Some provisional bignum debugging has begun to detect inconsistent BIGNUM

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

diff --git a/crypto/bn/bn_recp.c b/crypto/bn/bn_recp.c
index 80539c5e2c570d9ab19555864312e0201999ce39..22cbcfc49b7885f5f1a0647c2281b71ccc23a0a6 100644 (file)
--- a/crypto/bn/bn_recp.c
+++ b/crypto/bn/bn_recp.c
@@ -72,7 +72,7 @@ BN_RECP_CTX *BN_RECP_CTX_new(void)
        {
        BN_RECP_CTX *ret;
 
-       if ((ret=(BN_RECP_CTX *)Malloc(sizeof(BN_RECP_CTX))) == NULL)
+       if ((ret=(BN_RECP_CTX *)OPENSSL_malloc(sizeof(BN_RECP_CTX))) == NULL)
                return(NULL);
 
        BN_RECP_CTX_init(ret);
@@ -88,23 +88,24 @@ void BN_RECP_CTX_free(BN_RECP_CTX *recp)
        BN_free(&(recp->N));
        BN_free(&(recp->Nr));
        if (recp->flags & BN_FLG_MALLOCED)
-               Free(recp);
+               OPENSSL_free(recp);
        }
 
 int BN_RECP_CTX_set(BN_RECP_CTX *recp, const BIGNUM *d, BN_CTX *ctx)
        {
-       BN_copy(&(recp->N),d);
-       BN_zero(&(recp->Nr));
+       if (!BN_copy(&(recp->N),d)) return 0;
+       if (!BN_zero(&(recp->Nr))) return 0;
        recp->num_bits=BN_num_bits(d);
        recp->shift=0;
        return(1);
        }
 
-int BN_mod_mul_reciprocal(BIGNUM *r, BIGNUM *x, BIGNUM *y, BN_RECP_CTX *recp,
-            BN_CTX *ctx)
+int BN_mod_mul_reciprocal(BIGNUM *r, const BIGNUM *x, const BIGNUM *y,
+       BN_RECP_CTX *recp, BN_CTX *ctx)
        {
        int ret=0;
        BIGNUM *a;
+       const BIGNUM *ca;
 
        BN_CTX_start(ctx);
        if ((a = BN_CTX_get(ctx)) == NULL) goto err;
@@ -114,21 +115,21 @@ int BN_mod_mul_reciprocal(BIGNUM *r, BIGNUM *x, BIGNUM *y, BN_RECP_CTX *recp,
                        { if (!BN_sqr(a,x,ctx)) goto err; }
                else
                        { if (!BN_mul(a,x,y,ctx)) goto err; }
+               ca = a;
                }
        else
-               a=x; /* Just do the mod */
+               ca=x; /* Just do the mod */
 
-       BN_div_recp(NULL,r,a,recp,ctx);
-       ret=1;
+       ret = BN_div_recp(NULL,r,ca,recp,ctx);
 err:
        BN_CTX_end(ctx);
        return(ret);
        }
 
-int BN_div_recp(BIGNUM *dv, BIGNUM *rem, BIGNUM *m, BN_RECP_CTX *recp,
-            BN_CTX *ctx)
+int BN_div_recp(BIGNUM *dv, BIGNUM *rem, const BIGNUM *m,
+       BN_RECP_CTX *recp, BN_CTX *ctx)
        {
-       int i,j,ret=0,ex;
+       int i,j,ret=0;
        BIGNUM *a,*b,*d,*r;
 
        BN_CTX_start(ctx);
@@ -146,8 +147,8 @@ int BN_div_recp(BIGNUM *dv, BIGNUM *rem, BIGNUM *m, BN_RECP_CTX *recp,
 
        if (BN_ucmp(m,&(recp->N)) < 0)
                {
-               BN_zero(d);
-               BN_copy(r,m);
+               if (!BN_zero(d)) return 0;
+               if (!BN_copy(r,m)) return 0;
                BN_CTX_end(ctx);
                return(1);
                }
@@ -157,36 +158,34 @@ int BN_div_recp(BIGNUM *dv, BIGNUM *rem, BIGNUM *m, BN_RECP_CTX *recp,
         * we need multiply ABCDEF by 3 digests of the reciprocal of ab
         *
         */
-       i=BN_num_bits(m);
-       if (i%2) i--;
-
-       j=recp->num_bits*2;
-       if (j > i)
-               {
-               i=j;
-               ex=0;
-               }
-       else
-               {
-               ex=(i-j)/2;
-               }
 
-       j=i/2;
+       /* i := max(BN_num_bits(m), 2*BN_num_bits(N)) */
+       i=BN_num_bits(m);
+       j=recp->num_bits<<1;
+       if (j>i) i=j;
 
+       /* Nr := round(2^i / N) */
        if (i != recp->shift)
                recp->shift=BN_reciprocal(&(recp->Nr),&(recp->N),
-                       i,ctx);
+                       i,ctx); /* BN_reciprocal returns i, or -1 for an error */
+       if (recp->shift == -1) goto err;
 
-       if (!BN_rshift(a,m,j-ex)) goto err;
+       /* d := |round(round(m / 2^BN_num_bits(N)) * recp->Nr / 2^(i - BN_num_bits(N)))|
+        *    = |round(round(m / 2^BN_num_bits(N)) * round(2^i / N) / 2^(i - BN_num_bits(N)))|
+        *   <= |(m / 2^BN_num_bits(N)) * (2^i / N) * (2^BN_num_bits(N) / 2^i)|
+        *    = |m/N|
+        */
+       if (!BN_rshift(a,m,recp->num_bits)) 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-recp->num_bits)) 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)
@@ -204,6 +203,8 @@ int BN_div_recp(BIGNUM *dv, BIGNUM *rem, BIGNUM *m, BN_RECP_CTX *recp,
        ret=1;
 err:
        BN_CTX_end(ctx);
+       if(dv) bn_fix_top(dv);
+       if(rem) bn_fix_top(rem);
        return(ret);
        } 
 
@@ -211,20 +212,21 @@ err:
  * We actually calculate with an extra word of precision, so
  * we can do faster division if the remainder is not required.
  */
-int BN_reciprocal(BIGNUM *r, BIGNUM *m, int len, BN_CTX *ctx)
+/* r := 2^len / m */
+int BN_reciprocal(BIGNUM *r, const BIGNUM *m, int len, BN_CTX *ctx)
        {
        int ret= -1;
        BIGNUM t;
 
        BN_init(&t);
 
-       BN_zero(&t);
+       if (!BN_zero(&t)) goto err;
        if (!BN_set_bit(&t,len)) goto err;
 
        if (!BN_div(r,NULL,&t,m,ctx)) goto err;
+
        ret=len;
 err:
        BN_free(&t);
        return(ret);
        }
-