Access control Access policies 1 Access time 1 Antennas 1 Block-chain 1 Blockchain CP-ABE 1 Cloud-based 1 Cloud-based IoD 1 Cloud-based internet of drone 1 Cloud-computing 1 Digital storage 1 Hidden access policy 1 Internet of things 1 Limited access time 1 Privacy-preserving techniques 1 Security 1 Sensitive data 1 Vehicle to vehicle communications 1 blockchain 1 hidden access policy 1 limited access times 1