International Association
for Cryptologic Research

We present Olingo, a framework for threshold lattice signatures that is the first to offer all desired properties for real-world implementations of quantum-secure threshold signatures: small keys and signatures, low communication and round complexity, non-interactive online signing, distributed key generation (DKG), and identifiable abort.

Our starting point is the framework of Gur, Katz, and Silde (PQCrypto 2024). We change the underlying signature scheme to Raccoon (Katsumata et al., Crypto 2024), remove the trapdoor commitments, and apply numerous improvements and optimizations to achieve all the above properties. We provide detailed proofs of security for our new framework and present concrete parameters and benchmarks.

At the $128$-bit security level, for up to $1024$ parties and supporting $2^{60}$ signatures, our scheme has $2.6$ KB public keys and $9.7$ KB signatures; while signing requires communication of $953$ KB per party. Using the LaBRADOR proof system (Beullens and Seiler, Crypto 2023), this can be further reduced to $596$ KB. An optimistic non-interactive version of our scheme requires only $83$ KB communication per party.