Provably Secure Three-party Password-based Authenticated Key Exchange from RLWE (Full Version), by Chao Liu and Zhongxiang Zheng and Keting Jia and Qidi You

Three-party key exchange, where two clients aim to agree a session key with the help of a trusted server, is prevalent in present-day systems. In this paper, we present a practical and secure three-party password-based authenticated key exchange protocol over ideal lattices. Aside from hash functions our protocol does not rely on external primitives in the construction and the security of our protocol is directly relied on the Ring Learning with Errors (RLWE) assumption. Our protocol attains provable security. A proof-of-concept implementation shows our protocol is indeed practical.