Patent ID: 6105862
Filing Date: 2000-08-22
Classification: G06Q,G07F

Abstract:
A method for performing electronic transactions between a card, a service provider having at least one terminal configured to accept said card and a centralized system configured to be connected to said terminal, each card having a card secret key and a card certificate which is a function of a card identity and of two card parameters defining a card public key, said function depending on said card secret key, each card further having a card secret debit key based on said card identity, said terminal having a terminal identity and knowing said card public key, said centralized system knowing said card secret debit key based on said card identity, said method comprising the steps of:transmitting from the terminal to the card the terminal identity and a parameter comprising at least a sum to be debited from a card balance;checking by said card that said card balance is not lower than said sum;computing by said card a first signature which is a function of the card secret debit key and of said parameter transmitted from the terminal;debiting by said card the sum from the card balance, said first signature being a proof that the sum has been debited from the card balance;computing by said card a second signature which is a function of said parameter transmitted from the terminal and of said first signature using said card secret key;transmitting from the card to the terminal said first signature, said second signature and said card certificate;checking by said terminal said card certificate by using the card public key;recovering by said terminal the card identity and the two parameters of said card;checking by said terminal said second signature by using the card public key;storing in said terminal data corresponding to said first signature, said parameter transmitted from the terminal and said card identity for performed transactions;collecting said data corresponding to performed transactions by said centralized system;obtaining by the centralized system secret debit keys corresponding to identities of cards having performed a transaction;checking by the centralized system first signatures, computed by said cards, based on card secret debit keys of said cards; andcrediting the service provider of sums on condition that said first signatures check with said card secret debit keys.