Cryptography – Key management – Having particular key generator
Patent
1998-08-07
2000-04-04
Swann, Tod R.
Cryptography
Key management
Having particular key generator
380 44, 380 47, 275 41, 429 8, 331 78, H01L 4900
Patent
active
060470682
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention concerns a method for determining an encryption key associated with an integrated circuit. It also concerns a rendered secure integrated circuit implementing said method.
BACKGROUND OF THE INVENTION
The invention can be applied advantageously for rendering smart cards secure, especially the smart cards used in encrypted television.
Generally speaking, smarts cards comprise a plastic card body and an electronic module inserted in a cavity fitted in said card body. The electronic module is made up of an integrated circuit or chip placed on a support provided with metallic zones for ensuring the electric link between the module and a card reader. The integrated circuit can be an EEPROM type memory for, for example, telecard applications or a microprocessor for bank card, mobile `phone or even encrypted television applications.
Thus, most of the smart cards are used to carry out electronic transactions, which naturally implies that there is an attempt to defraud those systems using smart cards so as to be able to benefit from the services provided by these systems without paying for said services.
So as to avoid or, at least, limit the fraud, the information exchanged with the smart card electronic module are encrypted according to various well-documented methods. It merely suffices to be aware that the messages received by the integrated circuits of the cards are encrypted with keys known an encrypting keys and are stored in the non-volatile memory of the circuits. These keys can be protected against any external reading by masking the level of the memory plane in which they are recorded by several levels of metal serving as a screen whilst taking part in the dynamics of the circuit.
However, the degree of safety obtained is not absolute as it is always possible for an experienced defrauder to gain access to the secret keys via a functional analysis of the integrated circuit.
SUMMARY OF THE INVENTION
Also, the technical problem to be resolved by the object of the present invention concerns proposing a method for determining an encryption key associated with an integrated circuit having a memory plane, said method making it possible to reach a level for a much higher protection of the encryption keys owing in particular to a static storage of the keys outside the memory plane and therefore inaccessible by means of a functional analysis of the circuit.
According to the present invention, the solution to the technical problem consists of said method comprising the following stages: the surface of the memory plane, resistivity material, basis of the random distribution of the electric resistances connecting the various electric contacts C.sub.i of the matrix.
Thus, the resistively random structure of said layer is used as a generator of the encryption key Kr associated with the integrated circuit. This key is therefore never stored in the memory plane of the circuit and, because of this, is restored on each occasion the integrated circuit is charged. Furthermore, it can be observed that the material layer forms a screen which protects the circuit against fraudulent readings. If this layer is removed or altered, the key is modified and the information shall stay encrypted permanently. It is possible to read by a device external to the integrated circuit the values of the resistances taken into account by the method of the invention so as to determine the encrypting key Kr.
One first improvement consists of providing the integrated circuit with an alarm mechanism. This makes it possible to detect attempts of fraud and take particular steps, such as the erasing of sensitive information.
According to the invention, to achieve this, the stage (c) further includes the determination on initialization of the integrated circuit of another resistive key KA, known as an alarm key, which is entered in a non-volatile memory of said circuit, and said second resistive key KA is measured on each charging of the integrated circuit and compared with the stored value of KA, the en
REFERENCES:
patent: 3209279 (1965-09-01), Kambouris
patent: 3519952 (1970-07-01), Buegel
patent: 3675148 (1972-07-01), Edwards
patent: 4243950 (1981-01-01), Proud, Jr.
patent: 4272731 (1981-06-01), Day et al.
patent: 5886385 (1999-03-01), Arisumi et al.
Rhelimi Alain
Rigal Vincent
Rose Rene
Callahan Paul E.
Schlumberger Industries
Swann Tod R.
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