International Association
for Cryptologic Research

Every cryptographic implementation on embedded device is vulnerable to side-channel attacks. To prevent these attacks, the main countermeasure consists in splitting each sensitive variable in shares and processing them independently. With the upcoming of new algorithms designed to resist quantum computers and the complexity of their operations, this protection represents a real challenge. In this article, we present an attack on an earlier attempt to protect the decoder of BIKE cryptosystem against first-order attack. Additionally, we introduce a new procedure for the high-order masking of the decoder, up-to-date with its latest improvement. We also present the first fully masked implementation of the whole cryptosystem, including the key generation and the encapsulation. Eventually, to assess the correctness of our countermeasures and initiate further comparison, we implemented our countermeasures in C and provide benchmarks of their performance.