Research of Knapback on Unbiased Coin Cast Protocol

In this paper, according to knapback problem's characteristics, introduce zero-knowledge proof and unbiased coin cast protocols in theroy, and apply it to zero-knowledge proof and unbiased coin cast sucessfully by proving and analysing. More, we prove it's security theoretically and prove knapback has broad applicability by the extension of zero-knowledge proof, and so prove practicability of knapback problem with facts.