Dual-Mode Cryptosystem Based On The Learning With Errors Problem

The existing LWE-based dual-mode scheme could not fit the framework of dual-mode cryptosystem very well. In this paper, we give two solutions of constructing "full-fledged" dual-mode cryptosystems based on LWE. In our first construction, we give a modified "dual version" of Peikert et al.'s (Crypto'08) construction, in which the simulated public keys can be uniformly and randomly chosen just like the real ones, thus it can fit the framework of dual-mode cryptosystem very well. Then, our second construction gets rid of the lattice trapdoor, which is known as lacking of efficiency and is used in our first construction as well as Peikert et al.'s construction.