A Secure and Efficient Randomized RLWE‐based Key Exchange Scheme

Key exchange protocols allow more than one entity to freshly construct an identical key without knowing it in advance. In recent years, the construction of signal‐based ring learning with error (RLWE) based key exchange protocols (KEPs) has been an important area of post‐quantum research. These protocols derive shared secrets by quantizing noisy ring products in the convolution ring , where and is a prime number. In this paper, we cryptanalyze one of the recently proposed KEP of Pursharthi et al., and show that it is prone to an information‐theoretic signal leakage attack. We then put forward a new protocol, called Masked‐Signal RLWE (MS‐RLWE), and show that it is safe against information‐theoretic signal leakage attack. Additionally, we show that our protocol is semantically secure in the random oracle model and it is also resistant to key mismatch attacks. Finally, we compare our scheme with several other KEPs in terms of computational complexity and resistance with respect to various attacks.