Research And Design On More Function Secret Sharing Scheme

Secret sharing system provides an effective and practical method for the key management and data confidentiality of the information security, which has become t an important branch of the network information security research and modern cryptography field. With the popularity of computer networks, as well as the rapid development of e-commerce, the simple secret sharing scheme has been unable to meet safety and performance requirements of the key management. In the current key management that can be encountered such problem as the participant set changes, multi-secret sharing and other issues in practical applications, which need to update participants' keys, not only bring difficulties to key management, but increase the system's computing and communications costs, therefore the traditional single-secret sharing scheme has been unable to meet the large volume of data and application requirements. People urgent need effective multi-secret sharing scheme to share the growing volume of secret information. At the same time, network crime is increasing seriously, which requires participants to verify the dealer in the process of the secret send and the verifying between participants in the process of the secret reconstruction. Therefore, To design dynamic adding members and verifiable multi-secret scheme not only has great theoretical significance, but also has important practical value. Many scholars at home and abroad have improved Shamir (t,n) threshold secret sharing scheme to overcome the above problems. However, their schemes only resolved one or two problems, can not solve all the above problems comprehensively.This dissertation summarized the development process and the current situation of the existing more function secret sharing schemes, discover that the available secret sharing schemes have problems on the repeated use of shadow, dynamic member addition, participants deception, dynamic secret addition, scheme efficiency and so on. In order to deal with these problems, this paper proposes several relatively secure and efficient more function secret sharing scheme based on the known knowledge. The main contributions of this paper are summarized as follows:1. Analyzed security and efficient of the protocol for member expansion in secret sharing schemes given by Dong et al, pointing out the flaws in security and efficient of their protocol, and gave a new verifiable secret redistribution protocol according to threshold secret sharing schemes2. Ting-Yi Chang, Min-Shiang Hwang and Wei-Lin-Pang Yang Wu pointed an improvement scheme (CHY ) to overcome the security problem of the Lin-Wu (t,n) threshold verifiable multi-secret sharing scheme; In this paper, we analysis the security of CHY scheme and point out the shared secrets is insecure. In order to enhance the security of CHY scheme, we give an improvement on CHY scheme.3. In order to deal with the problems of existing more function secret sharing schemes, a new more function (t, n) threshold secret sharing scheme is proposed based on Shamir (t, n) threshold secret sharing scheme, RSA cryptographic system and discrete logarithm problem. In this scheme, multi-secret can be shared. The shadows don't need to be changed when the shared secret is renewed or new participants are added. Moreover, the efficient solutions against multiform cheating are proposed, therefore the scheme is highly security and practicality.