byte[] smallMessage = new byte[5];
        assertDoesNotThrow(() -> context.encryptMessage(smallMessage, 1L));

        // Large message should trigger rotation and fail
        byte[] largeMessage = new byte[50];
        Exception exception = assertThrows(CIFSException.class, () -> context.encryptMessage(largeMessage, 2L));

        setField(session, "sessionId", 99L);

        when(enc.encryptMessage(any(byte[].class), eq(99L))).thenReturn(new byte[] { 9, 9 });
        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 });

     * @throws CIFSException if encryption fails or is not enabled
     */
    public byte[] encryptMessage(byte[] message) throws CIFSException {
        if (this.encryptionContext == null) {
            throw new CIFSException("Encryption not enabled for this session");
        }
        return this.encryptionContext.encryptMessage(message, this.sessionId);
    }

    /**

     * @param sessionId
     *            session identifier
     * @return encrypted message with transform header
     * @throws CIFSException
     *             if encryption fails
     */
    public byte[] encryptMessage(final byte[] message, final long sessionId) throws CIFSException {
        if (message == null) {
            throw new IllegalArgumentException("Message cannot be null");
        }