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Google DeepMind's AI Validates Signal's Encryption Protocol
· Confirmed
In Short: Google DeepMind researchers announced they have used an AI tool called AlphaProof Code to produce a machine-checked mathematical proof that the encryption code behind Signal's messaging protocol behaves as designed.
The proof covers Signal's post-quantum PQXDH handshake and Triple Ratchet, validating the design's forward secrecy, authentication, post-compromise security, and handshake secrecy.
In a test, the team reintroduced two bugs that had previously been found and fixed in Signal's code, and the framework produced proofs showing the altered software was insecure.
The researchers demonstrated the effectiveness of the tool by reintroducing two bugs that had previously been found and fixed in Signal's code, showing that the tool could identify these issues.
Signal's chief technology officer, Ehren Kret, said the work gives greater confidence in the code's privacy guarantees.
Google DeepMind researchers used agentic AI to mathematically prove several key cryptographic guarantees of the Signal protocol, the encryption system behind Signal, Google Messages, and WhatsApp.
The process began with researchers and AI agents translating Signal’s security goals into formal mathematical specifications.
Google DeepMind's approach enables significant expansion in formal verification, addressing a long-standing challenge in cybersecurity.
The framework demonstrated its robustness by successfully identifying insecurities in isolated versions of Signal’s code containing reintroduced, previously fixed bugs.
Google DeepMind published the work on November 10, alongside a technical paper, and has released the specifications and proofs as open source on GitHub.
The technical paper describes the result as the first protocol-level security proofs for the unmodified code of a widely deployed cryptographic protocol implementation.
Unlike traditional verification methods that focus on protocol design, AlphaProof Code bridges the gap between design and implementation.
Swarat Chaudhuri, a DeepMind research scientist, said the next step is to apply this technology during the software design process – not just to cryptographic protocols but code in general.
What this adds
This marks the first time AI has been employed to verify a widely deployed cryptographic protocol at such depth.
Google DeepMind's approach enables significant expansion in formal verification, addressing a long-standing challenge in cybersecurity.
The framework demonstrated its robustness by successfully identifying insecurities in isolated versions of Signal’s code containing reintroduced, previously fixed bugs.
Background
Google DeepMind researchers announced they have used an AI tool called AlphaProof Code to produce a machine-checked mathematical proof that the encryption code behind Signal's messaging protocol behaves as designed.
Google DeepMind researchers announced they have used an AI tool called AlphaProof Code to produce a machine-checked mathematical proof that the encryption code behind Signal's messaging protocol behaves as designed.
What's confirmed
- Google DeepMind researchers said they have used AI agents to produce a machine-checked mathematical proof that the encryption code behind Signal's messaging protocol behaves as designed, a result the lab frames as an early step toward software whose security can be demonstrated rather than merely tested.
- "If you can now verify the correctness of these implementations, then you can rest easy," said Pushmeet Kohli, chief scientist at Google Cloud and DeepMind's vice president of research.
- "It's a system that is fundamentally built for human AI collaboration," Swarat Chaudhuri, a research scientist at Google DeepMind and a professor at the University of Texas at Austin, said in an interview.
- "While prior formal verification focused on smaller portions of the code, Google DeepMind's approach enables significant expansion," Signal chief technology officer Ehren Kret said in a statement.
- In a test of the system, the team reintroduced two bugs that had previously been found and fixed in Signal's code.
- In this case the proof covered Signal's post-quantum PQXDH handshake and Triple Ratchet, validating the design's forward secrecy, authentication, post-compromise security and handshake secrecy.
- The process began with researchers and AI agents translating Signal’s security goals into formal mathematical specifications.
- This marks the first time AI has been employed to verify a widely deployed cryptographic protocol at such depth, addressing a long-standing challenge in cybersecurity.
- Google DeepMind researchers used a new AI tool called AlphaProof Code to mathematically prove several key cryptographic guarantees of the Signal protocol, the encryption system behind Signal, Google Messages and WhatsApp, according to a report published November 10, 2026.
- Researchers at Google DeepMind ran AlphaProof Code against the Signal protocol for four weeks and found no new flaws in the parts they examined.
- And it demonstrates Google DeepMind's formal verification capabilities using a new AI framework called AlphaProof Code.
- Google DeepMind researchers used agentic AI to mathematically prove, or “formally verify,” a number of the Signal protocol’s key cryptographic guarantees—a landmark development for the widely used cryptography and AI itself.
What's still developing
- The work, announced in a DeepMind blog post on Monday, marks the first time a widely deployed cryptographic protocol has been formally verified down to the exact code running on people’s devices, by AI or by any other method.
- DeepMind is releasing the specification and proof it built for the Signal analysis, in the hope of helping other formal verification projects.
- Signal president Meredith Whittaker issued a blunt warning on June 20 that AI agents like Microsoft Copilot are surveillance infrastructure in disguise, arguing their sweeping access to contacts, messages, and credentials effectively nullifies end-to-end encryption.
- Source : Google DeepMind melds humans and AI agents to vet Signal's secure messaging techniques, by Thomas Claburn, theregister, Nov 10, 2026 Adobe announced always-on AI agents for Firefly at its Max conference in Miami Beach, with a beta planned for early 2027.
- However, encouragement can be taken from the fact that when tested against older versions of Signal that contained known vulnerabilities, it identified those and flagged them as failing formal verification.
- Ars Technica has been separating the signal from the noise for over 25 years.
- The proofs cover the parts of Signal that guard a conversation: the PQXDH handshake that sets up a chat and the Triple Ratchet that changes the key for every message, including the post-quantum layer meant to resist future quantum computers.
- Since 2023, Signal has been upgrading its encryption technology so that it remains secure against the future, hypothetical threat of quantum computers.
- The tool found no new vulnerabilities in the parts of the Signal Protocol examined but identified known weaknesses in older versions. 3.
- Google DeepMind said the technology could make advanced software security checks faster and less expensive, potentially extending them to critical systems such as medical devices and power grids.
- Agentic AI can significantly cut down the time of the latter project, enabling analyses like DeepMind's Signal evaluation.
- “We are very excited by this result, but there is a long distance to go before we are able to scale this to all the software of the world, and we want to do that,” Swarat Chaudhuri, a DeepMind research scientist, tells WIRED.