Electrical computers and digital processing systems: support – Multiple computer communication using cryptography – Protection at a particular protocol layer
Patent
1998-03-26
2000-05-02
Peeso, Thomas R.
Electrical computers and digital processing systems: support
Multiple computer communication using cryptography
Protection at a particular protocol layer
713168, 380255, G09C 308
Patent
active
060584815
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The present invention relates to a method and a circuit for producing an authentication code enabling the access to a microcircuit to be secure.
The present invention relates in particular to the field of smart cards, and more particularly to wired-logic microcircuits that are used in smart cards.
Under the generic term of "chip cards", two principal categories of cards are indeed meant, whose technology is different: on one hand, the microprocessor cards, and, on the other hand, the cards called "smart cards". Unlike microprocessor cards, smart cards are only provided with a wired-logic microcircuit, which offers much fewer possibilities in terms of facility of use, data processing ability, programming, and in particular in terms of security and fraud protection than a microprocessor microcircuit.
In compensation, wired-logic microcircuits have the advantage of a simpler structure and a very low cost price, so that smart cards have had an important development last years for applications where a high level of security was not necessary. Thus the use of pre-payment cards like telephone cards has been generalised. New applications such as electronic purses or electronic keys (in particular in the field of cars) are, at present, being considered for use on a large scale.
It is however necessary that wired-logic microcircuits should provide a much greater security level in the future than at present for the development of these numerous future applications and, as regards security in use, that they should be able to compete with microprocessor circuits which are provided with improved software security mechanisms.
Thus, a general purpose of the present invention is to improve the protection mechanisms of wired-logic microcircuits, keeping in mind that manufacturing costs rise very quickly when sophisticated security functions are to be performed.
As a reminder, FIG. 1 shows the structure and the working of a microcircuit 1 of a conventional smart card. The wired-logic microcircuit 1 mainly comprises a serial memory 2 (i.e. a bit by bit accessible memory), an authentication circuit 3 and a sequential logic circuit 4 which controls the functioning of the various elements by means of a clock signal H which is provided by a terminal 10 into which the card is inserted. The memory 2 contains, stored in bit form, a serial number of the card NI (or identification number of the microcircuit) and transaction data DA, for example data representing the monetary value of the card or a number of telephone pulses. The authentication circuit 3 has a serial input 3-1 for receiving an input code CE and a serial output 3-2 for producing an authentication code CA. Furthermore, the microcircuit 1 is provided with contact pins for the electrical interface with the terminal 10, among which an input-output contact pin I/O for the digital data communication, a contact pin RST for initialising the microcircuit, a contact pin H for the input of the clock signal and two contact pins Vcc and GND for power supply. The output of the memory 2 as well as the input 3-1 and the 30 output 3-2 of the authentication circuit are coupled to the input-output contact pin I/O. The digital data circulate in serial form, that is bit by bit in synchronism with the lock signal, which allows a simplification of the internal structure of the circuit, as the connections between the various elements are limited to one wire only.
When the card is inserted into the terminal 10, the terminal 10 has to determine, for security reasons, if the card is authentic or fraudulent. The authentication circuit 3 thus takes part into a verification procedure as hereunder described for verifying the authenticity of the card. It is first recalled that the terminal 10, which is generally provided with a microprocessor 11 controlled by a programme memory 12, knows the secrets of the security mechanisms introduced into the card.
Step 1--The terminal 10 generates a random binary code ALEXT and applies it as an input code CE to the authentication circu
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Inside Technologies
Peeso Thomas R.
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