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Curve25519 library for Java

There is a newer version: 0.5.0

/**
 * Copyright (C) 2014-2016 Open Whisper Systems
 *
 * Licensed according to the LICENSE file in this repository.
 */

package org.whispersystems.curve25519;

class NativeCurve25519Provider implements Curve25519Provider {

  private static boolean   libraryPresent         = false;
  private static Throwable libraryFailedException = null;

  static {
    try {
      System.loadLibrary("curve25519");
      libraryPresent = true;
    } catch (UnsatisfiedLinkError | SecurityException e) {
      libraryPresent         = false;
      libraryFailedException = e;
    }
  }

  private SecureRandomProvider secureRandomProvider = new JCESecureRandomProvider();

  NativeCurve25519Provider() throws NoSuchProviderException {
    if (!libraryPresent) throw new NoSuchProviderException(libraryFailedException);

    try {
      smokeCheck(31337);
    } catch (UnsatisfiedLinkError ule) {
      throw new NoSuchProviderException(ule);
    }
  }

  @Override
  public boolean isNative() {
    return true;
  }

  @Override
  public byte[] generatePrivateKey() {
    byte[] random = getRandom(PRIVATE_KEY_LEN);
    return generatePrivateKey(random);
  }

  @Override
  public byte[] getRandom(int length) {
    byte[] result = new byte[length];
    secureRandomProvider.nextBytes(result);

    return result;
  }

  @Override
  public void setRandomProvider(SecureRandomProvider provider) {
    this.secureRandomProvider = provider;
  }

  @Override
  public native byte[] calculateAgreement(byte[] ourPrivate, byte[] theirPublic);

  @Override
  public native byte[] generatePublicKey(byte[] privateKey);

  @Override
  public native byte[] generatePrivateKey(byte[] random);

  @Override
  public native byte[] calculateSignature(byte[] random, byte[] privateKey, byte[] message);

  @Override
  public native boolean verifySignature(byte[] publicKey, byte[] message, byte[] signature);

  @Override
  public native byte[] calculateVrfSignature(byte[] random, byte[] privateKey, byte[] message);

  @Override
  public native byte[] verifyVrfSignature(byte[] publicKey, byte[] message, byte[] signature)
      throws VrfSignatureVerificationFailedException;

  private native boolean smokeCheck(int dummy);

}