Challenge-response token

A challenge-response token utilizes a central server to generate a challenge (such as a random string of numbers), which a user would then enter into the token. The token then calculates a response that serves as a one-time numeric password that is entered into the system. If the response from the user is the same as the response expected by the server, the user will be granted access to the system. In some implementations, the user must enter a PIN before the server will generate a challenge.