/*******************************************************************************
* 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 java.io.UnsupportedEncodingException;
import ch.ethz.inf.vs.scandium.util.DatagramReader;
import ch.ethz.inf.vs.scandium.util.DatagramWriter;
/**
* When using preshared keys for key agreement, the client indicates which key
* to use by including a "PSK identity" in this message. The server can
* potentially provide a "PSK identity hint" to help the client in selecting
* which identity to use. See <a
* href="http://tools.ietf.org/html/rfc4279#section-2">RFC 4279</a> for details.
*
* @author Stefan Jucker
*
*/
public class PSKClientKeyExchange extends ClientKeyExchange {
// DTLS-specific constants ////////////////////////////////////////
private static final int IDENTITY_LENGTH_BITS = 16;
private static final String CHAR_SET = "UTF8";
// Members ////////////////////////////////////////////////////////
/**
* The PSK identity MUST be first converted to a character string, and then
* encoded to octets using UTF-8. See <a
* href="http://tools.ietf.org/html/rfc4279#section-5.1">RFC 4279</a>.
*/
private byte[] identityEncoded;
/** The identity in cleartext. */
private String identity;
// Constructors ///////////////////////////////////////////////////
public PSKClientKeyExchange(String identity) {
this.identity = identity;
try {
this.identityEncoded = identity.getBytes(CHAR_SET);
} catch (UnsupportedEncodingException e) {
e.printStackTrace();
}
}
public PSKClientKeyExchange(byte[] identityEncoded) {
this.identityEncoded = identityEncoded;
try {
this.identity = new String(identityEncoded, CHAR_SET);
} catch (UnsupportedEncodingException e) {
e.printStackTrace();
}
}
// Methods ////////////////////////////////////////////////////////
@Override
public int getMessageLength() {
// fixed: 2 bytes for the length field
// http://tools.ietf.org/html/rfc4279#section-2: opaque psk_identity<0..2^16-1>;
return 2 + identityEncoded.length;
}
@Override
public String toString() {
StringBuilder sb = new StringBuilder(super.toString());
sb.append(super.toString());
sb.append("\t\tPSK Identity: " + identity + "\n");
return sb.toString();
}
// Serialization //////////////////////////////////////////////////
@Override
public byte[] fragmentToByteArray() {
DatagramWriter writer = new DatagramWriter();
writer.write(identityEncoded.length, IDENTITY_LENGTH_BITS);
writer.writeBytes(identityEncoded);
return writer.toByteArray();
}
public static HandshakeMessage fromByteArray(byte[] byteArray) {
DatagramReader reader = new DatagramReader(byteArray);
int length = reader.read(IDENTITY_LENGTH_BITS);
byte[] identityEncoded = reader.readBytes(length);
return new PSKClientKeyExchange(identityEncoded);
}
// Getters and Setters ////////////////////////////////////////////
public String getIdentity() {
return identity;
}
public void setIdentity(String identity) {
this.identity = identity;
}
}