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Signal Protocol cryptography library for Java
/**
* Copyright (C) 2014-2016 Open Whisper Systems
*
* Licensed according to the LICENSE file in this repository.
*/
package org.whispersystems.libsignal.groups.ratchet;
import org.whispersystems.libsignal.kdf.HKDFv3;
import org.whispersystems.libsignal.util.ByteUtil;
/**
* The final symmetric material (IV and Cipher Key) used for encrypting
* individual SenderKey messages.
*
* @author Moxie Marlinspike
*/
public class SenderMessageKey {
private final int iteration;
private final byte[] iv;
private final byte[] cipherKey;
private final byte[] seed;
public SenderMessageKey(int iteration, byte[] seed) {
byte[] derivative = new HKDFv3().deriveSecrets(seed, "WhisperGroup".getBytes(), 48);
byte[][] parts = ByteUtil.split(derivative, 16, 32);
this.iteration = iteration;
this.seed = seed;
this.iv = parts[0];
this.cipherKey = parts[1];
}
public int getIteration() {
return iteration;
}
public byte[] getIv() {
return iv;
}
public byte[] getCipherKey() {
return cipherKey;
}
public byte[] getSeed() {
return seed;
}
}