BN_div_recp fix. I've ran divtest for 10 mins and it didn't exhibit a

[openssl.git] / crypto / bn / bn_recp.c

diff --git a/crypto/bn/bn_recp.c b/crypto/bn/bn_recp.c
index 85b4ac814882b0586048b8c51f7d1fd2d7144a17..a6d7900a3cc9710b2c4d53c3bd42e580846856c5 100644 (file)
--- a/crypto/bn/bn_recp.c
+++ b/crypto/bn/bn_recp.c
@@ -91,7 +91,7 @@ void BN_RECP_CTX_free(BN_RECP_CTX *recp)
                Free(recp);
        }
 
-int BN_RECP_CTX_set(BN_RECP_CTX *recp, BIGNUM *d, BN_CTX *ctx)
+int BN_RECP_CTX_set(BN_RECP_CTX *recp, const BIGNUM *d, BN_CTX *ctx)
        {
        BN_copy(&(recp->N),d);
        BN_zero(&(recp->Nr));
@@ -106,7 +106,8 @@ int BN_mod_mul_reciprocal(BIGNUM *r, BIGNUM *x, BIGNUM *y, BN_RECP_CTX *recp,
        int ret=0;
        BIGNUM *a;
 
-       a= &(ctx->bn[ctx->tos++]);
+       BN_CTX_start(ctx);
+       if ((a = BN_CTX_get(ctx)) == NULL) goto err;
        if (y != NULL)
                {
                if (x == y)
@@ -120,33 +121,34 @@ int BN_mod_mul_reciprocal(BIGNUM *r, BIGNUM *x, BIGNUM *y, BN_RECP_CTX *recp,
        BN_div_recp(NULL,r,a,recp,ctx);
        ret=1;
 err:
-       ctx->tos--;
+       BN_CTX_end(ctx);
        return(ret);
        }
 
 int BN_div_recp(BIGNUM *dv, BIGNUM *rem, BIGNUM *m, BN_RECP_CTX *recp,
             BN_CTX *ctx)
        {
-       int i,j,tos,ret=0,ex;
+       int i,j,ret=0;
        BIGNUM *a,*b,*d,*r;
 
-       tos=ctx->tos;
-       a= &(ctx->bn[ctx->tos++]);
-       b= &(ctx->bn[ctx->tos++]);
+       BN_CTX_start(ctx);
+       a=BN_CTX_get(ctx);
+       b=BN_CTX_get(ctx);
        if (dv != NULL)
                d=dv;
        else
-               d= &(ctx->bn[ctx->tos++]);
+               d=BN_CTX_get(ctx);
        if (rem != NULL)
                r=rem;
        else
-               r= &(ctx->bn[ctx->tos++]);
+               r=BN_CTX_get(ctx);
+       if (a == NULL || b == NULL || d == NULL || r == NULL) goto err;
 
        if (BN_ucmp(m,&(recp->N)) < 0)
                {
                BN_zero(d);
                BN_copy(r,m);
-               ctx->tos=tos;
+               BN_CTX_end(ctx);
                return(1);
                }
 
@@ -157,38 +159,38 @@ int BN_div_recp(BIGNUM *dv, BIGNUM *rem, BIGNUM *m, BN_RECP_CTX *recp,
         */
        i=BN_num_bits(m);
 
-       j=recp->num_bits*2;
-       if (j > i)
-               {
-               i=j;
-               ex=0;
-               }
-       else
-               {
-               ex=(i-j)/2;
-               }
-
-       j=i/2;
+       j=recp->num_bits<<1;
+       if (j>i) i=j;
+       j>>=1;
 
        if (i != recp->shift)
                recp->shift=BN_reciprocal(&(recp->Nr),&(recp->N),
                        i,ctx);
 
-       if (!BN_rshift(a,m,j-ex)) goto err;
+       if (!BN_rshift(a,m,j)) goto err;
        if (!BN_mul(b,a,&(recp->Nr),ctx)) goto err;
-       if (!BN_rshift(d,b,j+ex)) goto err;
+       if (!BN_rshift(d,b,i-j)) goto err;
        d->neg=0;
        if (!BN_mul(b,&(recp->N),d,ctx)) goto err;
        if (!BN_usub(r,m,b)) goto err;
        r->neg=0;
 
-       j=0;
 #if 1
+       j=0;
        while (BN_ucmp(r,&(recp->N)) >= 0)
                {
                if (j++ > 2)
                        {
+#if 0
+                       /* work around some bug:
+                          -1CC0E177F93042B29D309839F8019DB93404D7A395F1E162
+                          5383BF622A20B17E1BAA999336988B82B93F5FB77B55B4B68
+                          9412000000000031 / 298EB5957DBFB8CBB2CC2A9F789D2B5
+                          fails, for example. */
+                       ret=BN_div(dv,rem,m,&(recp->N),ctx);
+#else
                        BNerr(BN_F_BN_MOD_MUL_RECIPROCAL,BN_R_BAD_RECIPROCAL);
+#endif
                        goto err;
                        }
                if (!BN_usub(r,r,&(recp->N))) goto err;
@@ -200,7 +202,7 @@ int BN_div_recp(BIGNUM *dv, BIGNUM *rem, BIGNUM *m, BN_RECP_CTX *recp,
        d->neg=m->neg^recp->N.neg;
        ret=1;
 err:
-       ctx->tos=tos;
+       BN_CTX_end(ctx);
        return(ret);
        }