A Simple and Efficient CCA-Secure Lattice KEM in the Standard Model.

We present, to date, the most efficient public-key encapsulation mechanism from integer lattices in the standard model. Our construction achieves adaptive CCA security through a “direct” chosen-ciphertext security technique without relying on any generic transformation. The security of our construction is based on the standard learning-with-errors assumption. The efficiency of our construction is almost the same as the best known non-adaptive CCA-secure construction.