  An announcement scheme is a system that facilitates vehicles to broadcast
road-related information in vehicular ad hoc networks (VANETs) in order to
improve road safety and efficiency. Here we propose a new cryptographic
primitive for public updating of reputation score based on the
Boneh-Boyen-Shacham short group signature scheme. This allows private
reputation score retrieval without a secure channel. Using this we devise a
privacy-aware announcement scheme using reputation systems which is reliable,
auditable and robust.
