class X25519 {

  @SuppressWarnings("NarrowingCompoundAssignment")
  public static byte[] generatePrivateKey() {
    byte[] privateKey = Random.randBytes(Field25519.FIELD_LEN);

    privateKey[0] |= 7;
    privateKey[31] &= 63;
    privateKey[31] |= 128;

    return privateKey;
  }

}