Captain Up User Integration - Signing a User Object in PHP

sign_user.php

<?php

// Signs a user object with your API secret.
// See: https://captainup.com/help/javascript/user-integration
// 
// @param secret - {String} Your Captain Up API secret
// @param user - {Associative Array} the user dictionary
// @return {String} the signed user string
function sign_user($secret, $user) {
	// Remove all `null`, `undefined`, arrays and objects from the object
	foreach($user as $key => $value) {
		if(empty($value) || $value == '') {
			unset($user[$key]);
		}
	}
	// Sort the array alphabetically by the key names
	ksort($user, SORT_LOCALE_STRING);
	// Join each key-value pair with a '='...
	$signed_user = array();
	foreach ($user as $key => $value) {
		array_push($signed_user, $key."=".$value);
	}
	// ... and join each pair with '&'
	$signed_user = implode("&",$signed_user);
	// Sign the serialized object with SHA-512 in lowercase hexadecimal digits
	$signed_user = hash_hmac('sha512', $signed_user, $secret);
	// Encode it as Base64
	$signed_user = base64_encode($signed_user);
	// remove new lines and and the '=' part at the end, and return
	return preg_replace('/(\n|=+\n?$)/', '', $signed_user);
}

// Example Usage:
$user = array(
	"id" => "guid-in-your-site",
	"name" => "Almog Melamed",
	"avatar" => "https://example.com/user-profile-picture.png",
	"empty" => null // Just a test, to see that empty values are removed properly
);
// Remember to use your own API secret below
// This will output:: "NzFjMWRhM2VhMDcyZDQyYzBhNGE4Yjk3MDdjNTQ0ZTU4NDg2N2EzYjc0Nzg4NmIzMjhkODA1YTJkOWFiZGY3ZjI0YzU3NGY3YjcwYzFiMGM1MzlhYzVjOGE0Mjg5ZmNkYzVhOGI0MDQyZTRkYTAzOTRlM2RjNzFmZTdmNTVkMGI"
echo sign_user('YOUR-API-SECRET', $user)."\n";