Miniplay API: Parameters validation snippet (PHP)

gistfile1.txt

/* 1. Decode all get parameters */
    foreach ($_GET as $key=>$value) 
        $_GET[$key] = urldecode($value); /* 1. May not be needed in your language */
/* 2. Check signature */
    if ($_GET['mini_signature'] != signParameters("YOUR_API_KEY",$_GET)) {
        die("The 'mp_*' parameters signature is invalid");
    } else {
        echo "The 'mp_*' parameters signature is valid!";
    }
/* 3. Helper function definition, yeah, it will look so good inside a class :) */
    /**
     * Signs an array of mp_* parameters, 
     * @param string $apiKey
     * @param array $parameters
     * @return string signature
     */
    function signParameters($apiKey, array $parameters) {
        foreach ($parameters as $key=>$value) {
            if (substr($key,0,3)!="mp_") unset($parameters[$key]); /* Exclude parameter from validation */
            $parameters[$key] = (string)$value; /* Cast to string not needed in PHP but other languages may need it. */
        }
        return md5($apiKey.json_encode($parameters));
    }