Patent ID: 6487659
Filing Date: 2002-11-26
Classification: H04L

Abstract:
A conditional authentication device which verifies the legitimacy of proof data generated for proving the authority of a user and which determines whether or not conditions added to the authority of the user are satisfied to authenticate the user's authority, said conditional authentication device including:a first memory part which stores first authentication data; a second memory part which stores control information for generation of said proof data; a third memory part which stores proof support information, said proof support information being generated by performing a predetermined computation for both authentication characteristic information and said control information for generation of the proof data stored in said second memory part; a proof data generation part, said proof data generation part comprising a proof data generation device controlling part which performs predetermined processing or condition determination in accordance with said control information for generation of the proof data, and a first computation part which generates the proof data, using at least said first authentication data, said control information for generation of the proof data and said proof support information; and a verification part which verifies whether or not the proof data generated by said proof data generation part is based on said authentication characteristic information, said proof data generation part generating legitimate proof data only when there are given said first authentication data which is legitimate, said control information for generation of the proof data and said proof support information, and said authentication characteristic information being a decryption key on an asymmetric cryptosysytem which utilizes a discrete logarithm problem on a finite group G.