How to secure variable send through URL? - php

Question

I'm using PHP and CI framework, I want to send variable through URL but I want it to be somewhat encrypted.
For example i want to send variable named id:
www.trythis.com/site?id=123
I want it to be
www.trythis.com/site?id=VkxSiOW31S
The encrypted text is just an example.
How can I do that? or is there CI function that can do this?
Note: I already try base64_encode but it somehow can't be used in CI due to its special characters such as ==.

Answer 1

CodeIgniter has Encryption Class. You can use that class to encrypt and decrypt. To configure follow the steps
Setting your Key
$config['encryption_key'] = "YOUR KEY";
Initializing the Class
$this->load->library('encrypt');
To encode use
$id = '123';
$encrypted_id = $this->encrypt->encode($id);
//$url = 'www.trythis.com/site?id=' . $encrypted_id;
And to decode
//$encrypted_id = $_GET['id'];
$decrypted_id = $this->encrypt->decode($encrypted_id);

Answer 2

I made this class for the same purpose:
class Cypher
{
public $encrypted;
public $decrypted;
public function __construct($_value) {
$this->encrypted = $this->encrypting($_value);
$this->decrypted = $this->decrypting($_value);
}
private function encrypting($_value) {
$key = pack('H*', "bcb04b7e103a0cd8b54763051cef08bc55abe029fdebae5e1d417e2ffb2a00a3");
$iv_size = mcrypt_get_iv_size(MCRYPT_RIJNDAEL_128, MCRYPT_MODE_CBC);
$iv = mcrypt_create_iv($iv_size, MCRYPT_RAND);
$utf8 = utf8_encode($_value);
$cipher = mcrypt_encrypt(MCRYPT_RIJNDAEL_128, $key, $utf8, MCRYPT_MODE_CBC, $iv);
$cipher = $iv.$cipher;
$base64 = base64_encode($_value);
return $base64;
}
private function decrypting($_value) {
return base64_decode($_value);
}
}
Let's try your example:
$cypher = new Cypher('123');
header("location: www.trythis.com/site?id=".$cypher -> encrypted);
On www.trythis.com/site page:
$id = isset($_GET['id']) ? new Cypher($_GET['id']) : "";
echo $id -> decrypted;