Researching And Realization Of Dynamic(t,n)Secret Sharing Scheme

As the rapid development of computer networks, the society pay more and more attention on the confidential information. Secret Sharing is one of the important way to save securely important information and data. Threshold secret sharing system can improve system's security and robustness by secret splitting and responsibility division.Firstly, this dissertation presents some knowledge that refers to the Public-key cryptography. Then it introduces the main idea of threshold secret sharing scheme, discuss some typical schemes on the threshold secret sharing scheme, and detailedly analyses the advantage and the disadvantage of four multi-secret sharing schemes. We propose a Dynamic (t,n) Secret Sharing Scheme which overcomes the problems and deficiencies of those schemes refered adove. There are some features in our scheme as follow:(1) The creditable center distributes secret shares once only in initialization phase. In the phase of multi-secret sharing, those shares can be used repeatedly, though threshold value changed. So our scheme Significantly enhances the utilization rate of the secret shares.(2) The secret sender can change the value of threshold dynamicly during secret sharing phase, that makes the scheme more flexibility. As the value of threshold changed, the public key of the participator group and the public shares must be refreshed also. Hence, there is no need to re-initialization, when processing secret sharing time after time.In succession, we discuss the key algorithms of the scheme, such as big number calculation, Lagrange interpolation algorithm in Galois field, generator choice algorithm, big prime test algorithm and so on. Also, we use VC++ 6.0 to design a prototype system in windows XP. The result shows that our scheme which has good security and robustness, is right and feasible. At last, we summarize our dissertation and expect the future of threshold secret sharing.