Assessing cryptographic entropy
AssigneeCerticom Corp.
InventorDaniel Richard L. Brown
Life of this patent
Estimating the term…
Abstract
Systems, methods, software, and combinations thereof for evaluating entropy in a cryptography system are described. In some aspects, sample values are produced by an entropy source system. A typicality can be determined for each of the sample values. A grading is determined for preselected distributions based on the typicalities of the sample values. A subset of the preselected distributions are selected based on the gradings. An entropy of the entropy source system is calculated based on the subset of the plurality of distributions.
Claims16
A method for assessing entropy in a cryptography system, the method comprising:
- obtaining a sample value produced by an entropy source system;
- determining a typicality grading for each of a preselected plurality of probability distributions, the typicality gradings providing a comparison among the plurality of probability distributions, the typicality grading for each individual probability distribution being determined based on the cumulative probability of values that are, according to that individual probability distribution, less probable than the sample value;
- wherein the typicality grading gk(x,p) for each individual probability distribution is determined according to:
- g
- k
-
- (
- x
- ,
- p
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- =
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- ∑
- y
- :
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- p
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-
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-
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- +
- k
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- =
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- where k ε [0,1] represents an inclusivity level between zero and one inclusive, Pp (x) represents the probability of the sample value x according to the individual probability distribution p, and y:
- Pp (y) <Pp (x) represents the values that are less probable than the sample value;
- selecting a subset of the plurality of probability distributions based on the typicality gradings;
- and
- calculating an entropy of the entropy source system based on the subset of the plurality of probability distributions.
A method for assessing entropy in a cryptography system, the method comprising:
- obtaining a sample value produced by an entropy source system;
- determining a typicality grading for each of a preselected plurality of probability distributions, the typicality gradings providing a comparison among the plurality of probability distributions, the typicality grading for each individual probability distribution being determined based on the cumulative probability of values that are, according to that individual probability distribution, less probable than the sample value;
- wherein the cumulative probability of values that are less probable than the sample value comprises the sum:
- (
- ∑
- y
- :
- P
- p
-
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- y
- )
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- P
- p
-
- (
- x
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-
-
- P
- p
-
- (
- y
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- )
- ,
- where Pp (x) represents the probability of the sample value x according to the individual probability distribution p, and y:
- Pp (y) <Pp (x) represents the values that are less probable than the sample value;
- selecting a subset of the plurality of probability distributions based on the typicality gradings;
- and
- calculating an entropy of the entropy source system based on the subset of the plurality of probability distributions.
Dependencies are inferred from the claim text.