• PriVeto: a fully private two round veto protocol.

      Samiran, Bag; Muhammad Ajmal, Azad; Feng, Hao; Warwick University; Derby University (Institution of Engineering and Technology, 2018-12-04)
      Veto is a prerogative to unilaterally overrule a decision. A private veto protocol consists of a number of participants who wish to decide whether or not to veto a particular motion without revealing the individual opinions. Essentially all participants jointly perform a multi-party computation (MPC) on a boolean-OR function where an input of "1" represents veto and "0" represents not veto. In 2006, Hao and Zieli´ nski presented a two round veto protocol named Anonymous Veto network (AV-net), which is exceptionally efficient in terms of the number of rounds, computation and bandwidth usage. However, AV-net has two generic issues: 1) a participant who has submitted a veto can find out whether she is the only one who vetoed; 2) the last participant who submits her input can pre-compute the boolean-OR result before submission, and may amend her input based on that knowledge. These two issues generally apply to any multi-round veto protocol where participants commit their input in the last round. In this paper, we propose a novel solution to address both issues within two rounds, which are the best possible round efficiency for a veto protocol. Our new private veto protocol, called PriVeto, has similar system complexities to AV-net, but it binds participants to their inputs in the very first round, eliminating the possibility of runtime changes to any of the inputs. At the end of the protocol, participants are strictly limited to learning nothing more than the output of the boolean-OR function and their own inputs.
    • TrustVote: Privacy-preserving node ranking in vehicular networks

      Muhammad AJmal, Azad; Samiran, Bag; Simon, Parkinson; Feng, Hao; Derby University; Warwick University; Huddersfield University; Warwick University (IEEE, 2018-11-12)
      The Internet of Vehicles (IoV) is the network of connected vehicles and transport infrastructure units (Roadside Units (RSU)), which utilizes emerging wireless systems (4G, 5G, LTE) for the communication and sharing of information. The network of connected vehicles enables users to disseminate critical information about events happening on the road (for example accidents, traffic congestions, and hazards). The exchange of information between vehicles and roadside units could improve the driving experience and road safety, as well as help drivers to identify the hazardous and safe routes in a timely manner. The sharing of critical information between vehicles is advantageous to the driver; however, at the same time, malicious actors could mislead drivers by spreading fraudulent and fake messages. Fraudulent messages can have a negative impact on the infrastructure, and more significantly, have potential to cause threats to life. It is therefore essential that vehicles can evaluate the credibility of those who send messages (vehicles or roadside units) before taking any action. In this paper, we present TrustVote, a collaborative crowdsourcing-based vehicle reputation system that enables vehicles to evaluate the credibility of other vehicles in a connected vehicular network. The TrustVote system allows participating vehicles to hide their rating/feedback scores and the list of interacted vehicles under a homomorphic cryptographic layer, which can only be unfolded as an aggregate. The proposed approach also considers the trust weight of a vehicle providing the rating scores while computing the aggregate reputation of the vehicles. A prototype of TrustVote is developed and its performance is evaluated in terms of the computational and communication overheads.