5.2 User authentication
The USIM shall support means to authenticate the user, to provide, for example, protection against the use of stolen cards. For the USIM, authentication shall be performed by the verification of a numeric PIN of four (4) to eight (8) decimal digits.
A function to disable user authentication may exist which may be inhibited by the application provider, in which case the user shall always use the PIN. Otherwise, the user may decide whether or not to make use of the user authentication function. If disabled, the user authentication function remains disabled until the user specifically re-enables it.