Paper 2025/2163

Splitting the MAYO: A Component-Wise Fault Injection Attack on Randomized MAYO

Abstract

We present a practical component-wise fault injection attack against randomized MAYO implementations. The attack targets the final addition of oil and vinegar components during signing. Depending on compiler optimization, a fault may expose either oil coefficients directly or vinegar coefficients that can be used to recover the oil coefficient via the public verification algorithm. By accumulating partial coefficient-wise information across multiple faulty signatures and exploiting the linear structure of the oil space, we recover the full secret key. Unlike prior attacks, our method does not rely on deterministic signing, memory reuse, or faulting the hash function. We validate the attack on ARM Cortex-M4 platforms using clock glitching and electromagnetic fault injection, and recover the MAYO-1 key for both the {\tt -O3} and {\tt -Os} compiler optimization settings. Additionally, we show that existing lightweight countermeasures are ineffective against our attack, exposing critical implementation weaknesses and underscoring the need for robust fault-resilient protections for multivariate post-quantum signatures.