# Google says its new AI proved Signal’s encryption in weeks

Source: [The New Stack](https://thenewstack.io/gemini-4-carbon-swarm/) · 2026-11-10 · Cloud & DevOps
Page: https://themorning.dev/story/google-says-its-new-ai-proved-signal-s-encryption-in-weeks-fed18abda5a30c5b
Kind: research · Impact: medium

## In brief

- Google DeepMind used its AlphaProof Code agent framework to formally verify core encryption in Signal's libsignal.
- The AI agents wrote about three million lines of proofs in Lean, as part of a four-week proof-of-concept.
- The work links protocol-level security guarantees to a widely used cryptographic implementation, which the researchers say is a first for AI-assisted proofs.

## Why it matters

It shows AI agents can help produce machine-checked proofs for real production cryptographic code, which could make formal verification practical for more software, though human experts still decide what to prove.

## Versions

- Gemini 4 Carbon

## Timeline

- 2026-11-10: Google DeepMind announces AlphaProof Code verification of Signal's core encryption

## What developers say

Hacker News commenters were largely impressed that AI agents formally verified Signal's cryptography and saw it as a sign of safer software to come. Others questioned whether a Lean proof truly matches the implementation, how the proof model was checked, and whether the work replaces human expertise. Several noted the value of the reintroduced bugs test and the limits of the approach beyond cryptography. (sentiment: mixed)

> It’s nothing short of amazing that a huge codebase like Signal’s is apparently not only secure in a practical sense, but secure even in a strict formal sense. — p-e-w, Hacker News

> Since code is cheap there is no excuse to not have verification everywhere. — hoppp, Hacker News

> How do you prove the lean code represents what the code its proving? — whattheheckheck, Hacker News

## Coverage

- [Google Widens Gemini 4 Carbon Access After AI Agents Verify Signal Code](https://www.securityweek.com/google-widens-gemini-4-carbon-access-after-ai-agents-verify-signal-code/) — SecurityWeek, 2026-11-10
- [Google says its new AI proved Signal’s encryption in weeks](https://thenewstack.io/gemini-4-carbon-swarm/) — The New Stack, 2026-11-10
- [Introducing AlphaProof Code: a breakthrough in verifying complex software at depth](https://deepmind.google/blog/introducing-alphaproof-code/) — Google DeepMind News, 2026-11-10
- [Google DeepMind melds humans and AI agents to vet Signal's secure messaging techniques](https://www.theregister.com/ai-and-ml/2026/11/10/google-deepmind-melds-humans-and-ai-agents-to-vet-signals-secure-messaging-techniques/5308625) — www.theregister.com - Articles, 2026-11-10
- [Google DeepMind researchers used agentic AI framework AlphaProof Code to verify the Signal protocol's cryptographic guarantees, in a four-week proof-of-concept (Lily Hay Newman/Wired)](https://www.techmeme.com/261110/p14#a261110p14) — Techmeme, 2026-11-10
- [A New AI Tool From Google DeepMind Proved the Signal Protocol Is Secure](https://www.wired.com/story/a-new-ai-tool-from-google-deepmind-formally-verified-the-signal-protocol/) — Security Latest, 2026-11-10

## Discussions

- [Hacker News](https://news.ycombinator.com/item?id=50439193): 414 points, 138 comments

Tags: formal-verification, signal, ai-agents, cryptography, lean, google-deepmind

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Brief generated by AI (claude-haiku-5-5) from the reporting listed under Coverage. Headlines belong to their publishers. The Morning Dev – https://themorning.dev