A Voltage Template Attack on the Modular Polynomial Subtraction in Kyber

Abstract

Kyber is one of the four final Key Encapsulation Mechanism (KEM) competitors of the National Institute of Standards and Technology PostQuantum Cryptography standardization competition. This paper reveals the vulnerability of Kyber under a voltage template side channel attack: the modular polynomial subtraction operation in Kyber.CCAKEM.Dec. In this paper, by splicing data under different selected ciphertexts, a small number of traces are required to recover the secret key. Experiments show that the recovering accuracy of secret key achieves 100% when using 330 traces, and it still achieves 98% when only using 44 traces.