Use MONT_WORD macro to control if the word-based or the bignum
algorithm is used.
diff --git a/crypto/bn/bn.h b/crypto/bn/bn.h
index 8ac8acd..472eb2c 100644
--- a/crypto/bn/bn.h
+++ b/crypto/bn/bn.h
@@ -260,7 +260,6 @@
/* Used for montgomery multiplication */
typedef struct bn_mont_ctx_st
{
- int use_word; /* 0 for word form, 1 for bignum form */
int ri; /* number of bits in R */
BIGNUM RR; /* used to convert to montgomery form */
BIGNUM N; /* The modulus */
diff --git a/crypto/bn/bn_mont.c b/crypto/bn/bn_mont.c
index 35a30a0..7bb0b91 100644
--- a/crypto/bn/bn_mont.c
+++ b/crypto/bn/bn_mont.c
@@ -67,6 +67,8 @@
#include "cryptlib.h"
#include "bn_lcl.h"
+#define MONT_WORD /* use the faster word-based algorithm */
+
int BN_mod_mul_montgomery(BIGNUM *r, BIGNUM *a, BIGNUM *b,
BN_MONT_CTX *mont, BN_CTX *ctx)
{
@@ -105,135 +107,123 @@
return(0);
}
-#define BN_RECURSION_MONT
-
int BN_from_montgomery(BIGNUM *ret, 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;
-#ifdef BN_RECURSION_MONT
- if (mont->use_word)
-#endif
- {
- BIGNUM *n,*r;
- BN_ULONG *ap,*np,*rp,n0,v,*nrp;
- int al,nl,max,i,x,ri;
+ if (!BN_copy(r,a)) goto err;
+ n= &(mont->N);
- if ((r = BN_CTX_get(ctx)) == NULL) goto err;
+ 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); }
- if (!BN_copy(r,a)) goto err;
- n= &(mont->N);
+ max=(nl+al+1); /* allow for overflow (no?) XXX */
+ if (bn_wexpand(r,max) == NULL) goto err;
+ if (bn_wexpand(ret,max) == NULL) goto err;
- 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;
+ r->neg=a->neg^n->neg;
+ np=n->d;
+ rp=r->d;
+ nrp= &(r->d[nl]);
- 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;
- if (bn_wexpand(ret,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 */
+ /* clear the top words of T */
#if 1
- for (i=r->top; i<max; i++) /* memset? XXX */
- r->d[i]=0;
+ 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));
+ memset(&(r->d[r->top]),0,(max-r->top)*sizeof(BN_ULONG));
#endif
- r->top=max;
- n0=mont->n0;
+ r->top=max;
+ n0=mont->n0;
#ifdef BN_COUNT
-printf("word BN_from_montgomery %d * %d\n",nl,nl);
+ printf("word BN_from_montgomery %d * %d\n",nl,nl);
#endif
- for (i=0; i<nl; i++)
- {
- v=bn_mul_add_words(rp,np,nl,(rp[0]*n0)&BN_MASK2);
- 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_fix_top(r);
-
- /* mont->ri will be a multiple of the word size */
-#if 0
- BN_rshift(ret,r,mont->ri);
-#else
- x=ri;
- rp=ret->d;
- ap= &(r->d[x]);
- if (r->top < x)
- al=0;
- else
- al=r->top-x;
- ret->top=al;
- 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
-
- if (BN_ucmp(ret, &(mont->N)) >= 0)
- {
- BN_usub(ret,ret,&(mont->N)); /* XXX */
- }
- retn=1;
- }
-#ifdef BN_RECURSION_MONT
- else /* bignum version */
+ for (i=0; i<nl; i++)
{
- BIGNUM *t1,*t2;
-
- 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;
- BN_rshift(ret,t2,mont->ri);
-
- if (BN_ucmp(ret,&mont->N) >= 0)
- BN_usub(ret,ret,&mont->N);
- retn=1;
+ v=bn_mul_add_words(rp,np,nl,(rp[0]*n0)&BN_MASK2);
+ 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_fix_top(r);
+
+ /* mont->ri will be a multiple of the word size */
+#if 0
+ BN_rshift(ret,r,mont->ri);
+#else
+ x=ri;
+ rp=ret->d;
+ ap= &(r->d[x]);
+ if (r->top < x)
+ al=0;
+ else
+ al=r->top-x;
+ ret->top=al;
+ 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;
+ BN_rshift(ret,t2,mont->ri);
+#endif /* MONT_WORD */
+
+ if (BN_ucmp(ret, &(mont->N)) >= 0)
+ {
+ BN_usub(ret,ret,&(mont->N));
+ }
+ retn=1;
err:
BN_CTX_end(ctx);
return(retn);
@@ -253,7 +243,6 @@
void BN_MONT_CTX_init(BN_MONT_CTX *ctx)
{
- ctx->use_word=0;
ctx->ri=0;
BN_init(&(ctx->RR));
BN_init(&(ctx->N));
@@ -281,16 +270,11 @@
R= &(mont->RR); /* grab RR as a temp */
BN_copy(&(mont->N),mod); /* Set N */
-#ifdef BN_RECURSION_MONT
- /* the word-based algorithm is faster */
- if (mont->N.top > BN_MONT_CTX_SET_SIZE_WORD)
-#endif
+#ifdef MONT_WORD
{
BIGNUM tmod;
BN_ULONG buf[2];
- mont->use_word=1;
-
mont->ri=(BN_num_bits(mod)+(BN_BITS2-1))/BN_BITS2*BN_BITS2;
BN_zero(R);
BN_set_bit(R,BN_BITS2); /* R */
@@ -314,10 +298,8 @@
mont->n0=Ri.d[0];
BN_free(&Ri);
}
-#ifdef BN_RECURSION_MONT
- else
+#else /* !MONT_WORD */
{ /* bignum version */
- mont->use_word=0;
mont->ri=BN_num_bits(mod);
BN_zero(R);
BN_set_bit(R,mont->ri); /* R = 2^ri */
@@ -349,7 +331,6 @@
BN_copy(&(to->RR),&(from->RR));
BN_copy(&(to->N),&(from->N));
BN_copy(&(to->Ni),&(from->Ni));
- to->use_word=from->use_word;
to->ri=from->ri;
to->n0=from->n0;
return(to);
diff --git a/doc/crypto/BN_mod_mul_montgomery.pod b/doc/crypto/BN_mod_mul_montgomery.pod
index f237f72..0f0c137 100644
--- a/doc/crypto/BN_mod_mul_montgomery.pod
+++ b/doc/crypto/BN_mod_mul_montgomery.pod
@@ -58,7 +58,6 @@
typedef struct bn_mont_ctx_st
{
- int use_word; /* 0 for word form, 1 for bignum form */
int ri; /* number of bits in R */
BIGNUM RR; /* R^2 (used to convert to Montgomery form) */
BIGNUM N; /* The modulus */
