Data processing: measuring – calibrating – or testing – Measurement system in a specific environment – Chemical analysis
Reexamination Certificate
1999-02-23
2001-02-06
Wachsman, Hal (Department: 2857)
Data processing: measuring, calibrating, or testing
Measurement system in a specific environment
Chemical analysis
C702S031000, C702S032000, C714S030000, C713S194000
Reexamination Certificate
active
06185507
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a microprocessor, in particular for use in a chip card, with a control unit and with a housing surrounding the control unit. Furthermore, the invention relates to a chip card with such a microprocessor.
To an increasing degree, payment processes for relatively small amounts of money are processed with the aid of a chip card system. In this respect, a chip card has the function of a “money storage facility”. There being provided on a chip card a microprocessor which has a control unit, a data memory for storing the amount of money stored on the chip card, interfaces, in particular for inputting and outputting data which are relevant to payments, a control device for controlling the processing procedure of the data which are processed in conjunction with the chip card, and an instruction memory which stores the operating program for the control device. Such chip card systems are used in the field of credit cards, in pay TV application systems and also in systems for monitoring access to devices concerned with security and to buildings.
Shortly after the introduction of the first chip card systems, attempts were made to manipulate chip cards in order to obtain illegitimate advantages with such manipulated chip cards. For example, attempts have been made to simulate chip cards and to provide their data memories with a manipulated credit balance.
This has been counteracted by encrypting the data present in the data memory of the chip card in such a way that it is no longer possible to simulate the data. For this purpose, algorithms such as DES (Data Encryption Standard), PES (Proposed Encryption Standard), DSA (Digital Signature Algorithm), DEA (Data Encryption Algorithm), and RSA (Reversed Shamir-Adelman Cryptoalgorithm) are used.
However, a significant weakness of known chip card systems continues to be that the microprocessor, which is surrounded by a housing, can easily be exposed. To do this, the housing of the microprocessor is subjected to an aggressive substance, such as an acid for example, over a specific period of time, so that the housing is etched away and the microprocessor is exposed. The structural configuration of the exposed microprocessor can then be analyzed. In order to do this, different input signals can be applied to the terminals of the microprocessor, so that information on the program, present in the instruction memory, for controlling the processing procedure can be acquired. This information can be used to decrypt, for example, the data in the data memory.
Published, European Patent Application EP 0 565 480 A2 discloses how to use indicator elements in chip cards which react in an unambiguous and discernible fashion to physical influences or other influences aimed at destroying the function of chip the cards.
Published, Non-Prosecuted German Patent Application DE 41 15 398 A1 discloses a method for manufacturing a biosensor with a planarized surface which reduces the risk of diaphragms tearing. It includes the steps of producing a gate insulator, producing and structuring a polysilicon layer, implementing a source and a drain, exposing an active gate region, arranging an ISFET within a housing in such a way that the active gate region of the ISFET comes to be situated within a window of the housing, and applying the biological or biochemical diaphragm to the active gate region.
The paper “An ISFET-FIA System for High Precision pH Recording” in Sensors and Actuators B, 15-16 (1993) 68-74 (P. Woias et al.) discloses an ISFET sensor for measuring a pH value in a fluid which has a high degree of stability and high measuring accuracy even at low flow velocities.
Published, European Patent Application EP 0 481 881 A1, corresponding to U.S. Pat. No. 5,465,349, discloses an integrated circuit which has a program memory, a data memory, an I/O port and a register. The register stores the signals of the sensors for unusual operating conditions. When unusual operating conditions occur, the microprocessor stops operating.
SUMMARY OF THE INVENTION
It is accordingly an object of the invention to provide a microprocessor, in particular for use in a chip card, with a control unit and with a housing surrounding the control unit that overcomes the above-mentioned disadvantages of the prior art devices of this general type, which are protected against manipulation.
With the foregoing and other objects in view there is provided, in accordance with the invention, a microprocessor, including: a control unit; a housing surrounding the control unit; at least one sensor connected to the control unit and disposed in a region of the housing and outputting a sensor measurement signal; at least one substance disposed in the region of the housing and being detectable by the at least one sensor, the at least one substance having at least two components, at least one of the at least two components present in a predefined concentration detectable by the at least one sensor; a memory connected to the control unit, the sensor measurement signal generated by the at least one sensor containing a value reflective of the predefined concentration being received by the control unit and stored in the memory; and The control unit going into an inactive state if the sensor measurement signal differs from a predefined threshold concentration.
The object is in particular achieved according to the invention in that at least one sensor which indicates ambient states and which is connected to the control unit is provided in the region of the housing of the microprocessor. The control unit is configured in such a way that it can be placed in an inactive state if a measurement signal that indicates a predetermined ambient state is fed to it from the sensor.
Alternatively, the control unit can also be configured in such a way that it can be placed in an inactive state if no measurement signal that indicates a specific ambient state is fed to it from the sensor.
The invention is based on the basic idea of providing a chip card with a microprocessor which can no longer easily be exposed by chemical and/or physical methods without significantly deactivating or destroying the microprocessor itself. For this purpose, a sensor that is connected to the control unit is provided. The control unit regularly senses the sensor and checks whether the sensor is indicating an ambient state that corresponds, for example, to the ambient state when the microprocessor was fabricated. If the ambient state in the region of the sensor is modified, for example by applying a chemical, the signal originating from the sensor changes, and this is sensed and detected by the control unit. In this case, the control unit goes into an inactive state, so that, even when a microprocessor has been exposed, its function can no longer easily be discerned. With regard to the above, the term “control unit” is to be understood in a broad sense, that is to say any component of the microprocessor or of the chip card may be deactivated as long as it is ensured that access to the data or to the structure of the data memory, program memory or control unit is prevented or made more difficult.
According to the invention, it is also possible to provide a sensor which indicates as an “ambient state”, in particular, the presence of typical chemicals used for exposing microprocessors. For example, sensors that respond to acids can be used. If such a sensor indicates the presence of an acid in the region of the housing, it can be assumed that an attempt has been made to manipulate the microprocessor. This is sensed by the control unit, in response to which it goes into an inactive state.
According to the invention, the two embodiments are also possible at the same time, at least two sensors or one sensor with a double function then being provided. In this case, the control unit is configured in such a way that it can be placed in an inactive state if one sensor feeds it a measurement signal which indicates a predetermined “suspicious” ambient state and/or if the other sensor st
Heitzer Josef
Huber Michael
Stampka Peter
Greenberg Laurence A.
Lerner Herbert L.
Siemens Aktiengesellschaft
Stemer Werner H.
Wachsman Hal
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