Silithium: a Compact, FIPS-Friendly, Hybrid Signature (Q20b)
The transition to post-quantum cryptography involves balancing the long-term threat of quantum adversaries with the need for post-quantum algorithms and their implementations to gain maturity safely. Hybridization, i.e. combining classical and post-quantum schemes, offers a practical and safe solution, and is the path recommended by several European agencies. A key concern in hybridization is non-separability, i.e. preventing the extraction of one component from the whole hybrid scheme. The current approach of concatenating a classical and a PQC signature does not satisfy this property.
This talk will first recall the recommended approach to hybridization as well as the desired properties for hybrid schemes. It will then present Silithium, a hybrid signature built on elliptic curves and ML-DSA, that: does not require any modification of the underlying PQC scheme, satisfies the non-separability property, is easy to implement, and performs better than the concatenation of ML-DSA and ECDSA in terms of execution time and signature size.