Patent ID: 8949609
Filing Date: 2015-02-03
Classification: H04L

Abstract:
1. An anonymous authentication signature system constituted by mutually connecting a user device which generates and outputs signature data for a document inputted by a user and a verification device which verifies whether or not the signature data generated by the user device is proper and outputs a result thereof, wherein: the user device includes a first recording unit which stores first system parameters as respective first parameters given in advance, a disclosure public key, a user public key, a user private key, a member certificate, and an attribute certificate, an input/output unit which receives input of the document from the user and a plurality of attributes the user intends to disclose, a cryptograph generator which generates a cryptograph based on at least two from among the first parameters, a signature text generator which generates a signature text from the cryptograph and generates a zero-knowledge signature text from the attribute certificate corresponding to each of the attributes to be disclosed, and a signature outputter which outputs the cryptograph and the zero-knowledge signature text as the signature data, along with the document and the plurality of attributes to be disclosed; the verification device includes a second recording unit which stores second system parameter as respective second parameters given in advance, the disclosure public key, the user public key, and the attribute certificate, an input receiver which receives the input of the document and the signature data from the user device, and a zero-knowledge certification verifier which judges whether or not a zero-knowledge certification text contained in the signature data is acceptable by verifying the zero-knowledge certification text contained in the signature data by using each of the second parameters, and receives the signature data when judged as acceptable; the user public key and the attribute certificate are generated by using a same power; the signature data contains a first element which does not include the plurality of attributes to be disclosed and includes the user private key, and a second element which includes the plurality of attributes to be disclosed and does not include the user private key; and the signature text generator of the user device combines a part of the user public key and a part of the attribute certificate corresponding to an attribute that is disclosed to generate the zero-knowledge signature text showing that the combined data satisfies an expression defined in advance.