Google Teams Use Gemini 4 Carbon to Verify Signal Protocol Code

What happened

Google teams used Gemini 4 Carbon on a security challenge involving mathematical proofs for the code underlying the Signal protocol. Google DeepMind researchers used AlphaProof Code to guide agents in verifying the protocol down to compiled device code, closing a gap where real-world implementations can diverge from protocol-level reasoning.

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Reported by 5 sources

The story so far

Google DeepMind used AlphaProof Code to formally verify selected cryptographic guarantees in the compiled code underlying the Signal protocol. The four-week proof of concept generated more than six million lines of Lean proofs, which Lean checked automatically; human experts reviewed every specification and examined the roughly one percent of the codebase flagged for a second look. The work found no new vulnerabilities in the portions examined. Tests using two previously fixed bugs produced machine-checked proofs that the older, buggy versions were insecure. DeepMind is releasing its specification and proof to support further formal verification work.