/*******************************************************************************
* Copyright (c) 2014, Institute for Pervasive Computing, ETH Zurich.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of the Institute nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS "AS IS" AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* This file is part of the Scandium (Sc) Security for Californium.
******************************************************************************/
package ch.ethz.inf.vs.scandium.dtls;
import ch.ethz.inf.vs.scandium.dtls.AlertMessage.AlertDescription;
import ch.ethz.inf.vs.scandium.dtls.AlertMessage.AlertLevel;
import ch.ethz.inf.vs.scandium.util.DatagramReader;
import ch.ethz.inf.vs.scandium.util.DatagramWriter;
/**
* The change cipher spec protocol exists to signal transitions in ciphering
* strategies. The protocol consists of a single message, which is encrypted and
* compressed under the current (not the pending) connection state. The
* ChangeCipherSpec message is sent by both the client and the server to notify
* the receiving party that subsequent records will be protected under the newly
* negotiated CipherSpec and keys. For further details see <a
* href="http://tools.ietf.org/html/rfc5246#section-7.1">RFC 5246</a>.
*
* @author Stefan Jucker
*
*/
public class ChangeCipherSpecMessage implements DTLSMessage {
// DTLS-specific constants ////////////////////////////////////////
private static final int CCS_BITS = 8;
// Members ////////////////////////////////////////////////////////
private CCSType CCSProtocolType;
// Constructor ////////////////////////////////////////////////////
public ChangeCipherSpecMessage() {
CCSProtocolType = CCSType.CHANGE_CIPHER_SPEC;
}
// Change Cipher Spec Enum ////////////////////////////////////////
/**
* See <a href="http://tools.ietf.org/html/rfc5246#section-7.1">RFC 5246</a>
* for specification.
*
* @author Stefan Jucker
*
*/
public enum CCSType {
CHANGE_CIPHER_SPEC(1);
private int code;
private CCSType(int code) {
this.code = code;
}
public int getCode() {
return code;
}
}
// Methods ////////////////////////////////////////////////////////
public CCSType getCCSProtocolType() {
return CCSProtocolType;
}
@Override
public String toString() {
StringBuilder sb = new StringBuilder();
sb.append("\tChange Cipher Spec Message\n");
return sb.toString();
}
// Serialization //////////////////////////////////////////////////
// @Override
public byte[] toByteArray() {
DatagramWriter writer = new DatagramWriter();
writer.write(CCSProtocolType.getCode(), CCS_BITS);
return writer.toByteArray();
}
public static DTLSMessage fromByteArray(byte[] byteArray) throws HandshakeException {
DatagramReader reader = new DatagramReader(byteArray);
int code = reader.read(CCS_BITS);
if (code == CCSType.CHANGE_CIPHER_SPEC.getCode()) {
return new ChangeCipherSpecMessage();
} else {
String message = "Unknown Change Cipher Spec code received: " + code;
AlertMessage alert = new AlertMessage(AlertLevel.FATAL, AlertDescription.HANDSHAKE_FAILURE);
throw new HandshakeException(message, alert);
}
}
}