Patent
1996-07-15
1998-12-15
Peeso, Thomas
395284, 395285, G01R 3100
Patent
active
058505245
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a method for testing the authenticity of a data carrier according to the preamble of claim 1. The invention relates further to a data carrier assembly for carrying out the method.
2. Description of Related Art
A method for authenticity testing is known e.g. from EP-A1 0 321 728. In the known method the data carrier is switched by a control signal transmitted by an external device from the normal mode to the checking mode in which authenticity testing takes place. For this purpose the data carrier has an additional switching logic which performs this switch-over in accordance with the external signal. In the checking mode the data carrier is then fed checking data from outside which are processed by an additional electronic circuit, e.g. in the form of an analog computer. The time the analog computer takes to process the checking data constitutes an authenticity feature for the data carrier. In the known method the authenticity testing occurring in the checking mode of the data carrier is decoupled from the normal mode so that the normal mode, which as a rule follows standardized protocols, is not disturbed by the authenticity testing. However this means that a switch-over by means of the additional switching logic from the normal mode to the checking mode is necessary before each authenticity testing.
SUMMARY OF THE INVENTION
The objective of the invention is to propose a method for testing the authenticity of a data carrier wherein the authenticity testing is compatible with existing standardized protocols and can be done with low circuit complexity.
This problem is solved by the features stated in claim 1.
The basic idea of the invention is that the first transmission or receptinon of data used for authenticity testing occurs during the power-up sequence for the data carrier in which the data line has as yet no defined state for data exchange with an external device. For example the data line can be in an undefined state for a defined time domain during the power-up sequence according to the standard ISO/IEC 7816-3. Since the first transmission or reception of data is completed within the time domain defined by the standard, the data exchange standardized for communication with chip cards is not disturbed. The test procedure can therefore take place according to the invention with existing protocols conforming to standards.
The data carrier has an additional special circuit which transmits to, or receives from, an external device the data required for authenticity testing within said time domain for which the data line need have no state defined by the protocol.
In a first embodiment e.g. an identification of the data carrier realized in hardware can be transmitted to the external device within said time domain. The external device, e.g. card reading device, likewise has a special circuit permitting reception of the data transmitted by the card within this time domain so that the device can perform authenticity testing. But even if the device has no such special circuit and is thus not in a position to receive the data transmitted by the card within said time, the communication protocol is not disturbed by transmission of the data. Therefore no errors can occur in the protocol run when the card communicates with a conventional device within this time.
According to a development the special circuit located on the integrated circuit of the data carrier can also generate a random number within said time domain which is then logically combined with the data carrier identification by the special switching logic of the data carrier, the result of combination being transmitted from the data carrier to the external device within said time domain, but at the latest in the answer-to-reset signal (ATR). The use of a random number makes a replay attack impossible, i.e. replay of tie previously transmitted data.
In a further embodiment the external device, e.g. card reading device, can also have an additional circuit which serves to g
REFERENCES:
patent: 5148435 (1992-09-01), Ray, Jr. et al.
patent: 5612961 (1997-03-01), Cabezas et al.
Effing Wolfgang
Lamla Michael
Rankl Wolfgang
Weikmann Franz
Giesecke & Devrient GmbH
Peeso Thomas
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