Multi signature verification system, electronic signature attaching apparatus, data addition apparatus, and electronic signature verification apparatus
AssigneeNtt Docomo, Inc.
InventorsHiroshi Fujimoto, Takashi Suzuki, Takehiro Nakayama, Atsushi Takeshita
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Abstract
A multi signature verification system adds new additional data to original data with a signature attached thereto and verifies validity of the original data and the additional data. The system includes an electronic signature attaching apparatus including an electronic signature attaching unit attaching an electronic signature to original data previously created, acquired trapdoor hash value, and identification information, a data addition apparatus, and an electronic signature verification apparatus.
Claims9
A multi-signature verification system configured to add an additional data to an original data previously created and configured to verify the original data and the additional data, the system comprising:
- an electronic signature attaching apparatus including an electronic signature attaching unit configured to attach an electronic signature to the original data previously created, to a first trapdoor hash value created by a data addition apparatus, and to an identification information;
- the data addition apparatus including:
- a data adding unit configured to add additional data including at least new created data to the original data;
- and
- a determination value calculating unit configured to calculate a determination value distinct from the electronic signature, such that an output of a trapdoor hash function using the determination value and the additional data as an input is equal to the first trapdoor hash value created by the data addition apparatus;
- and
- an electronic signature verification apparatus including:
- a trapdoor hash value calculating unit configured to calculate a second trapdoor hash value based on the additional data and the determination value;
- and
- a verifying unit configured to verify the additional data by comparing the second trapdoor hash value calculated by the trapdoor hash value calculating unit and the first trapdoor hash value created by the data addition apparatus, wherein
- the identification information identifies the data addition apparatus which has created the first trapdoor hash value.
A data addition apparatus attaching new data to original data created in an electronic signature attaching apparatus, comprising:
- a trapdoor hash value creating unit configured to create a first trapdoor hash value;
- a first outputting unit configured to output the first trapdoor hash value created by the trapdoor hash value creating unit and identification information identifying a data addition apparatus which has created the first trapdoor hash value;
- a data adding unit configured to add additional data including at least new created data to the original data;
- a determination value calculating unit configured to calculate a determination value distinct from the electronic signature, such that a second trapdoor hash value output from a trapdoor hash function using the determination value and the additional data as input is equal to the first trapdoor hash value created by the trapdoor hash value creating unit;
- and
- a second outputting unit configured to output the additional data and the determination value.
An electronic signature verification apparatus configured to verify original data previously created and additional data added to the original data, the apparatus comprising:
- a data acquiring unit configured to acquire the additional data including at least new created data and a determination value, the determination value being a value such that a first trapdoor hash value output from a trapdoor hash function using the determination value and the additional data as an input is equal to a second trapdoor hash value created by a data addition apparatus;
- a trapdoor hash value calculating unit configured to calculate the first trapdoor hash value based on the additional data and the determination value, the determination value being distinct from the electronic signature;
- and
- a verifying unit configured to verify the additional data by comparing the first trapdoor hash value calculated by the trapdoor hash value calculating unit and the second trapdoor hash value created by the data addition apparatus.
Dependencies are inferred from the claim text.