A Multi-authority Attribute-based Encryption Scheme With Pre-decryption

Attribute-based Encryption(ABE) could achieve user’s access control according to itsattributes.Moreover,so it can be used in cloud computing and fine-grained access control.However,there remain several problems in the present attribute based system before it becomespractical.The foremost one is efficiency:the decryption of ciphertext and users become morecomplicated since the traditional one-to-one communication model changes tomulti-to-multi.Thus,it is very important to improve the overall efficiency of the existingscheme.Another problem is attribute revocation.In order to meet the increasingly requirements inthe application,how to apply proxy re-encryption to attribute revocation and solve attributerevocation problem is considerable.This thesis firstly gives some analysis on the related works about attribute based encryptionschemes,summarizing their relationships and developmental tendency.Then researche on decryptionefficiency has been made to come up with a attribute-based encryption scheme with pre-decryptionbased on existing algorithms.This scheme lay the partial decryption operation on cloud server anduser just carry out the final decryption.This scheme can improve decryption efficiency dependingon the big calculating power of cloud server and protect user’s privacy,which especially applied tothe scenery that user access cloud server through smart device.Besides,in order to solve the attributerevocation problem,this thesis show a directional proxy re-encryption scheme,which enables aciphertext encrypted under a delegator’s public to be translated into a ciphertext of a delegatee by asemi-trusted proxy.This scheme can protect user’s privacy.Finally,we simulate the thesis according to experiment based on our improvement and giveproof about the security.It can be proved that this thesis can improve decryption efficiency and issecurity.