Method of digitally signing data and a data repository storing digitally signed data
AssigneeHewlett-Packard Development Company, L.P.
InventorsMark Henry Butler, Scott Alan Stanley
Life of this patent
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Abstract
A hierarchical digital signature method is provided by which different levels of data elements of a data entry are processed in turn to derive function values (for example hash function values) for data elements in the level which are to form part of the digital signature. All function values for one level are combined in a further function to provide an additional function value, and the additional function value is used in the processing of data elements in the next level nearer to the root. This provides a digital signature which can use only selected data elements of a data entry, and which is not sensitive to the ordering of the data entry structure.
Claims16
A method of providing a digital signature to a data entry for storing in a data repository, the data entry comprising a root and a tree of data elements at different levels from the root, the method comprising:
- identifying, by a processor, data elements of the data entry which are to be digitally signed;
- performing, by the processor, a function on those identified data elements in a level furthest from the root to obtain a first set of results relating to that level;
- performing, by the processor, the function on the first set of results to obtain a level function value derived from the identified data elements in the level;
- changing, by the processor, level to a new level one nearer to the root, and performing the function on a second set of results comprising those identified data elements in the new level as well as the level function value for the level one further from the root, thereby to obtain a level function value derived from the identified data elements in the new level,
- wherein the changing of level is repeated until the level is the first level after the root, and a single function value is obtained which combines function values for all of the identified data elements.
A data repository system comprising:
- a data repository;
- a client interface for instructions from client applications, wherein the client interface is configured to:
- receive a definition of a type of data to be stored;
- receive a definition of digital signature rules for the defined data type;
- and
- receive data for storing in the data repository,
- wherein the system further comprises a processor configured to:
- identify data elements of a data entry in the data repository which are to be digitally signed based on the digital signature rules, wherein the data entry has a root and a tree of data elements at different levels from the root;
- and
- perform a hierarchical digital signature algorithm by which different levels of the identified data elements of the data entry are processed in turn, wherein the hierarchical digital signal algorithm comprises:
- applying a digital signature function on those identified data elements in a level furthest from the root to obtain a first set of results relating to that level, the first set of results including function values produced by applying the digital signature function on the corresponding identified data elements;
- applying the digital signature function on the first set of results to obtain an additional function value derived from the identified data elements in the level;
- changing level to a new level one nearer to the root, and applying the digital signature function on a second set of results comprising function values for those identified data elements in the new level as well as the additional function value for the level one further from the root, thereby to obtain an additional function value derived from the identified data elements in the new level,
- wherein the changing of level is repeated until a single function value is obtained which combines the function values for all of the identified data elements.
A method of providing a digital signature to a data entry for storing in a data repository, the data entry comprising a root and a tree of data elements at different levels from the root, the method comprising:
- identifying, by a processor, data elements of the data entry which are to be digitally signed;
- performing, by the processor, a function on the identified data elements to obtain function values;
- and
- for each level of the data entry, obtaining a corresponding single combined function value which is used to represent the identified data elements in the level and in all levels further from the root, wherein for each level which is not the furthest level from the root, the corresponding single combined function value is obtained by applying the function on the function values of the identified data elements of the respective level and the single combined function value for the level one further from the root,
- wherein the single combined function value for the first level after the root comprises the digital signature.
Dependencies are inferred from the claim text.