#include "cryptlib.h"
#include "bn_lcl.h"
-#ifdef OPENSSL_FIPS
-#include <openssl/fips.h>
-#endif
-
#define MONT_WORD /* use the faster word-based algorithm */
#ifdef MONT_WORD
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;
#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
{
#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;
+ BN_ULONG *nrp;
+ size_t m;
- 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
+ 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 *)(((size_t)rp&~m1)|((size_t)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;
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);
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