The Research On Cipherertext-Policy Attribute-based Encryption With Attribute Revocation And Its Applications

With the rapid development of the Internet of things,big data,cloud computing and other new technologies continue deeply affecting the style of learning,working,life and other fields,resulting in gradually increase of security issues and challenges.Traditional cryptography techniques,however,do not fully meet the needs of people in different applications,so modern cryptography technology requires continuous improvement and innovation.This thesis focuses on solving the actual security needs of the personal health record(PHR)system.The ciphertext-policy attribute-based encryption scheme is analyzed and studied in detail in order to solve the problem of attribute revocation,outsourcing decryption,weight attribute in the PHR system.The major works are as follows:(1)The ciphertext-policy attribute-based encryption schemes are well studied and analyzed.Inspired by the idea of the mediator proposed by Ibraimi,a novel mediated and attribute-based encryption scheme is proposed based on the attribute-based encryption scheme proposed by Waters.The proposed encryption scheme has the abilities of attribute revocation and outsourcing decryption.The mediator is very important in the proposed scheme.At one hand,it helps to verify legitimacy of the user's attributes and do attribute revocation.At the other hand,it assists to calculating most of the decryption operations,allowing the user-end to achieve lightweight computing.The proposed encryption scheme is of choose plaintext attack security.The proposed scheme outperform other encryption schemes in the personal health record system.(2)A kind of ciphertext-policy attribute-based encryption scheme with weights of timely revocation is proposed.The proposed encryption scheme is inspired by the Key Tree presented by Hur,the ciphertexts updating strategy by Ma and the weight attribute encryption scheme by Liu.The proposed encryption scheme supports more fine-grained timely revocation of attributes which is more suitable for the Personal health record system.