Research on the Validity Duration of Off-line E-cash

摘要

To solve the drawback of the present electionic cash (E-cash) schemes that the size of bank's transcripts database expands without bound, the concept of validity duration of E-cash is introduced in this paper. Through improving the users' blind transforms of Brands' scheme, we design an efficient off-line E-cash system based on the restrictive blind signature and repressentation problem. The security analysis shows that the users can not forge a valid electronic coin or double spend it, in addition,the bank can not trace an honest users' payment behaviours. In compare with Brand's scheme, our scheme reduces storage costs and computation overhead of the users and the banks. Most of all, the electronic cashes will be authorized within a limit periodonly, the size of bank's transcripts database becomes controllable.