SECURITY FILE SYSTEM AND METHOD FOR SECRUING DATA IN A PORTABLE DATA CARRIER

A security file system for a portable data carrier provides improved security for the data carrier and for data contained in files in the data carrier. Although the data carrier may be embodied to look and feel much like an ordinary credit card, it contains a computer and a programmable memory with operating power and input and output data provided through a contactless interface. In order to provide security for the data carrier, the security file system on the data carrier includes a stored access code for verifying the identity of an individual attempting to access the data carrier, and an appropriate routine for limiting the number of unsuccessful attempts to access the data carrier. The security file system is also configurable to include select ones of multiple stored access codes for enabling the retrieval and modification of data in corresponding select ones of the files. The routine similarly limits the number of unsuccessful attempts to access these files. Operation of the routine is such that a counter in the data carrier is advanced a count each time a code is externally provided to the data carrier. If this external code compares favorably with the stored access code, the counter is reset to its previous count and access to the data carrier is permitted. If the external code does not compare favorably with the stored access code, however, the counter is not reset. When the counter advances to a predetermined number, the data carrier is locked preventing further access attempts or, alternatively, the data erased from the data carrier. In limiting access to select files, the routine similarly locks or erases the data in the selected file in the same manner.