org.whispersystems.libsignal.kdf.HKDF Maven / Gradle / Ivy

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/**
 * Copyright (C) 2013-2016 Open Whisper Systems
 *
 * Licensed according to the LICENSE file in this repository.
 */

package org.whispersystems.libsignal.kdf;

import org.signal.client.internal.Native;

public abstract class HKDF {
  private static final int HASH_OUTPUT_SIZE  = 32;

  public static HKDF createFor(int messageVersion) {
    switch (messageVersion) {
      case 2:  return new HKDFv2();
      case 3:  return new HKDFv3();
      default: throw new AssertionError("Unknown version: " + messageVersion);
    }
  }

  public byte[] deriveSecrets(byte[] inputKeyMaterial, byte[] info, int outputLength) {
    return Native.HKDF_DeriveSecrets(getVersion(), inputKeyMaterial, null, info, outputLength);
  }

  public byte[] deriveSecrets(byte[] inputKeyMaterial, byte[] salt, byte[] info, int outputLength) {
    return Native.HKDF_DeriveSecrets(getVersion(), inputKeyMaterial, salt, info, outputLength);
  }

  protected abstract int getVersion();

}