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bn_exp.c: further optimizations using more ideas from

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http://eprint.iacr.org/2011/239.
This commit is contained in:
Andy Polyakov 2011-10-17 17:41:49 +00:00
parent 3f66f2040a
commit 8329e2e776
2 changed files with 156 additions and 113 deletions
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83
crypto/bn/asm/x86_64-mont5.pl
View File

@ -607,7 +607,6 @@ $code.=<<___;
add $A[1],$N[1] # np[j]*m1+ap[j]*bp[i]+tp[j] add $A[1],$N[1] # np[j]*m1+ap[j]*bp[i]+tp[j]
lea 4($j),$j # j+=2 lea 4($j),$j # j+=2
adc \$0,%rdx adc \$0,%rdx
mov $N[1],(%rsp) # tp[j-1]
mov %rdx,$N[0] mov %rdx,$N[0]
jmp .Linner4x jmp .Linner4x
.align 16 .align 16
@ -626,7 +625,7 @@ $code.=<<___;
adc \$0,%rdx adc \$0,%rdx
add $A[0],$N[0] add $A[0],$N[0]
adc \$0,%rdx adc \$0,%rdx
mov $N[0],-24(%rsp,$j,8) # tp[j-1] mov $N[1],-32(%rsp,$j,8) # tp[j-1]
mov %rdx,$N[1] mov %rdx,$N[1]
mulq $m0 # ap[j]*bp[i] mulq $m0 # ap[j]*bp[i]
@ -643,7 +642,7 @@ $code.=<<___;
adc \$0,%rdx adc \$0,%rdx
add $A[1],$N[1] add $A[1],$N[1]
adc \$0,%rdx adc \$0,%rdx
mov $N[1],-16(%rsp,$j,8) # tp[j-1] mov $N[0],-24(%rsp,$j,8) # tp[j-1]
mov %rdx,$N[0] mov %rdx,$N[0]
mulq $m0 # ap[j]*bp[i] mulq $m0 # ap[j]*bp[i]
@ -660,7 +659,7 @@ $code.=<<___;
adc \$0,%rdx adc \$0,%rdx
add $A[0],$N[0] add $A[0],$N[0]
adc \$0,%rdx adc \$0,%rdx
mov $N[0],-8(%rsp,$j,8) # tp[j-1] mov $N[1],-16(%rsp,$j,8) # tp[j-1]
mov %rdx,$N[1] mov %rdx,$N[1]
mulq $m0 # ap[j]*bp[i] mulq $m0 # ap[j]*bp[i]
@ -678,7 +677,7 @@ $code.=<<___;
adc \$0,%rdx adc \$0,%rdx
add $A[1],$N[1] add $A[1],$N[1]
adc \$0,%rdx adc \$0,%rdx
mov $N[1],-32(%rsp,$j,8) # tp[j-1] mov $N[0],-40(%rsp,$j,8) # tp[j-1]
mov %rdx,$N[0] mov %rdx,$N[0]
cmp $num,$j cmp $num,$j
jl .Linner4x jl .Linner4x
@ -697,7 +696,7 @@ $code.=<<___;
adc \$0,%rdx adc \$0,%rdx
add $A[0],$N[0] add $A[0],$N[0]
adc \$0,%rdx adc \$0,%rdx
mov $N[0],-24(%rsp,$j,8) # tp[j-1] mov $N[1],-32(%rsp,$j,8) # tp[j-1]
mov %rdx,$N[1] mov %rdx,$N[1]
mulq $m0 # ap[j]*bp[i] mulq $m0 # ap[j]*bp[i]
@ -715,10 +714,11 @@ $code.=<<___;
adc \$0,%rdx adc \$0,%rdx
add $A[1],$N[1] add $A[1],$N[1]
adc \$0,%rdx adc \$0,%rdx
mov $N[1],-16(%rsp,$j,8) # tp[j-1] mov $N[0],-24(%rsp,$j,8) # tp[j-1]
mov %rdx,$N[0] mov %rdx,$N[0]
movq %xmm0,$m0 # bp[i+1] movq %xmm0,$m0 # bp[i+1]
mov $N[1],-16(%rsp,$j,8) # tp[j-1]
xor $N[1],$N[1] xor $N[1],$N[1]
add $A[0],$N[0] add $A[0],$N[0]
@ -831,6 +831,10 @@ ___
{ {
my ($inp,$num,$tbl,$idx)=$win64?("%rcx","%rdx","%r8", "%r9") : # Win64 order my ($inp,$num,$tbl,$idx)=$win64?("%rcx","%rdx","%r8", "%r9") : # Win64 order
("%rdi","%rsi","%rdx","%rcx"); # Unix order ("%rdi","%rsi","%rdx","%rcx"); # Unix order
my $out=$inp;
my $STRIDE=2**5*8;
my $N=$STRIDE/4;
$code.=<<___; $code.=<<___;
.globl bn_scatter5 .globl bn_scatter5
.type bn_scatter5,\@abi-omnipotent .type bn_scatter5,\@abi-omnipotent
@ -849,6 +853,61 @@ bn_scatter5:
.Lscatter_epilogue: .Lscatter_epilogue:
ret ret
.size bn_scatter5,.-bn_scatter5 .size bn_scatter5,.-bn_scatter5
.globl bn_gather5
.type bn_gather5,\@abi-omnipotent
.align 16
bn_gather5:
___
$code.=<<___ if ($win64);
.LSEH_begin_bn_gather5:
# I can't trust assembler to use specific encoding:-(
.byte 0x48,0x83,0xec,0x28 #sub \$0x28,%rsp
.byte 0x0f,0x29,0x34,0x24 #movaps %xmm6,(%rsp)
.byte 0x0f,0x29,0x7c,0x24,0x10 #movdqa %xmm7,0x10(%rsp)
___
$code.=<<___;
mov $idx,%r11
shr \$`log($N/8)/log(2)`,$idx
and \$`$N/8-1`,%r11
not $idx
lea .Lmagic_masks(%rip),%rax
and \$`2**5/($N/8)-1`,$idx # 5 is "window size"
lea 96($tbl,%r11,8),$tbl # pointer within 1st cache line
movq 0(%rax,$idx,8),%xmm4 # set of masks denoting which
movq 8(%rax,$idx,8),%xmm5 # cache line contains element
movq 16(%rax,$idx,8),%xmm6 # denoted by 7th argument
movq 24(%rax,$idx,8),%xmm7
jmp .Lgather
.align 16
.Lgather:
movq `0*$STRIDE/4-96`($tbl),%xmm0
movq `1*$STRIDE/4-96`($tbl),%xmm1
pand %xmm4,%xmm0
movq `2*$STRIDE/4-96`($tbl),%xmm2
pand %xmm5,%xmm1
movq `3*$STRIDE/4-96`($tbl),%xmm3
pand %xmm6,%xmm2
por %xmm1,%xmm0
pand %xmm7,%xmm3
por %xmm2,%xmm0
lea $STRIDE($tbl),$tbl
por %xmm3,%xmm0
movq %xmm0,($out) # m0=bp[0]
lea 8($out),$out
sub \$1,$num
jnz .Lgather
___
$code.=<<___ if ($win64);
movaps %xmm6,(%rsp)
movaps %xmm7,0x10(%rsp)
lea 0x28(%rsp),%rsp
___
$code.=<<___;
ret
.LSEH_end_bn_gather5:
.size bn_gather5,.-bn_gather5
___ ___
} }
$code.=<<___; $code.=<<___;
@ -980,6 +1039,10 @@ mul_handler:
.rva .LSEH_end_bn_mul4x_mont_gather5 .rva .LSEH_end_bn_mul4x_mont_gather5
.rva .LSEH_info_bn_mul4x_mont_gather5 .rva .LSEH_info_bn_mul4x_mont_gather5
.rva .LSEH_begin_bn_gather5
.rva .LSEH_end_bn_gather5
.rva .LSEH_info_bn_gather5
.section .xdata .section .xdata
.align 8 .align 8
.LSEH_info_bn_mul_mont_gather5: .LSEH_info_bn_mul_mont_gather5:
@ -992,6 +1055,12 @@ mul_handler:
.rva mul_handler .rva mul_handler
.rva .Lmul4x_alloca,.Lmul4x_body,.Lmul4x_epilogue # HandlerData[] .rva .Lmul4x_alloca,.Lmul4x_body,.Lmul4x_epilogue # HandlerData[]
.align 8 .align 8
.LSEH_info_bn_gather5:
.byte 0x01,0x0d,0x05,0x00
.byte 0x0d,0x78,0x01,0x00 #movaps 0x10(rsp),xmm7
.byte 0x08,0x68,0x00,0x00 #movaps (rsp),xmm6
.byte 0x04,0x42,0x00,0x00 #sub rsp,0x28
.align 8
___ ___
} }

186
crypto/bn/bn_exp.c
View File

@ -535,23 +535,17 @@ err:
* as cache lines are concerned. The following functions are used to transfer a BIGNUM * as cache lines are concerned. The following functions are used to transfer a BIGNUM
* from/to that table. */ * 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; size_t i, j;
if (bn_wexpand(b, top) == NULL) if (top > b->top)
return 0; top = b->top; /* this works because 'buf' is explicitly zeroed */
while (b->top < top)
{
b->d[b->top++] = 0;
}
for (i = 0, j=idx; i < top * sizeof b->d[0]; i++, j+=width) for (i = 0, j=idx; i < top * sizeof b->d[0]; i++, j+=width)
{ {
buf[j] = ((unsigned char*)b->d)[i]; buf[j] = ((unsigned char*)b->d)[i];
} }
bn_correct_top(b);
return 1; return 1;
} }
@ -587,14 +581,13 @@ int BN_mod_exp_mont_consttime(BIGNUM *rr, const BIGNUM *a, const BIGNUM *p,
{ {
int i,bits,ret=0,window,wvalue; int i,bits,ret=0,window,wvalue;
int top; int top;
BIGNUM *r;
BN_MONT_CTX *mont=NULL; BN_MONT_CTX *mont=NULL;
int numPowers; int numPowers;
unsigned char *powerbufFree=NULL; unsigned char *powerbufFree=NULL;
int powerbufLen = 0; int powerbufLen = 0;
unsigned char *powerbuf=NULL; unsigned char *powerbuf=NULL;
BIGNUM computeTemp, *am=NULL; BIGNUM tmp, am;
bn_check_top(a); bn_check_top(a);
bn_check_top(p); bn_check_top(p);
@ -614,10 +607,7 @@ int BN_mod_exp_mont_consttime(BIGNUM *rr, const BIGNUM *a, const BIGNUM *p,
return ret; return ret;
} }
/* Initialize BIGNUM context and allocate intermediate result */
BN_CTX_start(ctx); 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. /* Allocate a montgomery context if it was not supplied by the caller.
* If this is not done, things will break in the montgomery part. * If this is not done, things will break in the montgomery part.
@ -635,25 +625,13 @@ int BN_mod_exp_mont_consttime(BIGNUM *rr, const BIGNUM *a, const BIGNUM *p,
#if defined(OPENSSL_BN_ASM_MONT5) #if defined(OPENSSL_BN_ASM_MONT5)
if (window==6 && bits<=1024) window=5; /* ~5% improvement of 2048-bit RSA sign */ if (window==6 && bits<=1024) window=5; /* ~5% improvement of 2048-bit RSA sign */
#endif #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 /* Allocate a buffer large enough to hold all of the pre-computed
* powers of a, plus computeTemp. * powers of am, am itself and tmp.
*/ */
numPowers = 1 << window; numPowers = 1 << window;
powerbufLen = sizeof(m->d[0])*(top*numPowers + powerbufLen = sizeof(m->d[0])*(top*numPowers +
(top>numPowers?top:numPowers)); ((2*top)>numPowers?(2*top):numPowers));
#ifdef alloca #ifdef alloca
if (powerbufLen < 3072) if (powerbufLen < 3072)
powerbufFree = alloca(powerbufLen+MOD_EXP_CTIME_MIN_CACHE_LINE_WIDTH); powerbufFree = alloca(powerbufLen+MOD_EXP_CTIME_MIN_CACHE_LINE_WIDTH);
@ -670,28 +648,31 @@ int BN_mod_exp_mont_consttime(BIGNUM *rr, const BIGNUM *a, const BIGNUM *p,
powerbufFree = NULL; powerbufFree = NULL;
#endif #endif
computeTemp.d = (BN_ULONG *)(powerbuf + sizeof(m->d[0])*top*numPowers); /* lay down tmp and am right after powers table */
computeTemp.top = computeTemp.dmax = top; tmp.d = (BN_ULONG *)(powerbuf + sizeof(m->d[0])*top*numPowers);
computeTemp.neg = 0; am.d = tmp.d + top;
computeTemp.flags = BN_FLG_STATIC_DATA; tmp.top = am.top = 0;
tmp.dmax = am.dmax = top;
tmp.neg = am.neg = 0;
tmp.flags = am.flags = BN_FLG_STATIC_DATA;
/* Initialize the intermediate result. Do this early to save double conversion, /* prepare a^0 in Montgomery domain */
* once each for a^0 and intermediate result. #if 1
*/ if (!BN_to_montgomery(&tmp,BN_value_one(),mont,ctx)) goto err;
if (!BN_to_montgomery(r,BN_value_one(),mont,ctx)) goto err; #else
tmp.d[0] = (0-m->d[0])&BN_MASK2; /* 2^(top*BN_BITS2) - m */
/* Initialize computeTemp as a^1 with montgomery precalcs */ for (i=1;i<top;i++)
am = BN_CTX_get(ctx); tmp.d[i] = (~m->d[i])&BN_MASK2;
if (am==NULL) goto err; tmp.top = top;
#endif
/* prepare a^1 in Montgomery domain */
if (a->neg || BN_ucmp(a,m) >= 0) if (a->neg || BN_ucmp(a,m) >= 0)
{ {
if (!BN_mod(am,a,m,ctx)) goto err; if (!BN_mod(&am,a,m,ctx)) goto err;
if (!BN_to_montgomery(am,am,mont,ctx)) goto err; if (!BN_to_montgomery(&am,&am,mont,ctx)) goto err;
} }
else if (!BN_to_montgomery(am,a,mont,ctx)) goto err; else if (!BN_to_montgomery(&am,a,mont,ctx)) goto err;
if (!BN_copy(&computeTemp, am)) goto err;
#if defined(OPENSSL_BN_ASM_MONT5) #if defined(OPENSSL_BN_ASM_MONT5)
/* This optimization uses ideas from http://eprint.iacr.org/2011/239, /* This optimization uses ideas from http://eprint.iacr.org/2011/239,
@ -707,95 +688,83 @@ int BN_mod_exp_mont_consttime(BIGNUM *rr, const BIGNUM *a, const BIGNUM *p,
const BN_ULONG *n0,int num,int power); const BN_ULONG *n0,int num,int power);
void bn_scatter5(const BN_ULONG *inp,size_t num, void bn_scatter5(const BN_ULONG *inp,size_t num,
void *table,size_t power); void *table,size_t power);
void bn_gather5(BN_ULONG *out,size_t num,
void *table,size_t power);
BN_ULONG *acc, *np=mont->N.d, *n0=mont->n0; BN_ULONG *np=mont->N.d, *n0=mont->n0;
bn_scatter5(r->d,r->top,powerbuf,0); bn_scatter5(tmp.d,top,powerbuf,0);
bn_scatter5(am->d,am->top,powerbuf,1); 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);
acc = computeTemp.d;
/* bn_mul_mont() and bn_mul_mont_gather5() assume fixed length inputs.
* Pad the inputs with zeroes.
*/
if (bn_wexpand(am,top)==NULL || bn_wexpand(r,top)==NULL ||
bn_wexpand(&computeTemp,top)==NULL)
goto err;
for (i = am->top; i < top; ++i)
{
am->d[i] = 0;
}
for (i = computeTemp.top; i < top; ++i)
{
computeTemp.d[i] = 0;
}
for (i = r->top; i < top; ++i)
{
r->d[i] = 0;
}
#if 0 #if 0
for (i=2; i<32; i++) for (i=3; i<32; i++)
{ {
bn_mul_mont_gather5(acc,am->d,powerbuf,np,n0,top,i-1); /* Calculate a^i = a^(i-1) * a */
bn_scatter5(acc,top,powerbuf,i); bn_mul_mont_gather5(tmp.d,am.d,powerbuf,np,n0,top,i-1);
bn_scatter5(tmp.d,top,powerbuf,i);
} }
#else #else
/* same as above, but uses squaring for 1/2 of operations */ /* same as above, but uses squaring for 1/2 of operations */
for (i=2; i<32; i*=2) for (i=4; i<32; i*=2)
{ {
bn_mul_mont(acc,acc,acc,np,n0,top); bn_mul_mont(tmp.d,tmp.d,tmp.d,np,n0,top);
bn_scatter5(acc,top,powerbuf,i); bn_scatter5(tmp.d,top,powerbuf,i);
} }
for (i=3; i<8; i+=2) for (i=3; i<8; i+=2)
{ {
int j; int j;
bn_mul_mont_gather5(acc,am->d,powerbuf,np,n0,top,i-1); bn_mul_mont_gather5(tmp.d,am.d,powerbuf,np,n0,top,i-1);
bn_scatter5(acc,top,powerbuf,i); bn_scatter5(tmp.d,top,powerbuf,i);
for (j=2*i; j<32; j*=2) for (j=2*i; j<32; j*=2)
{ {
bn_mul_mont(acc,acc,acc,np,n0,top); bn_mul_mont(tmp.d,tmp.d,tmp.d,np,n0,top);
bn_scatter5(acc,top,powerbuf,j); bn_scatter5(tmp.d,top,powerbuf,j);
} }
} }
for (; i<16; i+=2) for (; i<16; i+=2)
{ {
bn_mul_mont_gather5(acc,am->d,powerbuf,np,n0,top,i-1); bn_mul_mont_gather5(tmp.d,am.d,powerbuf,np,n0,top,i-1);
bn_scatter5(acc,top,powerbuf,i); bn_scatter5(tmp.d,top,powerbuf,i);
bn_mul_mont(acc,acc,acc,np,n0,top); bn_mul_mont(tmp.d,tmp.d,tmp.d,np,n0,top);
bn_scatter5(acc,top,powerbuf,2*i); bn_scatter5(tmp.d,top,powerbuf,2*i);
} }
for (; i<32; i+=2) for (; i<32; i+=2)
{ {
bn_mul_mont_gather5(acc,am->d,powerbuf,np,n0,top,i-1); bn_mul_mont_gather5(tmp.d,am.d,powerbuf,np,n0,top,i-1);
bn_scatter5(acc,top,powerbuf,i); bn_scatter5(tmp.d,top,powerbuf,i);
} }
#endif #endif
acc = r->d; 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 /* Scan the exponent one window at a time starting from the most
* significant bits. * significant bits.
*/ */
bits--;
while (bits >= 0) while (bits >= 0)
{ {
for (wvalue=0, i=0; i<5; i++,bits--) for (wvalue=0, i=0; i<5; i++,bits--)
wvalue = (wvalue<<1)+BN_is_bit_set(p,bits); wvalue = (wvalue<<1)+BN_is_bit_set(p,bits);
bn_mul_mont(acc,acc,acc,np,n0,top); bn_mul_mont(tmp.d,tmp.d,tmp.d,np,n0,top);
bn_mul_mont(acc,acc,acc,np,n0,top); bn_mul_mont(tmp.d,tmp.d,tmp.d,np,n0,top);
bn_mul_mont(acc,acc,acc,np,n0,top); bn_mul_mont(tmp.d,tmp.d,tmp.d,np,n0,top);
bn_mul_mont(acc,acc,acc,np,n0,top); bn_mul_mont(tmp.d,tmp.d,tmp.d,np,n0,top);
bn_mul_mont(acc,acc,acc,np,n0,top); bn_mul_mont(tmp.d,tmp.d,tmp.d,np,n0,top);
bn_mul_mont_gather5(acc,acc,powerbuf,np,n0,top,wvalue); bn_mul_mont_gather5(tmp.d,tmp.d,powerbuf,np,n0,top,wvalue);
} }
r->top=top; tmp.top=top;
bn_correct_top(r); bn_correct_top(&tmp);
} }
else else
#endif #endif
{ {
if (!MOD_EXP_CTIME_COPY_TO_PREBUF(r, top, powerbuf, 0, numPowers)) goto err; 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 (!MOD_EXP_CTIME_COPY_TO_PREBUF(&am, top, powerbuf, 1, numPowers)) goto err;
/* If the window size is greater than 1, then calculate /* If the window size is greater than 1, then calculate
* val[i=2..2^winsize-1]. Powers are computed as a*a^(i-1) * val[i=2..2^winsize-1]. Powers are computed as a*a^(i-1)
@ -804,19 +773,25 @@ int BN_mod_exp_mont_consttime(BIGNUM *rr, const BIGNUM *a, const BIGNUM *p,
*/ */
if (window > 1) 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 */ /* 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; 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;
} }
} }
/* Scan the exponent one window at a time starting from the most
* significant bits.
*/
bits--; 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) while (bits >= 0)
{ {
wvalue=0; /* The 'value' of the window */ wvalue=0; /* The 'value' of the window */
@ -824,20 +799,20 @@ int BN_mod_exp_mont_consttime(BIGNUM *rr, const BIGNUM *a, const BIGNUM *p,
/* Scan the window, squaring the result as we go */ /* Scan the window, squaring the result as we go */
for (i=0; i<window; i++,bits--) for (i=0; i<window; i++,bits--)
{ {
if (!BN_mod_mul_montgomery(r,r,r,mont,ctx)) goto err; if (!BN_mod_mul_montgomery(&tmp,&tmp,&tmp,mont,ctx)) goto err;
wvalue = (wvalue<<1)+BN_is_bit_set(p,bits); wvalue = (wvalue<<1)+BN_is_bit_set(p,bits);
} }
/* Fetch the appropriate pre-computed value from the pre-buf */ /* 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 */ /* 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 */ /* 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; ret=1;
err: err:
if ((in_mont == NULL) && (mont != NULL)) BN_MONT_CTX_free(mont); if ((in_mont == NULL) && (mont != NULL)) BN_MONT_CTX_free(mont);
@ -846,7 +821,6 @@ err:
OPENSSL_cleanse(powerbuf,powerbufLen); OPENSSL_cleanse(powerbuf,powerbufLen);
if (powerbufFree) OPENSSL_free(powerbufFree); if (powerbufFree) OPENSSL_free(powerbufFree);
} }
if (am!=NULL) BN_clear(am);
BN_CTX_end(ctx); BN_CTX_end(ctx);
return(ret); return(ret);
} }