Beaver Triples: How to Multiply Secrets Without Revealing Them (and Keep Your Sanity)

Imagine you and a colleague each hold a piece of a puzzle, but you want to compute something together without showing your fragments. Sounds like a spy movie plot? Actually, it's routine in Secure Multi-Party Computation (MPC), and Beaver Triples are the star.

Beaver Triples are pre-generated triples of numbers (a, b, c) where c = a * b, but each party only knows their share. With them, you can multiply secret values by exchanging only a mask, not the secrets themselves. It's like handing a friend an encrypted note and getting back the result without them ever opening the envelope.

Of course, preparing these triples is a separate quest: they need to be generated in advance, requiring either a trusted dealer or cryptographic protocols like oblivious transfer. But once you have a stash of these triples, you can multiply secrets fast and securely. Developers familiar with the pain of late-night deploys will appreciate: at least here you don't have to restart production after every operation.

METABYTE studio's comment: If you thought multiplying secrets was only for spies, MPC with Beaver Triples proves otherwise. In our projects, we also love unconventional solutions, but we usually get by without cryptography at the multiplication level — though who knows, maybe the next client will ask us to protect addition too.