1. A lattice-based cryptography method comprising: obtaining a first value of a public parameter previously used in a first execution of a lattice-based cryptography protocol; generating, by operation of one or more processors, a second value of the public parameter based on the first value of the public parameter and random information; and using the second value of the public parameter in a second execution of the lattice-based cryptography protocol, wherein the second execution of the lattice-based cryptography protocol comprises: generating a public key based on the second value of the public parameter; and sending the public key to a correspondent over a channel.