However, some such systems, such as RSA's Secur ID, allow the user to resynchronize the server with the token, sometimes by entering several consecutive passcodes.
Most also cannot have replaceable batteries and only last up to 5 years before having to be replaced – so there is additional cost.
Tokens in this category automatically transmit the authentication information to the client computer once a physical connection is made, eliminating the need for the user to manually enter the authentication information.
However, in order to use a connected token, the appropriate input device must be installed.
Some tokens have an audio capability designed for vision-impaired people.
Using public key cryptography, it is possible to prove possession of a private key without revealing that key.
Tokens can contain chips with functions varying from very simple to very complex, including multiple authentication methods.