CCA secure multi-recipient KEM from LPN

Abstract

We propose a novel multiple-recipient key-encapsulation mechanism (mKEM) scheme which takes multiple public keys as input and outputs a single key shared by corresponding recipients. We construct our scheme in the random oracle model based on low-noise LPN assumption which is a post-quantum problem. In the game simulation of security proof, a variant of Extended Knapsack LPN (which can be proved equivalent to standard LPN) is used to handle the decapsulation queries. The property of LPN problem provides randomness reuse property to shorten the length of the ciphertext compared with traditional way.