The Reserarch Of Attribute Based Signature And Encryption Algorithm

The 21 st Century is an age of information.With the rapid development of electronic technology,instant messaging,online shopping,online video and other Internet technologies,information has changed people's daily life in an unprecedented way.However,the Internet not only brings convenience but also faces many security risks to our lives.The US surveillance program PRISM,Yahoo mail stolen,and the event of leakege warn us the importance of information security.Traditional cryptography has been difficult to meet the requirements of information security.Therefore,it has great academic significance and extensive application value to study the emerging cryptographic technology to provide users with confidential,complete,usable,controllable and undeniable information security services.Attribute-based cryptosystem is the generalization and development of identity-based cryptosystem.Attribute is used to divide the population in a fine-grained way.This scheme combines access policy to ensure that only users whose attribute sets satisfy the access policy can perform cryptographic operations,such as decryption and signature.It overcomes the shortcomings of the traditional public key cryptosystem,such as complex management,hierarchical protection,and so on.Providing a powerful algorithm support to achieve authentication and data confidentiality protection in cloud computing and e-health.Attribute based cryptosystem has become a hot topic in the related field gradually,owing to its priorities of strong expressive ability,flexible use,easy to protect user's privacy,and can realize one-to-many data sharing.In this paper,we study the attribution-based public key signature and encryption algorithm,main contents are included as follows:(1)This paper summarizes the basic knowledge of number theory and related cryptographic techniques,including basic knowledge of group,finite field,lattice,bilinear pairing,classical mathematical difficult assumptions,definition of access structure and secret sharing method.At the same time,the provable security theory including formal definition,security model and security protocol method in public key cryptosystem is briefly introduced.(2)In view of the problem that the existing attribution-based threshold ring signature schemes can not simultaneously possess unconditional strong anonymity and resist collusion aggression,and there are many issuses such as attribute key escrow,fixed signature threshold and low verification efficiency,this paper gives the formal definitions and security model for the multi-authority attribute-based threshold ring signature scheme firstly.Then a multi-authority attribute-based variable threshold ring signature scheme is presented.Our scheme uses distributed key generation protocol to constrain the rights of attribute authority,and to overcome the problem of attribute key escrow.Through embedding a random identity factor in each user's attribute key,and introducing a random fuzzy parameter in each signature,the scheme can provides both unconditional strong anonymity and collusion resistance.In addition,a batch verification algorithm is proposed to improve the efficiency of verification.Under random oracle model and computational Diffie–Hellman assumption,the proposal can be proven to be existentially unforgeable and can resist collusion attacks launched by the malicious users with the complementary attributes in chosen message attack.(3)There are many issues in the existing lattice attribute based encryption schemes,such as attribute key escrow,coarse attribute revocation granularity and inflexible access policy.In view of the defects above,this paper gives the formal definitions and security model for the multi-authority attribute-based encryption scheme supporting attribute revocation firstly.Then a lattice multi-authority ABE scheme supporting fine-grained attribute revocation is proposed.This scheme can resist the quantum cryptographic analysis by introducing the idea of lattice.It overcomes the problem of attribute key escrow which exists widely in existing ABE schemes by distributed way.By using linear secret sharing scheme to realize flexible access strategy,in the process of secret sharing,select different random vectors to resist collusion attacks launched by the malicious users.In addition,using the idea of binary tree to revocate the attribute in a fine-grained manner.Under the standard model and decision learning with error assumption,the proposed scheme is proved to be indistinguishable under the chosen plaintext attack.