Add ecp_keypair struct, init/free and constants

include/polarssl/ecp.h

@@ -91,6 +91,25 @@ typedef struct
 }
 ecp_group;
 
+/**
+ * \brief           ECP key pair structure
+ *
+ * A generic key pair that could be used for ECDSA, fixed ECDH, etc.
+ * Usage can be restricted to a particular algorithm by the 'alg' field,
+ * see POLARSSL_ECP_KEY_ALG_* constants (default: unrestricted).
+ *
+ * \sa ecdh_context
+ * \sa ecdsa_context
+ */
+typedef struct
+{
+    ecp_group grp;      /*!<  Elliptic curve and base point     */
+    mpi d;              /*!<  our secret value                  */
+    ecp_point Q;        /*!<  our public value                  */
+    int alg;            /*!<  algorithm to use this key with    */
+}
+ecp_keypair;
+
 /**
  * RFC 5114 defines a number of standardized ECP groups for use with TLS.
  *
@@ -139,6 +158,16 @@ ecp_group;
  */
 #define POLARSSL_ECP_TLS_NAMED_CURVE    3   /**< ECCurveType's named_curve */
 
+/*
+ * Algorithm identifiers from RFC 5480 for use with EC keys
+ */
+#define POLARSSL_ECP_KEY_ALG_UNRESTRICTED   0   /**< RFC 5480 2.1.1 */
+#define POLARSSL_ECP_KEY_ALG_ECDH           1   /**< RFC 5480 2.1.2 */
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
 /**
  * \brief           Initialize a point (as zero)
  */
@@ -149,6 +178,11 @@ void ecp_point_init( ecp_point *pt );
  */
 void ecp_group_init( ecp_group *grp );
 
+/**
+ * \brief           Initialize a key pair (as an invalid one)
+ */
+void ecp_keypair_init( ecp_keypair *key );
+
 /**
  * \brief           Free the components of a point
  */
@@ -159,6 +193,11 @@ void ecp_point_free( ecp_point *pt );
  */
 void ecp_group_free( ecp_group *grp );
 
+/**
+ * \brief           Free the components of a key pair
+ */
+void ecp_keypair_free( ecp_keypair *key );
+
 /**
  * \brief           Set a point to zero
  *