Integrated circuit identification system

Details Integrated circuit identification system Integrated circuit identification system

1998-01-02

2001-05-08

Dharia, Rupal (Department: 2181)

Electrical computers and digital processing systems: support

Multiple computer communication using cryptography

Protection at a particular protocol layer

C327S149000, C327S151000, C327S153000, C348S180000, C348S476000, C348S525000

Reexamination Certificate

active

06230270

ABSTRACT:

FIELD OF THE INVENTION
This invention generally relates to integrated circuit identification systems, and more particularly, to improved circuits and methods for identification systems for integrated circuits.
BACKGROUND OF THE INVENTION
Access control in a set top box, or in any other type of pay-per-view system, is often controlled by encrypting the material, and selectively decrypting the authorized material or program. For some conventional set top box chips, this conditional access/decryption scheme is controlled by a smart card containing the key management and accounting software, and a software application called the “verifier”.
The verifier is part of the application software supplied by a set top box manufacturer and by NDC (News Digital Systems); it is NDC which is responsible for the set top box security.
When a set top box manufacturer decides to use a particular decryption chip for their set top box, they have to port the verifier to their specific set top box, and then confirm that none of the final application software interferes with, or defeats the security system. This is often a very painful and expensive process. Expensive to the box manufacturer, and painful to both them and NDC to ensure the security system still works properly.
Further if critical parts of the NDC system become internal to an integrated circuit set top box chip, including the decryption function, NDC still desires a way to identify uniquely the system. Current settop boxes use a small EEPROM in the decryption chip with a unique serial number in it. Unfortunately, embedded EEPROM/flash capability is always process specific and does not shrink or migrate very readily as the decryption chip is shrunk or especially when an ASIC containing other settop box components and the decryption chip is shrunk. One alternative solution is to have a small EEPROM on the settop box system board that contains the serial number. While this approach works fine, it has two disadvantages: 1) the cost of the separate EEPROM, and 2) the ability of an unauthorized user to change the serial number by changing or re-programming the EEPROM.
Although it is important that each settop box IC or ASIC operate in the same manner electrically, it would be beneficial from a cost and security standpoint if the integrated circuit chip or ASIC containing the decryption function could generate a unique serial number.
These and other disadvantages of the prior art are overcome by the present invention, however, and improved methods and apparatus for identification systems for integrated circuits are provided.
SUMMARY OF THE INVENTION
Generally, and in one form of the present invention, an improved IC including decryption functions employs a method for determining if the environment of an integrated circuit has been modified, comprising: providing a first VCXO (voltage controlled crystal oscillator) as part of said integrated circuit, providing a second VCXO, adjusting one of said VCXOs in a first preselected manner, determining a first frequency count of said adjusted VCXO during a first preselected time interval using said other VCXO, adjusting said one of said VCXOs in a second preselected manner, determining a second frequency count of said adjusted VCXO during said first preselected time interval using said other VCXO, averaging said first and second frequency count to provide an average frequency count, adjusting said average frequency count in a predetermined manner, and comparing said adjusted average frequency count to a previously determined average frequency count to determine if the environment of said circuit has been modified.
The present invention provides a method for generating a unique electronic signature/characteristic for an integrated circuit, comprising: providing a first VCXO as part of said integrated circuit, providing a second VCXO, adjusting one of said VCXOs in a preselected manner, and determining said unique electronic characteristic from said adjusted VCXO during a preselected time interval using said other VCXO.
It is an object of the present invention to provide a method that allows a chip from a settop box IC or ASIC design to operate in the same manner electrically and still generate a unique serial number.
It is an object of the present invention to provide a method that allows a chip from a settop box IC or ASIC design to operate in the same manner electrically and still generate a unique serial number based upon variables of the system in which it is located.
These and other objects and advantages of the present invention will become apparent from the following detailed description wherein reference is made to the Figures in the accompanying drawings.


REFERENCES:
patent: 3952253 (1976-04-01), DeVolpi et al.
patent: 5097490 (1992-03-01), Hulsing, II et al.

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