Integrated circuit identification system
First Claim
1. A method for determining if a system in which an integrated circuit is operating has been altered, changed or modified, comprising:
- providing a first voltage controlled crystal oscillator (“
VCXO”
) as part of said integrated circuit, providing a second VCXO as part of said system or said integrated circuit, 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 determined by said other VCXO, and comparing said frequency count to a previously stored, determined or provided frequency count to determine if said system in which said circuit is operating has been altered, changed or modified.
1 Assignment
0 Petitions
Accused Products
Abstract
An improved integrated circuit including decryption functions employs a method for determining if its environment has been modified, by providing a first VCXO as part of the integrated circuit, providing a second VCXO, adjusting one of the VCXOs in a first preselected manner, determining a first frequency count of the adjusted VCXO during a first preselected time interval using the other VCXO, adjusting the one of the VCXOs in a second preselected manner, determining a second frequency count of the adjusted VCXO during the first preselected time interval using the other VCXO, averaging the first and second frequency count to provide an average frequency count, adjusting the average frequency count in a predetermined manner, and comparing the adjusted average frequency count to a previously stored, determined, or provided average frequency count to determine if the environment of the integrated circuit has been modified.
95 Citations
19 Claims
-
1. A method for determining if a system in which an integrated circuit is operating has been altered, changed or modified, comprising:
-
providing a first voltage controlled crystal oscillator (“
VCXO”
) as part of said integrated circuit,providing a second VCXO as part of said system or said integrated circuit, 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 determined by said other VCXO, and comparing said frequency count to a previously stored, determined or provided frequency count to determine if said system in which said circuit is operating has been altered, changed or modified. - View Dependent Claims (2, 3, 4, 5, 6)
-
-
7. A method for determining if an environment in which an integrated circuit operates has been modified, comprising:
-
providing a first voltage controlled crystal oscillator (“
VCXO”
) as part of said integrated circuit,providing a second VCXO as part of said environment or said integrated circuit, 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 determined by 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 determined by 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 said environment in which said circuit operates has been modified. - View Dependent Claims (8, 9, 10, 11, 12)
-
-
13. A method for generating a unique electronic signature for an integrated circuit, comprising:
-
providing a first voltage controlled crustal oscillator (“
VCXO”
) as part of said integrated circuit,providing a second VCXO as a part of said integrated circuit or an external circuit associated with said integrated circuit, adjusting one of said VCXOs in preselected manner, and determining a unique electronic characteristic from said adjusted VCXO during a preselected time interval determined by said other VCXO. - View Dependent Claims (14, 15, 16)
-
-
17. Circuitry for generating a unique electronic signature for an integrated circuit, comprising:
-
a first voltage controlled crystal oscillator (VCXO) which is a portion of said integrated circuit;
a second VCXO which is a portion of said integrated circuit or an external circuit associated with said integrated circuit;
a counter coupled to said first VCXO for producing a frequency count of said first VCXO by counting output cycles of said first VCXO; and
said counter also coupled to said second VCXO and responsive to output cycles produced by said second VCXO for counting a number of output cycles of said first VCXO that occur during a time interval derived from said output cycles of said second VCXO. - View Dependent Claims (18, 19)
-
Specification