Researching Of Secret Sharing Without A Trusted Party

With the rapid development of computer and network technology, people have paid more and more attention to information security. Recent secret sharing has changed the previous single encryption mode, and it can improve the security, robustness and availability of its system. Therefore, the research on secret sharing has both theoretical significance and extensive application value.This thesis firstly introduces the development of threshold secret sharing, with several typical threshold secret sharing schemes is discussed further in detail, focusing on analyses of their advantages and disadvantages. In regard to the shortcomings existed in secret sharing schemes with trusted parties, a certification scheme is proposed based on secret sharing without a trusted party. This thesis has finished the following work:(1) A scheme is proposed based on secret sharing without a trusted party. According to the scheme, the CA is composed of a number of stand-alone servers. The user's public key certificate is produced collaboratively both by the stand-alone servers of its CA and the users themselves without the participation of any trusted party.(2) Theoretical analyses of security and robustness are provided for the scheme. CA's private key is distributed in all servers. When the number of servers is smaller than the threshold value, then signatures can not be given out by the private key of CA, therefore the security of system is ensured. When a certain number of servers fail to work or get attacked, so long as the number of servers is no less than the threshold value, then the normal operation of the system will not be affected, for this reason the robustness of the system is enhanced.(3) The prototype system of the scheme is realized by using VC++6.0 and miracl database in Windows XP system. The experimental results show that the scheme is workable and correct.At last, a summary and an outlook are given at the end of the thesis.