Nick Sullivan

@nicksullivan.org

Asymmetries in action

If you weren't aware, I had a small part in helping design TLS 1.3 back in the day. Today, I presented some new work at the TLS working group meeting in Vienna to upgrade its the key schedule from SHA-2 (the workhorse) to Keccak, the algorithm behind SHA-3. www.ietf.org/archive/id/d...

XOF-based key schedules for TLS 1.3

TLS 1.3 runs its entire key schedule on HKDF over SHA-2. This document defines an extension that replaces that schedule with one built on an extendable-output function (XOF): the negotiated KDF gove...

ietf.org

It feels disingenuous to recognize the difference between an informational RFC published by the IETF and the Independent Submission stream, but not recognize the difference between standards track and informational RFCs. Is an RFC and RFC, or do you care about the Category: and Stream: at the top?

Every lock needs a key. The hard part is not always designing the lock. Sometimes it is getting the key to the person who needs it. That is the problem I look at in the third post in my CDT series on Encrypted Client Hello. cdt.org/insights/dis...

Distributing the Keys for Private Access to the Web

Breaking the DNS Dependencych-22" class="toc-anchor">ECH’s Catch-22thing-strange-in-the-dns" href="#something-strange-in-the-dns" class="toc-anchor">Something Strange in the DNS use it. That’s the fun...

cdt.org

I'm in Toronto discussing how websites can specify their preferences regarding how their content is used by search engines and AI crawlers. Here's what we have so far:

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Encrypted Client Hello is now RFC 9849 This RFC defines an extension to Transport Layer Security that improves privacy for web users. Huge team effort and a win for the internet at large. Now to get deployment up... Some words I wrote about this for @cdt.org: cdt.org/insights/enc...

Encrypted Client Hello: Closing the SNI Metadata Gap

Referencesent-deployment-and-adoption" href="#current-deployment-and-adoption" class="toc-anchor">Current Deployment and Adoptionor">Trial by Firewall-security-systems" href="#adapting-network-securit...

cdt.org

I’m happy to be joining the USENIX Security ’26 Enigma organizing committee this year, after having the chance to speak at Enigma three times. It has a long history as a home for early, practice-driven security ideas, often where work first gets aired before it’s fully polished or widely deployed.

News! I’ll be joining the Internet Architecture Board(IAB) starting March 2026 at IETF 125 in Shenzhen(I’ll be participating remotely). The IAB is part of the IETF ecosystem. It looks across Internet protocol work to provide architecture-level oversight and help keep the standards process healthy.

Here are seven things I’m looking forward to in the next month. Tomorrow, I’ll be guest lecturing with Kyle Hogan at NYU for Sunoo Park’s class on public interest tech. The theme: bikeshedding and how to get things done in internet standards.