Patent ID: 8583932

Claim:
A signature device comprising: a unit for receiving inputs of an authentication authority public key, an anonymous authentication certificate, a signature key, a text, an attribute proof set, and an attribute public key; an attribute set representation value generation unit for generating an attribute set representation value from the inputted attribute proof set and the inputted attribute public key; an attribute set representation key generation unit for generating an attribute set representation key from the attribute proof set; a non-interactive zero-knowledge proof generation unit for generating a non-interactive zero-knowledge proof from the inputted authentication authority public key, the inputted anonymous authentication certificate, the inputted signature key, the inputted text, the attribute set representation value generated by the attribute set representation value generation unit, and the attribute set representation key generated by the attribute set representation key generation unit; and a signature output unit for outputting the non-interactive zero-knowledge proof as signature data, wherein the attribute proof set is a set of one or more pairs of an attribute and an attribute key, the attribute public key comprises elements of a cyclic group, wherein the number of the elements is proportional to the number of the attributes that are simultaneously disclosable, the attribute set representation value is the sum of results acquired by multiplying each element of the attribute public key by a coefficient calculated from values of the attributes included in the attribute proof set, and the attribute set representation key is the sum of results acquired by multiplying each element of the attribute key included in the attribute proof set by a coefficient calculated from values of the attributes included in the attribute proof set.