return key;
    }

    /**
     * Get raw key bytes
     *
     * @param sessionId unique session identifier
     * @return raw key bytes, or null if not found
     */
    public byte[] getRawKey(String sessionId) {
        checkNotClosed();

        byte[] key = rawKeys.get(sessionId);
        if (key != null) {
            return key.clone(); // Return a copy to prevent modification
        }

        byte[] rawKey = keyManager.getRawKey(sessionId);
        assertNotNull(rawKey, "Should retrieve raw key");
        assertArrayEquals(testKey, rawKey, "Raw key should match");

        // Verify we get a copy, not the original
        rawKey[0] = (byte) ~rawKey[0];
        byte[] rawKey2 = keyManager.getRawKey(sessionId);
        assertArrayEquals(testKey, rawKey2, "Should still match original");

        return this.cipherId;
    }

    private byte[] getEncryptionKey() {
        if (keyManager != null) {
            String encKeyId = sessionId + "-enc";
            byte[] key = keyManager.getRawKey(encKeyId);
            if (key == null) {
                throw new IllegalStateException("Encryption key not found in SecureKeyManager");
            }
            return key;
        }