Upgradeable timestamp mechanism
AssigneeStorage Technology Corporation
InventorsJames P. Hughes, Axelle Apvrille
Life of this patent
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Abstract
A method, computer program product, and data processing system for generating and validating an upgradeable digital timestamp of a document is disclosed. The digital timestamp includes a hash value, a current time, and a digital signature. Over time, as computer and cryptanalytic technology progresses, upgrade timestamps are applied to the document that take advantage of more advanced, more difficult to break hash functions or digital signature schemes. These upgrade timestamps are applied preventatively at a point in time just prior to the timestamp's being able to be compromised.
Claims48
A method of upgrading the integrity of a first timestamp having a first digital signature, the method comprising:
- computing a hash value of the first digital signature;
- combining the hash value with a current time value to form a second data item;
- computing a second digital signature based on the second data item;
- and
- combining the second data item and the second digital signature to form a second timestamp.
A method of upgrading the integrity of a first timestamp of a document, wherein the first timestamp includes a first hash value computed with a first hash function, the method comprising:
- calculating a second hash value of the document using a second hash function;
- combining the second hash value with a current time value to form a data item;
- computing a digital signature of the data item;
- and
- combining the digital signature and the data item to form a second timestamp.
A method of verifying the integrity of an upgrade timestamp associated with an earlier timestamp, comprising:
- verifying integrity of a first digital signature associated with the upgrade timestamp;
- calculating a first hash value of a second digital signature associated with the earlier timestamp;
- and
- verifying that the first hash value matches a second hash value associated with the upgrade timestamp.
A method comprising:
- verifying integrity of each of a plurality of digital signatures, wherein each of the plurality of digital signatures signs a timestamp, and each timestamp includes a hash value of a common document, each hash value having been calculated with a different hash function.
A computer program product in a computer readable medium for upgrading the integrity of a first timestamp having a first digital signature, comprising functional descriptive data that, when executed by a computer, enables the computer to perform acts including:
- computing a hash value of the first digital signature;
- combining the hash value with a current time value to form a second data item;
- computing a second digital signature based on the second data item;
- and
- combining the second data item and the second digital signature to form a second timestamp.
A computer program product in a computer readable medium, for upgrading the integrity of a first timestamp of a document, wherein the first timestamp includes a first hash value computed with a first hash function, comprising functional descriptive data that, when executed by a computer, enables the computer to perform acts including:
- calculating a second hash value of the document using a second hash function;
- combining the second hash value with a current time value to form a data item;
- computing a digital signature of the data item;
- and
- combining the digital signature and the data item to form a second timestamp.
A computer program product in a computer-readable medium, for verifying the integrity of an upgrade timestamp associated with an earlier timestamp, comprising functional descriptive data that, when executed by a computer, enables the computer to perform acts including:
- verifying integrity of a first digital signature associated with the upgrade timestamp;
- calculating a first hash value of a second digital signature associated with the earlier timestamp;
- and
- verifying that the first hash value matches a second hash value associated with the upgrade timestamp.
A computer program product in a computer-readable medium, comprising functional descriptive data that, when executed by a computer, enables the computer to perform acts including:
- verifying integrity of each of a plurality of digital signatures, wherein each of the plurality of digital signatures signs a timestamp, and each timestamp includes a hash value of a common document, each hash value having been calculated with a different hash function.
A data processing system for upgrading the integrity of a first timestamp having a first digital signature, comprising means for:
- computing a hash value of the first digital signature;
- combining the hash value with a current time value to form a second data item;
- computing a second digital signature based on the second data item;
- and
- combining the second data item and the second digital signature to form a second timestamp.
A data processing system for upgrading the integrity of a first timestamp of a document, wherein the first timestamp includes a first hash value computed with a first hash function, the data processing system comprising means for:
- calculating a second hash value of the document using a second hash function;
- combining the second hash value with a current time value to form a data item;
- computing a digital signature of the data item;
- and
- combining the digital signature and the data item to form a second timestamp.
A data processing system for verifying the integrity of an upgrade timestamp associated with an earlier timestamp, comprising means for:
- verifying integrity of a first digital signature associated with the upgrade timestamp;
- calculating a first hash value of a second digital signature associated with the earlier timestamp;
- and
- verifying that the first hash value matches a second hash value associated with the upgrade timestamp.
A data processing system comprising means for:
- verifying integrity of each of a plurality of digital signatures, wherein each of the plurality of digital signatures signs a timestamp, and each timestamp includes a hash value of a common document, each hash value having been calculated with a different hash function.
Dependencies are inferred from the claim text.