Miniplay API: Parameters validation snippet (PHP)

mpParametersValidationSnippet.php

<?php
    /* 1. Decode all get parameters */
        // Only if your system configuration or language doesn't automatically decodes it
        // foreach ($_GET as $key => $value) $_GET[$key] = urldecode($value);
    /* 2. Check signature */
        if ($_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 by concatenating the values to the api key 
	     * @param string $apiKey
	     * @param array $parameters
	     * @return string signature
	     */
	    function mpSignParameters($apiKey, array $parameters) {
	    	ksort($parameters); /* Sort array alphabetically by its keys (Although they should be already sorted by key) */
	    	$signatureString = "";
	        foreach ($parameters as $key=>$value) {
	            if (substr($key,0,3)==="mp_") $signatureString.=(string)$value;
	        }
	        return md5($apiKey.$signatureString);
	    }
?>