<?php
  public function signData($data)
    {
        $adapter = EccFactory::getAdapter();
        $generator = EccFactory::getNistCurves()->generator256();
        $useDerandomizedSignatures = true;
        $algorithm = 'sha256';
        $pemSerializer = new PemPrivateKeySerializer(new DerPrivateKeySerializer($adapter));
        $key = $pemSerializer->parse($this->key);
        $hasher = new SignHasher($algorithm, $adapter);
        $hash = $hasher->makeHash($data, $generator);
        if ($useDerandomizedSignatures) {
            $random = \Mdanter\Ecc\Random\RandomGeneratorFactory::getHmacRandomGenerator($key, $hash, $algorithm);
        } else {
            $random = \Mdanter\Ecc\Random\RandomGeneratorFactory::getRandomGenerator();
        }
        $randomK = $random->generate($generator->getOrder());
        $signer = new Signer($adapter);
        $signature = $signer->sign($key, $hash, $randomK);
        $serializer = new DerSignatureSerializer();
        $serializedSig = $serializer->serialize($signature);
        return $serializedSig;
    }