Research On Resilient Secret Sharing Scheme And Its Applications

Cryptography is the core technology of information security, the modern cryptosystem scheme fully depends on the security of the key. Secret sharing is a technology of sharing a secret among a group of participants. It protects important information from missing, being destroyed and being changed. Secret sharing schemes protect the secrecy and integrity of information by distributing the information over different servers. Secret sharing scheme is an important branch in the field of modern cryptography of key management and be widely applied to network security.In1979,the first (t , n ) threshold secret sharing seheme,based on the lagrange interpolating polynomial and projective geometry , were proposed by A.Shamir and G.Blakley respectively. Threshold secret sharing is one of the important ways to save securely important information and data, the security goals of these traditional schemes are building a defensive mechanism of the system, so that systems can not be attacked from Single-point Failure, in order to prevent over-concentration and abuse of secret. However, this method exist a considerable number of vulnerable points in the majority of applications, especially in the network-based distributed systems. Because of complex interactions between components in the distributed networks,especially difficult to prevent the vulnerable points and the invasion can not be avoied. Hence, the project propose resilient secret sharing schemes which not only overcome the existing secure shortcomings, but also take Vulnerability-oriented security of communication environment into full account. The goal of resilient secret sharing scheme is that when system is attacked, during secret reconstruction even if some participants'shares have been damaged, or manipulated by a malicious attacker, the system can provide security and robustness by increasing or decreasing the threshold parameters and ensure to provide normal and key services for users.The way to realize the resilience is threshold changeablility. The character of threshold changeable secret sharing scheme is that up to t participants'shares missed because of network faults, authorized subset of participants can corporate to recover the secret without requesting additional transmissions from the dealer.The main contributions of this thesis are as follows:1. Aim at the communication rate and security problems of the exiting threshold changeable secret sharing schemes, we analysis the partial broadcast channel deeply and propose a improved threshold changeable secret sharing protocol based on the partial broadcast channel. It decrease the communication cost and increase the numbers of the communication channels and resist to collusion attack. Our scheme has characteristics of verifiability and changeability, which has striking advantages in communication cost and computation cost comparing to other traditional threshold changeable secret sharing schemes.2. We study the verifiability of the existing schemes and analysis deeply binary symmetric polynomial. We propose a scheme easy to verify and threshold changeable by analysising and attacking the MDM scheme and IRSS scheme, respectively. This protocol is a resilent scheme and easy to embed into other cryptographic primitive.3. At last, we use VC++ 6.0 and miracle library to design a resilient prototype system in windows XP. The experiments results show that the improved algorithm in this paper not only avoids unnecessary overhand, but also ensures high-security.