Google Opens Carbon Access to Paying Developers and Businesses

Google has expanded access to its Gemini 4 Carbon artificial intelligence model to paying developers and enterprises following a milestone in automated software verification. DeepMind used Carbon-powered agents alongside Claude Opus 5.5 to formally verify security guarantees in the reference code for the Signal protocol, which also underpins WhatsApp and Google Messages. The mathematical proofs confirmed core properties such as authentication and forward secrecy in compiled machine code within four weeks. While the breakthrough demonstrates automated auditing capabilities, access to specialised cybersecurity vulnerability discovery tools remains restricted to select members of Google's Fairwind Program.

Key Facts

How Did AI Agents Formally Verify the Signal Protocol Code?

DeepMind paired five human researchers with artificial intelligence agents running on Gemini 4 Carbon and Claude Opus 5.5 to write formal specifications. Carbon-based agents generated approximately 6.5 million lines of mathematical proofs validated by the Lean proof assistant, confirming security guarantees across compiled machine code in four weeks rather than years.

The formal verification project, named AlphaProof Code, evaluated libsignal, the Signal protocol's reference implementation that also runs in variants within WhatsApp and Google Messages. Researchers mathematically demonstrated that guarantees such as forward secrecy, post-compromise security, and authentication hold for compiled machine code rather than high-level design specifications alone. To establish that the technique identifies real defects, the team reinserted two previously patched libsignal bugs and proved they breached the security guarantees. However, Google noted the results applied to its own build running via a command-line wrapper rather than Signal's standalone consumer apps, while side channels were excluded from portions of the analysis.

Google announced it is publicly releasing both the formal specifications and the verification proofs.

What Capabilities and Pricing Apply to Gemini 4 Carbon?

Google opened commercial access to Gemini 4 Carbon for paying developers via the Gemini API, Gemini for business, and Google AI Ultra subscriptions. Introductory pricing stands at $2 per million input tokens and $10 per million output tokens until 30 November, after which both service rates will double.

General access excludes Carbon for cyber, which remains restricted to members of Google's Fairwind Program. Google claims Carbon for cyber leads key benchmarks for discovering, exploiting, and fixing software flaws. Security firm Wiz used the model to identify zero-day vulnerabilities across two major SaaS providers within two hours. Additionally, Google's Cloud Vulnerability Research team used Carbon to confirm exploitability for two vulnerabilities in a popular open-source project comparable in severity to PHP2Shell, enabling maintainers to reclassify the issues as critical and deploy urgent fixes.

Organisations requiring Carbon for cyber must secure membership in Google's Fairwind Program to access its vulnerability discovery tools.

What Should You Do?

The disclosure does not identify active vulnerabilities in production messaging clients, and no direct software patches are currently required for end users.

• Review Google's publicly released specifications and Lean proofs to evaluate automated formal verification methods for cryptographic codebases.
• Access Gemini 4 Carbon via the Gemini API or Gemini for business under introductory pricing before token rates double after 30 November.
• Apply for Google's Fairwind Program if your security team requires access to the specialised Carbon for cyber tooling.
• Report any suspected cyber security incidents in Malaysia to Cyber999 through the Malaysian Computer Emergency Response Team (MyCERT).

Common Questions

Does the verification effort indicate that Signal is vulnerable?

No. DeepMind verified that the core security guarantees of the libsignal reference implementation hold in compiled machine code. Researchers tested the framework by reinserting two older, already-patched vulnerabilities to confirm detection, but found no active security flaws within Signal's production consumer applications.

Which communication platforms utilise the Signal protocol?

The Signal protocol's reference implementation is libsignal. According to the report, variants of the protocol are also deployed in widespread communication services including WhatsApp and Google Messages, though the formal proofs specifically evaluated Google's own command-line wrapped build of the reference codebase.

What specific results were achieved with Carbon for cyber?

Google stated that Wiz leveraged Carbon for cyber to discover zero-day flaws at two major SaaS providers within two hours. Furthermore, Google's Cloud Vulnerability Research team confirmed two critical exploitable flaws in an open-source project comparable in severity to PHP2Shell.

Sources and Methodology

This dispatch is based entirely on reporting published by SecurityWeek. In accordance with editorial standards, this report relies strictly on the provided source text and does not reference unverified vendor materials or secondary disclosures.