USB token refers to a small device with a USB port, often in the form of a keychain. It is used for authentication. USB tokens can perform similar cryptographic functions to a smart card, for example. The advantage is that no reader is required. USB tokens generate a unique number combination that is calculated using the locally stored personal key and the current time. The number combination is valid for a definable period of time. During this time, the user must authenticate himself using a login procedure with the number combination. USB tokens have their own central processing unit (CPU) for the common encryption methods.
