Patent ID: 8200977
Filing Date: 2012-06-12
Classification: H04L

Abstract:
1. A group signature system comprising a group manager device, a signer device and a verifier device capable of communicating with each other, each device using a group signature scheme, wherein the group manager device comprises: a parameter storing module configured to store a public parameter including a prime order q and a generator g a group key generating module configured to generate a group secret key including values a, bεZ a member secret key generating module configured to calculate a member secret key composed of representation (k a signer tracing information calculating module configured to calculate signer tracing information T the signer device comprises: a signer storing module configured to store the public parameter including the prime order q and the generator g an encrypted text generating module configured to generate encrypted text data of the signer tracing information T a zero-knowledge proof generating module configured to generate a zero-knowledge proof showing that the signer device knows the member secret key and the encrypted text data is correctly generated based on the signer tracing information T a module that transmits, to the verifier device, a group signature composed of the encrypted text data and the zero knowledge proof, and the message, and the verifier device comprises: a verifier storing module configured to store the public parameter including the prime order q and the generator g a module that receives the group signature and the message from the signer device; a verifying module configured to verify correctness of the group signature, based on the received group signature and message, the public parameter and the group public key in the verifier storing module; and a module that transmits the verified result to the signer device.