keyManager.close();
        assertThrows(IllegalStateException.class, () -> keyManager.storeSessionKey("session", testKey, "AES"));
    }

    @Test
    public void testMultipleCloseCalls() {
        keyManager.storeSessionKey("session", testKey, "AES");

        keyManager.close();
        keyManager.close(); // Should not throw

                assertTrue(e.getMessage() != null, "Exception should have a message");
            }
        }

        @Test
        @DisplayName("Should handle multiple close calls gracefully")
        void testMultipleCloseCalls() throws Exception {
            byte[] sessionKey = new byte[16];
            Arrays.fill(sessionKey, (byte) 0xEE);