Research On Attribute-based Signature Scheme In Cloud Computing Environment

Attribute-based signature allows the signer to have a series of attribute information and sign the message without revealing the specific identity information,then the signature can be verified to satisfy the specific access control structure.Attribute-based signature has attracted much attention due to its unique advantages,and many achievements have been achieved.Current attribute-based signature schemes based on LSSS matrix have flexible access structure,but the computational cost of signature and verification is high.In order to reduce the computational complexity of signature and verification,the thesis improves attribute-based signature,combining with the idea of outsourcing computing,and proposes an outsourced attribute-based signature scheme in cloud computing environment.To outsource modular power calculation of signature process and pairing calculation of verification process to cloud service providers,the scheme provides cloud service providers with outsourcing keys and transformed signatures.Signers and verifiers can complete message signature and verification with only a few calculations after receiving the calculation results provided by cloud service providers.Security analysis shows that the scheme has signature privacy,and based on the assumption of computing Diffie-Hellman problem,it has unforgeability and outsourcing security under the random oracle model.Besides,considering that the traditional attribute-based signature scheme needs high computational cost and takes up too much computational resources,the thesis improves attribute-based signature,combining with the idea of proxy signature,and proposes an attribute-based non-paired proxy signature scheme in cloud computing environment.The signer delegate signature rights to a proxy who can be verified to satisfy the specific access control structure,then the proxy signs the message in the name of the signer to solve the problems of the signer who is not online or has limited computing power.The scheme does not need to run any bilinear pairing computation,and has good computational efficiency.Security analysis shows that the scheme has signature privacy,and based on the assumption of elliptic curve discrete logarithm problem,it has strong unforgeability under the random oracle model,that is,the adversary can not forge an effective proxy signature only by relying on the signature key or proxy key.