I wrote up in the TLS mailing list why I think composite signatures (ML-DSA + ECDSA/RSA) are a net negative, will hurt the ecosystem, and should not be implemented. Hybrid key exchange was simple and self-contained. Hybrid signatures would be a mountain of complexity in delicate, critical code.

A warm, brilliant, funny man. The class was mostly foundations of cryptography: hard-core bits, ZK proofs, semantic security, etc. At our open book final, he stopped at a student with large pile of extra books on the floor, smiled his infectious smile, and exclaimed "Ah! A security blanket!" RIP

Here we go. The upstream FreeBSD details are in this long post. red.anthropic.com/2026/mythos-... Other than saying "look in this specific source file" (they run a different job for every file), there was no directed guidance. "Mythos Preview fully autonomously identified and then exploited ..."

It has been quite the few weeks for “security work we are not going to tell you details of.”

Wealthy leader, threatening to attack Persia, announcing that a great empire will be destroyed if he does, and not realizing that the prophecy is ambigous about which empire. I have many criticisms for the writers, but in particular could they stop plagiarizing from Herodotus?

Partial blame to Microsoft and Zoom for normalizing the need to install new software just to make video calls, despite browsers being perfectly capable. They make it extra hard to even find the web-only links. simonwillison.net/2026/Apr/3/s...

A very nice explainer why "if you're so worried about quantum computers, why haven't they factored 21 yet?" isn't a very convincing argument. Look at the labels of the graph, and how extremely close the various lines are for factoring 21 and 2048 bit numbers. Polynomial scaling remains […]

"Welcome to the Eternal September of open source", says the America Online of open source, 18 years into that September. (GitHub has done some great things for open source, but still, wow, what a headline to choose.) github.blog/open-source/...

Dan Lorenc is exactly right: "I blame[] the Trivy breach on GitHub. The design of Actions is plain irresponsible today and ignores a decade of supply chain security work from other ecosystems." www.linkedin.com/posts/danlor...

The best part of this regexp is the ? on the third line (which applies only to the g). alex000kim.com/posts/2026-0...

It may or may not be true that whether or not you race to use AI heavily right now will determine whether you’re part of a future wealthy elite ruling class or are left behind in poverty and powerlessness. But if it is true, this strikes me as a deeply immoral future worth fighting hard against.

"Cognitive surrender". www.nytimes.com/2026/03/29/o...

In my 2023 ACM talk, to illustrate how supply chain security is more than just build deps graphs, I showed a graph of the servers involved in building and serving Go releases. Has anyone done something like this but for GitHub Actions? We have examples now of attacks moving between actions.

Are you still hiding if no one is looking? People aren't reading the code at all—they'd see the weird decoder+eval—and machines can see that and also the private use code points. Also, it's been public since May 2025 and GitHub/NPM/Microsoft have done nothing. www.aikido.dev/blog/glasswo...

If this podcast episode is the only good thing that comes of AI, it will have been worth it—

“Floating-Point Printing and Parsing Can Be Simple And Fast” The fastest known floating-point printer and parsing algorithms - fixed-width printing, shortest-width printing, and parsing, all in 400 lines of Go. research.swtch.com/fp research.swtch.com/fp-proof

“Pulling a New Proof from Knuth's Fixed-Point Printer” Happy 88th Birthday to Don Knuth! And thanks again to @robpike.io for Ivy. research.swtch.com/fp-knuth

This was a fun conversation. Thanks to ACM Bytecast for having me on. learning.acm.org/bytecast/ep7...

Happy to see someone outside Google rebuild/verify Go toolchains. Thanks @agwa.name! www.agwa.name/blog/post/ve... "So far, Source Spotter has successfully reproduced every toolchain since Go 1.21.0, for every architecture and operating system. As of publication time, that's 2,672 toolchains!"

There is some chatter about a CA misissuing a certificate for 1.1.1.1. This CA (crt.sh?caid=201916, only ~300 certs) is only trusted by the Microsoft root program and the eIDAS QWAC trusted list. MS has not been actively managing their roots for years, and the EU wanted to push theirs on browsers.

Heading home from #GopherCon 2025 in NYC. As usual, many people asked how to get one of the amazing Go gopher Hawaiian shirts by Renee French. I've posted the details at github.com/rsc/gophersh.... (I know one person who has made pajama pants with the pattern. Socks might be nice too.) Enjoy!

Side point: this demonstrates the benefits of plain text file formats. When @robpike.io implemented the coverage tool he made it emit a simple line-based text file that Russ could then manipulate with the ubiquitous Unix tools.

Another fun magic trick! Differential Coverage for Debugging research.swtch.com/diffcover

Fifty Years of Open Source Software Supply Chain Security We are all struggling with a massive shift that has happened in the past 10 or 20 years in the software industry. For decades, software reuse was only a lofty goal. Now it's very real. queue.acm.org/detail.cfm?i... @swtch.com

With 8 minutes to go, @damienmiller.bsky.social sends me the only funny April Fool's joke of the day. Notably because I was on the team of people writing the firewall rules for Rob Pike's plan 9 desktop at Google. @tailscale.com fixes it (albeit ten years too late).

Yeah, about that... tailscale.com/blog/plan9-p... That gives the backstory :)

i was going to say it was hilarious but i wished it was real and then i realized it was

I only respect april fools jokes that commit to the bit. This? This is commitment.

This was a lot of fun!

"Tailscale Enterprise Plan 9 Support" tailscale.com/plan9 (A little thing I wrote and worked on over the past few weekends with @swtch.com)

@swtch.com you might be interested in this… zellyn.com/2022/01/gopi...

Does anyone know the effective time limit for GitHub comment edits being included in the comment text that is emailed to issue subscribers? GitHub renders "- #12345" differently on web (nice link with title and issue status) vs email (literally a useless blue #12345). 1/3

I have found exclusive footage of the mystery drones over New Jersey. youtu.be/qsb74pW7goU?...

Day 4 part 1 adventofcode.com/2024/day/4 #AdventOfCode pad dot-pads the matrix to avoid wraparound. x y shift m rotates the matrix x left, y down. d(=x y) shift4 m produces the 4 matrices shifted by d*0 1 2 3. d XMAS m identifies the X in XMAS in direction d.

Well, it's been 2/3 of a year since the xz attack. Is software safer now? Serious question. What improvements have we made?

Day 3 part 1. The function 'c step s' steps the state machine state s to incorporate the new character c. (step/ flip x) runs the state machine over the whole string, left to right. The reduction base case for "...yz" is 'y' step 'z', which step rewrites to ('y' step 'z' step initial-state).

Ivy remains a good choice for #AdventOfCode. Day 1: sample = transp read "sample.txt" op sort x = x[up x] op solve x = +/abs (sort x[1]) - sort x[2] solve sample op solve2 x = +/x[1] * +/x[1] o.== x[2] solve2 sample adventofcode.com (Ivy in 2021: www.youtube.com/playlist?lis...)

SVG, HTML5 Canvas, Apple Core Graphics, PDF, and probably many others all use the same core vector graphics model and operators, which I think of as from PostScript. Did the creators of PostScript invent these, did they originate in some even earlier system?

Learn a new magic trick! Hash-Based Bisect Debugging in Compilers and Runtimes research.swtch.com/bisect

This article attributes the xz attack to a Chinese hacker who texted about it, including claiming that they have at least one other open source bug. thenightly.com.au/world/chines...

A walkthrough of the xz attack shell script. An RC4 variant in Awk, what more could you want? research.swtch.com/xz-script

I put together a timeline of the xz attack, dating back to 2021. Corrections or additions welcome here on Bluesky. research.swtch.com/xz-timeline

The late, truly great Luiz Barroso wrote some very good, short essays on engineering practices at Google. He published them on his web site in a single PDF. The three one-pagers on pages 2, 3, and 4 are each gems.