Cryptanalysis of a lattice based key exchange protocol

A lattice is a set of points in n-dimensional space with a periodic structure.Lattice-based cryptosystem holds a great promise for post-quantum cryptography[1],as they enjoy very strong security proofs based on the worst-case hardness,relatively efficient implementations,as well as great simplicity.The first lattice-based cryptosystem was proposed by Ajtai and Dwork[2],whose security is based on the lattice problems in the worstcase.After their seminal work,several latticebased cryptosystems have been proposed till now,