GoKawiilGoogle DeepMind uses AI agents to formally verify Signal protocol's code
Google DeepMind researchers say they used a new agentic framework called AlphaProof Code to mathematically prove key security properties of the actual code behind the Signal protocol, which underpins encrypted messaging in apps like Signal and Google Messages. The system combined human experts, who defined formal specifications and reviewed select results, with AI agents powered by Gemini Carbon that generated over six million lines of proof code in the Lean language. DeepMind states this is the first time a widely deployed cryptographic protocol's implementation has been formally verified at this depth, by AI or any other method.
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Formal verification is considered the gold standard for proving software is free of certain flaws, but it has historically been too labor-intensive to apply to large, real-world codebases like Signal's. If AI agents can automate most of this work while leaving only a small fraction for human review, as DeepMind claims here, it could make rigorous security proofs practical for other widely used cryptographic systems. This may also signal a broader shift toward AI-assisted formal methods becoming a standard tool in security-critical software engineering, though wider adoption and independent scrutiny of the results would still be needed.
- DeepMind's AlphaProof Code formally verified the real code of the Signal protocol, not just a model of it.
- AI agents generated over six million lines of Lean proof code, with humans reviewing only about 1% of the codebase.
- DeepMind says this is the first formal verification of a widely deployed cryptographic protocol's implementation by any method.
Source: deepmind.google — Pushmeet Kohli, 2026-11-10
Published there as: “AlphaProof Code”
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