Rename mont_data to order_mont.

It's confusing to have both mont and mont_data on EC_GROUP. The
documentation was also wrong.

Change-Id: I4e2e3169ed79307018212fba51d015bbbe5c4227
Reviewed-on: https://boringssl-review.googlesource.com/10348
Reviewed-by: Adam Langley <agl@google.com>
Commit-Queue: David Benjamin <davidben@google.com>
CQ-Verified: CQ bot account: commit-bot@chromium.org <commit-bot@chromium.org>

crypto/fipsmodule/ec/ec.c

@@ -456,7 +456,7 @@ static EC_GROUP *ec_group_new_from_data(unsigned built_in_index) {
 
   const BN_MONT_CTX **monts = *built_in_curve_scalar_field_monts();
   if (monts != NULL) {
-    group->mont_data = monts[built_in_index];
+    group->order_mont = monts[built_in_index];
   }
 
   group->generator = P;
@@ -514,8 +514,8 @@ void EC_GROUP_free(EC_GROUP *group) {
   OPENSSL_free(group);
 }
 
-const BN_MONT_CTX *ec_group_get_mont_data(const EC_GROUP *group) {
-  return group->mont_data;
+const BN_MONT_CTX *ec_group_get_order_mont(const EC_GROUP *group) {
+  return group->order_mont;
 }
 
 EC_GROUP *EC_GROUP_dup(const EC_GROUP *a) {
@@ -533,7 +533,7 @@ EC_GROUP *EC_GROUP_dup(const EC_GROUP *a) {
     return NULL;
   }
 
-  ret->mont_data = a->mont_data;
+  ret->order_mont = a->order_mont;
   ret->curve_name = a->curve_name;
 
   if (a->generator != NULL) {

crypto/fipsmodule/ec/internal.h

@@ -119,7 +119,7 @@ struct ec_group_st {
 
   int curve_name; /* optional NID for named curve */
 
-  const BN_MONT_CTX *mont_data; /* data for ECDSA inverse */
+  const BN_MONT_CTX *order_mont; /* data for ECDSA inverse */
 
   /* The following members are handled by the method functions,
    * even if they appear generic */
@@ -147,10 +147,10 @@ struct ec_point_st {
 EC_GROUP *ec_group_new(const EC_METHOD *meth);
 int ec_group_copy(EC_GROUP *dest, const EC_GROUP *src);
 
-/* ec_group_get_mont_data returns a Montgomery context for operations in the
- * scalar field of |group|. It may return NULL in the case that |group| is not
- * a built-in group. */
-const BN_MONT_CTX *ec_group_get_mont_data(const EC_GROUP *group);
+/* ec_group_get_order_mont returns a Montgomery context for operations modulo
+ * |group|'s order. It may return NULL in the case that |group| is not a
+ * built-in group. */
+const BN_MONT_CTX *ec_group_get_order_mont(const EC_GROUP *group);
 
 int ec_wNAF_mul(const EC_GROUP *group, EC_POINT *r, const BIGNUM *g_scalar,
                 const EC_POINT *p, const BIGNUM *p_scalar, BN_CTX *ctx);

crypto/fipsmodule/ecdsa/ecdsa.c

@@ -280,10 +280,10 @@ static int ecdsa_sign_setup(const EC_KEY *eckey, BN_CTX *ctx_in, BIGNUM **kinvp,
     }
 
     /* Compute the inverse of k. The order is a prime, so use Fermat's Little
-     * Theorem. Note |ec_group_get_mont_data| may return NULL but
+     * Theorem. Note |ec_group_get_order_mont| may return NULL but
      * |bn_mod_inverse_prime| allows this. */
     if (!bn_mod_inverse_prime(kinv, k, order, ctx,
-                              ec_group_get_mont_data(group))) {
+                              ec_group_get_order_mont(group))) {
       OPENSSL_PUT_ERROR(ECDSA, ERR_R_BN_LIB);
       goto err;
     }