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Methods, apparatuses, and systems for identifying a digital fingerprint. One embodiment compensates for the inaccuracies resulting from the unstable nature of the circuits that yield digital fingerprints and, therefore, allows for reliable identification of these digital fingerprints. According to o

Methods, apparatuses, and systems for identifying a digital fingerprint. One embodiment compensates for the inaccuracies resulting from the unstable nature of the circuits that yield digital fingerprints and, therefore, allows for reliable identification of these digital fingerprints. According to one embodiment, the digital fingerprint (identification) is divided into a plurality of sections and stored in a database. According to this embodiment, fingerprints are identified by comparing the sections of the fingerprint to be identified with corresponding sections of the fingerprints stored in the database. The matching fingerprint, in one embodiment, is the fingerprint associated with a statistically sufficient number of matching fingerprint sections. Other embodiments of the present invention optimize the section lookup methodology based on the stability of the sections of the fingerprint.

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What is claimed is: 1. A method for resolving the most probable digital fingerprint from a circuit, the circuit outputting a digital fingerprint comprising a series of bits, the method comprising the steps of: (a) polling the circuit, the circuit being disposed on a silicon die and comprising two o

What is claimed is: 1. A method for resolving the most probable digital fingerprint from a circuit, the circuit outputting a digital fingerprint comprising a series of bits, the method comprising the steps of: (a) polling the circuit, the circuit being disposed on a silicon die and comprising two or more devices formed on the silicon die, for a digital fingerprint, the digital fingerprint being based at least in part on an electrical characteristic of the two or more devices of the circuit due to a process by which the silicon die was manufactured, wherein the digital fingerprint comprises at least two sections, each section comprising a series of bits; (b) recording the digital fingerprint; (c) repeating steps (a) and (b) a desired number of times to result in one or more fingerprinting values for a corresponding iteration of said polling and said recording; (d) calculating a most probable digital fingerprint from the one or more fingerprinting values yielded in steps (a)-(c); (e) calculating a stability value of each bit in said digital fingerprint; and (f) for each section, storing the stability value of the least stable bit in each section in association with a section identifier and the most probable digital fingerprint calculated in step (d). 2. The method of claim 1 further comprising the step of (e) storing the most probable digital fingerprint. 3. The method of claim 1 further comprising the step of (g) transmitting the most probable digital fingerprint calculated in step (d), and the section identifiers and corresponding stability values stored in step (f). 4. The method of claim 1 further comprising the step of (g) transmitting at least two section identifiers and corresponding sections of the most probable digital fingerprint, the sections having the highest stability values calculated in step (e). 5. The method of claim 4 wherein the number of sections transmitted in step (g) is statistically sufficient to find a matching digital fingerprint. 6. An apparatus providing a digital fingerprint comprising: a digital fingerprint circuit, said digital fingerprint circuit outputting a digital fingerprint comprising a plurality of bits corresponding to electrical characteristics of a plurality of devices, the digital fingerprint circuit being disposed on a silicon die and comprising the plurality of devices formed on the silicon die, the digital fingerprint being based at least in part on an electrical characteristic of the plurality of devices of the circuit due to a process by which the silicon die was manufactured; and a control circuit, said control circuit operably connected to the digital fingerprint circuit and programmed to iteratively read the digital fingerprint a predetermined number of times; wherein the control circuit calculates the most probable digital fingerprint based on the iterative reads of the digital fingerprint circuit, wherein the digital fingerprint comprises a plurality of sections, each of the sections comprising a plurality of bits, wherein the control circuit calculates a stability value for each bit of the digital fingerprint, and wherein, for each section of the digital fingerprint, the control circuit stores in the memory the stability value of the least stable bit. 7. The apparatus of claim 6 further comprising a memory operably connected to the control circuit; wherein the control circuit stores the most probable digital fingerprint in the memory. 8. The apparatus of claim 6 wherein the control circuit calculates a stability value for at least one bit of the digital fingerprint based on the iterative reads of the digital fingerprint circuit. 9. The apparatus of claim 6 further comprising means for transmitting the digital fingerprint and the stability values stored in the memory. 10. A method for resolving an identification, said method comprising the steps of (a) receiving a digital fingerprint corresponding to characteristics of a circuit, the circuit being disposed on a silicon die and comprising two or more devices formed on the silicon die, the digital fingerprint being based at least in part on an electrical characteristic of the two or more devices of the circuit due to a process by which the silicon die was manufactured; (b) dividing the digital fingerprint into at least two sections, the sections comprising a series of bits; (c) storing the sections in association with an index identification in a database; (d) repeating steps (a)-(c) a desired number of times; (e) calculating a stability value of each bit in said digital fingerprint; (f) for each section, storing the stability value of the least stable bit in each section in association with a section identifier; (g) scanning the database for sections stored in step (c) that match the sections of step (b); and (h) selecting the index identification associated with a statistically sufficient number of matching sections. 11. The method of claim 10 wherein said storing step (c) comprises the steps of (c1) storing each section in a separate table in association with the index identification. 12. The method of claim 11 wherein separate database servers support each table. 13. A method for identifying a digital fingerprint corresponding to an integrated circuit from a database including a population of fingerprints, the method comprising the steps of: (a) receiving a digital fingerprint of the integrated circuit, the integrated circuit comprising two or more devices formed on the integrated circuit, the digital fingerprint being based at least in part on an electrical characteristic of the two or more devices of the integrated circuit due to a process by which the integrated circuit was manufactured, wherein the digital fingerprint comprises at least two sections, wherein the sections comprise a series of bits; (b) receiving section identifiers and corresponding stability values for each section of the digital fingerprint; (c) for each section, storing the stability value of the least stable bit in association with the section identifier; (d) using sections having the highest stability values, scanning for sections of the fingerprints stored in the database that match corresponding sections of the digital fingerprint received in step (a); (e) selecting the digital fingerprint stored in the database associated with a statistically sufficient number of matching sections. 14. The method of claim 13 wherein the database comprises at least two section tables each of which stores a separate section of the fingerprints in association with a corresponding index identification; and wherein the scanning step (d) comprises scanning the section tables with corresponding sections of the digital fingerprint received in step (a). 15. The method of claim 14 wherein a separate database server supports each section table. 16. The method of claim 14 further comprising the steps of (f) if no digital fingerprint corresponds to a statistically sufficient number of matching sections, scanning the database for all sections stored in the section tables that match the sections received in step (a); and, (g) selecting the digital fingerprint associated with a statistically sufficient number of matching sections.