Differential power analysis method and apparatus
First Claim
1. A method for evaluating the security of a cryptographic device to recover useful information about a key, said device containing at least said key and a circuit configured to perform cryptographic operations using said key, said method comprising:
- (a) connecting said device to an analog-to-digital converter configured to measure an attribute related to operation of said device;
(b) sending a plurality of command sequences to said device, where each said command sequence causes said device to perform a cryptographic operation to process data using said key;
(c) during processing of each said cryptographic operation, recording a plurality of measurements of said attribute by using said analog-to-digital converter; and
(d) determining whether information about said key is leaking from said device by statistically combining said recorded measurements.
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Accused Products
Abstract
Information leaked from smart cards and other tamper resistant cryptographic devices can be statistically analyzed to determine keys or other secret data. A data collection and analysis system is configured with an analog-to-digital converter connected to measure the device'"'"'s consumption of electrical power, or some other property of the target device, that varies during the device'"'"'s processing. As the target device performs cryptographic operations, data from the A/D converter are recorded for each cryptographic operation. The stored data are then processed using statistical analysis, yielding the entire key, or partial information about the key that can be used to accelerate a brute force search or other attack.
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Citations
19 Claims
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1. A method for evaluating the security of a cryptographic device to recover useful information about a key, said device containing at least said key and a circuit configured to perform cryptographic operations using said key, said method comprising:
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(a) connecting said device to an analog-to-digital converter configured to measure an attribute related to operation of said device;
(b) sending a plurality of command sequences to said device, where each said command sequence causes said device to perform a cryptographic operation to process data using said key;
(c) during processing of each said cryptographic operation, recording a plurality of measurements of said attribute by using said analog-to-digital converter; and
(d) determining whether information about said key is leaking from said device by statistically combining said recorded measurements. - View Dependent Claims (11, 13, 14, 15, 16, 17, 19)
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2. A method for evaluating the security of a cryptographic device to recover useful information about a key, said device containing at least said key and a circuit configured to perform cryptographic operations using said key, said method comprising:
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(a) connecting said device to an analog-to-digital converter configured to measure electromagnetic radiation during operation of said device;
(b) sending a plurality of command sequences to said device, where each said command sequence causes said device to perform a cryptographic operation to process data using said key;
(c) during processing of each said cryptographic operation, recording a plurality of measurements of said radiation by using said analog-to-digital converter; and
(d) determining whether information about said key is leaking from said device by statistically combining said recorded measurements. - View Dependent Claims (8, 9, 10)
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3. A method for evaluating the security of a cryptographic device to recover useful information about a key, said device containing at least said key and a circuit configured to perform cryptographic operations using said key, said method comprising:
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(a) connecting said device to an analog-to-digital converter configured to measure an amount of power consumed on an external power input to said device;
(b) sending a plurality of command sequences to said device, where each said command sequence causes said device to perform a cryptographic operation to process data using said key;
(c) during processing of each said cryptographic operation, recording a plurality of measurements of said power by using said analog-to-digital converter; and
(d) determining whether information about said key is leaking from said device by statistically combining said recorded measurements. - View Dependent Claims (4, 5, 6, 7)
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12. A system for evaluating the security of a cryptographic hardware, comprising:
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(a) a device containing at least a key and a circuit configured to perform cryptographic operations using said key;
(b) an analog-to-digital converter connected to said device and configured to measure an attribute related to operation of said device;
(c) data storage system configured to record a plurality of measurements of said attribute, where said measurements are taken by said analog-to-digital converter during processing of each said cryptographic operation; and
(d) statistical processing system for combining said measurements to determine whether information about said key is leaking from said device.
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18. A method for analyzing externally measurable characteristics of a cryptographic device, said device containing a secret key and configured to perform cryptographic operations with said key, to recover information about said key, said method comprising:
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(a) connecting said device to an analog-to-digital converter configured to measure said characteristic during operation of said device;
(b) during a said cryptographic operation, using said analog-to-digital converter to measure a plurality of measurements of said attribute;
(c) storing said set of measurements in a memory;
(d) repeating said (b) and (c) a plurality of times to produce a plurality of sets;
(e) computing the alignment of said measurements in said plurality of sets such that measurements corresponding to a single point of interest can be compared;
(f) generating a guess of a value of a portion of said key;
(g) using said guess, computing an average of a subset of said aligned measurements; and
(h) verifying correctness of said guess by detecting existence of a bias in said average.
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Specification