This commit completes recent modular exponentiation optimizations on

x86_64 platform. It targets specifically RSA1024 sign (using ideas
from http://eprint.iacr.org/2011/239) and adds more than 10% on most
platforms. Overall performance improvement relative to 1.0.0 is ~40%
in average, with best result of 54% on Westmere. Incidentally ~40%
is average improvement even for longer key lengths.

4 files changed, 988 insertions, 43 deletions

diff --git a/crypto/bn/Makefile b/crypto/bn/Makefile
index 4ae6af5060..1fd8e33371 100644
--- a/crypto/bn/Makefile
+++ b/crypto/bn/Makefile
@@ -98,6 +98,8 @@ x86_64-gcc.o:	asm/x86_64-gcc.c
 	$(CC) $(CFLAGS) -c -o $@ asm/x86_64-gcc.c
 x86_64-mont.s:	asm/x86_64-mont.pl
 	$(PERL) asm/x86_64-mont.pl $(PERLASM_SCHEME) > $@
+x86_64-mont5.s:	asm/x86_64-mont5.pl
+	$(PERL) asm/x86_64-mont5.pl $(PERLASM_SCHEME) > $@
 x86_64-gf2m.s:  asm/x86_64-gf2m.pl
 	$(PERL) asm/x86_64-gf2m.pl $(PERLASM_SCHEME) > $@
 modexp512-x86_64.s:	asm/modexp512-x86_64.pl
diff --git a/crypto/bn/asm/x86_64-mont.pl b/crypto/bn/asm/x86_64-mont.pl
index 4f330b81f3..c2a308ddfa 100755
--- a/crypto/bn/asm/x86_64-mont.pl
+++ b/crypto/bn/asm/x86_64-mont.pl
@@ -1,7 +1,7 @@
 #!/usr/bin/env perl
 
 # ====================================================================
-# Written by Andy Polyakov <appro@fy.chalmers.se> for the OpenSSL
+# Written by Andy Polyakov <appro@openssl.org> for the OpenSSL
 # project. The module is, however, dual licensed under OpenSSL and
 # CRYPTOGAMS licenses depending on where you obtain it. For further
 # details see http://www.openssl.org/~appro/cryptogams/.
@@ -142,6 +142,7 @@ $code.=<<___;
 	jne	.L1st
 
 	add	%rax,$hi1
+	mov	($ap),%rax		# ap[0]
 	adc	\$0,%rdx
 	add	$hi0,$hi1		# np[j]*m1+ap[j]*bp[0]
 	adc	\$0,%rdx
@@ -161,7 +162,6 @@ $code.=<<___;
 .Louter:
 	mov	($bp,$i,8),$m0		# m0=bp[i]
 	xor	$j,$j			# j=0
-	mov	($ap),%rax		# ap[0]
 	mov	$n0,$m1
 	mov	(%rsp),$lo0
 	mulq	$m0			# ap[0]*bp[i]
@@ -208,6 +208,7 @@ $code.=<<___;
 	jne	.Linner
 
 	add	%rax,$hi1
+	mov	($ap),%rax		# ap[0]
 	adc	\$0,%rdx
 	add	$lo0,$hi1		# np[j]*m1+ap[j]*bp[i]+tp[j]
 	mov	(%rsp,$j,8),$lo0
diff --git a/crypto/bn/asm/x86_64-mont5.pl b/crypto/bn/asm/x86_64-mont5.pl
new file mode 100755
index 0000000000..b7b1ef6161
--- /dev/null
+++ b/crypto/bn/asm/x86_64-mont5.pl
@@ -0,0 +1,834 @@
+#!/usr/bin/env perl
+
+# ====================================================================
+# Written by Andy Polyakov <appro@openssl.org> for the OpenSSL
+# project. The module is, however, dual licensed under OpenSSL and
+# CRYPTOGAMS licenses depending on where you obtain it. For further
+# details see http://www.openssl.org/~appro/cryptogams/.
+# ====================================================================
+
+# August 2011.
+#
+# Companion to x86_64-mont.pl that optimizes cache-timing attack
+# countermeasures. The subroutines are produced by replacing bp[i]
+# references in their x86_64-mont.pl counterparts with cache-neutral
+# references to powers table computed in BN_mod_exp_mont_consttime.
+# In addition subroutine that scatters elements of the powers table
+# is implemented, so that scatter-/gathering can be tuned without
+# bn_exp.c modifications.
+
+$flavour = shift;
+$output  = shift;
+if ($flavour =~ /\./) { $output = $flavour; undef $flavour; }
+
+$win64=0; $win64=1 if ($flavour =~ /[nm]asm|mingw64/ || $output =~ /\.asm$/);
+
+$0 =~ m/(.*[\/\\])[^\/\\]+$/; $dir=$1;
+( $xlate="${dir}x86_64-xlate.pl" and -f $xlate ) or
+( $xlate="${dir}../../perlasm/x86_64-xlate.pl" and -f $xlate) or
+die "can't locate x86_64-xlate.pl";
+
+open STDOUT,"| $^X $xlate $flavour $output";
+
+# int bn_mul_mont_gather5(
+$rp="%rdi";	# BN_ULONG *rp,
+$ap="%rsi";	# const BN_ULONG *ap,
+$bp="%rdx";	# const BN_ULONG *bp,
+$np="%rcx";	# const BN_ULONG *np,
+$n0="%r8";	# const BN_ULONG *n0,
+$num="%r9";	# int num,
+		# int idx);	# 0 to 2^5-1, "index" in $bp holding
+				# pre-computed powers of a', interlaced
+				# in such manner that b[0] is $bp[idx],
+				# b[1] is [2^5+idx], etc.
+$lo0="%r10";
+$hi0="%r11";
+$hi1="%r13";
+$i="%r14";
+$j="%r15";
+$m0="%rbx";
+$m1="%rbp";
+
+$code=<<___;
+.text
+
+.globl	bn_mul_mont_gather5
+.type	bn_mul_mont_gather5,\@function,6
+.align	64
+bn_mul_mont_gather5:
+	test	\$3,${num}d
+	jnz	.Lmul_enter
+	cmp	\$8,${num}d
+	jb	.Lmul_enter
+	jmp	.Lmul4x_enter
+
+.align	16
+.Lmul_enter:
+	mov	`($win64?56:8)`(%rsp),%r10d	# load 7th argument
+	push	%rbx
+	push	%rbp
+	push	%r12
+	push	%r13
+	push	%r14
+	push	%r15
+
+	mov	${num}d,${num}d
+	lea	2($num),%r11
+	mov	%rsp,%rax
+	neg	%r11
+	lea	(%rsp,%r11,8),%rsp	# tp=alloca(8*(num+2))
+	and	\$-1024,%rsp		# minimize TLB usage
+
+	mov	%rax,8(%rsp,$num,8)	# tp[num+1]=%rsp
+.Lmul_body:
+	mov	$bp,%r12		# reassign $bp
+___
+		$bp="%r12";
+		$STRIDE=2**5*8;		# 5 is "window size"
+		$N=$STRIDE/4;		# should match cache line size
+$code.=<<___;
+	mov	%r10,%r11
+	shr	\$`log($N/8)/log(2)`,%r10
+	and	\$`$N/8-1`,%r11
+	not	%r10
+	lea	.Lmagic_masks(%rip),%rax
+	and	\$`2**5/($N/8)-1`,%r10	# 5 is "window size"
+	lea	96($bp,%r11,8),$bp	# pointer within 1st cache line
+	movq	0(%rax,%r10,8),%xmm4	# set of masks denoting which
+	movq	8(%rax,%r10,8),%xmm5	# cache line contains element
+	movq	16(%rax,%r10,8),%xmm6	# denoted by 7th argument
+	movq	24(%rax,%r10,8),%xmm7
+
+	movq	`0*$STRIDE/4-96`($bp),%xmm0
+	movq	`1*$STRIDE/4-96`($bp),%xmm1
+	pand	%xmm4,%xmm0
+	movq	`2*$STRIDE/4-96`($bp),%xmm2
+	pand	%xmm5,%xmm1
+	movq	`3*$STRIDE/4-96`($bp),%xmm3
+	pand	%xmm6,%xmm2
+	por	%xmm1,%xmm0
+	pand	%xmm7,%xmm3
+	por	%xmm2,%xmm0
+	lea	$STRIDE($bp),$bp
+	por	%xmm3,%xmm0
+
+	movq	%xmm0,$m0		# m0=bp[0]
+
+	mov	($n0),$n0		# pull n0[0] value
+	mov	($ap),%rax
+
+	xor	$i,$i			# i=0
+	xor	$j,$j			# j=0
+
+	movq	`0*$STRIDE/4-96`($bp),%xmm0
+	movq	`1*$STRIDE/4-96`($bp),%xmm1
+	pand	%xmm4,%xmm0
+	movq	`2*$STRIDE/4-96`($bp),%xmm2
+	pand	%xmm5,%xmm1
+
+	mov	$n0,$m1
+	mulq	$m0			# ap[0]*bp[0]
+	mov	%rax,$lo0
+	mov	($np),%rax
+
+	movq	`3*$STRIDE/4-96`($bp),%xmm3
+	pand	%xmm6,%xmm2
+	por	%xmm1,%xmm0
+	pand	%xmm7,%xmm3
+
+	imulq	$lo0,$m1		# "tp[0]"*n0
+	mov	%rdx,$hi0
+
+	por	%xmm2,%xmm0
+	lea	$STRIDE($bp),$bp
+	por	%xmm3,%xmm0
+
+	mulq	$m1			# np[0]*m1
+	add	%rax,$lo0		# discarded
+	mov	8($ap),%rax
+	adc	\$0,%rdx
+	mov	%rdx,$hi1
+
+	lea	1($j),$j		# j++
+	jmp	.L1st_enter
+
+.align	16
+.L1st:
+	add	%rax,$hi1
+	mov	($ap,$j,8),%rax
+	adc	\$0,%rdx
+	add	$hi0,$hi1		# np[j]*m1+ap[j]*bp[0]
+	mov	$lo0,$hi0
+	adc	\$0,%rdx
+	mov	$hi1,-16(%rsp,$j,8)	# tp[j-1]
+	mov	%rdx,$hi1
+
+.L1st_enter:
+	mulq	$m0			# ap[j]*bp[0]
+	add	%rax,$hi0
+	mov	($np,$j,8),%rax
+	adc	\$0,%rdx
+	lea	1($j),$j		# j++
+	mov	%rdx,$lo0
+
+	mulq	$m1			# np[j]*m1
+	cmp	$num,$j
+	jne	.L1st
+
+	movq	%xmm0,$m0		# bp[1]
+
+	add	%rax,$hi1
+	mov	($ap),%rax		# ap[0]
+	adc	\$0,%rdx
+	add	$hi0,$hi1		# np[j]*m1+ap[j]*bp[0]
+	adc	\$0,%rdx
+	mov	$hi1,-16(%rsp,$j,8)	# tp[j-1]
+	mov	%rdx,$hi1
+	mov	$lo0,$hi0
+
+	xor	%rdx,%rdx
+	add	$hi0,$hi1
+	adc	\$0,%rdx
+	mov	$hi1,-8(%rsp,$num,8)
+	mov	%rdx,(%rsp,$num,8)	# store upmost overflow bit
+
+	lea	1($i),$i		# i++
+	jmp	.Louter
+.align	16
+.Louter:
+	xor	$j,$j			# j=0
+	mov	$n0,$m1
+	mov	(%rsp),$lo0
+
+	movq	`0*$STRIDE/4-96`($bp),%xmm0
+	movq	`1*$STRIDE/4-96`($bp),%xmm1
+	pand	%xmm4,%xmm0
+	movq	`2*$STRIDE/4-96`($bp),%xmm2
+	pand	%xmm5,%xmm1
+
+	mulq	$m0			# ap[0]*bp[i]
+	add	%rax,$lo0		# ap[0]*bp[i]+tp[0]
+	mov	($np),%rax
+	adc	\$0,%rdx
+
+	movq	`3*$STRIDE/4-96`($bp),%xmm3
+	pand	%xmm6,%xmm2
+	por	%xmm1,%xmm0
+	pand	%xmm7,%xmm3
+
+	imulq	$lo0,$m1		# tp[0]*n0
+	mov	%rdx,$hi0
+
+	por	%xmm2,%xmm0
+	lea	$STRIDE($bp),$bp
+	por	%xmm3,%xmm0
+
+	mulq	$m1			# np[0]*m1
+	add	%rax,$lo0		# discarded
+	mov	8($ap),%rax
+	adc	\$0,%rdx
+	mov	8(%rsp),$lo0		# tp[1]
+	mov	%rdx,$hi1
+
+	lea	1($j),$j		# j++
+	jmp	.Linner_enter
+
+.align	16
+.Linner:
+	add	%rax,$hi1
+	mov	($ap,$j,8),%rax
+	adc	\$0,%rdx
+	add	$lo0,$hi1		# np[j]*m1+ap[j]*bp[i]+tp[j]
+	mov	(%rsp,$j,8),$lo0
+	adc	\$0,%rdx
+	mov	$hi1,-16(%rsp,$j,8)	# tp[j-1]
+	mov	%rdx,$hi1
+
+.Linner_enter:
+	mulq	$m0			# ap[j]*bp[i]
+	add	%rax,$hi0
+	mov	($np,$j,8),%rax
+	adc	\$0,%rdx
+	add	$hi0,$lo0		# ap[j]*bp[i]+tp[j]
+	mov	%rdx,$hi0
+	adc	\$0,$hi0
+	lea	1($j),$j		# j++
+
+	mulq	$m1			# np[j]*m1
+	cmp	$num,$j
+	jne	.Linner
+
+	movq	%xmm0,$m0		# bp[i+1]
+
+	add	%rax,$hi1
+	mov	($ap),%rax		# ap[0]
+	adc	\$0,%rdx
+	add	$lo0,$hi1		# np[j]*m1+ap[j]*bp[i]+tp[j]
+	mov	(%rsp,$j,8),$lo0
+	adc	\$0,%rdx
+	mov	$hi1,-16(%rsp,$j,8)	# tp[j-1]
+	mov	%rdx,$hi1
+
+	xor	%rdx,%rdx
+	add	$hi0,$hi1
+	adc	\$0,%rdx
+	add	$lo0,$hi1		# pull upmost overflow bit
+	adc	\$0,%rdx
+	mov	$hi1,-8(%rsp,$num,8)
+	mov	%rdx,(%rsp,$num,8)	# store upmost overflow bit
+
+	lea	1($i),$i		# i++
+	cmp	$num,$i
+	jl	.Louter
+
+	xor	$i,$i			# i=0 and clear CF!
+	mov	(%rsp),%rax		# tp[0]
+	lea	(%rsp),$ap		# borrow ap for tp
+	mov	$num,$j			# j=num
+	jmp	.Lsub
+.align	16
+.Lsub:	sbb	($np,$i,8),%rax
+	mov	%rax,($rp,$i,8)		# rp[i]=tp[i]-np[i]
+	mov	8($ap,$i,8),%rax	# tp[i+1]
+	lea	1($i),$i		# i++
+	dec	$j			# doesnn't affect CF!
+	jnz	.Lsub
+
+	sbb	\$0,%rax		# handle upmost overflow bit
+	xor	$i,$i
+	and	%rax,$ap
+	not	%rax
+	mov	$rp,$np
+	and	%rax,$np
+	mov	$num,$j			# j=num
+	or	$np,$ap			# ap=borrow?tp:rp
+.align	16
+.Lcopy:					# copy or in-place refresh
+	mov	($ap,$i,8),%rax
+	mov	$i,(%rsp,$i,8)		# zap temporary vector
+	mov	%rax,($rp,$i,8)		# rp[i]=tp[i]
+	lea	1($i),$i
+	sub	\$1,$j
+	jnz	.Lcopy
+
+	mov	8(%rsp,$num,8),%rsi	# restore %rsp
+	mov	\$1,%rax
+	mov	(%rsi),%r15
+	mov	8(%rsi),%r14
+	mov	16(%rsi),%r13
+	mov	24(%rsi),%r12
+	mov	32(%rsi),%rbp
+	mov	40(%rsi),%rbx
+	lea	48(%rsi),%rsp
+.Lmul_epilogue:
+	ret
+.size	bn_mul_mont_gather5,.-bn_mul_mont_gather5
+___
+{{{
+my @A=("%r10","%r11");
+my @N=("%r13","%rdi");
+$code.=<<___;
+.type	bn_mul4x_mont_gather5,\@function,6
+.align	16
+bn_mul4x_mont_gather5:
+.Lmul4x_enter:
+	mov	`($win64?56:8)`(%rsp),%r10d	# load 7th argument
+	push	%rbx
+	push	%rbp
+	push	%r12
+	push	%r13
+	push	%r14
+	push	%r15
+
+	mov	${num}d,${num}d
+	lea	4($num),%r11
+	mov	%rsp,%rax		# !!!!
+	neg	%r11
+	lea	(%rsp,%r11,8),%rsp	# tp=alloca(8*(num+4))
+	and	\$-1024,%rsp		# minimize TLB usage
+
+	mov	%rax,8(%rsp,$num,8)	# tp[num+1]=%rsp
+.Lmul4x_body:
+	mov	$rp,16(%rsp,$num,8)	# tp[num+2]=$rp
+	mov	%rdx,%r12		# reassign $bp
+___
+		$bp="%r12";
+		$STRIDE=2**5*8;		# 5 is "window size"
+		$N=$STRIDE/4;		# should match cache line size
+$code.=<<___;
+	mov	%r10,%r11
+	shr	\$`log($N/8)/log(2)`,%r10
+	and	\$`$N/8-1`,%r11
+	not	%r10
+	lea	.Lmagic_masks(%rip),%rax
+	and	\$`2**5/($N/8)-1`,%r10	# 5 is "window size"
+	lea	96($bp,%r11,8),$bp	# pointer within 1st cache line
+	movq	0(%rax,%r10,8),%xmm4	# set of masks denoting which
+	movq	8(%rax,%r10,8),%xmm5	# cache line contains element
+	movq	16(%rax,%r10,8),%xmm6	# denoted by 7th argument
+	movq	24(%rax,%r10,8),%xmm7
+
+	movq	`0*$STRIDE/4-96`($bp),%xmm0
+	movq	`1*$STRIDE/4-96`($bp),%xmm1
+	pand	%xmm4,%xmm0
+	movq	`2*$STRIDE/4-96`($bp),%xmm2
+	pand	%xmm5,%xmm1
+	movq	`3*$STRIDE/4-96`($bp),%xmm3
+	pand	%xmm6,%xmm2
+	por	%xmm1,%xmm0
+	pand	%xmm7,%xmm3
+	por	%xmm2,%xmm0
+	lea	$STRIDE($bp),$bp
+	por	%xmm3,%xmm0
+
+	movq	%xmm0,$m0		# m0=bp[0]
+	mov	($n0),$n0		# pull n0[0] value
+	mov	($ap),%rax
+
+	xor	$i,$i			# i=0
+	xor	$j,$j			# j=0
+
+	movq	`0*$STRIDE/4-96`($bp),%xmm0
+	movq	`1*$STRIDE/4-96`($bp),%xmm1
+	pand	%xmm4,%xmm0
+	movq	`2*$STRIDE/4-96`($bp),%xmm2
+	pand	%xmm5,%xmm1
+
+	mov	$n0,$m1
+	mulq	$m0			# ap[0]*bp[0]
+	mov	%rax,$A[0]
+	mov	($np),%rax
+
+	movq	`3*$STRIDE/4-96`($bp),%xmm3
+	pand	%xmm6,%xmm2
+	por	%xmm1,%xmm0
+	pand	%xmm7,%xmm3
+
+	imulq	$A[0],$m1		# "tp[0]"*n0
+	mov	%rdx,$A[1]
+
+	por	%xmm2,%xmm0
+	lea	$STRIDE($bp),$bp
+	por	%xmm3,%xmm0
+
+	mulq	$m1			# np[0]*m1
+	add	%rax,$A[0]		# discarded
+	mov	8($ap),%rax
+	adc	\$0,%rdx
+	mov	%rdx,$N[1]
+
+	mulq	$m0
+	add	%rax,$A[1]
+	mov	8($np),%rax
+	adc	\$0,%rdx
+	mov	%rdx,$A[0]
+
+	mulq	$m1
+	add	%rax,$N[1]
+	mov	16($ap),%rax
+	adc	\$0,%rdx
+	add	$A[1],$N[1]
+	lea	4($j),$j		# j++
+	adc	\$0,%rdx
+	mov	$N[1],(%rsp)
+	mov	%rdx,$N[0]
+	jmp	.L1st4x
+.align	16
+.L1st4x:
+	mulq	$m0			# ap[j]*bp[0]
+	add	%rax,$A[0]
+	mov	-16($np,$j,8),%rax
+	adc	\$0,%rdx
+	mov	%rdx,$A[1]
+
+	mulq	$m1			# np[j]*m1
+	add	%rax,$N[0]
+	mov	-8($ap,$j,8),%rax
+	adc	\$0,%rdx
+	add	$A[0],$N[0]		# np[j]*m1+ap[j]*bp[0]
+	adc	\$0,%rdx
+	mov	$N[0],-24(%rsp,$j,8)	# tp[j-1]
+	mov	%rdx,$N[1]
+
+	mulq	$m0			# ap[j]*bp[0]
+	add	%rax,$A[1]
+	mov	-8($np,$j,8),%rax
+	adc	\$0,%rdx
+	mov	%rdx,$A[0]
+
+	mulq	$m1			# np[j]*m1
+	add	%rax,$N[1]
+	mov	($ap,$j,8),%rax
+	adc	\$0,%rdx
+	add	$A[1],$N[1]		# np[j]*m1+ap[j]*bp[0]
+	adc	\$0,%rdx
+	mov	$N[1],-16(%rsp,$j,8)	# tp[j-1]
+	mov	%rdx,$N[0]
+
+	mulq	$m0			# ap[j]*bp[0]
+	add	%rax,$A[0]
+	mov	($np,$j,8),%rax
+	adc	\$0,%rdx
+	mov	%rdx,$A[1]
+
+	mulq	$m1			# np[j]*m1
+	add	%rax,$N[0]
+	mov	8($ap,$j,8),%rax
+	adc	\$0,%rdx
+	add	$A[0],$N[0]		# np[j]*m1+ap[j]*bp[0]
+	adc	\$0,%rdx
+	mov	$N[0],-8(%rsp,$j,8)	# tp[j-1]
+	mov	%rdx,$N[1]
+
+	mulq	$m0			# ap[j]*bp[0]
+	add	%rax,$A[1]
+	mov	8($np,$j,8),%rax
+	adc	\$0,%rdx
+	lea	4($j),$j		# j++
+	mov	%rdx,$A[0]
+
+	mulq	$m1			# np[j]*m1
+	add	%rax,$N[1]
+	mov	-16($ap,$j,8),%rax
+	adc	\$0,%rdx
+	add	$A[1],$N[1]		# np[j]*m1+ap[j]*bp[0]
+	adc	\$0,%rdx
+	mov	$N[1],-32(%rsp,$j,8)	# tp[j-1]
+	mov	%rdx,$N[0]
+	cmp	$num,$j
+	jl	.L1st4x
+
+	mulq	$m0			# ap[j]*bp[0]
+	add	%rax,$A[0]
+	mov	-16($np,$j,8),%rax
+	adc	\$0,%rdx
+	mov	%rdx,$A[1]
+
+	mulq	$m1			# np[j]*m1
+	add	%rax,$N[0]
+	mov	-8($ap,$j,8),%rax
+	adc	\$0,%rdx
+	add	$A[0],$N[0]		# np[j]*m1+ap[j]*bp[0]
+	adc	\$0,%rdx
+	mov	$N[0],-24(%rsp,$j,8)	# tp[j-1]
+	mov	%rdx,$N[1]
+
+	mulq	$m0			# ap[j]*bp[0]
+	add	%rax,$A[1]
+	mov	-8($np,$j,8),%rax
+	adc	\$0,%rdx
+	mov	%rdx,$A[0]
+
+	mulq	$m1			# np[j]*m1
+	add	%rax,$N[1]
+	mov	($ap),%rax		# ap[0]
+	adc	\$0,%rdx
+	add	$A[1],$N[1]		# np[j]*m1+ap[j]*bp[0]
+	adc	\$0,%rdx
+	mov	$N[1],-16(%rsp,$j,8)	# tp[j-1]
+	mov	%rdx,$N[0]
+
+	movq	%xmm0,$m0		# bp[1]
+
+	xor	$N[1],$N[1]
+	add	$A[0],$N[0]
+	adc	\$0,$N[1]
+	mov	$N[0],-8(%rsp,$j,8)
+	mov	$N[1],(%rsp,$j,8)	# store upmost overflow bit
+
+	lea	1($i),$i		# i++
+.align	4
+.Louter4x:
+	xor	$j,$j			# j=0
+	movq	`0*$STRIDE/4-96`($bp),%xmm0
+	movq	`1*$STRIDE/4-96`($bp),%xmm1
+	pand	%xmm4,%xmm0
+	movq	`2*$STRIDE/4-96`($bp),%xmm2
+	pand	%xmm5,%xmm1
+
+	mov	(%rsp),$A[0]
+	mov	$n0,$m1
+	mulq	$m0			# ap[0]*bp[i]
+	add	%rax,$A[0]		# ap[0]*bp[i]+tp[0]
+	mov	($np),%rax
+	adc	\$0,%rdx
+
+	movq	`3*$STRIDE/4-96`($bp),%xmm3
+	pand	%xmm6,%xmm2
+	por	%xmm1,%xmm0
+	pand	%xmm7,%xmm3
+
+	imulq	$A[0],$m1		# tp[0]*n0
+	mov	%rdx,$A[1]
+
+	por	%xmm2,%xmm0
+	lea	$STRIDE($bp),$bp
+	por	%xmm3,%xmm0
+
+	mulq	$m1			# np[0]*m1
+	add	%rax,$A[0]		# "$N[0]", discarded
+	mov	8($ap),%rax
+	adc	\$0,%rdx
+	mov	%rdx,$N[1]
+
+	mulq	$m0			# ap[j]*bp[i]
+	add	%rax,$A[1]
+	mov	8($np),%rax
+	adc	\$0,%rdx
+	add	8(%rsp),$A[1]		# +tp[1]
+	adc	\$0,%rdx
+	mov	%rdx,$A[0]
+
+	mulq	$m1			# np[j]*m1
+	add	%rax,$N[1]
+	mov	16($ap),%rax
+	adc	\$0,%rdx
+	add	$A[1],$N[1]		# np[j]*m1+ap[j]*bp[i]+tp[j]
+	lea	4($j),$j		# j+=2
+	adc	\$0,%rdx
+	mov	$N[1],(%rsp)		# tp[j-1]
+	mov	%rdx,$N[0]
+	jmp	.Linner4x
+.align	16
+.Linner4x:
+	mulq	$m0			# ap[j]*bp[i]
+	add	%rax,$A[0]
+	mov	-16($np,$j,8),%rax
+	adc	\$0,%rdx
+	add	-16(%rsp,$j,8),$A[0]	# ap[j]*bp[i]+tp[j]
+	adc	\$0,%rdx
+	mov	%rdx,$A[1]
+
+	mulq	$m1			# np[j]*m1
+	add	%rax,$N[0]
+	mov	-8($ap,$j,8),%rax
+	adc	\$0,%rdx
+	add	$A[0],$N[0]
+	adc	\$0,%rdx
+	mov	$N[0],-24(%rsp,$j,8)	# tp[j-1]
+	mov	%rdx,$N[1]
+
+	mulq	$m0			# ap[j]*bp[i]
+	add	%rax,$A[1]
+	mov	-8($np,$j,8),%rax
+	adc	\$0,%rdx
+	add	-8(%rsp,$j,8),$A[1]
+	adc	\$0,%rdx
+	mov	%rdx,$A[0]
+
+	mulq	$m1			# np[j]*m1
+	add	%rax,$N[1]
+	mov	($ap,$j,8),%rax
+	adc	\$0,%rdx
+	add	$A[1],$N[1]
+	adc	\$0,%rdx
+	mov	$N[1],-16(%rsp,$j,8)	# tp[j-1]
+	mov	%rdx,$N[0]
+
+	mulq	$m0			# ap[j]*bp[i]
+	add	%rax,$A[0]
+	mov	($np,$j,8),%rax
+	adc	\$0,%rdx
+	add	(%rsp,$j,8),$A[0]	# ap[j]*bp[i]+tp[j]
+	adc	\$0,%rdx
+	mov	%rdx,$A[1]
+
+	mulq	$m1			# np[j]*m1
+	add	%rax,$N[0]
+	mov	8($ap,$j,8),%rax
+	adc	\$0,%rdx
+	add	$A[0],$N[0]
+	adc	\$0,%rdx
+	mov	$N[0],-8(%rsp,$j,8)	# tp[j-1]
+	mov	%rdx,$N[1]
+
+	mulq	$m0			# ap[j]*bp[i]
+	add	%rax,$A[1]
+	mov	8($np,$j,8),%rax
+	adc	\$0,%rdx
+	add	8(%rsp,$j,8),$A[1]
+	adc	\$0,%rdx
+	lea	4($j),$j		# j++
+	mov	%rdx,$A[0]
+
+	mulq	$m1			# np[j]*m1
+	add	%rax,$N[1]
+	mov	-16($ap,$j,8),%rax
+	adc	\$0,%rdx
+	add	$A[1],$N[1]
+	adc	\$0,%rdx
+	mov	$N[1],-32(%rsp,$j,8)	# tp[j-1]
+	mov	%rdx,$N[0]
+	cmp	$num,$j
+	jl	.Linner4x
+
+	mulq	$m0			# ap[j]*bp[i]
+	add	%rax,$A[0]
+	mov	-16($np,$j,8),%rax
+	adc	\$0,%rdx
+	add	-16(%rsp,$j,8),$A[0]	# ap[j]*bp[i]+tp[j]
+	adc	\$0,%rdx
+	mov	%rdx,$A[1]
+
+	mulq	$m1			# np[j]*m1
+	add	%rax,$N[0]
+	mov	-8($ap,$j,8),%rax
+	adc	\$0,%rdx
+	add	$A[0],$N[0]
+	adc	\$0,%rdx
+	mov	$N[0],-24(%rsp,$j,8)	# tp[j-1]
+	mov	%rdx,$N[1]
+
+	mulq	$m0			# ap[j]*bp[i]
+	add	%rax,$A[1]
+	mov	-8($np,$j,8),%rax
+	adc	\$0,%rdx
+	add	-8(%rsp,$j,8),$A[1]
+	adc	\$0,%rdx
+	lea	1($i),$i		# i++
+	mov	%rdx,$A[0]
+
+	mulq	$m1			# np[j]*m1
+	add	%rax,$N[1]
+	mov	($ap),%rax		# ap[0]
+	adc	\$0,%rdx
+	add	$A[1],$N[1]
+	adc	\$0,%rdx
+	mov	$N[1],-16(%rsp,$j,8)	# tp[j-1]
+	mov	%rdx,$N[0]
+
+	movq	%xmm0,$m0		# bp[i+1]
+
+	xor	$N[1],$N[1]
+	add	$A[0],$N[0]
+	adc	\$0,$N[1]
+	add	(%rsp,$num,8),$N[0]	# pull upmost overflow bit
+	adc	\$0,$N[1]
+	mov	$N[0],-8(%rsp,$j,8)
+	mov	$N[1],(%rsp,$j,8)	# store upmost overflow bit
+
+	cmp	$num,$i
+	jl	.Louter4x
+___
+{
+my @ri=("%rax","%rdx",$m0,$m1);
+$code.=<<___;
+	mov	16(%rsp,$num,8),$rp	# restore $rp
+	mov	0(%rsp),@ri[0]		# tp[0]
+	pxor	%xmm0,%xmm0
+	mov	8(%rsp),@ri[1]		# tp[1]
+	shr	\$2,$num		# num/=4
+	lea	(%rsp),$ap		# borrow ap for tp
+	xor	$i,$i			# i=0 and clear CF!
+
+	sub	0($np),@ri[0]
+	mov	16($ap),@ri[2]		# tp[2]
+	mov	24($ap),@ri[3]		# tp[3]
+	sbb	8($np),@ri[1]
+	lea	-1($num),$j		# j=num/4-1
+	jmp	.Lsub4x
+.align	16
+.Lsub4x:
+	mov	@ri[0],0($rp,$i,8)	# rp[i]=tp[i]-np[i]
+	mov	@ri[1],8($rp,$i,8)	# rp[i]=tp[i]-np[i]
+	sbb	16($np,$i,8),@ri[2]
+	mov	32($ap,$i,8),@ri[0]	# tp[i+1]
+	mov	40($ap,$i,8),@ri[1]
+	sbb	24($np,$i,8),@ri[3]
+	mov	@ri[2],16($rp,$i,8)	# rp[i]=tp[i]-np[i]
+	mov	@ri[3],24($rp,$i,8)	# rp[i]=tp[i]-np[i]
+	sbb	32($np,$i,8),@ri[0]
+	mov	48($ap,$i,8),@ri[2]
+	mov	56($ap,$i,8),@ri[3]
+	sbb	40($np,$i,8),@ri[1]
+	lea	4($i),$i		# i++
+	dec	$j			# doesnn't affect CF!
+	jnz	.Lsub4x
+
+	mov	@ri[0],0($rp,$i,8)	# rp[i]=tp[i]-np[i]
+	mov	32($ap,$i,8),@ri[0]	# load overflow bit
+	sbb	16($np,$i,8),@ri[2]
+	mov	@ri[1],8($rp,$i,8)	# rp[i]=tp[i]-np[i]
+	sbb	24($np,$i,8),@ri[3]
+	mov	@ri[2],16($rp,$i,8)	# rp[i]=tp[i]-np[i]
+
+	sbb	\$0,@ri[0]		# handle upmost overflow bit
+	mov	@ri[3],24($rp,$i,8)	# rp[i]=tp[i]-np[i]
+	xor	$i,$i			# i=0
+	and	@ri[0],$ap
+	not	@ri[0]
+	mov	$rp,$np
+	and	@ri[0],$np
+	lea	-1($num),$j
+	or	$np,$ap			# ap=borrow?tp:rp
+
+	movdqu	($ap),%xmm1
+	movdqa	%xmm0,(%rsp)
+	movdqu	%xmm1,($rp)
+	jmp	.Lcopy4x
+.align	16
+.Lcopy4x:					# copy or in-place refresh
+	movdqu	16($ap,$i),%xmm2
+	movdqu	32($ap,$i),%xmm1
+	movdqa	%xmm0,16(%rsp,$i)
+	movdqu	%xmm2,16($rp,$i)
+	movdqa	%xmm0,32(%rsp,$i)
+	movdqu	%xmm1,32($rp,$i)
+	lea	32($i),$i
+	dec	$j
+	jnz	.Lcopy4x
+
+	shl	\$2,$num
+	movdqu	16($ap,$i),%xmm2
+	movdqa	%xmm0,16(%rsp,$i)
+	movdqu	%xmm2,16($rp,$i)
+___
+}
+$code.=<<___;
+	mov	8(%rsp,$num,8),%rsi	# restore %rsp
+	mov	\$1,%rax
+	mov	(%rsi),%r15
+	mov	8(%rsi),%r14
+	mov	16(%rsi),%r13
+	mov	24(%rsi),%r12
+	mov	32(%rsi),%rbp
+	mov	40(%rsi),%rbx
+	lea	48(%rsi),%rsp
+.Lmul4x_epilogue:
+	ret
+.size	bn_mul4x_mont_gather5,.-bn_mul4x_mont_gather5
+___
+}}}
+
+{
+my ($inp,$num,$tbl,$idx)=$win64?("%rcx","%rdx","%r8", "%r9") : # Win64 order
+				("%rdi","%rsi","%rdx","%rcx"); # Unix order
+$code.=<<___;
+.globl	bn_scatter5
+.type	bn_scatter5,\@abi-omnipotent
+.align	16
+bn_scatter5:
+	lea	($tbl,$idx,8),$tbl
+.Lscatter:
+	mov	($inp),%rax
+	lea	8($inp),$inp
+	mov	%rax,($tbl)
+	lea	32*8($tbl),$tbl
+	sub	\$1,$num
+	jnz	.Lscatter
+	ret
+.size	bn_scatter5,.-bn_scatter5
+___
+}
+$code.=<<___;
+.align	64
+.Lmagic_masks:
+	.long	0,0, 0,0, 0,0, -1,-1
+	.long	0,0, 0,0, 0,0,  0,0
+.asciz	"Montgomery Multiplication with scatter/gather for x86_64, CRYPTOGAMS by <appro\@openssl.org>"
+___
+
+$code =~ s/\`([^\`]*)\`/eval($1)/gem;
+
+print $code;
+close STDOUT;
diff --git a/crypto/bn/bn_exp.c b/crypto/bn/bn_exp.c
index ce31ad0a58..5b00aa1e3c 100644
--- a/crypto/bn/bn_exp.c
+++ b/crypto/bn/bn_exp.c
@@ -114,6 +114,18 @@
 #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
 
@@ -562,7 +574,7 @@ 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
@@ -573,17 +585,16 @@ 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 computeTemp, *am=NULL;
 
 	bn_check_top(a);
 	bn_check_top(p);
@@ -621,39 +632,149 @@ 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
+ 	/* 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;
 
 	/* Allocate a buffer large enough to hold all of the pre-computed
-	 * powers of a.
+	 * powers of a, plus computeTemp.
 	 */
 	numPowers = 1 << window;
-	powerbufLen = sizeof(m->d[0])*top*numPowers;
-	if ((powerbufFree=(unsigned char*)OPENSSL_malloc(powerbufLen+MOD_EXP_CTIME_MIN_CACHE_LINE_WIDTH)) == NULL)
+	powerbufLen = sizeof(m->d[0])*(top*numPowers +
+				(top>numPowers?top:numPowers));
+	if (powerbufLen < 3072)
+		powerbufFree = alloca(powerbufLen+MOD_EXP_CTIME_MIN_CACHE_LINE_WIDTH);
+	else 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);
 
+	if (powerbufLen < 3072)
+		powerbufFree = NULL;
+
+	computeTemp.d = (BN_ULONG *)(powerbuf + sizeof(m->d[0])*top*numPowers);
+	computeTemp.top = computeTemp.dmax = top;
+	computeTemp.neg = 0;
+	computeTemp.flags = BN_FLG_STATIC_DATA;
+
  	/* 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;
 
 	/* 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;
+	if (am==NULL) goto err;
 
 	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;
+	else	if (!BN_to_montgomery(am,a,mont,ctx))	goto err;
+
+	if (!BN_copy(&computeTemp, am)) goto err;
+
+	if (bn_wexpand(am,top)==NULL ||	bn_wexpand(r,top)==NULL)
+		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);
+
+	BN_ULONG *acc, *np=mont->N.d, *n0=mont->n0;
+
+	bn_scatter5(r->d,r->top,powerbuf,0);
+	bn_scatter5(am->d,am->top,powerbuf,1);
+
+	acc = computeTemp.d;
+#if 0
+	for (i=2; i<32; i++)
+		{
+		bn_mul_mont_gather5(acc,am->d,powerbuf,np,n0,top,i-1);
+		bn_scatter5(acc,top,powerbuf,i);
+		}
+#else
+	/* same as above, but uses squaring for 1/2 of operations */
+	for (i=2; i<32; i*=2)
+		{
+		bn_mul_mont(acc,acc,acc,np,n0,top);
+		bn_scatter5(acc,top,powerbuf,i);
+		}
+	for (i=3; i<8; i+=2)
+		{
+		int j;
+		bn_mul_mont_gather5(acc,am->d,powerbuf,np,n0,top,i-1);
+		bn_scatter5(acc,top,powerbuf,i);
+		for (j=2*i; j<32; j*=2)
+			{
+			bn_mul_mont(acc,acc,acc,np,n0,top);
+			bn_scatter5(acc,top,powerbuf,j);
+			}
+		}
+	for (; i<16; i+=2)
+		{
+		bn_mul_mont_gather5(acc,am->d,powerbuf,np,n0,top,i-1);
+		bn_scatter5(acc,top,powerbuf,i);
+		bn_mul_mont(acc,acc,acc,np,n0,top);
+		bn_scatter5(acc,top,powerbuf,2*i);
+		}
+	for (; i<32; i+=2)
+		{
+		bn_mul_mont_gather5(acc,am->d,powerbuf,np,n0,top,i-1);
+		bn_scatter5(acc,top,powerbuf,i);
+		}
+#endif
+	acc = r->d;
+
+	/* Scan the exponent one window at a time starting from the most
+	 * significant bits.
+	 */
+	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(acc,acc,acc,np,n0,top);
+		bn_mul_mont(acc,acc,acc,np,n0,top);
+		bn_mul_mont(acc,acc,acc,np,n0,top);
+		bn_mul_mont(acc,acc,acc,np,n0,top);
+		bn_mul_mont(acc,acc,acc,np,n0,top);
+		bn_mul_mont_gather5(acc,acc,powerbuf,np,n0,top,wvalue);
+		}
+
+	r->top=top;
+	bn_correct_top(r);
+	}
+    else
+#endif
+	{
+	if (!MOD_EXP_CTIME_COPY_TO_PREBUF(r, 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
@@ -666,46 +787,34 @@ int BN_mod_exp_mont_consttime(BIGNUM *rr, const BIGNUM *a, const BIGNUM *p,
 		for (i=2; 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(&computeTemp,am,&computeTemp,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(&computeTemp, 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
+	/* Scan the exponent one window at a time starting from the most
  	 * significant bits.
  	 */
- 	while (idx >= 0)
+	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);
+			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(&computeTemp, 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(r,r,&computeTemp,mont,ctx)) goto err;
   		}
+	}
 
  	/* Convert the final result from montgomery to standard format */
 	if (!BN_from_montgomery(rr,r,mont,ctx)) goto err;
@@ -715,10 +824,9 @@ err:
 	if (powerbuf!=NULL)
 		{
 		OPENSSL_cleanse(powerbuf,powerbufLen);
-