code: public byte[] calculateVrfSignature(byte[] privateKey, byte[] message) {
      if (privateKey == null || privateKey.length != 32) {
        throw new IllegalArgumentException("Invalid private key!");
      }
  
      byte[] random = provider.getRandom(64);
      return provider.calculateVrfSignature(random, privateKey, message);
    }
docs: Calculates a Unique Curve25519 signature.
  
  @param privateKey The private Curve25519 key to create the signature with.
  @param message The message to sign.
  @return A 96-byte signature.