum->neg=0;
-	div_n=sdiv->top;
-	num_n=snum->top;
-	loop=num_n-div_n;
-	/* Lets setup a 'window' into snum
-	 * This is the part that corresponds to the current
-	 * 'area' being divided */
-	wnum.neg   = 0;
-	wnum.d     = &(snum->d[loop]);
-	wnum.top   = div_n;
-	/* only needed when BN_ucmp messes up the values between top and max */
-	wnum.dmax  = snum->dmax - loop; /* so we don't step out of bounds */
-
-	/* Get the top 2 words of sdiv */
-	/* div_n=sdiv->top; */
-	d0=sdiv->d[div_n-1];
-	d1=(div_n == 1)?0:sdiv->d[div_n-2];
-
-	/* pointer to the 'top' of snum */
-	wnump= &(snum->d[num_n-1]);
-
-	/* Setup to 'res' */
-	res->neg= (num->neg^divisor->neg);
-	if (!bn_wexpand(res,(loop+1))) goto err;
-	res->top=loop;
-	resp= &(res->d[loop-1]);
-
-	/* space for temp */
-	if (!bn_wexpand(tmp,(div_n+1))) goto err;
 
-	if (BN_ucmp(&wnum,sdiv) >= 0)
+	if (no_branch)
 		{
-		/* If BN_DEBUG_RAND is defined BN_ucmp changes (via
-		 * bn_pollute) the const bignum arguments =>
-		 * clean the values between top and max again */
-		bn_clear_top2max(&wnum);
-		bn_sub_words(wnum.d, wnum.d, sdiv->d, div_n);
-		*resp=1;
-		}
-	else
-		res->top--;
-	/* if res->top == 0 then clear the neg value otherwise decrease
-	 * the resp pointer */
-	if (res->top == 0)
-		res->neg = 0;
-	else
-		resp--;
-
-	for (i=0; i<loop-1; i++, wnump--, resp--)
-		{
-		BN_ULONG q,l0;
-		/* the first part of the loop uses the top two words of
-		 * snum and sdiv to calculate a BN_ULONG q such that
-		 * | wnum - sdiv * q | < sdiv */
-#if defined(BN_DIV3W) && !defined(OPENSSL_NO_ASM)
-		BN_ULONG bn_div_3_words(BN_ULONG*,BN_ULONG,BN_ULONG);
-		q=bn_div_3_words(wnump,d1,d0);
-#else
-		BN_ULONG n0,n1,rem=0;
-
-		n0=wnump[0];
-		n1=wnump[-1];
-		if (n0 == d0)
-			q=BN_MASK2;
-		else 			/* n0 < d0 */
-			{
-#ifdef BN_LLONG
-			BN_ULLONG t2;
-
-#if defined(BN_LLONG) && defined(BN_DIV2W) && !defined(bn_div_words)
-			q=(BN_ULONG)(((((BN_ULLONG)n0)<<BN_BITS2)|n1)/d0);
-#else
-			q=bn_div_words(n0,n1,d0);
-#ifdef BN_DEBUG_LEVITTE
-			fprintf(stderr,"DEBUG: bn_div_words(0x%08X,0x%08X,0x%08\
-X) -> 0x%08X\n",
-				n0, n1, d0, q);
-#endif
-#endif
-
-#ifndef REMAINDER_IS_ALREADY_CALCULATED
-			/*
-			 * rem doesn't have to be BN_ULLONG. The least we
-			 * know it's less that d0, isn't it?
-			 */
-			rem=(n1-q*d0)&BN_MASK2;
-#endif
-			t2=(BN_ULLONG)d1*q;
-
-			for (;;)
-				{
-				if (t2 <= ((((BN_ULLONG)rem)<<BN_BITS2)|wnump[-2]))
-					break;
-				q--;
-				rem += d0;
-				if (rem < d0) break; /* don't let rem overflow */
-				t2 -= d1;
-				}
-#else /* !BN_LLONG */
-			BN_ULONG t2l,t2h;
-
-			q=bn_div_words(n0,n1,d0);
-#ifdef BN_DEBUG_LEVITTE
-			fprintf(stderr,"DEBUG: bn_div_words(0x%08X,0x%08X,0x%08\
-X) -> 0x%08X\n",
-				n0, n1, d0, q);
-#endif
-#ifndef REMAINDER_IS_ALREADY_CALCULATED
-			rem=(n1-q*d0)&BN_MASK2;
-#endif
-
-#if defined(BN_UMULT_LOHI)
-			BN_UMULT_LOHI(t2l,t2h,d1,q);
-#elif defined(BN_UMULT_HIGH)
-			t2l = d1 * q;
-			t2h = BN_UMULT_HIGH(d1,q);
-#else
+		/* Since we don't know whether snum is larger than sdiv,
+		 * we pad snum with enough zeroes without changing its
+		 * value. 
+		 */
+		if (snum->top <= sdiv->top+1) 
 			{
-			BN_ULONG ql, qh;
-			t2l=LBITS(d1); t2h=HBITS(d1);
-			ql =LBITS(q);  qh =HBITS(q);
-			mul64(t2l,t2h,ql,qh); /* t2=(BN_ULLONG)d1*q; */
+			if (bn_wexpand(snum, sdiv->top + 2) == NULL) goto err;
+			for (i = snum->top; i < sdiv->top + 2; i++) snum->d[i] = 0;
+			snum->top = sdiv->top + 2;
 			}
-#endif
-
-			for (;;)
-				{
-				if ((t2h < rem) ||
-					((t2h == rem) && (t2l <= wnump[-2])))
-					break;
-				q--;
-				rem += d0;
-				if (rem < d0) break; /* don't let rem overflow */
-				if (t2l < d1) t2h--; t2l -= d1;
-				}
-#endif /* !BN_LLONG */
-			}
-#endif /* !BN_DIV3W */
-
-		l0=bn_mul_words(tmp->d,sdiv->d,div_n,q);
-		tmp->d[div_n]=l0;
-		wnum.d--;
-		/* ingore top values of the bignums just sub the two 
-		 * BN_ULONG arrays with bn_sub_words */
-		if (bn_sub_words(wnum.d, wnum.d, tmp->d, div_n+1))
+		else
 			{
-			/* Note: As we have considered only the leading
-			 * two BN_ULONGs in the calculation of q, sdiv * q
-			 * might be greater than wnum (but then (q-1) * sdiv
-			 * is less or equal than wnum)
-			 */
-			q--;
-			if (bn_add_words(wnum.d, wnum.d, sdiv->d, div_n))
-				/* we can't have an overflow here (assuming
-				 * that q != 0, but if q == 0 then tmp is
-				 * zero anyway) */
-				(*wnump)++;
+			if (bn_wexpand(snum, snum->top + 1) == NULL) goto err;
+			snum->d[snum->top] = 0;
+			snum->top ++;
 			}
-		/* store part of the result */
-		*resp = q;
-		}
-	bn_correct_top(snum);
-	if (rm != NULL)
-		{
-		/* Keep a copy of the neg flag in num because if rm==num
-		 * BN_rshift() will overwrite it.
-		 */
-		int neg = num->neg;
-		BN_rshift(rm,snum,norm_shift);
-		if (!BN_is_zero(rm))
-			rm->neg = neg;
-		bn_check_top(rm);
-		}
-	BN_CTX_end(ctx);
-	return(1);
-err:
-	bn_check_top(rm);
-	BN_CTX_end(ctx);
-	return(0);
-	}
-
-
-/* BN_div_no_branch is a special version of BN_div. It does not contain
- * branches that may leak sensitive information.
- */
-static int BN_div_no_branch(BIGNUM *dv, BIGNUM *rm, const BIGNUM *num, 
-	const BIGNUM *divisor, BN_CTX *ctx)
-	{
-	int norm_shift,i,loop;
-	BIGNUM *tmp,wnum,*snum,*sdiv,*res;
-	BN_ULONG *resp,*wnump;
-	BN_ULONG d0,d1;
-	int num_n,div_n;
-
-	bn_check_top(dv);
-	bn_check_top(rm);
-	/* bn_check_top(num); */ /* 'num' has been checked in BN_div() */
-	bn_check_top(divisor);
-
-	if (BN_is_zero(divisor))
-		{
-		BNerr(BN_F_BN_DIV_NO_BRANCH,BN_R_DIV_BY_ZERO);
-		return(0);
-		}
-
-	BN_CTX_start(ctx);
-	tmp=BN_CTX_get(ctx);
-	snum=BN_CTX_get(ctx);
-	sdiv=BN_CTX_get(ctx);
-	if (dv == NULL)
-		res=BN_CTX_get(ctx);
-	else	res=dv;
-	if (sdiv == NULL || res == NULL) goto err;
-
-	/* First we normalise the numbers */
-	norm_shift=BN_BITS2-((BN_num_bits(divisor))%BN_BITS2);
-	if (!(BN_lshift(sdiv,divisor,norm_shift))) goto err;
-	sdiv->neg=0;
-	norm_shift+=BN_BITS2;
-	if (!(BN_lshift(snum,num,norm_shift))) goto err;
-	snum->neg=0;
-
-	/* Since we don't know whether snum is larger than sdiv,
-	 * we pad snum with enough zeroes without changing its
-	 * value. 
-	 */
-	if (snum->top <= sdiv->top+1) 
-		{
-		if (bn_wexpand(snum, sdiv->top + 2) == NULL) goto err;
-		for (i = snum->top; i < sdiv->top + 2; i++) snum->d[i] = 0;
-		snum->top = sdiv->top + 2;
-		}
-	else
-		{
-		if (bn_wexpand(snum, snum->top + 1) == NULL) goto err;
-		snum->d[snum->top] = 0;
-		snum->top ++;
 		}
 
 	div_n=sdiv->top;
@@ -500,12 +282,27 @@ static int BN_div_no_branch(BIGNUM *dv, BIGNUM *rm, const BIGNUM *num,
 	/* Setup to 'res' */
 	res->neg= (num->neg^divisor->neg);
 	if (!bn_wexpand(res,(loop+1))) goto err;
-	res->top=loop-1;
+	res->top=loop-no_branch;
 	resp= &(res->d[loop-1]);
 
 	/* space for temp */
 	if (!bn_wexpand(tmp,(div_n+1))) goto err;
 
+	if (!no_branch)
+		{
+		if (BN_ucmp(&wnum,sdiv) >= 0)
+			{
+			/* If BN_DEBUG_RAND is defined BN_ucmp changes (via
+			 * bn_pollute) the const bignum arguments =>
+			 * clean the values between top and max again */
+			bn_clear_top2max(&wnum);
+			bn_sub_words(wnum.d, wnum.d, sdiv->d, div_n);
+			*resp=1;
+			}
+		else
+			res->top--;
+		}
+
 	/* if res->top == 0 then clear the neg value otherwise decrease
 	 * the resp pointer */
 	if (res->top == 0)
@@ -638,7 +435,7 @@ X) -> 0x%08X\n",
 			rm->neg = neg;
 		bn_check_top(rm);
 		}
-	bn_correct_top(res);
+	if (no_branch)	bn_correct_top(res);
 	BN_CTX_end(ctx);
 	return(1);
 err:
@@ -646,5 +443,4 @@ err:
 	BN_CTX_end(ctx);
 	return(0);
 	}
-
 #endif
diff --git a/crypto/bn/bn_exp.c b/crypto/bn/bn_exp.c
index d9b6c737fc..2abf6fd678 100644
--- a/crypto/bn/bn_exp.c
+++ b/crypto/bn/bn_exp.c
@@ -113,6 +113,18 @@
 #include "cryptlib.h"
 #include "bn_lcl.h"
 
+#include <stdlib.h>
+#ifdef _WIN32
+# include <malloc.h>
+# ifndef alloca
+#  define alloca _alloca
+# endif
+#elif defined(__GNUC__)
+# ifndef alloca
+#  define alloca(s) __builtin_alloca((s))
+# endif
+#endif
+
 /* maximum precomputation table size for *variable* sliding windows */
 #define TABLE_SIZE	32
 
@@ -522,23 +534,17 @@ err:
  * as cache lines are concerned.  The following functions are used to transfer a BIGNUM
  * from/to that table. */
 
-static int MOD_EXP_CTIME_COPY_TO_PREBUF(BIGNUM *b, int top, unsigned char *buf, int idx, int width)
+static int MOD_EXP_CTIME_COPY_TO_PREBUF(const BIGNUM *b, int top, unsigned char *buf, int idx, int width)
 	{
 	size_t i, j;
 
-	if (bn_wexpand(b, top) == NULL)
-		return 0;
-	while (b->top < top)
-		{
-		b->d[b->top++] = 0;
-		}
-	
+	if (top > b->top)
+		top = b->top; /* this works because 'buf' is explicitly zeroed */
 	for (i = 0, j=idx; i < top * sizeof b->d[0]; i++, j+=width)
 		{
 		buf[j] = ((unsigned char*)b->d)[i];
 		}
 
-	bn_correct_top(b);
 	return 1;
 	}
 
@@ -561,7 +567,7 @@ static int MOD_EXP_CTIME_COPY_FROM_PREBUF(BIGNUM *b, int top, unsigned char *buf
 
 /* Given a pointer value, compute the next address that is a cache line multiple. */
 #define MOD_EXP_CTIME_ALIGN(x_) \
-	((unsigned char*)(x_) + (MOD_EXP_CTIME_MIN_CACHE_LINE_WIDTH - (((BN_ULONG)(x_)) & (MOD_EXP_CTIME_MIN_CACHE_LINE_MASK))))
+	((unsigned char*)(x_) + (MOD_EXP_CTIME_MIN_CACHE_LINE_WIDTH - (((size_t)(x_)) & (MOD_EXP_CTIME_MIN_CACHE_LINE_MASK))))
 
 /* This variant of BN_mod_exp_mont() uses fixed windows and the special
  * precomputation memory layout to limit data-dependency to a minimum
@@ -572,17 +578,15 @@ static int MOD_EXP_CTIME_COPY_FROM_PREBUF(BIGNUM *b, int top, unsigned char *buf
 int BN_mod_exp_mont_consttime(BIGNUM *rr, const BIGNUM *a, const BIGNUM *p,
 		    const BIGNUM *m, BN_CTX *ctx, BN_MONT_CTX *in_mont)
 	{
-	int i,bits,ret=0,idx,window,wvalue;
+	int i,bits,ret=0,window,wvalue;
 	int top;
- 	BIGNUM *r;
-	const BIGNUM *aa;
 	BN_MONT_CTX *mont=NULL;
 
 	int numPowers;
 	unsigned char *powerbufFree=NULL;
 	int powerbufLen = 0;
 	unsigned char *powerbuf=NULL;
-	BIGNUM *computeTemp=NULL, *am=NULL;
+	BIGNUM tmp, am;
 
 	bn_check_top(a);
 	bn_check_top(p);
@@ -602,10 +606,7 @@ int BN_mod_exp_mont_consttime(BIGNUM *rr, const BIGNUM *a, const BIGNUM *p,
 		return ret;
 		}
 
- 	/* Initialize BIGNUM context and allocate intermediate result */
 	BN_CTX_start(ctx);
-	r = BN_CTX_get(ctx);
-	if (r == NULL) goto err;
 
 	/* Allocate a montgomery context if it was not supplied by the caller.
 	 * If this is not done, things will break in the montgomery part.
@@ -620,40 +621,154 @@ int BN_mod_exp_mont_consttime(BIGNUM *rr, const BIGNUM *a, const BIGNUM *p,
 
 	/* Get the window size to use with size of p. */
 	window = BN_window_bits_for_ctime_exponent_size(bits);
+#if defined(OPENSSL_BN_ASM_MONT5)
+	if (window==6 && bits<=1024) window=5;	/* ~5% improvement of 2048-bit RSA sign */
+#endif
 
 	/* Allocate a buffer large enough to hold all of the pre-computed
-	 * powers of a.
+	 * powers of am, am itself and tmp.
 	 */
 	numPowers = 1 << window;
-	powerbufLen = sizeof(m->d[0])*top*numPowers;
+	powerbufLen = sizeof(m->d[0])*(top*numPowers +
+				((2*top)>numPowers?(2*top):numPowers));
+#ifdef alloca
+	if (powerbufLen < 3072)
+		powerbufFree = alloca(powerbufLen+MOD_EXP_CTIME_MIN_CACHE_LINE_WIDTH);
+	else
+#endif
 	if ((powerbufFree=(unsigned char*)OPENSSL_malloc(powerbufLen+MOD_EXP_CTIME_MIN_CACHE_LINE_WIDTH)) == NULL)
 		goto err;
 		
 	powerbuf = MOD_EXP_CTIME_ALIGN(powerbufFree);
 	memset(powerbuf, 0, powerbufLen);
 
- 	/* Initialize the intermediate result. Do this early to save double conversion,
-	 * once each for a^0 and intermediate result.
-	 */
- 	if (!BN_to_montgomery(r,BN_value_one(),mont,ctx)) goto err;
-	if (!MOD_EXP_CTIME_COPY_TO_PREBUF(r, top, powerbuf, 0, numPowers)) goto err;
+#ifdef alloca
+	if (powerbufLen < 3072)
+		powerbufFree = NULL;
+#endif
 
-	/* Initialize computeTemp as a^1 with montgomery precalcs */
-	computeTemp = BN_CTX_get(ctx);
-	am = BN_CTX_get(ctx);
-	if (computeTemp==NULL || am==NULL) goto err;
+	/* lay down tmp and am right after powers table */
+	tmp.d     = (BN_ULONG *)(powerbuf + sizeof(m->d[0])*top*numPowers);
+	am.d      = tmp.d + top;
+	tmp.top   = am.top  = 0;
+	tmp.dmax  = am.dmax = top;
+	tmp.neg   = am.neg  = 0;
+	tmp.flags = am.flags = BN_FLG_STATIC_DATA;
+
+	/* prepare a^0 in Montgomery domain */
+#if 1
+ 	if (!BN_to_montgomery(&tmp,BN_value_one(),mont,ctx))	goto err;
+#else
+	tmp.d[0] = (0-m->d[0])&BN_MASK2;	/* 2^(top*BN_BITS2) - m */
+	for (i=1;i<top;i++)
+		tmp.d[i] = (~m->d[i])&BN_MASK2;
+	tmp.top = top;
+#endif
 
+	/* prepare a^1 in Montgomery domain */
 	if (a->neg || BN_ucmp(a,m) >= 0)
 		{
-		if (!BN_mod(am,a,m,ctx))
-			goto err;
-		aa= am;
+		if (!BN_mod(&am,a,m,ctx))			goto err;
+		if (!BN_to_montgomery(&am,&am,mont,ctx))	goto err;
 		}
-	else
-		aa=a;
-	if (!BN_to_montgomery(am,aa,mont,ctx)) goto err;
-	if (!BN_copy(computeTemp, am)) goto err;
-	if (!MOD_EXP_CTIME_COPY_TO_PREBUF(am, top, powerbuf, 1, numPowers)) goto err;
+	else	if (!BN_to_montgomery(&am,a,mont,ctx))		goto err;
+
+#if defined(OPENSSL_BN_ASM_MONT5)
+    /* This optimization uses ideas from http://eprint.iacr.org/2011/239,
+     * specifically optimization of cache-timing attack countermeasures
+     * and pre-computation optimization. */
+
+    /* Dedicated window==4 case improves 512-bit RSA sign by ~15%, but as
+     * 512-bit RSA is hardly relevant, we omit it to spare size... */ 
+    if (window==5)
+	{
+	void bn_mul_mont_gather5(BN_ULONG *rp,const BN_ULONG *ap,
+			const void *table,const BN_ULONG *np,
+			const BN_ULONG *n0,int num,int power);
+	void bn_scatter5(const BN_ULONG *inp,size_t num,
+			void *table,size_t power);
+	void bn_gather5(BN_ULONG *out,size_t num,
+			void *table,size_t power);
+
+	BN_ULONG *np=mont->N.d, *n0=mont->n0;
+
+	/* BN_to_montgomery can contaminate words above .top
+	 * [in BN_DEBUG[_DEBUG] build]... */
+	for (i=am.top; i<top; i++)	am.d[i]=0;
+	for (i=tmp.top; i<top; i++)	tmp.d[i]=0;
+
+	bn_scatter5(tmp.d,top,powerbuf,0);
+	bn_scatter5(am.d,am.top,powerbuf,1);
+	bn_mul_mont(tmp.d,am.d,am.d,np,n0,top);
+	bn_scatter5(tmp.d,top,powerbuf,2);
+
+#if 0
+	for (i=3; i<32; i++)
+		{
+		/* Calculate a^i = a^(i-1) * a */
+		bn_mul_mont_gather5(tmp.d,am.d,powerbuf,np,n0,top,i-1);
+		bn_scatter5(tmp.d,top,powerbuf,i);
+		}
+#else
+	/* same as above, but uses squaring for 1/2 of operations */
+	for (i=4; i<32; i*=2)
+		{
+		bn_mul_mont(tmp.d,tmp.d,tmp.d,np,n0,top);
+		bn_scatter5(tmp.d,top,powerbuf,i);
+		}
+	for (i=3; i<8; i+=2)
+		{
+		int j;
+		bn_mul_mont_gather5(tmp.d,am.d,powerbuf,np,n0,top,i-1);
+		bn_scatter5(tmp.d,top,powerbuf,i);
+		for (j=2*i; j<32; j*=2)
+			{
+			bn_mul_mont(tmp.d,tmp.d,tmp.d,np,n0,top);
+			bn_scatter5(tmp.d,top,powerbuf,j);
+			}
+		}
+	for (; i<16; i+=2)
+		{
+		bn_mul_mont_gather5(tmp.d,am.d,powerbuf,np,n0,top,i-1);
+		bn_scatter5(tmp.d,top,powerbuf,i);
+		bn_mul_mont(tmp.d,tmp.d,tmp.d,np,n0,top);
+		bn_scatter5(tmp.d,top,powerbuf,2*i);
+		}
+	for (; i<32; i+=2)
+		{
+		bn_mul_mont_gather5(tmp.d,am.d,powerbuf,np,n0,top,i-1);
+		bn_scatter5(tmp.d,top,powerbuf,i);
+		}
+#endif
+	bits--;
+	for (wvalue=0, i=bits%5; i>=0; i--,bits--)
+		wvalue = (wvalue<<1)+BN_is_bit_set(p,bits);
+	bn_gather5(tmp.d,top,powerbuf,wvalue);
+
+	/* Scan the exponent one window at a time starting from the most
+	 * significant bits.
+	 */
+	while (bits >= 0)
+		{
+		for (wvalue=0, i=0; i<5; i++,bits--)
+			wvalue = (wvalue<<1)+BN_is_bit_set(p,bits);
+
+		bn_mul_mont(tmp.d,tmp.d,tmp.d,np,n0,top);
+		bn_mul_mont(tmp.d,tmp.d,tmp.d,np,n0,top);
+		bn_mul_mont(tmp.d,tmp.d,tmp.d,np,n0,top);
+		bn_mul_mont(tmp.d,tmp.d,tmp.d,np,n0,top);
+		bn_mul_mont(tmp.d,tmp.d,tmp.d,np,n0,top);
+		bn_mul_mont_gather5(tmp.d,tmp.d,powerbuf,np,n0,top,wvalue);
+		}
+
+	tmp.top=top;
+	bn_correct_top(&tmp);
+	}
+    else
+#endif
+	{
+	if (!MOD_EXP_CTIME_COPY_TO_PREBUF(&tmp, top, powerbuf, 0, numPowers)) goto err;
+	if (!MOD_EXP_CTIME_COPY_TO_PREBUF(&am,  top, powerbuf, 1, numPowers)) goto err;
 
 	/* If the window size is greater than 1, then calculate
 	 * val[i=2..2^winsize-1]. Powers are computed as a*a^(i-1)
@@ -662,62 +777,54 @@ int BN_mod_exp_mont_consttime(BIGNUM *rr, const BIGNUM *a, const BIGNUM *p,
 	 */
 	if (window > 1)
 		{
-		for (i=2; i<numPowers; i++)
+		if (!BN_mod_mul_montgomery(&tmp,&am,&am,mont,ctx))	goto err;
+		if (!MOD_EXP_CTIME_COPY_TO_PREBUF(&tmp, top, powerbuf, 2, numPowers)) goto err;
+		for (i=3; i<numPowers; i++)
 			{
 			/* Calculate a^i = a^(i-1) * a */
-			if (!BN_mod_mul_montgomery(computeTemp,am,computeTemp,mont,ctx))
+			if (!BN_mod_mul_montgomery(&tmp,&am,&tmp,mont,ctx))
 				goto err;
-			if (!MOD_EXP_CTIME_COPY_TO_PREBUF(computeTemp, top, powerbuf, i, numPowers)) goto err;
+			if (!MOD_EXP_CTIME_COPY_TO_PREBUF(&tmp, top, powerbuf, i, numPowers)) goto err;
 			}
 		}
 
- 	/* Adjust the number of bits up to a multiple of the window size.
- 	 * If the exponent length is not a multiple of the window size, then
- 	 * this pads the most significant bits with zeros to normalize the
- 	 * scanning loop to there's no special cases.
- 	 *
- 	 * * NOTE: Making the window size a power of two less than the native
-	 * * word size ensures that the padded bits won't go past the last
- 	 * * word in the internal BIGNUM structure. Going past the end will
- 	 * * still produce the correct result, but causes a different branch
- 	 * * to be taken in the BN_is_bit_set function.
- 	 */
- 	bits = ((bits+window-1)/window)*window;
- 	idx=bits-1;	/* The top bit of the window */
-
- 	/* Scan the exponent one window at a time starting from the most
- 	 * significant bits.
- 	 */
- 	while (idx >= 0)
+	bits--;
+	for (wvalue=0, i=bits%window; i>=0; i--,bits--)
+		wvalue = (wvalue<<1)+BN_is_bit_set(p,bits);
+	if (!MOD_EXP_CTIME_COPY_FROM_PREBUF(&tmp,top,powerbuf,wvalue,numPowers)) goto err;
+ 
+	/* Scan the exponent one window at a time starting from the most
+	 * significant bits.
+	 */
+ 	while (bits >= 0)
   		{
  		wvalue=0; /* The 'value' of the window */
  		
  		/* Scan the window, squaring the result as we go */
- 		for (i=0; i<window; i++,idx--)
+ 		for (i=0; i<window; i++,bits--)
  			{
-			if (!BN_mod_mul_montgomery(r,r,r,mont,ctx))	goto err;
-			wvalue = (wvalue<<1)+BN_is_bit_set(p,idx);
+			if (!BN_mod_mul_montgomery(&tmp,&tmp,&tmp,mont,ctx))	goto err;
+			wvalue = (wvalue<<1)+BN_is_bit_set(p,bits);
   			}
  		
 		/* Fetch the appropriate pre-computed value from the pre-buf */
-		if (!MOD_EXP_CTIME_COPY_FROM_PREBUF(computeTemp, top, powerbuf, wvalue, numPowers)) goto err;
+		if (!MOD_EXP_CTIME_COPY_FROM_PREBUF(&am, top, powerbuf, wvalue, numPowers)) goto err;
 
  		/* Multiply the result into the intermediate result */
- 		if (!BN_mod_mul_montgomery(r,r,computeTemp,mont,ctx)) goto err;
+ 		if (!BN_mod_mul_montgomery(&tmp,&tmp,&am,mont,ctx)) goto err;
   		}
+	}
 
  	/* Convert the final result from montgomery to standard format */
-	if (!BN_from_montgomery(rr,r,mont,ctx)) goto err;
+	if (!BN_from_montgomery(rr,&tmp,mont,ctx)) goto err;
 	ret=1;
 err:
 	if ((in_mont == NULL) && (mont != NULL)) BN_MONT_CTX_free(mont);
 	if (powerbuf!=NULL)
 		{
 		OPENSSL_cleanse(powerbuf,powerbufLen);
-		OPENSSL_free(powerbufFree);
+		if (powerbufFree) OPENSSL_free(powerbufFree);
 		}
- 	if (am!=NULL) BN_clear(am);
- 	if (computeTemp!=NULL) BN_clear(computeTemp);
 	BN_CTX_end(ctx);
 	return(ret);
 	}
@@ -988,4 +1095,3 @@ err:
 	bn_check_top(r);
 	return(ret);
 	}
-
diff --git a/crypto/bn/bn_gf2m.c b/crypto/bn/bn_gf2m.c
index 573156accb..ffe1b096ba 100644
--- a/crypto/bn/bn_gf2m.c
+++ b/crypto/bn/bn_gf2m.c
@@ -124,6 +124,7 @@ static const BN_ULONG SQR_tb[16] =
     SQR_tb[(w) >>  4 & 0xF] <<  8 | SQR_tb[(w)       & 0xF]
 #endif
 
+#if !defined(OPENSSL_BN_ASM_GF2m)
 /* Product of two polynomials a, b each with degree < BN_BITS2 - 1,
  * result is a polynomial r with degree < 2 * BN_BITS - 1
  * The caller MUST ensure that the variables have the right amount
@@ -218,7 +219,9 @@ static void bn_GF2m_mul_2x2(BN_ULONG *r, const BN_ULONG a1, const BN_ULONG a0, c
 	r[2] ^= m1 ^ r[1] ^ r[3];  /* h0 ^= m1 ^ l1 ^ h1; */
 	r[1] = r[3] ^ r[2] ^ r[0] ^ m1 ^ m0;  /* l1 ^= l0 ^ h0 ^ m0; */
 	}
-
+#else
+void bn_GF2m_mul_2x2(BN_ULONG *r, BN_ULONG a1, BN_ULONG a0, BN_ULONG b1, BN_ULONG b0);
+#endif 
 
 /* Add polynomials a and b and store result in r; r could be a or b, a and b 
  * could be equal; r is the bitwise XOR of a and b.
@@ -362,21 +365,17 @@ int BN_GF2m_mod_arr(BIGNUM *r, const BIGNUM *a, const int p[])
 int	BN_GF2m_mod(BIGNUM *r, const BIGNUM *a, const BIGNUM *p)
 	{
 	int ret = 0;
-	const int max = BN_num_bits(p) + 1;
-	int *arr=NULL;
+	int arr[6];
 	bn_check_top(a);
 	bn_check_top(p);
-	if ((arr = (int *)OPENSSL_malloc(sizeof(int) * max)) == NULL) goto err;
-	ret = BN_GF2m_poly2arr(p, arr, max);
-	if (!ret || ret > max)
+	ret = BN_GF2m_poly2arr(p, arr, sizeof(arr)/sizeof(arr[0]));
+	if (!ret || ret > (int)(sizeof(arr)/sizeof(arr[0])))
 		{
 		BNerr(BN_F_BN_GF2M_MOD,BN_R_INVALID_LENGTH);
-		goto err;
+		return 0;
 		}
 	ret = BN_GF2m_mod_arr(r, a, arr);
 	bn_check_top(r);
-err:
-	if (arr) OPENSSL_free(arr);
 	return ret;
 	}
 
@@ -531,18 +530,18 @@ int BN_GF2m_mod_inv(BIGNUM *r, const BIGNUM *a, const BIGNUM *p, BN_CTX *ctx)
 
 	BN_CTX_start(ctx);
 	
-	b = BN_CTX_get(ctx);
-	c = BN_CTX_get(ctx);
-	u = BN_CTX_get(ctx);
-	v = BN_CTX_get(ctx);
-	if (v == NULL) goto err;
+	if ((b = BN_CTX_get(ctx))==NULL) goto err;
+	if ((c = BN_CTX_get(ctx))==NULL) goto err;
+	if ((u = BN_CTX_get(ctx))==NULL) goto err;
+	if ((v = BN_CTX_get(ctx))==NULL) goto err;
 
-	if (!BN_one(b)) goto err;
 	if (!BN_GF2m_mod(u, a, p)) goto err;
-	if (!BN_copy(v, p)) goto err;
-
 	if (BN_is_zero(u)) goto err;
 
+	if (!BN_copy(v, p)) goto err;
+#if 0
+	if (!BN_one(b)) goto err;
+
 	while (1)
 		{
 		while (!BN_is_odd(u))
@@ -567,13 +566,86 @@ int BN_GF2m_mod_inv(BIGNUM *r, const BIGNUM *a, const BIGNUM *p, BN_CTX *ctx)
 		if (!BN_GF2m_add(u, u, v)) goto err;
 		if (!BN_GF2m_add(b, b, c)) goto err;
 		}
+#else
+	{
+	int i,	ubits = BN_num_bits(u),
+		vbits = BN_num_bits(v),	/* v is copy of p */
+		top = p->top;
+	BN_ULONG *udp,*bdp,*vdp,*cdp;
+
+	bn_wexpand(u,top);	udp = u->d;
+				for (i=u->top;i<top;i++) udp[i] = 0;
+				u->top = top;
+	bn_wexpand(b,top);	bdp = b->d;
+				bdp[0] = 1;
+				for (i=1;i<top;i++) bdp[i] = 0;
+				b->top = top;
+	bn_wexpand(c,top);	cdp = c->d;
+				for (i=0;i<top;i++) cdp[i] = 0;
+				c->top = top;
+	vdp = v->d;	/* It pays off to "cache" *->d pointers, because
+			 * it allows optimizer to be more aggressive.
+			 * But we don't have to "cache" p->d, because *p
+			 * is declared 'const'... */
+	while (1)
+		{
+		while (ubits && !(udp[0]&1))
+			{
+			BN_ULONG u0,u1,b0,b1,mask;
 
+			u0   = udp[0];
+			b0   = bdp[0];
+			mask = (BN_ULONG)0-(b0&1);
+			b0  ^= p->d[0]&mask;
+			for (i=0;i<top-1;i++)
+				{
+				u1 = udp[i+1];
+				udp[i] = ((u0>>1)|(u1<<(BN_BITS2-1)))&BN_MASK2;
+				u0 = u1;
+				b1 = bdp[i+1]^(p->d[i+1]&mask);
+				bdp[i] = ((b0>>1)|(b1<<(BN_BITS2-1)))&BN_MASK2;
+				b0 = b1;
+				}
+			udp[i] = u0>>1;
+			bdp[i] = b0>>1;
+			ubits--;
+			}
+
+		if (ubits<=BN_BITS2 && udp[0]==1) break;
+
+		if (ubits<vbits)
+			{
+			i = ubits; ubits = vbits; vbits = i;
+			tmp = u; u = v; v = tmp;
+			tmp = b; b = c; c = tmp;
+			udp = vdp; vdp = v->d;
+			bdp = cdp; cdp = c->d;
+			}
+		for(i=0;i<top;i++)
+			{
+			udp[i] ^= vdp[i];
+			bdp[i] ^= cdp[i];
+			}
+		if (ubits==vbits)
+			{
+			bn_correct_top(u);
+			ubits = BN_num_bits(u);
+			}
+		}
+	bn_correct_top(b);
+	}
+#endif
 
 	if (!BN_copy(r, b)) goto err;
 	bn_check_top(r);
 	ret = 1;
 
 err:
+#ifdef BN_DEBUG /* BN_CTX_end would complain about the expanded form */
+        bn_correct_top(c);
+        bn_correct_top(u);
+        bn_correct_top(v);
+#endif
   	BN_CTX_end(ctx);
 	return ret;
 	}
diff --git a/crypto/bn/bn_lcl.h b/crypto/bn/bn_lcl.h
index 8e5e98e3f2..d7dff0d90c 100644
--- a/crypto/bn/bn_lcl.h
+++ b/crypto/bn/bn_lcl.h
@@ -238,7 +238,7 @@ extern "C" {
 #  if defined(__DECC)
 #   include <c_asm.h>
 #   define BN_UMULT_HIGH(a,b)	(BN_ULONG)asm("umulh %a0,%a1,%v0",(a),(b))
-#  elif defined(__GNUC__)
+#  elif defined(__GNUC__) && __GNUC__>=2
 #   define BN_UMULT_HIGH(a,b)	({	\
 	register BN_ULONG ret;		\
 	asm ("umulh	%1,%2,%0"	\
@@ -247,7 +247,7 @@ extern "C" {
 	ret;			})
 #  endif	/* compiler */
 # elif defined(_ARCH_PPC) && defined(__64BIT__) && defined(SIXTY_FOUR_BIT_LONG)
-#  if defined(__GNUC__)
+#  if defined(__GNUC__) && __GNUC__>=2
 #   define BN_UMULT_HIGH(a,b)	({	\
 	register BN_ULONG ret;		\
 	asm ("mulhdu	%0,%1,%2"	\
@@ -257,7 +257,7 @@ extern "C" {
 #  endif	/* compiler */
 # elif (defined(__x86_64) || defined(__x86_64__)) && \
        (defined(SIXTY_FOUR_BIT_LONG) || defined(SIXTY_FOUR_BIT))
-#  if defined(__GNUC__)
+#  if defined(__GNUC__) && __GNUC__>=2
 #   define BN_UMULT_HIGH(a,b)	({	\
 	register BN_ULONG ret,discard;	\
 	asm ("mulq	%3"		\
@@ -280,6 +280,19 @@ extern "C" {
 #   define BN_UMULT_HIGH(a,b)		__umulh((a),(b))
 #   define BN_UMULT_LOHI(low,high,a,b)	((low)=_umul128((a),(b),&(high)))
 #  endif
+# elif defined(__mips) && (defined(SIXTY_FOUR_BIT) || defined(SIXTY_FOUR_BIT_LONG))
+#  if defined(__GNUC__) && __GNUC__>=2
+#   define BN_UMULT_HIGH(a,b)	({	\
+	register BN_ULONG ret;		\
+	asm ("dmultu	%1,%2"		\
+	     : "=h"(ret)		\
+	     : "r"(a), "r"(b) : "l");	\
+	ret;			})
+#   define BN_UMULT_LOHI(low,high,a,b)	\
+	asm ("dmultu	%2,%3"		\
+	     : "=l"(low),"=h"(high)	\
+	     : "r"(a), "r"(b));
+#  endif
 # endif		/* cpu */
 #endif		/* OPENSSL_NO_ASM */
 
diff --git a/crypto/bn/bn_mont.c b/crypto/bn/bn_mont.c
index 1a866880f5..427b5cf4df 100644
--- a/crypto/bn/bn_mont.c
+++ b/crypto/bn/bn_mont.c
@@ -177,31 +177,26 @@ err:
 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;
+	BN_ULONG *ap,*np,*rp,n0,v,carry;
+	int nl,max,i;
 
 	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); }
+	if (nl == 0) { ret->top=0; return(1); }
 
-	max=(nl+al+1); /* allow for overflow (no?) XXX */
+	max=(2*nl); /* carry is stored separately */
 	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 */
 #if 1
 	for (i=r->top; i<max; i++) /* memset? XXX */
-		r->d[i]=0;
+		rp[i]=0;
 #else
-	memset(&(r->d[r->top]),0,(max-r->top)*sizeof(BN_ULONG)); 
+	memset(&(rp[r->top]),0,(max-r->top)*sizeof(BN_ULONG)); 
 #endif
 
 	r->top=max;
@@ -210,7 +205,7 @@ static int BN_from_montgomery_word(BIGNUM *ret, BIGNUM *r, BN_MONT_CTX *mont)
 #ifdef BN_COUNT
 	fprintf(stderr,"word BN_from_montgomery_word %d * %d\n",nl,nl);
 #endif
-	for (i=0; i<nl; i++)
+	for (carry=0, i=0; i<nl; i++, rp++)
 		{
 #ifdef __TANDEM
                 {
@@ -228,61 +223,33 @@ static int BN_from_montgomery_word(BIGNUM *ret, BIGNUM *r, BN_MONT_CTX *mont)
 #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);
+		v = (v+carry+rp[nl])&BN_MASK2;
+		carry |= (v != rp[nl]);
+		carry &= (v <= rp[nl]);
+		rp[nl]=v;
 		}
-	al=r->top-ri;
 
-#define BRANCH_FREE 1
-#if BRANCH_FREE
-	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) */
+	if (bn_wexpand(ret,nl) == NULL) return(0);
+	ret->top=nl;
 	ret->neg=r->neg;
 
 	rp=ret->d;
-	ap=&(r->d[ri]);
+	ap=&(r->d[nl]);
 
+#define BRANCH_FREE 1
+#if BRANCH_FREE
 	{
-	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. */
+	BN_ULONG *nrp;
+	size_t m;
 
-	/* if (al==ri && !v) || al>ri) nrp=rp; else nrp=ap; */
-	/* in other words if subtraction result is real, then
+	v=bn_sub_words(rp,ap,np,nl)-carry;
+	/* 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 *)(((PTR_SIZE_INT)rp&~m1)|((PTR_SIZE_INT)ap&m1));
-	}
+	m=(0-(size_t)v);
+	nrp=(BN_ULONG *)(((PTR_SIZE_INT)rp&~m)|((PTR_SIZE_INT)ap&m));
 
-	/* '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)
+	for (i=0,nl-=4; i<nl; i+=4)
 		{
 		BN_ULONG t1,t2,t3,t4;
 		
@@ -295,40 +262,15 @@ static int BN_from_montgomery_word(BIGNUM *ret, BIGNUM *r, BN_MONT_CTX *mont)
 		rp[i+2]=t3;
 		rp[i+3]=t4;
 		}
-	for (ri+=4; i<ri; i++)
+	for (nl+=4; i<nl; i++)
 		rp[i]=nrp[i], ap[i]=0;
-	bn_correct_top(r);
-	bn_correct_top(ret);
+	}
 #else
-	if (bn_wexpand(ret,al) == NULL) return(0);
-	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];
-
-	if (BN_ucmp(ret, &(mont->N)) >= 0)
-		{
-		if (!BN_usub(ret,ret,&(mont->N))) return(0);
-		}
+	if (bn_sub_words (rp,ap,np,nl)-carry)
+		memcpy(rp,ap,nl*sizeof(BN_ULONG));
 #endif
+	bn_correct_top(r);
+	bn_correct_top(ret);
 	bn_check_top(ret);
 
 	return(1);
diff --git a/crypto/bn/bn_nist.c b/crypto/bn/bn_nist.c
index c6de032696..880989dd5f 100644
--- a/crypto/bn/bn_nist.c
+++ b/crypto/bn/bn_nist.c
@@ -319,6 +319,13 @@ static void nist_cp_bn(BN_ULONG *buf, BN_ULONG *a, int top)
 						:(to[(n)/2] =((m)&1)?(from[(m)/2]>>32):(from[(m)/2]&BN_MASK2l)))
 #define bn_32_set_0(to, n)		(((n)&1)?(to[(n)/2]&=BN_MASK2l):(to[(n)/2]=0));
 #define bn_cp_32(to,n,from,m)		((m)>=0)?bn_cp_32_naked(to,n,from,m):bn_32_set_0(to,n)
+# if defined(L_ENDIAN)
+#  if defined(__arch64__)
+#   define NIST_INT64 long
+#  else
+#   define NIST_INT64 long long
+#  endif
+# endif
 #else
 #define bn_cp_64(to, n, from, m) \
 	{ \
@@ -330,13 +337,15 @@ static void nist_cp_bn(BN_ULONG *buf, BN_ULONG *a, int top)
 	bn_32_set_0(to, (n)*2); \
 	bn_32_set_0(to, (n)*2+1); \
 	}
-#if BN_BITS2 == 32
 #define bn_cp_32(to, n, from, m)	(to)[n] = (m>=0)?((from)[m]):0;
 #define bn_32_set_0(to, n)		(to)[n] = (BN_ULONG)0;
-#endif
+# if defined(_WIN32) && !defined(__GNUC__)
+#  define NIST_INT64 __int64
+# else
+#  define NIST_INT64 long long
+# endif
 #endif /* BN_BITS2 != 64 */
 
-
 #define nist_set_192(to, from, a1, a2, a3) \
 	{ \
 	bn_cp_64(to, 0, from, (a3) - 3) \
@@ -350,9 +359,11 @@ int BN_nist_mod_192(BIGNUM *r, const BIGNUM *a, const BIGNUM *field,
 	int      top = a->top, i;
 	int      carry;
 	register BN_ULONG *r_d, *a_d = a->d;
-	BN_ULONG t_d[BN_NIST_192_TOP],
-	         buf[BN_NIST_192_TOP],
-		 c_d[BN_NIST_192_TOP],
+	union	{
+		BN_ULONG	bn[BN_NIST_192_TOP];
+		unsigned int	ui[BN_NIST_192_TOP*sizeof(BN_ULONG)/sizeof(unsigned int)];
+		} buf;
+	BN_ULONG c_d[BN_NIST_192_TOP],
 		*res;
 	PTR_SIZE_INT mask;
 	static const BIGNUM _bignum_nist_p_192_sqr = {
@@ -385,15 +396,48 @@ int BN_nist_mod_192(BIGNUM *r, const BIGNUM *a, const BIGNUM *field,
 	else
 		r_d = a_d;
 
-	nist_cp_bn_0(buf, a_d + BN_NIST_192_TOP, top - BN_NIST_192_TOP, BN_NIST_192_TOP);
+	nist_cp_bn_0(buf.bn, a_d + BN_NIST_192_TOP, top - BN_NIST_192_TOP, BN_NIST_192_TOP);
+
+#if defined(NIST_INT64)
+	{
+	NIST_INT64		acc;	/* accumulator */
+	unsigned int		*rp=(unsigned int *)r_d;
+	const unsigned int	*bp=(const unsigned int *)buf.ui;
+
+	acc  = rp[0];	acc += bp[3*2-6];
+			acc += bp[5*2-6]; rp[0] = (unsigned int)acc; acc >>= 32;
+
+	acc += rp[1];	acc += bp[3*2-5];
+			acc += bp[5*2-5]; rp[1] = (unsigned int)acc; acc >>= 32;
 
-	nist_set_192(t_d, buf, 0, 3, 3);
+	acc += rp[2];	acc += bp[3*2-6];
+			acc += bp[4*2-6];
+			acc += bp[5*2-6]; rp[2] = (unsigned int)acc; acc >>= 32;
+
+	acc += rp[3];	acc += bp[3*2-5];
+			acc += bp[4*2-5];
+			acc += bp[5*2-5]; rp[3] = (unsigned int)acc; acc >>= 32;
+
+	acc += rp[4];	acc += bp[4*2-6];
+			acc += bp[5*2-6]; rp[4] = (unsigned int)acc; acc >>= 32;
+
+	acc += rp[5];	acc += bp[4*2-5];
+			acc += bp[5*2-5]; rp[5] = (unsigned int)acc;
+
+	carry = (int)(acc>>32);
+	}
+#else
+	{
+	BN_ULONG t_d[BN_NIST_192_TOP];
+
+	nist_set_192(t_d, buf.bn, 0, 3, 3);
 	carry = (int)bn_add_words(r_d, r_d, t_d, BN_NIST_192_TOP);
-	nist_set_192(t_d, buf, 4, 4, 0);
+	nist_set_192(t_d, buf.bn, 4, 4, 0);
 	carry += (int)bn_add_words(r_d, r_d, t_d, BN_NIST_192_TOP);
-	nist_set_192(t_d, buf, 5, 5, 5)
+	nist_set_192(t_d, buf.bn, 5, 5, 5)
 	carry += (int)bn_add_words(r_d, r_d, t_d, BN_NIST_192_TOP);
-
+	}
+#endif
 	if (carry > 0)
 		carry = (int)bn_sub_words(r_d,r_d,_nist_p_192[carry-1],BN_NIST_192_TOP);
 	else
@@ -435,8 +479,7 @@ int BN_nist_mod_224(BIGNUM *r, const BIGNUM *a, const BIGNUM *field,
 	int	top = a->top, i;
 	int	carry;
 	BN_ULONG *r_d, *a_d = a->d;
-	BN_ULONG t_d[BN_NIST_224_TOP],
-	         buf[BN_NIST_224_TOP],
+	BN_ULONG buf[BN_NIST_224_TOP],
 		 c_d[BN_NIST_224_TOP],
 		*res;
 	PTR_SIZE_INT mask;
@@ -474,14 +517,54 @@ int BN_nist_mod_224(BIGNUM *r, const BIGNUM *a, const BIGNUM *field,
 
 #if BN_BITS2==64
 	/* copy upper 256 bits of 448 bit number ... */
-	nist_cp_bn_0(t_d, a_d + (BN_NIST_224_TOP-1), top - (BN_NIST_224_TOP-1), BN_NIST_224_TOP);
+	nist_cp_bn_0(c_d, a_d + (BN_NIST_224_TOP-1), top - (BN_NIST_224_TOP-1), BN_NIST_224_TOP);
 	/* ... and right shift by 32 to obtain upper 224 bits */
-	nist_set_224(buf, t_d, 14, 13, 12, 11, 10, 9, 8);
+	nist_set_224(buf, c_d, 14, 13, 12, 11, 10, 9, 8);
 	/* truncate lower part to 224 bits too */
 	r_d[BN_NIST_224_TOP-1] &= BN_MASK2l;
 #else
 	nist_cp_bn_0(buf, a_d + BN_NIST_224_TOP, top - BN_NIST_224_TOP, BN_NIST_224_TOP);
 #endif
+
+#if defined(NIST_INT64) && BN_BITS2!=64
+	{
+	NIST_INT64		acc;	/* accumulator */
+	unsigned int		*rp=(unsigned int *)r_d;
+	const unsigned int	*bp=(const unsigned int *)buf;
+
+	acc  = rp[0];	acc -= bp[7-7];
+			acc -= bp[11-7]; rp[0] = (unsigned int)acc; acc >>= 32;
+
+	acc += rp[1];	acc -= bp[8-7];
+			acc -= bp[12-7]; rp[1] = (unsigned int)acc; acc >>= 32;
+
+	acc += rp[2];	acc -= bp[9-7];
+			acc -= bp[13-7]; rp[2] = (unsigned int)acc; acc >>= 32;
+
+	acc += rp[3];	acc += bp[7-7];
+			acc += bp[11-7];
+			acc -= bp[10-7]; rp[3] = (unsigned int)acc; acc>>= 32;
+
+	acc += rp[4];	acc += bp[8-7];
+			acc += bp[12-7];
+			acc -= bp[11-7]; rp[4] = (unsigned int)acc; acc >>= 32;
+
+	acc += rp[5];	acc += bp[9-7];
+			acc += bp[13-7];
+			acc -= bp[12-7]; rp[5] = (unsigned int)acc; acc >>= 32;
+
+	acc += rp[6];	acc += bp[10-7];
+			acc -= bp[13-7]; rp[6] = (unsigned int)acc;
+
+	carry = (int)(acc>>32);
+# if BN_BITS2==64
+	rp[7] = carry;
+# endif
+	}	
+#else
+	{
+	BN_ULONG t_d[BN_NIST_224_TOP];
+
 	nist_set_224(t_d, buf, 10, 9, 8, 7, 0, 0, 0);
 	carry = (int)bn_add_words(r_d, r_d, t_d, BN_NIST_224_TOP);
 	nist_set_224(t_d, buf, 0, 13, 12, 11, 0, 0, 0);
@@ -493,6 +576,8 @@ int BN_nist_mod_224(BIGNUM *r, const BIGNUM *a, const BIGNUM *field,
 
 #if BN_BITS2==64
 	carry = (int)(r_d[BN_NIST_224_TOP-1]>>32);
+#endif
+	}
 #endif
 	u.f = bn_sub_words;
 	if (carry > 0)
@@ -548,9 +633,11 @@ int BN_nist_mod_256(BIGNUM *r, const BIGNUM *a, const BIGNUM *field,
 	int	i, top = a->top;
 	int	carry = 0;
 	register BN_ULONG *a_d = a->d, *r_d;
-	BN_ULONG t_d[BN_NIST_256_TOP],
-	         buf[BN_NIST_256_TOP],
-		 c_d[BN_NIST_256_TOP],
+	union	{
+		BN_ULONG bn[BN_NIST_256_TOP];
+		unsigned int ui[BN_NIST_256_TOP*sizeof(BN_ULONG)/sizeof(unsigned int)];
+		} buf;
+	BN_ULONG c_d[BN_NIST_256_TOP],
 		*res;
 	PTR_SIZE_INT mask;
 	union { bn_addsub_f f; PTR_SIZE_INT p; } u;
@@ -584,12 +671,87 @@ int BN_nist_mod_256(BIGNUM *r, const BIGNUM *a, const BIGNUM *field,
 	else
 		r_d = a_d;
 
-	nist_cp_bn_0(buf, a_d + BN_NIST_256_TOP, top - BN_NIST_256_TOP, BN_NIST_256_TOP);
+	nist_cp_bn_0(buf.bn, a_d + BN_NIST_256_TOP, top - BN_NIST_256_TOP, BN_NIST_256_TOP);
+
+#if defined(NIST_INT64)
+	{
+	NIST_INT64		acc;	/* accumulator */
+	unsigned int		*rp=(unsigned int *)r_d;
+	const unsigned int	*bp=(const unsigned int *)buf.ui;
+
+	acc = rp[0];	acc += bp[8-8];
+			acc += bp[9-8];
+			acc -= bp[11-8];
+			acc -= bp[12-8];
+			acc -= bp[13-8];
+			acc -= bp[14-8]; rp[0] = (unsigned int)acc; acc >>= 32;
+
+	acc += rp[1];	acc += bp[9-8];
+			acc += bp[10-8];
+			acc -= bp[12-8];
+			acc -= bp[13-8];
+			acc -= bp[14-8];
+			acc -= bp[15-8]; rp[1] = (unsigned int)acc; acc >>= 32;
+
+	acc += rp[2];	acc += bp[10-8];
+			acc += bp[11-8];
+			acc -= bp[13-8];
+			acc -= bp[14-8];
+			acc -= bp[15-8]; rp[2] = (unsigned int)acc; acc >>= 32;
+
+	acc += rp[3];	acc += bp[11-8];
+			acc += bp[11-8];
+			acc += bp[12-8];
+			acc += bp[12-8];
+			acc += bp[13-8];
+			acc -= bp[15-8];
+			acc -= bp[8-8];
+			acc -= bp[9-8];  rp[3] = (unsigned int)acc; acc >>= 32;
+
+	acc += rp[4];	acc += bp[12-8];
+			acc += bp[12-8];
+			acc += bp[13-8];
+			acc += bp[13-8];
+			acc += bp[14-8];
+			acc -= bp[9-8];
+			acc -= bp[10-8]; rp[4] = (unsigned int)acc; acc >>= 32;
+
+	acc += rp[5];	acc += bp[13-8];
+			acc += bp[13-8];
+			acc += bp[14-8];
+			acc += bp[14-8];
+			acc += bp[15-8];
+			acc -= bp[10-8];
+			acc -= bp[11-8]; rp[5] = (unsigned int)acc; acc >>= 32;
+
+	acc += rp[6];	acc += bp[14-8];
+			acc += bp[14-8];
+			acc += bp[15-8];
+			acc += bp[15-8];
+			acc += bp[14-8];
+			acc += bp[13-8];
+			acc -= bp[8-8];
+			acc -= bp[9-8];  rp[6] = (unsigned int)acc; acc >>= 32;
+
+	acc += rp[7];	acc += bp[15-8];
+			acc += bp[15-8];
+			acc += bp[15-8];
+			acc += bp[8 -8];
+			acc -= bp[10-8];
+			acc -= bp[11-8];
+			acc -= bp[12-8];
+			acc -= bp[13-8]; rp[7] = (unsigned int)acc;
+
+	carry = (int)(acc>>32);
+	}
+#else
+	{
+	BN_ULONG t_d[BN_NIST_256_TOP];
 
 	/*S1*/
-	nist_set_256(t_d, buf, 15, 14, 13, 12, 11, 0, 0, 0);
+	nist_set_256(t_d, buf.bn, 15, 14, 13, 12, 11, 0, 0, 0);
 	/*S2*/
-	nist_set_256(c_d, buf, 0, 15, 14, 13, 12, 0, 0, 0);
+	nist_set_256(c_d, buf.bn, 0, 15, 14, 13, 12, 0, 0, 0);
 	carry = (int)bn_add_words(t_d, t_d, c_d, BN_NIST_256_TOP);
 	/* left shift */
 		{
@@ -607,24 +769,26 @@ int BN_nist_mod_256(BIGNUM *r, const BIGNUM *a, const BIGNUM *field,
 		}
 	carry += (int)bn_add_words(r_d, r_d, t_d, BN_NIST_256_TOP);
 	/*S3*/
-	nist_set_256(t_d, buf, 15, 14, 0, 0, 0, 10, 9, 8);
+	nist_set_256(t_d, buf.bn, 15, 14, 0, 0, 0, 10, 9, 8);
 	carry += (int)bn_add_words(r_d, r_d, t_d, BN_NIST_256_TOP);
 	/*S4*/
-	nist_set_256(t_d, buf, 8, 13, 15, 14, 13, 11, 10, 9);
+	nist_set_256(t_d, buf.bn, 8, 13, 15, 14, 13, 11, 10, 9);
 	carry += (int)bn_add_words(r_d, r_d, t_d, BN_NIST_256_TOP);
 	/*D1*/
-	nist_set_256(t_d, buf, 10, 8, 0, 0, 0, 13, 12, 11);
+	nist_set_256(t_d, buf.bn, 10, 8, 0, 0, 0, 13, 12, 11);
 	carry -= (int)bn_sub_words(r_d, r_d, t_d, BN_NIST_256_TOP);
 	/*D2*/
-	nist_set_256(t_d, buf, 11, 9, 0, 0, 15, 14, 13, 12);
+	nist_set_256(t_d, buf.bn, 11, 9, 0, 0, 15, 14, 13, 12);
 	carry -= (int)bn_sub_words(r_d, r_d, t_d, BN_NIST_256_TOP);
 	/*D3*/
-	nist_set_256(t_d, buf, 12, 0, 10, 9, 8, 15, 14, 13);
+	nist_set_256(t_d, buf.bn, 12, 0, 10, 9, 8, 15, 14, 13);
 	carry -= (int)bn_sub_words(r_d, r_d, t_d, BN_NIST_256_TOP);
 	/*D4*/
-	nist_set_256(t_d, buf, 13, 0, 11, 10, 9, 0, 15, 14);
+	nist_set_256(t_d, buf.bn, 13, 0, 11, 10, 9, 0, 15, 14);
 	carry -= (int)bn_sub_words(r_d, r_d, t_d, BN_NIST_256_TOP);
 
+	}
+#endif
 	/* see BN_nist_mod_224 for explanation */
 	u.f = bn_sub_words;
 	if (carry > 0)
@@ -672,9 +836,11 @@ int BN_nist_mod_384(BIGNUM *r, const BIGNUM *a, const BIGNUM *field,
 	int	i, top = a->top;
 	int	carry = 0;
 	register BN_ULONG *r_d, *a_d = a->d;
-	BN_ULONG t_d[BN_NIST_384_TOP],
-	         buf[BN_NIST_384_TOP],
-		 c_d[BN_NIST_384_TOP],
+	union	{
+		BN_ULONG bn[BN_NIST_384_TOP];
+		unsigned int ui[BN_NIST_384_TOP*sizeof(BN_ULONG)/sizeof(unsigned int)];
+		} buf;
+	BN_ULONG c_d[BN_NIST_384_TOP],
 		*res;
 	PTR_SIZE_INT mask;
 	union { bn_addsub_f f; PTR_SIZE_INT p; } u;
@@ -709,10 +875,100 @@ int BN_nist_mod_384(BIGNUM *r, const BIGNUM *a, const BIGNUM *field,
 	else
 		r_d = a_d;
 
-	nist_cp_bn_0(buf, a_d + BN_NIST_384_TOP, top - BN_NIST_384_TOP, BN_NIST_384_TOP);
+	nist_cp_bn_0(buf.bn, a_d + BN_NIST_384_TOP, top - BN_NIST_384_TOP, BN_NIST_384_TOP);
+
+#if defined(NIST_INT64)
+	{
+	NIST_INT64		acc;	/* accumulator */
+	unsigned int		*rp=(unsigned int *)r_d;
+	const unsigned int	*bp=(const unsigned int *)buf.ui;
+
+	acc = rp[0];	acc += bp[12-12];
+			acc += bp[21-12];
+			acc += bp[20-12];
+			acc -= bp[23-12]; rp[0] = (unsigned int)acc; acc >>= 32;
+
+	acc += rp[1];	acc += bp[13-12];
+			acc += bp[22-12];
+			acc += bp[23-12];
+			acc -= bp[12-12];
+			acc -= bp[20-12]; rp[1] = (unsigned int)acc; acc >>= 32;
+
+	acc += rp[2];	acc += bp[14-12];
+			acc += bp[23-12];
+			acc -= bp[13-12];
+			acc -= bp[21-12]; rp[2] = (unsigned int)acc; acc >>= 32;
+
+	acc += rp[3];	acc += bp[15-12];
+			acc += bp[12-12];
+			acc += bp[20-12];
+			acc += bp[21-12];
+			acc -= bp[14-12];
+			acc -= bp[22-12];
+			acc -= bp[23-12]; rp[3] = (unsigned int)acc; acc >>= 32;
+
+	acc += rp[4];	acc += bp[21-12];
+			acc += bp[21-12];
+			acc += bp[16-12];
+			acc += bp[13-12];
+			acc += bp[12-12];
+			acc += bp[20-12];
+			acc += bp[22-12];
+			acc -= bp[15-12];
+			acc -= bp[23-12];
+			acc -= bp[23-12]; rp[4] = (unsigned int)acc; acc >>= 32;
+
+	acc += rp[5];	acc += bp[22-12];
+			acc += bp[22-12];
+			acc += bp[17-12];
+			acc += bp[14-12];
+			acc += bp[13-12];
+			acc += bp[21-12];
+			acc += bp[23-12];
+			acc -= bp[16-12]; rp[5] = (unsigned int)acc; acc >>= 32;
+			
+	acc += rp[6];	acc += bp[23-12];
+			acc += bp[23-12];
+			acc += bp[18-12];
+			acc += bp[15-12];
+			acc += bp[14-12];
+			acc += bp[22-12];
+			acc -= bp[17-12]; rp[6] = (unsigned int)acc; acc >>= 32;
+			
+	acc += rp[7];	acc += bp[19-12];
+			acc += bp[16-12];
+			acc += bp[15-12];
+			acc += bp[23-12];
+			acc -= bp[18-12]; rp[7] = (unsigned int)acc; acc >>= 32;
+			
+	acc += rp[8];	acc += bp[20-12];
+			acc += bp[17-12];
+			acc += bp[16-12];
+			acc -= bp[19-12]; rp[8] = (unsigned int)acc; acc >>= 32;
+			
+	acc += rp[9];	acc += bp[21-12];
+			acc += bp[18-12];
+			acc += bp[17-12];
+			acc -= bp[20-12]; rp[9] = (unsigned int)acc; acc >>= 32;
+			
+	acc += rp[10];	acc += bp[22-12];
+			acc += bp[19-12];
+			acc += bp[18-12];
+			acc -= bp[21-12]; rp[10] = (unsigned int)acc; acc >>= 32;
+			
+	acc += rp[11];	acc += bp[23-12];
+			acc += bp[20-12];
+			acc += bp[19-12];
+			acc -= bp[22-12]; rp[11] = (unsigned int)acc;
+
+	carry = (int)(acc>>32);
+	}
+#else
+	{
+	BN_ULONG t_d[BN_NIST_384_TOP];
 
 	/*S1*/
-	nist_set_256(t_d, buf, 0, 0, 0, 0, 0, 23-4, 22-4, 21-4);
+	nist_set_256(t_d, buf.bn, 0, 0, 0, 0, 0, 23-4, 22-4, 21-4);
 		/* left shift */
 		{
 		register BN_ULONG *ap,t,c;
@@ -729,29 +985,31 @@ int BN_nist_mod_384(BIGNUM *r, const BIGNUM *a, const BIGNUM *field,
 	carry = (int)bn_add_words(r_d+(128/BN_BITS2), r_d+(128/BN_BITS2), 
 		t_d, BN_NIST_256_TOP);
 	/*S2 */
-	carry += (int)bn_add_words(r_d, r_d, buf, BN_NIST_384_TOP);
+	carry += (int)bn_add_words(r_d, r_d, buf.bn, BN_NIST_384_TOP);
 	/*S3*/
-	nist_set_384(t_d,buf,20,19,18,17,16,15,14,13,12,23,22,21);
+	nist_set_384(t_d,buf.bn,20,19,18,17,16,15,14,13,12,23,22,21);
 	carry += (int)bn_add_words(r_d, r_d, t_d, BN_NIST_384_TOP);
 	/*S4*/
-	nist_set_384(t_d,buf,19,18,17,16,15,14,13,12,20,0,23,0);
+	nist_set_384(t_d,buf.bn,19,18,17,16,15,14,13,12,20,0,23,0);
 	carry += (int)bn_add_words(r_d, r_d, t_d, BN_NIST_384_TOP);
 	/*S5*/
-	nist_set_384(t_d, buf,0,0,0,0,23,22,21,20,0,0,0,0);
+	nist_set_384(t_d, buf.bn,0,0,0,0,23,22,21,20,0,0,0,0);
 	carry += (int)bn_add_words(r_d, r_d, t_d, BN_NIST_384_TOP);
 	/*S6*/
-	nist_set_384(t_d,buf,0,0,0,0,0,0,23,22,21,0,0,20);
+	nist_set_384(t_d,buf.bn,0,0,0,0,0,0,23,22,21,0,0,20);
 	carry += (int)bn_add_words(r_d, r_d, t_d, BN_NIST_384_TOP);
 	/*D1*/
-	nist_set_384(t_d,buf,22,21,20,19,18,17,16,15,14,13,12,23);
+	nist_set_384(t_d,buf.bn,22,21,20,19,18,17,16,15,14,13,12,23);
 	carry -= (int)bn_sub_words(r_d, r_d, t_d, BN_NIST_384_TOP);
 	/*D2*/
-	nist_set_384(t_d,buf,0,0,0,0,0,0,0,23,22,21,20,0);
+	nist_set_384(t_d,buf.bn,0,0,0,0,0,0,0,23,22,21,20,0);
 	carry -= (int)bn_sub_words(r_d, r_d, t_d, BN_NIST_384_TOP);
 	/*D3*/
-	nist_set_384(t_d,buf,0,0,0,0,0,0,0,23,23,0,0,0);
+	nist_set_384(t_d,buf.bn,0,0,0,0,0,0,0,23,23,0,0,0);
 	carry -= (int)bn_sub_words(r_d, r_d, t_d, BN_NIST_384_TOP);
 
+	}
+#endif
 	/* see BN_nist_mod_224 for explanation */
 	u.f = bn_sub_words;
 	if (carry > 0)
diff --git a/crypto/bn/bn_shift.c b/crypto/bn/bn_shift.c
index c4d301afc4..a6fca2c424 100644
--- a/crypto/bn/bn_shift.c
+++ b/crypto/bn/bn_shift.c
@@ -99,7 +99,7 @@ int BN_lshift1(BIGNUM *r, const BIGNUM *a)
 int BN_rshift1(BIGNUM *r, const BIGNUM *a)
 	{
 	BN_ULONG *ap,*rp,t,c;
-	int i;
+	int i,j;
 
 	bn_check_top(r);
 	bn_check_top(a);
@@ -109,22 +109,25 @@ int BN_rshift1(BIGNUM *r, const BIGNUM *a)
 		BN_zero(r);
 		return(1);
 		}
+	i = a->top;
+	ap= a->d;
+	j = i-(ap[i-1]==1);
 	if (a != r)
 		{
-		if (bn_wexpand(r,a->top) == NULL) return(0);
-		r->top=a->top;
+		if (bn_wexpand(r,j) == NULL) return(0);
 		r->neg=a->neg;
 		}
-	ap=a->d;
 	rp=r->d;
-	c=0;
-	for (i=a->top-1; i>=0; i--)
+	t=ap[--i];
+	c=(t&1)?BN_TBIT:0;
+	if (t>>=1) rp[i]=t;
+	while (i>0)
 		{
-		t=ap[i];
+		t=ap[--i];
 		rp[i]=((t>>1)&BN_MASK2)|c;
 		c=(t&1)?BN_TBIT:0;
 		}
-	bn_correct_top(r);
+	r->top=j;
 	bn_check_top(r);
 	return(1);
 	}
@@ -182,10 +185,11 @@ int BN_rshift(BIGNUM *r, const BIGNUM *a, int n)
 		BN_zero(r);
 		return(1);
 		}
+	i = (BN_num_bits(a)-n+(BN_BITS2-1))/BN_BITS2;
 	if (r != a)
 		{
 		r->neg=a->neg;
-		if (bn_wexpand(r,a->top-nw+1) == NULL) return(0);
+		if (bn_wexpand(r,i) == NULL) return(0);
 		}
 	else
 		{
@@ -196,7 +200,7 @@ int BN_rshift(BIGNUM *r, const BIGNUM *a, int n)
 	f= &(a->d[nw]);
 	t=r->d;
 	j=a->top-nw;
-	r->top=j;
+	r->top=i;
 
 	if (rb == 0)
 		{
@@ -212,9 +216,8 @@ int BN_rshift(BIGNUM *r, const BIGNUM *a, int n)
 			l= *(f++);
 			*(t++) =(tmp|(l<<lb))&BN_MASK2;
 			}
-		*(t++) =(l>>rb)&BN_MASK2;
+		if ((l = (l>>rb)&BN_MASK2)) *(t) = l;
 		}
-	bn_correct_top(r);
 	bn_check_top(r);
 	return(1);
 	}