A concise PHP reversible encryption function

// 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), 0,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), 0,mcrypt_get_iv_size (MCRYPT_CAST_256,MCRYPT_MODE_CFB)); $p_t = mcrypt_cfb (MCRYPT_CAST_256, $key, $c_t, MCRYPT_DECRYPT, $iv); return trim(chop($p_t)); }