ChiLow (EC2025) is a low latency cipher designed for in-line memory encryption. Low latency ciphers are getting increasingly popular due to a demand from industry. The main caveat is that these ciphers are notoriously hard to design, due to the tight constraints (sub nanosecond latency). Chilow uses a novel non-linear layer: ChiChi which is based on the Keccak Chi function and adapted for even-bit state sizes. This property, the aggressive amount of rounds, and the novelty of the construction have led to a remarkable amount of cryptanalysis in a short amount of time.
In this talk we first look at memory encryption as a general concept, why we need it in practice, and why low-latency ciphers are fun to look at. We then give a gentle introduction into MitM attacks. Finally we look at our attack on ChiLow, going from a simple yet efficient attack, through some optimizations, to a full-round attack on ChiLow breaking the designers' security claims.
Eran Lambooij is a PostDoctoral researcher at INRIA Paris in the COSMIQ team working on the analysis of symmetric ciphers focusing on small-domain and low-latency ciphers