Bit Flipping Key Encapsulation for the Post-Quantum Era

It is a matter of time before quantum computers will break the cryptosystems like RSA and ECC underpinning today’s internet protocols. As Post-Quantum Cryptography (PQC) is a low-cost approach compared to others like quantum key distribution, the National Institute of Standards and Technology (NIST) has recently reviewed and analyzed numerous approaches to PQC. As a PQC candidate, Bit Flipping Key Encapsulation (BIKE) is expected to be standardized as a general-purpose Key Encapsulation Mechanism (KEM) by NIST. However, it lacks a comprehensive review of BIKE associated with technical analysis. This paper aims to present an in-depth review and analysis of the BIKE scheme with respect to relevant attacks. We provide a comprehensive review of the original McEliece (ME) scheme and present a detailed discussion on its practical challenges. Furthermore, we provide an in-depth study on the challenges of ME and BIKE cryptosystems in achieving the Indistinguishability under Chosen-Ciphertext Attack (IND-CCA) security. We provide an analysis of these cryptosystems and their security against several attacks before pointing out the research gaps for strengthening BIKE.