Google DeepMind introduces AlphaProof Code, formally verifying Signal's cryptographic code

Google DeepMind researchers used AlphaProof Code, a multi-LLM agentic framework, to formally verify key security properties of the actual code underlying the Signal protocol. Agents powered by Gemini Carbon generated over six million lines of Lean, and human experts reviewed only about one percent of the codebase; the verification took four weeks, a task that historically takes expert teams years. When two previously fixed bugs were reintroduced into an isolated version of Signal's code, the system produced machine-checked proofs that the buggy versions were insecure, and DeepMind is open-sourcing its formal verification artifacts.