when(enc.decryptMessage(any(byte[].class))).thenReturn(new byte[] { 7, 7 });

        assertTrue(session.isEncryptionEnabled());
        assertSame(enc, session.getEncryptionContext());

        byte[] encOut = session.encryptMessage(new byte[] { 1, 2, 3 });
        assertArrayEquals(new byte[] { 9, 9 }, encOut);
        verify(enc, times(1)).encryptMessage(eq(new byte[] { 1, 2, 3 }), eq(99L));