Identity-based Interactive Aggregate Signatures from Lattices

Aggregate signature allows users to compress multiple signatures into a short signature (called an aggregate signature), and can reduce a total amount of signature-size on a channel. In particular, identity-based aggregate signature can reduce not only total signature-size but also total verification key-size, because it is possible to check the validity of multiple messages and an aggregate signature by using signers' IDs, instead of verification keys. Furthermore, we focus on lattice-based constructions as post-quantum cryptography, due to recent advancement of quantum computers. In this paper, we propose the first identity-based interactive aggregate signature scheme from lattices. The security of our scheme is based on a standard lattice assumption, and its aggregate signature-size is logarithmic in the number of signatures.