PHP Cookies - Simple cookie write/read methods that allow basic encryption

Saving and retrieving cookies is extremely simple in PHP using the setcookie() function and $_COOKIE super global variable. But what if you do no want to let the user see the data, let alone alter it? Here is simple cookie write/read methods that allow basic encryption. To delete a cookie, give a negative life

<?php // Global Cookie Life in seconds, can be overridden in the function call $cookieLife = 2592000; // 30days // Global key for encryption, can be overridden in the function call $encryptKey = '';//'mysecretkey'; /* @param $name - Name of cookie @param $val - Value of the cookie @param $time - Life of the cookie in seconds @param $key - Key for encrypting cookie @return TRUE on success else FALSE */ function writeCookie($name, $val, $time = null, $key = null){     $time = is_null($time) ? $GLOBALS['cookieLife'] : $time;     $key = is_null($key) ? $GLOBALS['encryptKey'] : $key;     $val = gzcompress(serialize($val) . $key);     $val = urlencode(base64_encode($val));     // Save the cookie if header is not already sent     if(!headers_sent()) {         return setcookie($name, $val, time() + $time, '/');     }else{         return FALSE;     } } /* @param $name - Name of Cookie @param $key - Key to decrypt, should be same as the one used for encrypting @param $default - Default value, if the specified cookie does not exist */ function readCookie($name, $key = null, $default=null){     if(isset($_COOKIE[$name])){         $key = is_null($key) ? $GLOBALS['encryptKey'] : $key;         $val = $_COOKIE[$name];         $val = base64_decode(urldecode($val));         $val = substr(gzuncompress($val), 0, strlen($val) - strlen($key));         $val = unserialize($val);         return $val;     }else{         return $default;     } } ?>

usage example

<?php // Counter using global key $counter1 = readCookie('counter1'); $counter1 = is_null($counter1) ? 0 : $counter1; $str = "Counter 1 - $counter1 (increments by 1)<br/>"; writeCookie('counter1', ++$counter1); // Counter with key passed during function call $counter2 = readCookie('counter2', 'mykey'); $counter2 = is_null($counter2) ? 0 : $counter2; $str .= "Counter 2 - $counter2 (Increments by 2)<br/>"; $counter2 += 2; writeCookie('counter2', $counter2, null, 'mykey'); // Read cookie, with default value if the specified cookie does not exist $counter3 = readCookie('counter3', null, 1); $str .= "Counter 3 - $counter3 (Doubles)<br/>"; $counter3 *= 2; writeCookie('counter3', $counter3); echo $str; // Invalid Cookie, does not work because output already started at previous line // If you have output buffering enabled, it will work though $counter = readCookie('counter', null, 1); $str .= "Counter Invalid - $counter (Remains 1 always)<br/>"; $counter *= 2; echo "Counter Invalid - $counter (Supposed to double, but always shows 2 since header already sent)"; writeCookie('counter', $counter); ?>