一个简洁的PHP可逆加密函数(分享)

// 加密数据并写到cookie里

$cookie_data = $this -> encrypt("nowamagic",$data);$cookie = array(
'name' => '$data',
'value' => $cookie_data,
'expire' => $user_expire,
'domain' => '',
'path' => '/',
'prefix' => ''
);
$this->input->set_cookie($cookie);

// 加密

public function encrypt($key,$plain_text) {
$plain_text = trim($plain_text);
$iv = substr(md5($key),mcrypt_get_iv_size (MCRYPT_CAST_256,MCRYPT_MODE_CFB));
$c_t = mcrypt_cfb (MCRYPT_CAST_256,$key,$plain_text,MCRYPT_ENCRYPT,$iv);
return trim(chop(base64_encode($c_t)));
}

使用的时候再解密：

if( isset($_COOKIE['data']) )
{

//用cookie给session赋值

$_SESSION['data'] = decrypt("nowamagic",$_COOKIE['data']);
}function decrypt($key,$c_t) {
$c_t = trim(chop(base64_decode($c_t)));
$iv = substr(md5($key),MCRYPT_MODE_CFB));
$p_t = mcrypt_cfb (MCRYPT_CAST_256,$c_t,MCRYPT_DECRYPT,$iv);
return trim(chop($p_t));
}