An Identity-based Ring Signature Scheme with Enhanced Privacy

There are many applications in which it is necessary to transmit authenticatable messages while achieving certain privacy goals such as signer ambiguity. The emerging area of vehicular ad-hoc network is a good example application domain with this requirement The ring signature technique that uses an ad-hoc group of signer identities is a widely used method for generating this type of privacy preserving digital signatures. The identity-based cryptographic techniques do not require certificates. The construction of ring signatures using identity-based cryptography allow for privacy preserving digital signatures to be created in application when certificates are not readily available or desirable such as in vehicle area networks. We propose a new designated verifier identity-based ring signature scheme that is secure against full key exposure attacks even for a small group size. This is a general purpose primitive that can be used in many application domains such as ubiquitous computing where signer ambiguity is required in small groups. We consider the usefulness of identity-based cryptographic primitives in vehicular ad-hoc networks and use a specific example application to illustrate the use of identity-based ring signatures as a tool to create privacy preserving authenticatable messages