<?php
/**
* decrypt AES 256
*
* @param data $edata
* @param string $password
* @return decrypted data
*/
function decrypt($edata, $password) {
$data = base64_decode($edata);
$salt = substr($data, 0, 16);
$ct = substr($data, 16);
$rounds = 3; // depends on key length
$data00 = $password.$salt;
$hash = array();
$hash[0] = hash('sha256', $data00, true);
$result = $hash[0];
for ($i = 1; $i < $rounds; $i++) {
$hash[$i] = hash('sha256', $hash[$i - 1].$data00, true);
$result .= $hash[$i];
}
$key = substr($result, 0, 32);
$iv = substr($result, 32,16);
return openssl_decrypt($ct, 'AES-256-CBC', $key, true, $iv);
}
/**
* crypt AES 256
*
* @param data $data
* @param string $password
* @return base64 encrypted data
*/
function encrypt($data, $password) {
// Set a random salt
$salt = openssl_random_pseudo_bytes(16);
$salted = '';
$dx = '';
// Salt the key(32) and iv(16) = 48
while (strlen($salted) < 48) {
$dx = hash('sha256', $dx.$password.$salt, true);
$salted .= $dx;
}
$key = substr($salted, 0, 32);
$iv = substr($salted, 32,16);
$encrypted_data = openssl_encrypt($data, 'AES-256-CBC', $key, true, $iv);
return base64_encode($salt . $encrypted_data);
}
class EncryptedSessionHandler extends SessionHandler
{
private $key;
public function __construct($key)
{
$this->key = $key;
}
public function read($id)
{
$data = parent::read($id);
if (!$data) {
return "";
} else {
return decrypt($data, $this->key);
}
}
public function write($id, $data)
{
$data = encrypt($data, $this->key);
return parent::write($id, $data);
}
}
// we'll intercept the native 'files' handler, but will equally work
// with other internal native handlers like 'sqlite', 'memcache' or 'memcached'
// which are provided by PHP extensions.
ini_set('session.save_handler', 'files');
$key = 'secret_string';
$handler = new EncryptedSessionHandler($key);
session_set_save_handler($handler, true);
session_start();
// proceed to set and retrieve values by key from $_SESSION