    @Test
    public void changePassword() throws KeyStoreException {

        ECKeyStore ks = new ECKeyStore();
        PrivateKey k1 = PrivateKey.fresh(NetworkType.TESTNET);

        // add a key
        String alias1 = ks.addKey(k1);

        // change password
        ks.changePassword("test".toCharArray());

        // retrieve the key
        PrivateKey k2 = ks.getKey(ECKeyStore.getUniqueID(k1));

        assertTrue(ks.containsKey(alias1));
        assertArrayEquals(k1.getBytes(), k2.getBytes());
        assertEquals(k1.getNetworkType(), k2.getNetworkType());
    }