Import of old SSLeay release: SSLeay 0.9.0b

[thirdparty/openssl.git] / crypto / bn / bn_mont.c

diff --git a/crypto/bn/bn_mont.c b/crypto/bn/bn_mont.c
index 932d10b73615ecc01a4b3dfdf8ba0ca1c14c72ed..e435df61f86130f3cfe4b527b91f893c1c33639f 100644 (file)
--- a/crypto/bn/bn_mont.c
+++ b/crypto/bn/bn_mont.c
@@ -1,5 +1,5 @@
 /* crypto/bn/bn_mont.c */
-/* Copyright (C) 1995-1997 Eric Young (eay@cryptsoft.com)
+/* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
  * All rights reserved.
  *
  * This package is an SSL implementation written
@@ -95,8 +95,8 @@ BN_MONT_CTX *mont;
 BN_CTX *ctx;
        {
        BIGNUM *n,*t1,*r;
-       BN_ULONG *ap,*np,*rp,k,n0,v,v2;
-       int al,nl,max,i,x;
+       BN_ULONG *ap,*np,*rp,n0,v;
+       int al,nl,max,i,x,ri;
        int retn=0;
 
        t1=ctx->bn[ctx->tos];
@@ -105,50 +105,76 @@ BN_CTX *ctx;
        if (!BN_copy(r,a)) goto err;
        n=mont->N;
 
-       if (!BN_copy(t1,a)) goto err;
-       BN_mask_bits(t1,mont->ri);
-
-       a=t1;
+       ap=a->d;
+       /* mont->ri is the size of mont->N in bits/words */
+       al=ri=mont->ri/BN_BITS2;
 
-       al=a->top;
        nl=n->top;
        if ((al == 0) || (nl == 0)) { r->top=0; return(1); }
 
        max=(nl+al+1); /* allow for overflow (no?) XXX */
-       if (bn_expand(r,(max)*BN_BITS2) == NULL) goto err;
+       if (bn_wexpand(r,max) == NULL) goto err;
+       if (bn_wexpand(ret,max) == NULL) goto err;
 
        r->neg=a->neg^n->neg;
-       ap=a->d;
        np=n->d;
        rp=r->d;
 
-       /* clear the top bytes of T */
+       /* clear the top words of T */
+#if 1
        for (i=r->top; i<max; i++) /* memset? XXX */
                r->d[i]=0;
-/*     memset(&(r->d[r->top]),0,(max-r->top)*sizeof(BN_ULONG)); */
+#else
+       memset(&(r->d[r->top]),0,(max-r->top)*sizeof(BN_ULONG)); 
+#endif
 
        r->top=max;
        n0=mont->n0;
 
        for (i=0; i<nl; i++)
                {
-               /* This is were part words probably goes wrong */
-               k=(rp[0]*n0)&BN_MASK2;
-               v=bn_mul_add_word(rp,np,nl,k);
-               
-               for (x=nl; v; x++)
+#if 0
+               int x1,x2;
+
+               if (i+4 > nl)
+                       {
+                       x2=nl;
+                       x1=0;
+                       }
+               else
                        {
-                       v2=rp[x];
-                       v2+=v;
-                       rp[x]=v2;
-                       v=((v2&BN_MASK2) < v)?1:0; /* ever true? XXX */
+                       x2=i+4;
+                       x1=nl-x2;
+                       }
+               v=bn_mul_add_words(&(rp[x1]),&(np[x1]),x2,(rp[x1]*n0)&BN_MASK2);
+#else
+               v=bn_mul_add_words(rp,np,nl,(rp[0]*n0)&BN_MASK2);
+#endif
+
+               if (((rp[nl]+=v)&BN_MASK2) < v)
+                       {
+                       for (x=(nl+1); (((++rp[x])&BN_MASK2) == 0); x++)
+                               ;
                        }
                rp++;
                }
        while (r->d[r->top-1] == 0)
                r->top--;
 
+       /* mont->ri will be a multiple of the word size */
+#if 0
        BN_rshift(ret,r,mont->ri);
+#else
+       ap=r->d;
+       rp=ret->d;
+       x=ri;
+       al=r->top-x;
+       for (i=0; i<al; i++)
+               {
+               rp[i]=ap[i+x];
+               }
+       ret->top=al;
+#endif
 
        if (BN_ucmp(ret,mont->N) >= 0)
                {