RobRichards\XMLSecLibs\XMLSecurityKey::signOpenSSL PHP Method

    private function signOpenSSL($data)
    {
        $algo = OPENSSL_ALGO_SHA1;
        if (!empty($this->cryptParams['digest'])) {
            $algo = $this->cryptParams['digest'];
        }
        if (!openssl_sign($data, $signature, $this->key, $algo)) {
            throw new Exception('Failure Signing Data: ' . openssl_error_string() . ' - ' . $algo);
        }
        return $signature;
    }