Research On Attribute Based Certificateless Encryption Scheme

In the general attribute-based encryption scheme,there is a completely trusted authority,which will generate corresponding private keys for the attributes of all users in the system.But when the central authority is compromised or is no longer trusted,then the entire system will no longer be secure,which is the key escrow problem.The more common way to solve this problem is to use distributed,which distributes the authority of the central organization to each organization,but this method has the problem of high system communication overhead.In the non-certificate encryption method,since the user’s private key is jointly generated by the organization and the user,the central organization no longer owns all the private keys of the system user,so this property can well solve the key escrow problem.Existing schemes of this type have the problems of high number of encryptions,long ciphertexts,and lack of security proofs.Therefore,the research focus of this thesis is to use the good property that certificateless encryption can solve the key escrow problem to solve the key escrow problem in attribute-based encryption.To address the above issues,this thesis proposes three attribute-based certificateless encryption schemes,with the main contributions as follows:(1)By studying certificateless encryption and attribute-based encryption,this thesis proposes a certificateless encryption scheme based on attribute-based encryption under ciphertext strategy to solve the key escrow problem in attribute-based encryption.Compared with existing schemes,this scheme improves encryption efficiency and decryption efficiency,and reduces calculation overhead.And the scheme proves its security under the random oracle model.Then solve the problem of longer decryption time and inflexible decryption in solution one.In this scheme,the final ciphertext is recalculated by constructing a polynomial.Users only need to use their own public key to calculate the ciphertext to quickly judge whether they can decrypt the ciphertext,which greatly improves the decryption efficiency and Decryption flexibility.(2)An attribute-based certificateless encryption scheme that can be applied in mobile cloud computing with verifiable outsourcing decryption in the Internet of Things is proposed.This scheme can not only protect the security of users in the system,reduce the communication overhead of the system,but also complex decryption operations It is handed over to the cloud server for processing,so the decryption pressure on the client can be reduced,it can be well adapted to the Internet of Things architecture and can improve the user experience.(3)An attribute-based certificateless encryption scheme under the key strategy is proposed,which is suitable for payment video websites and social network data protection scenarios.In this scheme,the linear secret sharing scheme is used to ensure the flexibility of access control,and it is also helpful to realize fine-grained access control.The number of ciphertexts in this scheme is only related to the number of users in the authorized user set,and the decryption of this scheme is also flexible and efficient.