Adaptively Secure Identity-Based Identification from Lattices without Random Oracles

We propose a concurrently secure, identity-based identification scheme from lattices. It offers adaptive-identity security in the standard model, quasi optimal online performance, optimal leakage resilience, and its security is based on mild worst-case assumptions in ideal lattices. Our scheme uses an ideal-lattice interpretation of the Bonsai tree concept in lattices (EUROCRYPT 2010), which we call convoluted Bonsai trees. It allows us to build an identity-based identification scheme in a new "static identity" model that is weaker than the standard "adaptive identity" model. We show that both models are equivalent under the existence of Chameleon hash functions.