Simple URL signature

SignatureProvider.php

<?php

namespace Http\Security;

class SignatureProvider
{

    private $key;
    private $algorithm;
    private $timeValidity;

    public function __construct($key, $algorithm, $timeValidity)
    {
        $this->key = $key;
        $this->algorithm = $algorithm;
        $this->timeValidity = $timeValidity;
    }

    public function generateSignature($url, $parameters = [])
    {
        $parameters['nonce'] = time();
        $signedData = base64_encode(http_build_query($parameters));
        $signature = hash_hmac($this->algorithm, $signedData, $this->key);

        $query = parse_url($url, PHP_URL_QUERY);

        return $url . (null === $query ? '?' : '&') . http_build_query(['signed_data' => $signedData, 'signature' => $signature]);
    }

    public function isSignatureValid($url)
    {
        $query = parse_url($url, PHP_URL_QUERY);
        parse_str($query, $parameters);

        if (!array_key_exists('signature', $parameters)) {
            return false;
        }

        if (!array_key_exists('signed_data', $parameters)) {
            return false;
        }
        
        parse_str(base64_decode($parameters['signed_data']), $signedData);
        
        if (!array_key_exists('nonce', $signedData)) {
            return false;
        }
        
        if ($signedData['nonce'] > time()) {
            return false;
        }
        
        if ($signedData['nonce'] < time() - $this->timeValidity) {
            return false;
        }
        
        if ($parameters['signature'] !== hash_hmac($this->algorithm, $parameters['signed_data'], $this->key)) {
            return false;
        }
        
        return true;
    }
}