| Predicate encryption is a more expressive public key encryption that evolved from identity-based encryption,which can perform fine-grained access control to data while protecting data privacy.However,the existing predicate encryption schemes are inefficient,and the expression of research on specific problems is insufficient,so it is difficult to meet the practical requirements.Therefore,this paper conducts detailed studies on the expression extension and efficiency improvement of predicate encryption for the requirements of the following two specific privacy-preserving scenarios:(1)In the privacy-preserving data consolidation scenario,if database B satisfies the condition:the attribute set of database A is complementary to its own,the encrypted data of database A can be accessed and the specific content can be obtained,thereby consolidating the two databases to obtain a complete database.However,the previous predicate encryption schemes are not expressive enough to handle this scenario.To solve this problem,this paper designs a complementary set predicate encryption(CSPE)scheme using Lagrangian interpolation and compression technology,and applies it to privacy-preserving data consolidation.This scheme is the first predicate encryption that can solve the set complementarity problem,which makes up for the lack of expression of the existing predicate encryption,and is efficient due to a constant size of ciphertext and private key.(2)In the privacy-preserving contact tracing scenario after the outbreak,if the epidemic prevention center satisfies the condition:the intersection of the trajectory set formed by the user’s two-dimension spatiotemporal(time and location)data and the two-dimension spatiotemporal trajectory set of the diagnosed person is not empty.then prevention center can access to the user’s encrypted data and obtain their private information,allowing timely notification of the user.In addition,most of the spatiotemporal data of users in this scenario are stored in storage-limited lightweight devices,such as mobile phones.However,previous predicate encryption schemes that can handle this problem require at least a linear size of ciphertext or private key,namely,require a large amount of storage and are not suitable for storage-limited lightweight devices.To solve this problem,this paper designs a non-empty intersection predicate encryption(NEIPE)scheme using deterministic private keys and a mapping technique,and applies it to privacy-preserving contact tracing.This scheme realizes constant-sized ciphertext and private key,so it is more suitable for storage-limited lightweight devices than existing schemes. |
