Research Of The Secret Sharing Technology And Its Applications

Secret sharing is an important tool for the information security and the data privacy, and it plays an important role in protecting important information and secret data from being lost, destroyed, viciously modified, or into wrong hands. Secret sharing has been one important branch of modern cryptography and also one important research field of information security. This dissertation reviews the research advances of the secret sharing technology and analysises the design characteristics of most of the existing secret sharing schemes and their restrict and effect on the applications, based on which several secure, efficient and practical secret sharing schemes are designed. In addition, the application of secret sharing in digital signature is studied with emphases, and some secure and efficient threshold digital signature algorithms are proposed.Firstly, this dissertation points out that the secret shadow distribution from the secret dealer to the participant will affect the application of the secret sharing more or less, raise the implementation cost, and degrade the security level of the whole system. By means of the intractability of discrete logarithm problem, a threshold secret sharing scheme is established, in which each participant's secret shadow is selected by the participant himself and even the secret dealer cannot gain anything about his secret shadow. All the shadows are as short as the shared secret, and each participant can share many secrets with other participants by holding only one shadow. Because the secret dealer does not have to distribute each participant's secret shadow, no secure channel is required to be established beforehand between each participant and the dealer. At the same time, the dealer does not have to record a too heavy load of secret data, and this ameliorates the security of the secret sharing system. The scheme is very useful, especially when there exists no secure channel between the dealer and each participant at all or such a channel is difficult to establish.Based on the same design thoughts, an alternative implementation of the above scheme is proposed. The new scheme has all the same characteristics as the old scheme: each participant's secret shadow is selected by the participant himself; all the shadows are as short as the shared secret; each participant's secret shadow can be used in multiple sharing sessions without being updated; the security is based on the security mechanism of the discrete logarithm. Compared with the old scheme, the advantages of the new scheme is the smaller amount of computation and the capability of supporting the cases that the shared secret is renewed dynamically, and old participants are deleted...