Research Of Secret Sharing Scheme And Access Control Method

With the popularization of the network application, the expansions of the network cover scope and the development of all kinds' network technology. The network information security became more and more important. Cryptography is the center of network security technology, in which the encryption and decryption, digital signature, identity authentication are important mechanism to protect information security. The security of them is based on the secret of private key. If private key leaked, the security of these mechanisms will be destroyed. Secret sharing scheme and threshold cryptosystem protect the security of private key in different way, and they provide some security scheme for some special application. These areas are worth studying. IEEE P1 363 makes threshold cryptosystem one of the studying content of the future standard.(t,n) threshold scheme is an easy and efficient way to secret sharing. Attackers must get more than threshold shares so that they can resume the privacy. This increases the difficulty and at the same time solves the power concentrated problem, because decryption and encryption and digital signature can be finished only after more than threshold participants' agreement.In this paper, we first discuss the security of the secret sharing scheme constructed by regular sequence, and analysis the security of the example constructed by regular sequence. The exmple show that we can restore the secret without enough threshold participants' agreement. This is a security bug of the scheme.Then we present two new access control schemes based on the schemes of dynamic access control in the user hierarchy before. We design the scheme mainly focusing on security, computation quantity and storage. The dynamic access control problems, such as, adding/deleting user classes, adding/deleting user relationships, and changing secret keys, are discussed. The security proof of the first scheme is based on the disperse logarithm problem (DLP); the security proof of the second scheme is based on decisional Diffie-Hellman (DDH) assumption.