Why Lean?

Markus de Medeiros wanted to understand garbled circuits. He had no formal training in cryptography. He spent an afternoon in Lean: a circuit evaluator in functional style, a custom DSL via metaprogramming, OpenSSL bindings via FFI, a correctness proof for his serializer, and a mutable garbling algorithm in imperative style. All in one tool. His conclusion: "I genuinely do not know of another tool…