Commitment system, common reference information generation device, commit generation device, commit reception device, commitment method, program

摘要

PROBLEM TO BE SOLVED: To provide a CRS reuse type accommodative safe combinable commitment system capable of reducing a common parameter length, a communication amount, and a calculation amount and a CRS reuse type static safe combinable commitment system.SOLUTION: A commitment system including a common reference information generation device 200, a commit generation device 300 (500), and a commit reception device 400 (600) is constituted by using a public-key crypto system PKE, a commitment TCOM with a falling door, a language Ldefined from the public-key crypto system PKE, and a sigma protocol Σ on the language L. The commit reception device 400 (600) opens information CT and Ψ which are received in advance from the commit generation device 300 (500) by using disclosed information (m, α, γ, r) and a random-number ε (m is confidential information, α is a first element of a first message of Σ, γ is a first message of Σ, ris the random-number, CT is an encryption of m, and Ψ is the encryption of predetermine hash value).SELECTED DRAWING: Figure 1