Authentication is of great importance in information security. Traditional method only focus on encryption of the content itself, which is the same with the later proposed methods named information hiding and digital watermark. Since data transmission is in the open network, it can easily be detected and intercepted by the malicious party. In this paper, we put forward a new method which utilize the communication channel, not the content, as the data carrier, and guarantee the validation of the user’s identity during the common data transmission. Specifically, by manipulating the inter-packet delays, we implement a prototype system for authentication and embed the authentication tag within the packet intervals based on network covert channel. By conducting a series of experiments, we prove that our method performs well in LAN and Campus Network.