International Association
for Cryptologic Research

CROSS is a code-based post-quantum digital signature scheme based on a zero-knowledge (ZK) framework. It is a second-round candidate of the National Institute of Standards and Technology’s additional call for standardizing post-quantum digital signatures. The memory footprint of this scheme is prohibitively large, especially for small embedded devices. In this work, we propose various techniques to reduce the memory footprint of the key generation, signature generation, and verification by as much as 50%, 52%, and 74%, respectively, on an ARM Cortex-M4 device. Moreover, our memory-optimized implementations adapt the countermeasure against the recently proposed (ASIACRYPT-24) fault attacks against the ZK-based signature schemes.