Anonymous and linkable ring signcryption scheme for location-based services in VANETs

In Location-Based Service (LBS), the vehicle user sends query messages, such as the nearest health centre, restaurant, etc., to the service provider for efficient and accurate service. The service provider gathers data regarding the received query, takes the service charge from the vehicle user, and provides these services efficiently and accurately. The service provider may reveal the vehicle user's privacy if the service provider is malicious. Similarly, if the vehicle user is malicious, he/she may also try to opt for the service from the service provider without paying the service charges. Therefore, vehicle users' queries and the service provider's data privacy are serious concerns in LBS. Some schemes, such as k-anonymity, cryptographic algorithms, etc., have been proposed to overcome these issues. The k-anonymity technique only offers vehicle users' query privacy. Cryptographic algorithms such as homomorphic encryption, oblivious transfer, etc., provide vehicle users' query and the service provider's data privacy at high communication and computation costs but reveal the vehicle user's identity. To overcome these problems, this work proposes an Anonymous and Linkable Ring Signcryption (ALRS) scheme for LBS in VANETs. It provides the service provider's data privacy and the vehicle user's query privacy, keeping the vehicle user's identity anonymous from the service provider. In addition, it maintains linkability (the number of times the same user requests a query) without revealing the identity of the vehicle user. Implementation and detailed results show that the ALRS scheme performed better than the current scheme regarding communication and computation costs and preserves all the privacy requirements.