Location-Preserving Matching Protocol For Ride-Hailing Service Based On Multi-Key Fully Homomorphic Encryption

In recent years,due to the convenience of online ride-hailing services,various online ride-hailing platforms have developed rapidly.The most important service of a service provider is to match the requesting passenger with the vehicle.However,in order to provide matching services,service providers need to collect sensitive user information,which will reveal the user’s location privacy.According to related requirements,this paper designs an online ride-hailing matching protocol with location privacy protection,and evaluates the protocol from three aspects: matching accuracy,matching security,and matching efficiency.In order to improve the matching accuracy,this paper studies the shortest path algorithm in the road network environment.Compared with the traditional matching algorithm,the matching accuracy of the protocol constructed based on the road network embedded algorithm has been significantly improved,and it is closer to the optimal matching algorithm in the actual road network environment.In order to improve the matching security,this paper studies the related technologies of fully homomorphic encryption.The user encrypts his location and uploads it to the service provider.The service provider performs calculations on the ciphertext,and interacts with the user to complete the matching of passengers and vehicles while protecting location privacy.However,in the traditional single-key fully homomorphic encryption algorithm,the service provider can only process the ciphertext encrypted by the same key,and the key holder can decrypt the ciphertext of all users.This paper studies the lattice-based cryptography system against quantum computer attacks.Based on the single-key fully homomorphic encryption scheme,the multi-key fully homomorphic encryption scheme is studied,and the relevant protocols constructed can be processed by service providers.Cipher text encrypted by different keys.For the ciphertext decryption operations involved in the protocol,this article uses noise flooding technology.Each participant only needs to decrypt a part of the data,and finally send the result to the service provider for summary,and the service provider calculates the final decryption result.It avoids the need to combine all user private keys to complete the decryption operation.In order to improve the matching efficiency,this paper aims at the disadvantage of high cost of multi-key fully homomorphic calculation,and expands and implements other bootstrap gate circuits based on the bootstrap NAND gate.The functions involved in the protocol can be composed of multiple basic gate circuits.The improved bootstrap gate circuit and parallel calculation improve the efficiency of service providers in processing ciphertext.