Patent ID: 6415142
Filing Date: 2002-07-02
Classification: G06Q,G07F,H04M,H04W

Abstract:
A smart card, which in normal use in a network allows the transfer of goods/services to a user of the card from a network operator by subtracting prepaid units of value stored in said card in exchange for said goods/services comprising a card-shaped carrier having a terminal, and an integrated circuit embedded in said carrier and connected to said terminal;said integrated circuit comprising a serial number register for storing a serial number unique to each card, and which number in said register in response to interrogations at said terminal being readable at said terminal, a prepaid units register for storing a number of units of prepaid value, and which number in said units register, in response to interrogations at said terminal being readable at said terminal, a key number register storing a key number, which has a first portion unique for each card, and a second portion which is common to a plurality of cards, and which is unique for a network operator, said key number in normal use of said card not being readable at said terminal, an algorithm stored in said card, said algorithm in normal use in said card not being readable in said terminal, a microprocessor for calculating a certificate in accordance with said algorithm as a function of said key number and the number in said prepaid register, and said certificate being readable at said terminal.