Signal cryptographic code verification… AI generates 6.5 million lines of proof code

Google DeepMind used its AlphaProof Code AI agent to formally verify key security properties of Signal's one-to-one messaging encryption code, producing roughly 6.5 million lines of proof code over a four-week analysis. The framework translates human-defined security conditions into mathematical statements and proves the code satisfies them, a stronger guarantee than input-based testing. The verification covered only one-to-one conversations, not group chats or the full Signal application. The result matters as a high-profile demonstration that AI-assisted formal verification can be applied to production cryptography at scale. What to watch next is whether the approach extends to group messaging and broader parts of the Signal codebase, and whether other protocols adopt similar AI-driven proofs.