ECC library bugfixes.

[openssl.git] / crypto / ec / ec2_mult.c

diff --git a/crypto/ec/ec2_mult.c b/crypto/ec/ec2_mult.c
index a8ead01d610d1d0fb717f8cbdac9b44d9269206a..e12b9b284a00298cec51623ec81193c2e86499b9 100644 (file)
--- a/crypto/ec/ec2_mult.c
+++ b/crypto/ec/ec2_mult.c
@@ -76,7 +76,7 @@
  * coordinates.
  * Uses algorithm Mdouble in appendix of 
  *     Lopez, J. and Dahab, R.  "Fast multiplication on elliptic curves over 
- *     GF(2^m) without precomputation".
+ *     GF(2^m) without precomputation" (CHES '99, LNCS 1717).
  * modified to not require precomputation of c=b^{2^{m-1}}.
  */
 static int gf2m_Mdouble(const EC_GROUP *group, BIGNUM *x, BIGNUM *z, BN_CTX *ctx)
@@ -107,8 +107,8 @@ static int gf2m_Mdouble(const EC_GROUP *group, BIGNUM *x, BIGNUM *z, BN_CTX *ctx
 /* Compute the x-coordinate x1/z1 for the point (x1/z1)+(x2/x2) in Montgomery 
  * projective coordinates.
  * Uses algorithm Madd in appendix of 
- *     Lopex, J. and Dahab, R.  "Fast multiplication on elliptic curves over 
- *     GF(2^m) without precomputation".
+ *     Lopez, J. and Dahab, R.  "Fast multiplication on elliptic curves over 
+ *     GF(2^m) without precomputation" (CHES '99, LNCS 1717).
  */
 static int gf2m_Madd(const EC_GROUP *group, const BIGNUM *x, BIGNUM *x1, BIGNUM *z1, 
        const BIGNUM *x2, const BIGNUM *z2, BN_CTX *ctx)
@@ -140,8 +140,8 @@ static int gf2m_Madd(const EC_GROUP *group, const BIGNUM *x, BIGNUM *x1, BIGNUM
 
 /* Compute the x, y affine coordinates from the point (x1, z1) (x2, z2) 
  * using Montgomery point multiplication algorithm Mxy() in appendix of 
- *     Lopex, J. and Dahab, R.  "Fast multiplication on elliptic curves over 
- *     GF(2^m) without precomputation".
+ *     Lopez, J. and Dahab, R.  "Fast multiplication on elliptic curves over 
+ *     GF(2^m) without precomputation" (CHES '99, LNCS 1717).
  * Returns:
  *     0 on error
  *     1 if return value should be the point at infinity
@@ -209,19 +209,19 @@ static int gf2m_Mxy(const EC_GROUP *group, const BIGNUM *x, const BIGNUM *y, BIG
 /* Computes scalar*point and stores the result in r.
  * point can not equal r.
  * Uses algorithm 2P of
- *     Lopex, J. and Dahab, R.  "Fast multiplication on elliptic curves over 
- *     GF(2^m) without precomputation".
+ *     Lopez, J. and Dahab, R.  "Fast multiplication on elliptic curves over 
+ *     GF(2^m) without precomputation" (CHES '99, LNCS 1717).
  */
 static int ec_GF2m_montgomery_point_multiply(const EC_GROUP *group, EC_POINT *r, const BIGNUM *scalar,
        const EC_POINT *point, BN_CTX *ctx)
        {
        BIGNUM *x1, *x2, *z1, *z2;
-       int ret = 0, i, j;
-       BN_ULONG mask;
+       int ret = 0, i;
+       BN_ULONG mask,word;
 
        if (r == point)
                {
-               ECerr(EC_F_EC_POINT_MUL, EC_R_INVALID_ARGUMENT);
+               ECerr(EC_F_EC_GF2M_MONTGOMERY_POINT_MULTIPLY, EC_R_INVALID_ARGUMENT);
                return 0;
                }
        
@@ -251,22 +251,24 @@ static int ec_GF2m_montgomery_point_multiply(const EC_GROUP *group, EC_POINT *r,
        if (!BN_GF2m_add(x2, x2, &group->b)) goto err; /* x2 = x^4 + b */
 
        /* find top most bit and go one past it */
-       i = scalar->top - 1; j = BN_BITS2 - 1;
+       i = scalar->top - 1;
        mask = BN_TBIT;
-       while (!(scalar->d[i] & mask)) { mask >>= 1; j--; }
-       mask >>= 1; j--;
+       word = scalar->d[i];
+       while (!(word & mask)) mask >>= 1;
+       mask >>= 1;
        /* if top most bit was at word break, go to next word */
        if (!mask) 
                {
-               i--; j = BN_BITS2 - 1;
+               i--;
                mask = BN_TBIT;
                }
 
        for (; i >= 0; i--)
                {
-               for (; j >= 0; j--)
+               word = scalar->d[i];
+               while (mask)
                        {
-                       if (scalar->d[i] & mask)
+                       if (word & mask)
                                {
                                if (!gf2m_Madd(group, &point->X, x1, z1, x2, z2, ctx)) goto err;
                                if (!gf2m_Mdouble(group, x2, z2, ctx)) goto err;
@@ -278,7 +280,6 @@ static int ec_GF2m_montgomery_point_multiply(const EC_GROUP *group, EC_POINT *r,
                                }
                        mask >>= 1;
                        }
-               j = BN_BITS2 - 1;
                mask = BN_TBIT;
                }
 
@@ -296,8 +297,8 @@ static int ec_GF2m_montgomery_point_multiply(const EC_GROUP *group, EC_POINT *r,
                }
 
        /* GF(2^m) field elements should always have BIGNUM::neg = 0 */
-       BN_set_sign(&r->X, 0);
-       BN_set_sign(&r->Y, 0);
+       BN_set_negative(&r->X, 0);
+       BN_set_negative(&r->Y, 0);
 
        ret = 1;
 
@@ -318,6 +319,7 @@ int ec_GF2m_simple_mul(const EC_GROUP *group, EC_POINT *r, const BIGNUM *scalar,
        int ret = 0;
        size_t i;
        EC_POINT *p=NULL;
+       EC_POINT *acc = NULL;
 
        if (ctx == NULL)
                {
@@ -337,29 +339,33 @@ int ec_GF2m_simple_mul(const EC_GROUP *group, EC_POINT *r, const BIGNUM *scalar,
                }
 
        if ((p = EC_POINT_new(group)) == NULL) goto err;
+       if ((acc = EC_POINT_new(group)) == NULL) goto err;
 
-       if (!EC_POINT_set_to_infinity(group, r)) goto err;
+       if (!EC_POINT_set_to_infinity(group, acc)) goto err;
 
        if (scalar)
                {
                if (!ec_GF2m_montgomery_point_multiply(group, p, scalar, group->generator, ctx)) goto err;
-               if (BN_get_sign(scalar)) 
+               if (BN_is_negative(scalar))
                        if (!group->meth->invert(group, p, ctx)) goto err;
-               if (!group->meth->add(group, r, r, p, ctx)) goto err;
+               if (!group->meth->add(group, acc, acc, p, ctx)) goto err;
                }
 
        for (i = 0; i < num; i++)
                {
                if (!ec_GF2m_montgomery_point_multiply(group, p, scalars[i], points[i], ctx)) goto err;
-               if (BN_get_sign(scalars[i]))
+               if (BN_is_negative(scalars[i]))
                        if (!group->meth->invert(group, p, ctx)) goto err;
-               if (!group->meth->add(group, r, r, p, ctx)) goto err;
+               if (!group->meth->add(group, acc, acc, p, ctx)) goto err;
                }
 
+       if (!EC_POINT_copy(r, acc)) goto err;
+
        ret = 1;
 
   err:
        if (p) EC_POINT_free(p);
+       if (acc) EC_POINT_free(acc);
        if (new_ctx != NULL)
                BN_CTX_free(new_ctx);
        return ret;