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09/19/2023 | Press release | Distributed by Public on 09/18/2023 18:30

Verisign to update DNSSEC algorithm

Duane Wessels is a Fellow at Verisign, with a focus on DNSSEC projects and root zone operations. This post originally appeared on the Verisign Blog and has been edited from the original version.

Verisign will soon make an important technology update to how we protect the top-level domains (TLDs) we operate. The vast majority of Internet users won't notice any difference, but the update will support enhanced security for several Verisign-operated TLDs and pave the way for broader adoption and the next era of Domain Name System (DNS) security measures.

Beginning in the next few months and continuing through the end of 2023, we will upgrade the algorithm we use to sign domain names in the .com, .net, and .edu zones with Domain Name System Security Extensions (DNSSEC).

In this blog, I'll outline the details of the upcoming change and what members of the DNS technical community need to know.

DNSSEC adoption

DNSSEC provides data authentication security to DNS responses. It does this by ensuring any altered data can be detected and blocked, thereby preserving the integrity of DNS data. Think of it as a chain of trust - one that helps avoid misdirection and allows users to trust that they have gotten to their intended online destination safely and securely.

In 2010, a major milestone occurred when the Internet Corporation for Assigned Names and Numbers (ICANN) and Verisign signed the DNS root zone with DNSSEC. Shortly after, Verisign introduced DNSSEC to its TLDs, beginning with .edu in mid-2010, .net in late 2010, and .com in early 2011. Additional TLDs operated by Verisign were subsequently signed as well.

Growth over time

Since the TLDs were first signed, we have observed two very distinct phases of growth in the number of signed second-level domains (SLDs).

The first growth phase occurred from 2012 to 2020. During that time, signed domains in the .com zone grew at about 0.1% of the base per year on average, reaching just over 1% by the end of 2020. In the .net zone, signed domains grew at about 0.1% of the base per year on average, reaching 1.2% by the end of 2020. These numbers demonstrated a slow but steady increase, which can be seen in Figure 1.

We've observed more pronounced growth in signed SLDs during the second growth phase, which began in 2020. This is largely due to a single registrar that enabled DNSSEC by default for their new registrations. For .com, the annual rate increased to 0.9% of the base, and for .net, it increased to 1.1% of the base. Currently, 4.2% of .com domains are signed and 5.1% of .net domains are signed. This accelerated growth is also visible in Figure 1.

As we look forward, Verisign anticipates continued growth in the number of domains signed with DNSSEC. To support continued adoption and help further secure the DNS, we're planning to make one very important change.

Rolling the algorithm

All Verisign TLDs are currently signed with DNSSEC algorithm 8, also known as RSA/SHA-256, as documented in our DNSSEC Practice Statements. Currently, we use a 2048-bit Key Signing Key (KSK), and 1280-bit Zone Signing Keys (ZSK). The RSA algorithm has served us (and the broader Internet) well for many years, but we wanted to take the opportunity to implement more robust security measures while also making more efficient use of resources that support DNSSEC-signed domain names.

We are planning to transition to the Elliptic Curve Digital Signature Algorithm (ECDSA), specifically Curve P-256 with SHA-256, or algorithm number 13, which allows for smaller signatures and improved cryptographic strength. This smaller signature size has a secondary benefit, as well: any potential DDoS attacks will have less amplification as a result of the smaller signatures. This could help protect victims from bad actors and cybercriminals.

Support for DNSSEC signing and validation with ECDSA has been well-established by various managed DNS providers, 78 other TLDs, and nearly 10 million signed SLDs. Additionally, research performed by APNIC and NLnet Labs shows that ECDSA support in validating resolvers has increased significantly in recent years.

The road to algorithm 13

How did we get to this point? It took a lot of careful preparation and planning, but with Internet stewardship at the forefront of our mission, we wanted to protect the DNS with the best technologies available to us. This means taking precise measures in everything we do, and this transition is no exception.

Initial planning

Algorithm 13 was on our radar for several years before we officially kicked off the implementation process this year. As mentioned previously, the primary motivating properties were the smaller signature size, with each signature being 96 bytes smaller than our current RSA signatures (160 bytes vs 64 bytes), and the improved cryptographic strength. This helps us plan for the future and prepare for a world where more domain names are signed with DNSSEC.

Testing

Each TLD will first implement the rollover to algorithm 13 in Verisign's Operational Test & Evaluation (OT&E) environment prior to implementing the process in production, for a total of two rollovers per TLD. Combined, this will result in six total rollovers across the .com, .net, and .edu TLDs. Rollovers between the individual TLDs will be spaced out to avoid overlap where possible.

The algorithm rollover for each TLD will follow this sequence of events:

  1. Publish algorithm 13 ZSK signatures alongside algorithm 8 ZSK signatures
  2. Publish algorithm 13 DNSKEY records alongside algorithm 8 DNSKEY records
  3. Publish the algorithm 13 DS record in the root zone and stop publishing the algorithm 8 DS record
  4. Stop publishing algorithm 8 DNSKEY records
  5. Stop publishing algorithm 8 ZSK signatures

Only when a successful rollover has been done in OT&E will we begin the process in production.

Who is affected, and when is the change happening?

Now that we've given the background, we know you're wondering: How might this affect me?

The change to a new DNSSEC-signing algorithm is expected to have no impact on the vast majority of Internet users, service providers, and domain registrants. According to the aforementioned research by APNIC and NLnet Labs, most DNSSEC validators support ECDSA, and any that do not will simply ignore the signatures and still be able to resolve domains in Verisign-operated TLDs.

Regarding timing, we plan to begin to transition to ECDSA in the third and fourth quarters of this year. We will start the transition process with .edu, then .net, and then .com. We are currently aiming to have these three TLDs transitioned before the end of the fourth quarter of 2023, but we will let the community know if our timeline shifts.

This algorithm rollover demonstrates yet another critical step we are taking toward making the Internet more secure, stable, and resilient. We look forward to enabling the change later this year, providing more efficient and stronger cryptographic security while optimizing resource utilization for DNSSEC-signed domain names.

The views expressed by the authors of this blog are their own and do not necessarily reflect the views of APNIC. Please note a Code of Conduct applies to this blog.