Signal Taps Cloudflare to Help Protect the Privacy of Hundreds of Millions of Users Through Key Transparency

Signal Taps Cloudflare to Help Protect the Privacy of Hundreds of Millions of Users Through Key Transparency

Cloudflare is helping Signal’s users worldwide gain extra confidence that their conversations are private and secure

SAN FRANCISCO–(BUSINESS WIRE)–Cloudflare, Inc. (NYSE: NET), the leading connectivity cloud company, announced today that it is serving as an independent Key Transparency auditor for Signal, the private messaging app trusted by hundreds of millions of people worldwide. With this partnership, Cloudflare is giving Signal users extra confidence that their conversations are private and secure, without requiring complicated manual verification steps.

End-to-end encryption keeps messages private by encrypting them so only the sender and recipient can read them. That system is only secure if users receive the right encryption keys from the messaging system. Historically, confirming this required users to manually compare QR codes with one another off-platform – in-person, for example. An alternative solution is “key transparency,” a system where messaging apps publish a tamper-evident log that records when new keys are distributed to users, and where multiple parties perform verifications on that log. External auditors are an important part of this system, ensuring that the same log is shown to everyone. Signal uses key transparency in its new feature called “automatic key verification,” which enables users to verify their keys without leaving the app. Cloudflare now serves as one of the external auditors of this system.

“Signal has set the global standard for private communication, and we’re glad to independently verify that standard is being upheld,” said Dane Knecht, Chief Technology Officer of Cloudflare. “The web moved to encrypted connections by default with HTTPS. Messaging did the same with end-to-end encryption. Independent auditing is the logical next step: not just promising encryption, but making it provable.”

Cloudflare’s auditing system periodically pulls batches of updates from Signal’s Key Transparency log and cryptographically verifies that each update is consistent with everything recorded before it. Once that check passes, Cloudflare signs the update and Signal delivers the signed update to its users who can then verify it and be sure that Signal is showing them a globally consistent view of the log. Users build off of this assurance to then verify that the log contains the proper keys for themselves and their contacts. Cloudflare’s auditor operates only over cryptographic proofs; it does not see users’ phone numbers, usernames, public keys, or message contents.

With Signal now added, Cloudflare strengthens the security of two of the largest private messaging platforms in the world, having been announced as an auditor for WhatsApp in 2024 The aim is for independent auditing to become a standard expectation for encrypted communication — not a rare exception.

About Cloudflare

Cloudflare, Inc. (NYSE: NET) is the leading connectivity cloud company. It empowers organizations to make their employees, applications and networks faster and more secure everywhere, while reducing complexity and cost. Cloudflare’s connectivity cloud delivers the most full-featured, unified platform of cloud-native products and developer tools, so any organization can gain the control they need to work, develop, and accelerate their business.

Powered by one of the world’s largest and most interconnected networks, Cloudflare blocks billions of threats online for its customers every day. It is trusted by millions of organizations – from the largest brands to entrepreneurs and small businesses to nonprofits, humanitarian groups, and governments across the globe.

Learn more about Cloudflare’s connectivity cloud at cloudflare.com/connectivity-cloud. Learn more about the latest Internet trends and insights at radar.cloudflare.com.

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Forward-Looking Statements

This press release contains forward-looking statements within the meaning of Section 27A of the Securities Act of 1933, as amended, and Section 21E of the Securities Exchange Act of 1934, as amended, which statements involve substantial risks and uncertainties. In some cases, you can identify forward-looking statements because they contain words such as “may,” “will,” “should,” “expects,” “explores,” “plans,” “anticipates,” “could,” “intends,” “targets,” “projects,” “contemplates,” “believes,” “estimates,” “predicts,” “potential,” or “continue,” or the negative of these words, or other similar terms or expressions that concern Cloudflare’s expectations, strategy, plans, or intentions. However, not all forward-looking statements contain these identifying words. Forward-looking statements expressed or implied in this press release include, but are not limited to, statements regarding the capabilities and effectiveness of Cloudflare’s global network and Cloudflare’s other products and technology, the benefits to Cloudflare’s customers from using Cloudflare’s global network and Cloudflare’s other products and technology, Cloudflare’s partnership with Signal for Cloudflare to serve as an independent Key Transparency auditor and the potential resulting benefits to Cloudflare customers, the potential opportunity for Cloudflare to attract additional customers and to expand sales to existing customers through Cloudflare’s partnership with Signal, Cloudflare’s technological development, future operations, growth, initiatives, or strategies, and comments made by Cloudflare’s Chief Technology Officer and others. Actual results could differ materially from those stated or implied in forward-looking statements due to a number of factors, including but not limited to, risks detailed in Cloudflare’s filings with the Securities and Exchange Commission (SEC), including Cloudflare’s Quarterly Report on Form 10-Q filed on August 6, 2026, as well as other filings that Cloudflare may make from time to time with the SEC.

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Cloudflare, Inc.

Daniella Vallurupalli

Vice President, Head of Global Communications

[email protected]

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