Cloudflare agrees to buy a GlobalSign root so its new certificate authority works on old devices
Cloudflare has agreed to buy a GlobalSign root and applied to four browser root programs to become a public certificate authority. It has not issued a certificate yet, and its post-quantum certificates are aimed at Chrome's quantum-resistant root store in early 2027.
The Engineer · Build desk
What happened
- Cloudflare's SSL/TLS documentation lists Let's Encrypt, Google Trust Services, SSL.com and Sectigo as the CAs behind its public certificates today, RuntimeWire reported.
- Issuance will run through ACME, so a client already pointed at an existing free CA can switch to Cloudflare by changing its directory URL.
- An April Cloudflare roadmap set mid-2027 for post-quantum authentication between visitors and Cloudflare, and 2029 for full post-quantum security across its products.
Why it matters
- Who's exposed exposure Teams that move a domain to post-quantum certificates take on a new monitoring job: Cloudflare advises watching CT logs for unexpected legacy certificates that would give clients a malicious downgrade path.
- What it costs cost Cloudflare estimates post-quantum signatures would grow CT log storage 40 times. Log operators and monitors would carry that cost under today's certificate format, and MTCs are Cloudflare's proposal to avoid it.
- What doesn't add up contradiction RuntimeWire, working from Cloudflare's X post, reported that the root was unnamed. The blog post names GlobalSign and a signed agreement, so the plan is further along than that report shows.
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A new root is slow to become useful. Even after a root program accepts it, the root has to propagate into operating systems, browsers and devices, and it never reaches clients that have stopped receiving updates [19]. Buying an existing root skips that wait. GlobalSign's has been trusted across browsers, operating systems and devices since 2012 [20], so it is about 14 years old [31].
Age is also a liability. The new root Cloudflare will submit is built for root programs that are starting to cap how old a trusted root may be [21]. "The established root gives us reach across the devices of the past. The new roots give us standing under the policies of the future," Cloudflare wrote [22]. I think two roots is the right design for a CA that wants old clients on day one. The bought root serves the long tail now, while the new one starts its years of propagation under the newer rules [21].
For more than a decade Cloudflare has been one of the largest consumers of publicly trusted certificates, by its own account, without issuing one [7]. It sits in front of more than 20 percent of global Internet request traffic [23]. Its own CA "would also place the company alongside established providers that currently supply its certificates," RuntimeWire wrote [8]. GlobalSign, the seller of the root, is not one of the four partners RuntimeWire found in Cloudflare's documentation [25]. Neither source says Cloudflare will stop buying from any of them.
The pitch is redundancy for free certificates. If the dominant free CA had a bad week, Cloudflare argues, much of the web would have no comparable free, automated alternative [29]. That CA is Let's Encrypt, which issues on the order of ten million certificates a day and serves more than 500 million sites, according to Cloudflare [24]. The blog calls it one of the best things to happen to the Internet in twenty years [26], then proposes to take some of its load. Universal SSL already works this way at the certificate level: every certificate ships with a backup under a separate key, issued by a different authority [27]. "A public CA is that same idea, but at the scale of the whole Internet," Cloudflare wrote [28].
Post-quantum is the harder engineering problem. Simply swapping post-quantum signatures into certificates at Internet scale would cause unacceptable performance degradation, Cloudflare says [9]. Merkle Tree Certificates record issued certificates in a Merkle tree, and an inclusion proof shows that a given certificate belongs to the logged set [10]. According to the IETF draft, as RuntimeWire summarised it, the design limits the size cost of post-quantum signatures while keeping issuance publicly accountable [10].
So far the evidence is experimental. Cloudflare reports a successful experimental deployment with Chrome this year [11], and an IETF presentation reported MTC tests on 1,000 Cloudflare-proxied domains [12]. RuntimeWire wrote that this is "evidence of technical testing, not evidence that the proposed CA has been approved" [12]. Those domains ran behind Cloudflare's own edge. For the result to transfer to other sites, browsers would have to accept a format that is still being developed at the IETF [5].
What to watch
- Whether the GlobalSign root purchase closes and Chrome, Apple, Microsoft and Mozilla accept Cloudflare's new root.
- Whether the IETF Merkle Tree Certificate draft settles in time for Chrome to admit an MTC root on the early-2027 target.
- Whether Cloudflare's SSL/TLS documentation drops or adds partner CAs once its own issuance starts.
Clarity's read
What the record supports and how the coverage leans. The claims behind it follow.
Reality
- Evidence55
- Adoption5
- Hype gap+20
- Incentives72
- Confidence60
Claim ledger
Ranked by verification strength, evidence, and original report placement.
- [1]
Cloudflare announced its intent to become a public certificate authority.
- [2]
Cloudflare is not issuing certificates yet and says it will be a little while before it does.
- [3]
Cloudflare's CA will support Merkle Tree Certificate issuance, targeting early 2027 for inclusion in Chrome's newly launched Quantum-resistant Root Store.
- [4]
Cloudflare currently works with Let's Encrypt, Google Trust Services, SSL.com and Sectigo for public certificates, according to its SSL/TLS documentation.
- [5]
MTCs are still being developed through the IETF, so Cloudflare's announcement does not mean browsers already accept its proposed certificate format.
- [6]
Cloudflare turned on Universal SSL during Birthday Week 2014, which it describes as twelve years ago.
- [7]
For more than a decade Cloudflare has been one of the largest consumers of publicly trusted certificates on the Internet and has never issued one itself.
- [8]
"It would also place the company alongside established providers that currently supply its certificates."
- [9]
Simply swapping post-quantum cryptography into certificates at Internet scale would lead to unacceptable performance degradation.
- [10]
With MTCs, certificates are recorded in a Merkle tree and an inclusion proof can show a certificate is part of the logged set; the design aims to limit the size burden of post-quantum signatures while preserving public accountability for issuance, according to the IETF draft.
- [11]
Cloudflare reports a successful experimental deployment of MTCs with Chrome this year.
- [12]
An IETF presentation reported testing MTCs on 1,000 Cloudflare-proxied domains; RuntimeWire wrote that this is "evidence of technical testing, not evidence that the proposed CA has been approved".
- [13]
In an April roadmap, Cloudflare targeted mid-2027 for post-quantum authentication between website visitors and Cloudflare using MTCs, and 2029 for full post-quantum security across its product suite.
- [14]
By Cloudflare's estimates, post-quantum signatures would increase the amount of data certificate transparency logs need to store by 40x.
- [15]
Cloudflare has applied for inclusion in the Chrome, Apple, Microsoft, and Mozilla root programs.
- [16]
Cloudflare has signed a definitive agreement to acquire an established, broadly trusted root from GlobalSign so it can offer certificates with the widest possible device reach the day it begins issuing.
- [17]
Cloudflare's CA will be ACME-first; anyone already pointed at an existing free CA can move to Cloudflare by changing a directory URL, with no new tooling.
- [18]
Cloudflare will provide standard MTC issuance at no cost.
- [19]
A brand-new root is not widely useful for years: after a root program accepts it, it must propagate into operating systems, browsers and devices, and it never reaches devices that have stopped receiving updates or never received them.
- [20]
The existing GlobalSign root has been trusted across browsers, operating systems, and devices since 2012, and reaches older clients a fresh root never will.
- [21]
The new root Cloudflare will submit to root programs is built for where the ecosystem is heading, including programs that are starting to cap how old a trusted root may be.
- [22]
"The established root gives us reach across the devices of the past. The new roots give us standing under the policies of the future."
- [23]
Cloudflare sits in front of more than 20 percent of global Internet request traffic.
- [24]
Let's Encrypt issues on the order of ten million certificates a day and serves more than 500 million sites.
- [25]
GlobalSign, the seller of the root, is not among the four CAs Cloudflare's documentation lists as its current public certificate partners.
- [26]
Cloudflare called Let's Encrypt one of the best things to happen to the Internet in twenty years, speaking as one of its largest users.
- [27]
Every Cloudflare Universal SSL certificate already ships with a backup certificate, wrapped with a separate key and issued from a different authority, ready to deploy if the primary is revoked or compromised.
- [28]
"A public CA is that same idea, but at the scale of the whole Internet."
- [29]
Cloudflare presents its CA as a new source of free certificates, arguing that if the dominant free certificate authority had a bad week, much of the web would have no comparable free, automated alternative ready to take the load.
- [30]
Domain owners who have upgraded to post-quantum authentication should monitor CT logs for unexpectedly issued legacy certificates to prevent clients from falling back on a malicious downgrade path.
- [31]
The GlobalSign root is about 14 years old at the time of the announcement.
- [32]
RuntimeWire, reporting from Cloudflare's September 29 post on X, wrote that Cloudflare did not specify the application process, the root it would use, or when certificates might be available.
Sources
2 independent publishers whose own reporting we read for this story.
- blog.cloudflare.comBuilding a certificate authority for the whole Internet
2 articles · September 29, 2026
- runtimewire.comCloudflare applies to issue web certificates as a post-quantum CA
1 article · September 29, 2026
Topics and entities
Topics
- Web PKI
- Certificate Transparency
- Post-Quantum Cryptography
Entities
- Let's Encrypt
- Google Chrome
- Google Trust Services
- Cloudflare
- IETF
- Merkle Tree Certificates
- Matthew Prince