key-exchange: Joint ke_test_vector format for DH and KEM

Both Diffie-Hellman (DH) and Key Encapsulation Mechanism (KEM) based
key exchange methods use a common ke_test_vector format. The
set_seed() function is used to provide deterministic private key
material for the crypto tests.

src/libstrongswan/crypto/key_exchange.h

@@ -134,16 +134,17 @@ struct key_exchange_t {
 		__attribute__((warn_unused_result));
 
 	/**
-	 * Set an explicit own private key to use.
+	 * Set a seed used for the derivation of private key material.
 	 *
-	 * Calling this method is usually not required, as the DH backend generates
-	 * an appropriate private value itself. It is optional to implement, and
-	 * used mostly for testing purposes.  The private key may be the actual key
-	 * or a seed for a DRBG.
+	 * Calling this method is usually not required, as the key exchange objects
+	 * generate the private key material themselves. This is optional to
+	 * implement, and used mostly for testing purposes.  The private key may be
+	 * the actual key or a DRBG instance.
 	 *
-	 * @param value		private key value to set
+	 * @param value		optional seed value to set (can be chunk_empty)
+	 * @param drbg		optional DRBG (can be NULL)
 	 */
-	bool (*set_private_key)(key_exchange_t *this, chunk_t value)
+	bool (*set_seed)(key_exchange_t *this, chunk_t value, drbg_t *drbg)
 		__attribute__((warn_unused_result));
 
 	/**