Research On Predicate Encryption Scheme Based On State Transition Mechanism

The rapid development and deep application of information technology continue to give birth to the innovation of new cryptographic technology.The traditional public key cryptosystem is difficult to meet the complex needs because of the lack of flexible encryption and decryption authorization mechanism.Predicate encryption is an extension of a series of encryption methods such as identity based encryption and attribute encryption.It can not only authorize the decryption of specific information with a specified identity,but also prevent the decryptor from exposing private information because the key is related to the identity information.It solves the problem that the user key is related to the user identity information in the identity based encryption scheme,For some problems that lead to partial privacy exposure,predicate encryption can avoid user privacy disclosure by hiding user characteristics,so it has more theoretical research significance and application value.Protection has important theoretical significance.The existing predicate encryption schemes include predicate combination dynamic transformation,parameter reuse and deterministic finite automata,but these methods have the problem of high overhead in decryption permission judgment.Based on this,this paper designs a new predicate encryption scheme based on deterministic finite state automata,uses Petri net and game logic,solves the problem of decryption user privacy exposure,and improves the efficiency of predicate encryption scheme based on deterministic finite state automata.The main research work of this paper includes:(1)The existing predicate encryption schemes for deterministic finite state automata are optimized.In the predicate encryption scheme based on deterministic finite state automata,in order to adapt to other methods,the ciphertext attribute and key attribute are coded once and once,so that the ciphertext key attribute coding becomes an intermediate quantity,which can be used by other schemes,and this intermediate quantity can not be directly used to determine the predicate encryption scheme of finite state automata,The second ciphertext coding and key coding are also needed,which significantly reduces the efficiency.By combining and optimizing the two codes,the coding is in place in one step,which is more suitable for determining the predicate encryption scheme of finite state automata,and further improves the computational efficiency of the scheme.(2)A new predicate encryption scheme based on Petri net is proposed.Based on the original predicate encryption scheme based on deterministic finite state automata,the deterministic finite state automata is replaced by Petri net structure for the first time,and the corresponding ciphertext code and key code are modified to make it compatible with Petri net structure;Further,the reachability prediction feature of Petri net is used to predict the decryption authority of the user applying for decryption,and the decryption of the user who cannot pass the prediction is rejected,so as to save the computational overhead and improve the operation speed;Finally,by adding the ciphertext attribute and key attribute of the decrypted user to the transition table,it does not need to be verified again when decrypting again,so as to greatly improve the efficiency.(3)A predicate encryption scheme based on game logic is proposed.Based on the original predicate encryption scheme based on deterministic finite state automata,deterministic finite state automata is replaced by game logic structure,which solves the possible congestion problem caused by a large number of users requesting decryption at the same time.Firstly,this paper formalizes the predicate encryption scheme based on game logic and its decryption permission definition,then realizes the specific construction of the scheme based on bilinear group,and gives the correctness proof and related property analysis of the scheme.