/*

 * otr4j, the open source java otr library.

 *

 * Distributable under LGPL license.

 * See terms of license at gnu.org.

 */

package net.java.otr4j.io.messages;

import java.io.IOException;

import java.util.Arrays;

import net.java.otr4j.OtrException;

import net.java.otr4j.crypto.OtrCryptoEngineImpl;

import net.java.otr4j.io.SerializationUtils;

/**

 * 

 * @author George Politis

 */

public class SignatureMessage extends AbstractEncodedMessage {

	// Fields.

	public byte[] xEncrypted;

	public byte[] xEncryptedMAC;

	// Ctor.

	protected SignatureMessage(int messageType, int protocolVersion,

			byte[] xEncrypted, byte[] xEncryptedMAC) {

		super(messageType, protocolVersion);

		this.xEncrypted = xEncrypted;

		this.xEncryptedMAC = xEncryptedMAC;

	}

	public SignatureMessage(int protocolVersion, byte[] xEncrypted,

			byte[] xEncryptedMAC) {

		this(MESSAGE_SIGNATURE, protocolVersion, xEncrypted, xEncryptedMAC);

	}

	// Memthods.

	public byte[] decrypt(byte[] key) throws OtrException {

		return new OtrCryptoEngineImpl().aesDecrypt(key, null, xEncrypted);

	}

	public boolean verify(byte[] key) throws OtrException {

		// Hash the key.

		byte[] xbEncrypted;

		try {

			xbEncrypted = SerializationUtils.writeData(xEncrypted);

		} catch (IOException e) {

			throw new OtrException(e);

		}

		byte[] xEncryptedMAC = new OtrCryptoEngineImpl().sha256Hmac160(

				xbEncrypted, key);

		// Verify signature.

		return Arrays.equals(xEncryptedMAC, xEncryptedMAC);

	}

	@Override

	public int hashCode() {

		final int prime = 31;

		int result = super.hashCode();

		result = prime * result + Arrays.hashCode(xEncrypted);

		result = prime * result + Arrays.hashCode(xEncryptedMAC);

		return result;

	}

	@Override

	public boolean equals(Object obj) {

		if (this == obj)

			return true;

		if (!super.equals(obj))

			return false;

		if (getClass() != obj.getClass())

			return false;

		SignatureMessage other = (SignatureMessage) obj;

		if (!Arrays.equals(xEncrypted, other.xEncrypted))

			return false;

		if (!Arrays.equals(xEncryptedMAC, other.xEncryptedMAC))

			return false;

		return true;

	}

}