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openssl/crypto/bn/bn_mont.c
Geoff Thorpe a721216f0f bignum: allow concurrent BN_MONT_CTX_set_locked() 
The lazy-initialisation of BN_MONT_CTX was serialising all threads, as
noted by Daniel Sands and co at Sandia. This was to handle the case that
2 or more threads race to lazy-init the same context, but stunted all
scalability in the case where 2 or more threads are doing unrelated
things! We favour the latter case by punishing the former. The init work
gets done by each thread that finds the context to be uninitialised, and
we then lock the "set" logic after that work is done - the winning
thread's work gets used, the losing threads throw away what they've done.

Signed-off-by: Geoff Thorpe <geoff@openssl.org>
2014-05-06 18:23:49 -04:00

738 lines
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/* crypto/bn/bn_mont.c */
/* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
* All rights reserved.
*
* This package is an SSL implementation written
* by Eric Young (eay@cryptsoft.com).
* The implementation was written so as to conform with Netscapes SSL.
*
* This library is free for commercial and non-commercial use as long as
* the following conditions are aheared to. The following conditions
* apply to all code found in this distribution, be it the RC4, RSA,
* lhash, DES, etc., code; not just the SSL code. The SSL documentation
* included with this distribution is covered by the same copyright terms
* except that the holder is Tim Hudson (tjh@cryptsoft.com).
*
* Copyright remains Eric Young's, and as such any Copyright notices in
* the code are not to be removed.
* If this package is used in a product, Eric Young should be given attribution
* as the author of the parts of the library used.
* This can be in the form of a textual message at program startup or
* in documentation (online or textual) provided with the package.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* "This product includes cryptographic software written by
* Eric Young (eay@cryptsoft.com)"
* The word 'cryptographic' can be left out if the rouines from the library
* being used are not cryptographic related :-).
* 4. If you include any Windows specific code (or a derivative thereof) from
* the apps directory (application code) you must include an acknowledgement:
* "This product includes software written by Tim Hudson (tjh@cryptsoft.com)"
*
* THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* The licence and distribution terms for any publically available version or
* derivative of this code cannot be changed. i.e. this code cannot simply be
* copied and put under another distribution licence
* [including the GNU Public Licence.]
*/
/* ====================================================================
* Copyright (c) 1998-2006 The OpenSSL Project. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
*
* 3. All advertising materials mentioning features or use of this
* software must display the following acknowledgment:
* "This product includes software developed by the OpenSSL Project
* for use in the OpenSSL Toolkit. (http://www.openssl.org/)"
*
* 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
* endorse or promote products derived from this software without
* prior written permission. For written permission, please contact
* openssl-core@openssl.org.
*
* 5. Products derived from this software may not be called "OpenSSL"
* nor may "OpenSSL" appear in their names without prior written
* permission of the OpenSSL Project.
*
* 6. Redistributions of any form whatsoever must retain the following
* acknowledgment:
* "This product includes software developed by the OpenSSL Project
* for use in the OpenSSL Toolkit (http://www.openssl.org/)"
*
* THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
* EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE OpenSSL PROJECT OR
* ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
* OF THE POSSIBILITY OF SUCH DAMAGE.
* ====================================================================
*
* This product includes cryptographic software written by Eric Young
* (eay@cryptsoft.com). This product includes software written by Tim
* Hudson (tjh@cryptsoft.com).
*
*/
/*
* Details about Montgomery multiplication algorithms can be found at
* http://security.ece.orst.edu/publications.html, e.g.
* http://security.ece.orst.edu/koc/papers/j37acmon.pdf and
* sections 3.8 and 4.2 in http://security.ece.orst.edu/koc/papers/r01rsasw.pdf
*/
#include <stdio.h>
#include "cryptlib.h"
#include "bn_lcl.h"
#define MONT_WORD /* use the faster word-based algorithm */
#if defined(MONT_WORD) && defined(OPENSSL_BN_ASM_MONT) && (BN_BITS2<=32)
/* This condition means we have a specific non-default build:
* In the 0.9.8 branch, OPENSSL_BN_ASM_MONT is normally not set for any
* BN_BITS2<=32 platform; an explicit "enable-montasm" is required.
* I.e., if we are here, the user intentionally deviates from the
* normal stable build to get better Montgomery performance from
* the 0.9.9-dev backport.
*
* In this case only, we also enable BN_from_montgomery_word()
* (another non-stable feature from 0.9.9-dev).
*/
#define MONT_FROM_WORD___NON_DEFAULT_0_9_8_BUILD
#endif
#ifdef MONT_FROM_WORD___NON_DEFAULT_0_9_8_BUILD
static int BN_from_montgomery_word(BIGNUM *ret, BIGNUM *r, BN_MONT_CTX *mont);
#endif
int BN_mod_mul_montgomery(BIGNUM *r, const BIGNUM *a, const BIGNUM *b,
BN_MONT_CTX *mont, BN_CTX *ctx)
{
BIGNUM *tmp;
int ret=0;
#if defined(OPENSSL_BN_ASM_MONT) && defined(MONT_WORD)
int num = mont->N.top;
if (num>1 && a->top==num && b->top==num)
{
if (bn_wexpand(r,num) == NULL) return(0);
#if 0 /* for OpenSSL 0.9.9 mont->n0 */
if (bn_mul_mont(r->d,a->d,b->d,mont->N.d,mont->n0,num))
#else
if (bn_mul_mont(r->d,a->d,b->d,mont->N.d,&mont->n0,num))
#endif
{
r->neg = a->neg^b->neg;
r->top = num;
bn_correct_top(r);
return(1);
}
}
#endif
BN_CTX_start(ctx);
tmp = BN_CTX_get(ctx);
if (tmp == NULL) goto err;
bn_check_top(tmp);
if (a == b)
{
if (!BN_sqr(tmp,a,ctx)) goto err;
}
else
{
if (!BN_mul(tmp,a,b,ctx)) goto err;
}
/* reduce from aRR to aR */
#ifdef MONT_FROM_WORD___NON_DEFAULT_0_9_8_BUILD
if (!BN_from_montgomery_word(r,tmp,mont)) goto err;
#else
if (!BN_from_montgomery(r,tmp,mont,ctx)) goto err;
#endif
bn_check_top(r);
ret=1;
err:
BN_CTX_end(ctx);
return(ret);
}
#ifdef MONT_FROM_WORD___NON_DEFAULT_0_9_8_BUILD
static int BN_from_montgomery_word(BIGNUM *ret, BIGNUM *r, BN_MONT_CTX *mont)
{
BIGNUM *n;
BN_ULONG *ap,*np,*rp,n0,v,*nrp;
int al,nl,max,i,x,ri;
n= &(mont->N);
/* mont->ri is the size of mont->N in bits (rounded up
to the word size) */
al=ri=mont->ri/BN_BITS2;
nl=n->top;
if ((al == 0) || (nl == 0)) { ret->top=0; return(1); }
max=(nl+al+1); /* allow for overflow (no?) XXX */
if (bn_wexpand(r,max) == NULL) return(0);
r->neg^=n->neg;
np=n->d;
rp=r->d;
nrp= &(r->d[nl]);
/* clear the top words of T */
for (i=r->top; i<max; i++) /* memset? XXX */
r->d[i]=0;
r->top=max;
#if 0 /* for OpenSSL 0.9.9 mont->n0 */
n0=mont->n0[0];
#else
n0=mont->n0;
#endif
#ifdef BN_COUNT
fprintf(stderr,"word BN_from_montgomery_word %d * %d\n",nl,nl);
#endif
for (i=0; i<nl; i++)
{
#ifdef __TANDEM
{
long long t1;
long long t2;
long long t3;
t1 = rp[0] * (n0 & 0177777);
t2 = 037777600000l;
t2 = n0 & t2;
t3 = rp[0] & 0177777;
t2 = (t3 * t2) & BN_MASK2;
t1 = t1 + t2;
v=bn_mul_add_words(rp,np,nl,(BN_ULONG) t1);
}
#else
v=bn_mul_add_words(rp,np,nl,(rp[0]*n0)&BN_MASK2);
#endif
nrp++;
rp++;
if (((nrp[-1]+=v)&BN_MASK2) >= v)
continue;
else
{
if (((++nrp[0])&BN_MASK2) != 0) continue;
if (((++nrp[1])&BN_MASK2) != 0) continue;
for (x=2; (((++nrp[x])&BN_MASK2) == 0); x++) ;
}
}
bn_correct_top(r);
/* mont->ri will be a multiple of the word size and below code
* is kind of BN_rshift(ret,r,mont->ri) equivalent */
if (r->top <= ri)
{
ret->top=0;
return(1);
}
al=r->top-ri;
if (bn_wexpand(ret,ri) == NULL) return(0);
x=0-(((al-ri)>>(sizeof(al)*8-1))&1);
ret->top=x=(ri&~x)|(al&x); /* min(ri,al) */
ret->neg=r->neg;
rp=ret->d;
ap=&(r->d[ri]);
{
size_t m1,m2;
v=bn_sub_words(rp,ap,np,ri);
/* this ----------------^^ works even in al<ri case
* thanks to zealous zeroing of top of the vector in the
* beginning. */
/* if (al==ri && !v) || al>ri) nrp=rp; else nrp=ap; */
/* in other words if subtraction result is real, then
* trick unconditional memcpy below to perform in-place
* "refresh" instead of actual copy. */
m1=0-(size_t)(((al-ri)>>(sizeof(al)*8-1))&1); /* al<ri */
m2=0-(size_t)(((ri-al)>>(sizeof(al)*8-1))&1); /* al>ri */
m1|=m2; /* (al!=ri) */
m1|=(0-(size_t)v); /* (al!=ri || v) */
m1&=~m2; /* (al!=ri || v) && !al>ri */
nrp=(BN_ULONG *)(((size_t)rp&~m1)|((size_t)ap&m1));
}
/* 'i<ri' is chosen to eliminate dependency on input data, even
* though it results in redundant copy in al<ri case. */
for (i=0,ri-=4; i<ri; i+=4)
{
BN_ULONG t1,t2,t3,t4;
t1=nrp[i+0];
t2=nrp[i+1];
t3=nrp[i+2]; ap[i+0]=0;
t4=nrp[i+3]; ap[i+1]=0;
rp[i+0]=t1; ap[i+2]=0;
rp[i+1]=t2; ap[i+3]=0;
rp[i+2]=t3;
rp[i+3]=t4;
}
for (ri+=4; i<ri; i++)
rp[i]=nrp[i], ap[i]=0;
bn_correct_top(r);
bn_correct_top(ret);
bn_check_top(ret);
return(1);
}
int BN_from_montgomery(BIGNUM *ret, const BIGNUM *a, BN_MONT_CTX *mont,
BN_CTX *ctx)
{
int retn=0;
BIGNUM *t;
BN_CTX_start(ctx);
if ((t = BN_CTX_get(ctx)) && BN_copy(t,a))
retn = BN_from_montgomery_word(ret,t,mont);
BN_CTX_end(ctx);
return retn;
}
#else /* !MONT_FROM_WORD___NON_DEFAULT_0_9_8_BUILD */
int BN_from_montgomery(BIGNUM *ret, const BIGNUM *a, BN_MONT_CTX *mont,
BN_CTX *ctx)
{
int retn=0;
#ifdef MONT_WORD
BIGNUM *n,*r;
BN_ULONG *ap,*np,*rp,n0,v,*nrp;
int al,nl,max,i,x,ri;
BN_CTX_start(ctx);
if ((r = BN_CTX_get(ctx)) == NULL) goto err;
if (!BN_copy(r,a)) goto err;
n= &(mont->N);
ap=a->d;
/* mont->ri is the size of mont->N in bits (rounded up
to the word size) */
al=ri=mont->ri/BN_BITS2;
nl=n->top;
if ((al == 0) || (nl == 0)) { r->top=0; return(1); }
max=(nl+al+1); /* allow for overflow (no?) XXX */
if (bn_wexpand(r,max) == NULL) goto err;
r->neg=a->neg^n->neg;
np=n->d;
rp=r->d;
nrp= &(r->d[nl]);
/* clear the top words of T */
#if 1
for (i=r->top; i<max; i++) /* memset? XXX */
r->d[i]=0;
#else
memset(&(r->d[r->top]),0,(max-r->top)*sizeof(BN_ULONG));
#endif
r->top=max;
n0=mont->n0;
#ifdef BN_COUNT
fprintf(stderr,"word BN_from_montgomery %d * %d\n",nl,nl);
#endif
for (i=0; i<nl; i++)
{
#ifdef __TANDEM
{
long long t1;
long long t2;
long long t3;
t1 = rp[0] * (n0 & 0177777);
t2 = 037777600000l;
t2 = n0 & t2;
t3 = rp[0] & 0177777;
t2 = (t3 * t2) & BN_MASK2;
t1 = t1 + t2;
v=bn_mul_add_words(rp,np,nl,(BN_ULONG) t1);
}
#else
v=bn_mul_add_words(rp,np,nl,(rp[0]*n0)&BN_MASK2);
#endif
nrp++;
rp++;
if (((nrp[-1]+=v)&BN_MASK2) >= v)
continue;
else
{
if (((++nrp[0])&BN_MASK2) != 0) continue;
if (((++nrp[1])&BN_MASK2) != 0) continue;
for (x=2; (((++nrp[x])&BN_MASK2) == 0); x++) ;
}
}
bn_correct_top(r);
/* mont->ri will be a multiple of the word size and below code
* is kind of BN_rshift(ret,r,mont->ri) equivalent */
if (r->top <= ri)
{
ret->top=0;
retn=1;
goto err;
}
al=r->top-ri;
# define BRANCH_FREE 1
# if BRANCH_FREE
if (bn_wexpand(ret,ri) == NULL) goto err;
x=0-(((al-ri)>>(sizeof(al)*8-1))&1);
ret->top=x=(ri&~x)|(al&x); /* min(ri,al) */
ret->neg=r->neg;
rp=ret->d;
ap=&(r->d[ri]);
{
size_t m1,m2;
v=bn_sub_words(rp,ap,np,ri);
/* this ----------------^^ works even in al<ri case
* thanks to zealous zeroing of top of the vector in the
* beginning. */
/* if (al==ri && !v) || al>ri) nrp=rp; else nrp=ap; */
/* in other words if subtraction result is real, then
* trick unconditional memcpy below to perform in-place
* "refresh" instead of actual copy. */
m1=0-(size_t)(((al-ri)>>(sizeof(al)*8-1))&1); /* al<ri */
m2=0-(size_t)(((ri-al)>>(sizeof(al)*8-1))&1); /* al>ri */
m1|=m2; /* (al!=ri) */
m1|=(0-(size_t)v); /* (al!=ri || v) */
m1&=~m2; /* (al!=ri || v) && !al>ri */
nrp=(BN_ULONG *)(((size_t)rp&~m1)|((size_t)ap&m1));
}
/* 'i<ri' is chosen to eliminate dependency on input data, even
* though it results in redundant copy in al<ri case. */
for (i=0,ri-=4; i<ri; i+=4)
{
BN_ULONG t1,t2,t3,t4;
t1=nrp[i+0];
t2=nrp[i+1];
t3=nrp[i+2]; ap[i+0]=0;
t4=nrp[i+3]; ap[i+1]=0;
rp[i+0]=t1; ap[i+2]=0;
rp[i+1]=t2; ap[i+3]=0;
rp[i+2]=t3;
rp[i+3]=t4;
}
for (ri+=4; i<ri; i++)
rp[i]=nrp[i], ap[i]=0;
bn_correct_top(r);
bn_correct_top(ret);
# else
if (bn_wexpand(ret,al) == NULL) goto err;
ret->top=al;
ret->neg=r->neg;
rp=ret->d;
ap=&(r->d[ri]);
al-=4;
for (i=0; i<al; i+=4)
{
BN_ULONG t1,t2,t3,t4;
t1=ap[i+0];
t2=ap[i+1];
t3=ap[i+2];
t4=ap[i+3];
rp[i+0]=t1;
rp[i+1]=t2;
rp[i+2]=t3;
rp[i+3]=t4;
}
al+=4;
for (; i<al; i++)
rp[i]=ap[i];
# endif
#else /* !MONT_WORD */
BIGNUM *t1,*t2;
BN_CTX_start(ctx);
t1 = BN_CTX_get(ctx);
t2 = BN_CTX_get(ctx);
if (t1 == NULL || t2 == NULL) goto err;
if (!BN_copy(t1,a)) goto err;
BN_mask_bits(t1,mont->ri);
if (!BN_mul(t2,t1,&mont->Ni,ctx)) goto err;
BN_mask_bits(t2,mont->ri);
if (!BN_mul(t1,t2,&mont->N,ctx)) goto err;
if (!BN_add(t2,a,t1)) goto err;
if (!BN_rshift(ret,t2,mont->ri)) goto err;
#endif /* MONT_WORD */
#if !defined(BRANCH_FREE) || BRANCH_FREE==0
if (BN_ucmp(ret, &(mont->N)) >= 0)
{
if (!BN_usub(ret,ret,&(mont->N))) goto err;
}
#endif
retn=1;
bn_check_top(ret);
err:
BN_CTX_end(ctx);
return(retn);
}
#endif /* MONT_FROM_WORD___NON_DEFAULT_0_9_8_BUILD */
BN_MONT_CTX *BN_MONT_CTX_new(void)
{
BN_MONT_CTX *ret;
if ((ret=(BN_MONT_CTX *)OPENSSL_malloc(sizeof(BN_MONT_CTX))) == NULL)
return(NULL);
BN_MONT_CTX_init(ret);
ret->flags=BN_FLG_MALLOCED;
return(ret);
}
void BN_MONT_CTX_init(BN_MONT_CTX *ctx)
{
ctx->ri=0;
BN_init(&(ctx->RR));
BN_init(&(ctx->N));
BN_init(&(ctx->Ni));
#if 0 /* for OpenSSL 0.9.9 mont->n0 */
ctx->n0[0] = ctx->n0[1] = 0;
#else
ctx->n0 = 0;
#endif
ctx->flags=0;
}
void BN_MONT_CTX_free(BN_MONT_CTX *mont)
{
if(mont == NULL)
return;
BN_free(&(mont->RR));
BN_free(&(mont->N));
BN_free(&(mont->Ni));
if (mont->flags & BN_FLG_MALLOCED)
OPENSSL_free(mont);
}
int BN_MONT_CTX_set(BN_MONT_CTX *mont, const BIGNUM *mod, BN_CTX *ctx)
{
int ret = 0;
BIGNUM *Ri,*R;
BN_CTX_start(ctx);
if((Ri = BN_CTX_get(ctx)) == NULL) goto err;
R= &(mont->RR); /* grab RR as a temp */
if (!BN_copy(&(mont->N),mod)) goto err; /* Set N */
mont->N.neg = 0;
#ifdef MONT_WORD
{
BIGNUM tmod;
BN_ULONG buf[2];
mont->ri=(BN_num_bits(mod)+(BN_BITS2-1))/BN_BITS2*BN_BITS2;
BN_zero(R);
#if 0 /* for OpenSSL 0.9.9 mont->n0, would be "#if defined(OPENSSL_BN_ASM_MONT) && (BN_BITS2<=32)",
only certain BN_BITS2<=32 platforms actually need this */
if (!(BN_set_bit(R,2*BN_BITS2))) goto err; /* R */
#else
if (!(BN_set_bit(R,BN_BITS2))) goto err; /* R */
#endif
buf[0]=mod->d[0]; /* tmod = N mod word size */
buf[1]=0;
BN_init(&tmod);
tmod.d=buf;
tmod.top = buf[0] != 0 ? 1 : 0;
tmod.dmax=2;
tmod.neg=0;
#if 0 /* for OpenSSL 0.9.9 mont->n0, would be "#if defined(OPENSSL_BN_ASM_MONT) && (BN_BITS2<=32)";
only certain BN_BITS2<=32 platforms actually need this */
tmod.top=0;
if ((buf[0] = mod->d[0])) tmod.top=1;
if ((buf[1] = mod->top>1 ? mod->d[1] : 0)) tmod.top=2;
if ((BN_mod_inverse(Ri,R,&tmod,ctx)) == NULL)
goto err;
if (!BN_lshift(Ri,Ri,2*BN_BITS2)) goto err; /* R*Ri */
if (!BN_is_zero(Ri))
{
if (!BN_sub_word(Ri,1)) goto err;
}
else /* if N mod word size == 1 */
{
if (bn_expand(Ri,(int)sizeof(BN_ULONG)*2) == NULL)
goto err;
/* Ri-- (mod double word size) */
Ri->neg=0;
Ri->d[0]=BN_MASK2;
Ri->d[1]=BN_MASK2;
Ri->top=2;
}
if (!BN_div(Ri,NULL,Ri,&tmod,ctx)) goto err;
/* Ni = (R*Ri-1)/N,
* keep only couple of least significant words: */
mont->n0[0] = (Ri->top > 0) ? Ri->d[0] : 0;
mont->n0[1] = (Ri->top > 1) ? Ri->d[1] : 0;
#else
/* Ri = R^-1 mod N*/
if ((BN_mod_inverse(Ri,R,&tmod,ctx)) == NULL)
goto err;
if (!BN_lshift(Ri,Ri,BN_BITS2)) goto err; /* R*Ri */
if (!BN_is_zero(Ri))
{
if (!BN_sub_word(Ri,1)) goto err;
}
else /* if N mod word size == 1 */
{
if (!BN_set_word(Ri,BN_MASK2)) goto err; /* Ri-- (mod word size) */
}
if (!BN_div(Ri,NULL,Ri,&tmod,ctx)) goto err;
/* Ni = (R*Ri-1)/N,
* keep only least significant word: */
# if 0 /* for OpenSSL 0.9.9 mont->n0 */
mont->n0[0] = (Ri->top > 0) ? Ri->d[0] : 0;
mont->n0[1] = 0;
# else
mont->n0 = (Ri->top > 0) ? Ri->d[0] : 0;
# endif
#endif
}
#else /* !MONT_WORD */
{ /* bignum version */
mont->ri=BN_num_bits(&mont->N);
BN_zero(R);
if (!BN_set_bit(R,mont->ri)) goto err; /* R = 2^ri */
/* Ri = R^-1 mod N*/
if ((BN_mod_inverse(Ri,R,&mont->N,ctx)) == NULL)
goto err;
if (!BN_lshift(Ri,Ri,mont->ri)) goto err; /* R*Ri */
if (!BN_sub_word(Ri,1)) goto err;
/* Ni = (R*Ri-1) / N */
if (!BN_div(&(mont->Ni),NULL,Ri,&mont->N,ctx)) goto err;
}
#endif
/* setup RR for conversions */
BN_zero(&(mont->RR));
if (!BN_set_bit(&(mont->RR),mont->ri*2)) goto err;
if (!BN_mod(&(mont->RR),&(mont->RR),&(mont->N),ctx)) goto err;
ret = 1;
err:
BN_CTX_end(ctx);
return ret;
}
BN_MONT_CTX *BN_MONT_CTX_copy(BN_MONT_CTX *to, BN_MONT_CTX *from)
{
if (to == from) return(to);
if (!BN_copy(&(to->RR),&(from->RR))) return NULL;
if (!BN_copy(&(to->N),&(from->N))) return NULL;
if (!BN_copy(&(to->Ni),&(from->Ni))) return NULL;
to->ri=from->ri;
#if 0 /* for OpenSSL 0.9.9 mont->n0 */
to->n0[0]=from->n0[0];
to->n0[1]=from->n0[1];
#else
to->n0=from->n0;
#endif
return(to);
}
BN_MONT_CTX *BN_MONT_CTX_set_locked(BN_MONT_CTX **pmont, int lock,
const BIGNUM *mod, BN_CTX *ctx)
{
BN_MONT_CTX *ret;
CRYPTO_r_lock(lock);
ret = *pmont;
CRYPTO_r_unlock(lock);
if (ret)
return ret;
/* We don't want to serialise globally while doing our lazy-init math in
* BN_MONT_CTX_set. That punishes threads that are doing independent
* things. Instead, punish the case where more than one thread tries to
* lazy-init the same 'pmont', by having each do the lazy-init math work
* independently and only use the one from the thread that wins the race
* (the losers throw away the work they've done). */
ret = BN_MONT_CTX_new();
if (!ret)
return NULL;
if (!BN_MONT_CTX_set(ret, mod, ctx))
{
BN_MONT_CTX_free(ret);
return NULL;
}
/* The locked compare-and-set, after the local work is done. */
CRYPTO_w_lock(lock);
if (*pmont)
{
BN_MONT_CTX_free(ret);
ret = *pmont;
}
else
*pmont = ret;
CRYPTO_w_unlock(lock);
return ret;
}
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