To get a TLS certificate issued, the requesting party must prove that they own the domain through a process called Domain Control Validation (DCV). As industry wide standards have evolved to enhance security measures, this process has become manual for Cloudflare customers that manage their DNS externally. Today, we’re excited to announce DCV Delegation — a feature that gives all customers the ability offload the DCV process to Cloudflare, so that all certificates can be auto-renewed without the management overhead.

Security is of utmost importance when it comes to managing web traffic, and one of the most critical aspects of security is ensuring that your application always has a TLS certificate that’s valid and up-to-date. Renewing TLS certificates can be an arduous and time-consuming task, especially as the recommended certificate lifecycle continues to gradually decrease, causing certificates to be renewed more frequently. Failure to get a certificate renewed can result in downtime or insecure connection which can lead to revenue decrease, mis-trust with your customers, and a management nightmare for your Ops team.

Every time a certificate is renewed with a Certificate Authority (CA), the certificate needs to pass a check called Domain Control Validation (DCV). This is a process that a CA goes through to verify that the party requesting the certificate does in fact own or control ownership over the domain for which the certificate is being requested. One of the benefits of using Cloudflare as your Authoritative DNS provider is that we can always prove ownership of your domain and therefore auto-renew your certificates. However, a big chunk of our customers manage their DNS externally. Before today, certificate renewals required these customers to make manual changes every time the certificate came up for renewal. Now, with DCV Delegation – you can let Cloudflare do all the heavy lifting.

DCV primer

Before we dive into how DCV Delegation works, let’s talk about it. DCV is the process of verifying that the party requesting a certificate owns or controls the domain for which they are requesting a certificate.

When a subscriber requests a certificate from a CA, the CA returns validation tokens that the domain owner needs to place. The token can be an HTTP file that the domain owner needs to serve from a specific endpoint or it can be a DNS TXT record that they can place at their Authoritative DNS provider. Once the tokens are placed, ownership has been proved, and the CA can proceed with the certificate issuance.

Better security practices for certificate issuance

Certificate issuance is a serious process. Any shortcomings can lead to a malicious actor issuing a certificate for a domain they do not own. What this means is that the actor could serve the certificate from a spoofed domain that looks exactly like yours and hijack and decrypt the incoming traffic. Because of this, over the last few years, changes have been put in place to ensure higher security standards for certificate issuances.

Shorter certificate lifetimes

The first change is the move to shorter lived certificates. Before 2011, a certificate could be valid for up to 96 months (about eight years). Over the last few years, the accepted validity period has been significantly shortened. In 2012, certificate validity went down to 60 months (5 years), in 2015 the lifespan was shortened to 39 months (about 3 years), in 2018 to 24 months (2 years), and in 2020, the lifetime was dropped to 13 months. Following the trend, we’re going to continue to see certificate lifetimes decrease even further to 3 month certificates as the standard. We’re already seeing this in action with Certificate Authorities like Let’s Encrypt and Google Trust Services offering a maximum validity period of 90 days (3 months). Shorter-lived certificates are aimed to reduce the compromise window in a situation where a malicious party has gained control over a TLS certificate or private key. The shorter the lifetime, the less time the bad actor can make use of the compromised material. At Cloudflare, we even give customers the ability to issue 2 week certificates to reduce the impact window even further.

While this provides a better security posture, it does require more overhead management for the domain owner, as they’ll now be responsible for completing the DCV process every time the certificate is up for renewal, which can be every 90 days. In the past, CAs would allow the re-use of validation tokens, meaning even if the certificate was renewed more frequently, the validation tokens could be re-used so that the domain owner wouldn’t need to complete DCV again. Now, more and more CAs are requiring unique tokens to be placed for every renewal, meaning shorter certificate lifetimes now result in additional management overhead.

Wildcard certificates now require DNS-based DCV

Aside from certificate lifetimes, the process required to get a certificate issued has developed stricter requirements over the last few years. The Certificate Authority/Browser Forum (CA/B Forum), the governing body that sets the rules and standards for certificates, has enforced or stricter requirements around certificate issuance to ensure that certificates are issued in a secure manner that prevents a malicious actor from obtaining certificates for domains they do not own.

In May 2021, the CA/B Forum voted to require DNS based validation for any certificate with a wildcard certificate on it. Meaning, that if you would like to get a TLS certificate that covers example.com and *.example.com, you can no longer use HTTP based validation, but instead, you will need to add TXT validation tokens to your DNS provider to get that certificate issued. This is because a wildcard certificate covers a large portion of the domain’s namespace. If a malicious actor receives a certificate for a wildcard hostname, they now have control over all of the subdomains under the domain. Since HTTP validation only proves ownership of a hostname and not the whole domain, it’s better to use DNS based validation for a certificate with broader coverage.

All of these changes are great from a security standpoint – we should be adopting these processes! However, this also requires domain owners to adapt to the changes. Failure to do so can lead to a certificate renewal failure and downtime for your application. If you’re managing more than 10 domains, these new processes become a management nightmare fairly quickly.

At Cloudflare, we’re here to help. We don’t think that security should come at the cost of reliability or the time that your team spends managing new standards and requirements. Instead, we want to make it as easy as possible for you to have the best security posture for your certificates, without the management overhead.

How Cloudflare helps customers auto-renew certificates

For years, Cloudflare has been managing TLS certificates for 10s of millions of domains. One of the reasons customers choose to manage their TLS certificates with Cloudflare is that we keep up with all the changes in standards, so you don’t have to.

One of the superpowers of having Cloudflare as your Authoritative DNS provider is that Cloudflare can add necessary DNS records on your behalf to ensure successful certificate issuances. If you’re using Cloudflare for your DNS, you probably haven’t thought about certificate renewals, because you never had to. We do all the work for you.

When the CA/B Forum announced that wildcard certificates would now require TXT based validation to be used, customers that use our Authoritative DNS didn’t even notice any difference – we continued to do the auto-renewals for them, without any additional work on their part.

While this provides a reliability and management boost to some customers, it still leaves out a large portion of our customer base — customers who use Cloudflare for certificate issuance with an external DNS provider.

There are two groups of customers that were impacted by the wildcard DCV change: customers with domains that host DNS externally – we call these “partial” zones – and SaaS providers that use Cloudflare’s SSL for SaaS product to provide wildcard certificates for their customers’ domains.

Customers with “partial” domains that use wildcard certificates on Cloudflare are now required to fetch the TXT DCV tokens every time the certificate is up for renewal and manually place those tokens at their DNS provider. With Cloudflare deprecating DigiCert as a Certificate Authority, certificates will now have a lifetime of 90 days, meaning this manual process will need to occur every 90 days for any certificate with a wildcard hostname.

Customers that use our SSL for SaaS product can request that Cloudflare issues a certificate for their customer’s domain – called a custom hostname. SaaS providers on the Enterprise plan have the ability to extend this support to wildcard custom hostnames, meaning we’ll issue a certificate for the domain (example.com) and for a wildcard (*.example.com). The issue with that is that SaaS providers will now be required to fetch the TXT DCV tokens, return them to their customers so that they can place them at their DNS provider, and do this process every 90 days. Supporting this requires a big change to our SaaS provider’s management system.

At Cloudflare, we want to help every customer choose security, reliability, and ease of use — all three! And that’s where DCV Delegation comes in.

Enter DCV Delegation: certificate auto-renewal for every Cloudflare customer

DCV Delegation is a new feature that allows customers who manage their DNS externally to delegate the DCV process to Cloudflare. DCV Delegation requires customers to place a one-time record that allows Cloudflare to auto-renew all future certificate orders, so that there’s no manual intervention from the customer at the time of the renewal.

How does it work?

Customers will now be able to place a CNAME record at their Authoritative DNS provider at their acme-challenge endpoint – where the DCV records are currently placed – to point to a domain on Cloudflare.

This record will have the the following syntax:

_acme-challenge. CNAME ..dcv.cloudflare.com

Let’s say I own example.com and need to get a certificate issued for it that covers the apex and wildcard record. I would place the following record at my DNS provider: _acme-challenge.example.com CNAME example.com..dcv.cloudflare.com. Then, Cloudflare would place the two TXT DNS records required to issue the certificate at  example.com..dcv.cloudflare.com.

As long as the partial zone or custom hostname remains Active on Cloudflare, Cloudflare will add the DCV tokens on every renewal. All you have to do is keep the CNAME record in place.

If you’re a “partial” zone customer or an SSL for SaaS customer, you will now see this card in the dashboard with more information on how to use DCV Delegation, or you can read our documentation to learn more.

DCV Delegation for Partial Zones:

DCV Delegation for Custom Hostnames:

The UUID in the CNAME target is a unique identifier. Each partial domain will have its own UUID that corresponds to all of the DCV delegation records created under that domain. Similarly, each SaaS zone will have one UUID that all custom hostnames under that domain will use. Keep in mind that if the same domain is moved to another account, the UUID value will change and the corresponding DCV delegation records will need to be updated.

If you’re using Cloudflare as your Authoritative DNS provider, you don’t need to worry about this! We already add the DCV tokens on your behalf to ensure successful certificate renewals.

What’s next?

Right now, DCV Delegation only allows delegation to one provider. That means that if you’re using multiple CDN providers or you’re using Cloudflare to manage your certificates but you’re also issuing certificates for the same hostname for your origin server then DCV Delegation won’t work for you. This is because once that CNAME record is pointed to Cloudflare, only Cloudflare will be able to add DCV tokens at that endpoint, blocking you or an external CDN provider from doing the same.

However, an RFC draft is in progress that will allow each provider to have a separate “acme-challenge” endpoint, based on the ACME account used to issue the certs. Once this becomes standardized and CAs and CDNs support it, customers will be able to use multiple providers for DCV delegation.

In conclusion, DCV delegation is a powerful feature that simplifies the process of managing certificate renewals for all Cloudflare customers. It eliminates the headache of managing certificate renewals, ensures that certificates are always up-to-date, and most importantly, ensures that your web traffic is always secure. Try DCV delegation today and see the difference it can make for your web traffic!

Via Cloudflare.com