encrypt and decrypt

<?php
$data = $_GET['pass'];//get password
$key = '1234567890123456';
function encrypt($data, $key){
    return base64_encode(
    mcrypt_encrypt(
        MCRYPT_RIJNDAEL_128,
        $key,
        $data,
        MCRYPT_MODE_CBC,
        "\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0"
    )
);
}
function decrypt($data, $key){
    $decode = base64_decode($data);
    return mcrypt_decrypt(
                    MCRYPT_RIJNDAEL_128,
                    $key,
                    $decode,
                    MCRYPT_MODE_CBC,
                    "\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0"
            );


}
echo $encrypted = encrypt($data, $key);
echo $decrypted= decrypt($encrypted, $key);

//Encoding and decoding with str_rot13()
function enrot13($enrot13){
    return str_rot13($enrot13);
}

function derot13($derot13){ //decode
    return str_rot13(str_rot13($derot13));
}


//Encode and decode with base64_encode() & base64_decode()
function enbase64($enstring){
    return base64_encode($enstring);
}

function debase64($destring){ //decode
    return base64_decode((base64_encode($destring));
}

//Deflate and inflate with gzdeflate() & gzinflate()
function gzinflate($string){
    return gzdeflate($string);
}

function gzdeflate($string){ //decode
    return gzinflate($string);
}

//first two functions — str_rot13() and base64_encode()
function gzinflateRot13($string){
    return gzdeflate($string, 9);// compression level set to 9 = maximum
}

function gzdeflateRot13($string){ //decode
    return gzinflate(gzdeflate($string, 9), strlen($string));// length set to same as $string
}

//Combined example: gzinflate(str_rot13(base64_decode()))
function allthre($string){
    return eval(gzinflate(str_rot13(base64_decode($string))));
}
//Php url encode and decode
function enUrl($string){
    return urlencode($string);
}

function deUrl($string){ //decode
    return urldecode($string);
}

//PHP string to hex and hex to string functions
function strToHex($string)
{
    $hex='';
    for ($i=0; $i < strlen($string); $i++)
    {
        $hex .= dechex(ord($string[$i]));
    }
    return $hex;
}

function hexToStr($hex) //decode
{
    $string='';
    for ($i=0; $i < strlen($hex)-1; $i+=2)
    {
        $string .= chr(hexdec($hex[$i].$hex[$i+1]));
    }
    return $string;
}

?>