Timed Zero Knowledge Proof (TZKP)

TZKP is derived from the ZKP protocol in the E-cash algorithms and it is designed for computing resource management. A typical service model is illustrated in the following diagram. Every user has a legitimate token. A user, UA reserves a service from a service provider. The service provider bundles a session time into the public part of UA's token. As needed, UA can either redeem the service directly at reserved session time, or transfers the reserved service to others before arrival of the reserved session time. Unlike the traditional E-cash schemes where all spent tokens need to be kept indefinitely, all spent TZKP tokens which have been accounted for within the session can be discarded safely after the session is expired. Even the service provider keeps the expired spent tokens surreptitiously no identity of an honest user can be exposed from the spent tokens. But the identity of double spending offender who transferred or redeemed the reserved service more than once within a session will be uniquely deciphered from the spent tokens.

Both ZKP and TZKP protocols have been implemented in C language, and C# with a big integer library, .NET framework. The software has been tested in RTDS lab, and the DETER networking testbed, and it is being used as the core software modules in a cybersecurity education tool Cybersecurity Remote Education Access Tool (CREAT) . A widely used secure hash function, SHA-1, is implemented in this software system for the withdrawal and transfer protocols. In the transfer phase, principals delegate resource statement and attributes described in XML format for easy expansions.

The following downloadable links provides the ZKP slides and the TZKP demo software.