Research Of Applying Secret Sharing Scheme To Group Authentication

As an important security service in information system,user authentication is always one of the main concerns of the information security.In recent years,with the development of social group communication,a new type of authentication called group authentication appears,which verifies whether all participants belong to a pre-defined group at once.Different from the one-to-one authentication in most conventional user authentication scheme,which has one prover and one verifier,group authentication is a many-to-many authentication which has multiple provers and multiple verifiers.In fact,each participant in the group authentication serves as both a prover and a verifier.Secret sharing scheme,an important topic of modern cryptography,originally aims to solve the decentralized key management problem and now is widely used in sensitive information management.Moreover,its properties of security and flexibility satisfy the requirement of security and functionality of the group authentication.As a result,it is natural to apply secret sharing to group authentication.The thesis briefly introduces the research status of group authentication,based on the research and analysis of the existing schemes.The thesis proposes 2 efficient and flexible(t,m,n)group authentication schemes.1.The thesis first proposes a simple(t,m,n)group authentication scheme based on randomized component,which authenticates all users at once.In the scheme,each participant constructs a randomized component to bind the token with all m participants and force all participants to join in the authentication.And the scheme recovers the secret with all components to check whether all participants are of the same group.Compared to the existing group authentication,each user of the scheme uses a single share as the token and thus the scheme is simpler,more efficient and flexible.2.The thesis then proposes an ideal tightly coupled(t,m,n)group authentication scheme,which solves the security problem caused by low information rate in existing schemes.In the scheme,all participants run a Random Number Selection Algorithm(RNSA)to generate random integers before constructing randomized components.Compared to the existing group authentication,the scheme is tightly coupled.It means that the scheme binds all participants into a tightly coupled group and requires all participants to be legal shareholders to pass the authentication.Moreover,an adversary cannot pass the authentication by forging a token.Meanwhile,the information rate is always 1 in this scheme,which guarantees the lowest data diffusion level.