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Controlling access to device-specific informationControlling access to device-specific information description/claimsThe Patent Description & Claims data below is from USPTO Patent Application 20070183194, Controlling access to device-specific information. Brief Patent Description - Full Patent Description - Patent Application Claims
RELATED APPLICATIONS [0001] This application is a continuation of U.S. application Ser. No. 10/407,603, "AUTHENTICATION OF INTEGRATED CIRCUITS," filed Apr. 4, 2003, and published as US2003/0204743A1 on Oct. 30, 2003, which claims priority to U.S. Provisional Application Ser. No. 60/373,140, filed Apr. 16, 2002, U.S. Provisional Application Ser. No. 60/387,373, filed Jun. 10, 2002, U.S. Provisional Application Ser. No. 60/444,910, filed Feb. 3, 2003, and U.S. Provisional Application Ser. No. 60/444,906, filed Feb. 3, 2003. Each of the above listed applications is incorporated herein by reference. [0002] This application is also related to the following U.S. applications filed concurrently with the present application: Ser. No. ______, "INTEGRATED CIRCUIT THAT USES A DYNAMIC CHARACTERISTIC OF THE CIRCUIT," Attorney Docket No. 01997-309002; Ser. No. ______, "DATA PROTECTION AND CRYPTOGRAPHIC FUNCTIONS USING A DEVICE-SPECIFIC VALUE," Attorney Docket No. 01997-309003; and Ser. No. ______, "RELIABLE GENERATION OF A DEVICE-SPECIFIC VALUE," Attorney Docket No. 01997-309004. TECHNICAL FIELD [0004] This invention relates to authentication of integrated circuits. BACKGROUND [0005] Integrated circuits that are fabricated using the same lithography masks can be uniquely identified by embedding a unique identifier in the chip, such as a serial number embedded in the chip by the manufacturer. Another example of generating a unique identifier is to incorporate an array of transistors in the chip, measure the threshold voltages of the transistors in the array, and output the measurements as the identifier. For a given number of chips made from the same lithography masks, if the number of transistors in the array is large enough, the identifiers generated from the array will be unique. Due to process variations in the fabrication of the chip, no two chips will have arrays of transistors whose threshold voltages are exactly the same. [0006] A secret key embedded in a chip can be used to authenticate the chip. Authentication means proving to a user that the chip is not a counterfeit, or proving that certain processing results are processed by the chip and not some other chip. For example secret keys are embedded in a smartcard. A card reader can authenticate a smartcard by asking smartcard to prove a particular secret key that is stored in a database. If there is a match, the smartcard is authenticated, and the card reader can proceed to transact with the smartcard. The secret key needs to remain secret so that an adversary cannot duplicate the key and falsify identity. [0007] An adversary may probe the chip to attempt to find the secret key using invasive methods, e.g., removal of the package and layers of the integrated circuit, or non-invasive methods, e.g., differential power analysis that attempts to determine the key by stimulating the integrated circuit chip and observing the power and ground rails. To prevent physical invasion of the chip, sensing circuitry may be included in the packaging of the chip to detect intrusion and erase sensitive information upon detection of intrusion. SUMMARY [0008] In one aspect, in general, a method for providing access to device-specific information includes providing a first value to the device, and then, in the device, using a second value that is a first one-way function of the provided first value to determine a third value such that the third value is a device-specific function of the second value. The third value is then accepted from the device and stored outside the device. Subsequent to accepting the third value from the device, the second value is provided to the device. In the device, the provided second value is used to determine the third value once again and a fourth value is determined that is a second one-way function of the third value. This determining of the fourth value is performed without disclosing the third value outside the device. The fourth value is accepted from the device. [0009] Aspects can include one or more of the following features. [0010] The accepted fourth value is compared with a value determined using the stored third value. [0011] At least one of the first one-way function and the second one-way function comprises a random hash function. [0012] The second one-way function comprises a message authentication code (MAC). [0013] The device-specific function comprises a function that depends on fabrication parameters that vary among like devices. [0014] The second value is computed in the device as the first one-way function of the provided first value. [0015] The second value is computed outside the device as the first one-way function of the first value. [0016] The second value is stored in association with the third value outside the device. [0017] In another aspect, in general, a method for accessing to a device-specific function implemented in a device involves two modes. In a first mode, a first value is provided to the device, and a third value is accepted from the device. The third value is the device-specific function applied to a second value that is determined from the first value. In a second mode, the second value is provided to the device, and a fourth value is accepted from the device. The fourth value depends on the third value. Disclosure of the third value in response to providing the second value to the device is prevented. [0018] Aspects can include one or more of the following features. [0019] The fourth value accepted from the device is compared with a fifth value computed from the accepted third value. For example, the comparison includes determining whether the fourth value matches the fifth value. [0020] In another aspect, in general, a method for operating a device involves two modes. In a first mode, a first value is accepted at the device, and a third value is provided from the device. The third value is a device-specific function applied to a second value that is determined from the first value. In a second mode, the second value is accepted at the device, and a fourth value that depends on the third value is provided from the device. Disclosure of the third value from the device in response to providing the second value to the device is prevented. [0021] Aspects can include one or more of the following features. Continue reading about Controlling access to device-specific information... Full patent description for Controlling access to device-specific information Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Controlling access to device-specific information patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. Fill in the keywords to be monitored. 3. Each week you receive an email with patent applications related to your keywords. Start now! - Receive info on patent apps like Controlling access to device-specific information or other areas of interest. ### Previous Patent Application: 3-level non-volatile semiconductor memory devices and related methods Next Patent Application: Non-volatile memory device with periodic refresh and method of programming such a device Industry Class: Static information storage and retrieval ### FreshPatents.com Support Thank you for viewing the Controlling access to device-specific information patent info. IP-related news and info Results in 0.61615 seconds Other interesting Feshpatents.com categories: Novartis , Pfizer , Philips , Polaroid , Procter & Gamble , 174 |
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