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cperciva

64,557 karma · joined June 21, 2007

Founder of tarsnap: http://www.tarsnap.com/

Email: <me>@tarsnap.com

Twitter: @<me>

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cperciva··on Launching Route 53 Files
Oh, I was being facetious. I'm pretty sure Jeff mentioned needing to spend time writing a style guide when he started having other Amazonians write posts for "his" blog.

As a non-Amazonian I've never seen it, of course.

cperciva··on Launching Route 53 Files
Wait, there's an official style guide?

(In all seriousness, I've been reading AWS launch posts for 20 years; this one was mainly imitating the S3 Files launch post but I diverged by adding the customer quote and the FAQ -- because of course I started this process with a PRFAQ, and some of the questions in the FAQ are legitimately important.)

cperciva··on Launching Route 53 Files
Files which aren't DNS keys get ignored by Route 53 Files. So you could absolutely have a git checkout and update your DNS with 'git pull'.
cperciva··on Launching Route 53 Files
There are apparently many people managing their S3 Objects by hand but long to have them in a file system, yes.
cperciva··on The Tariff Cost: analysis of the costs to Americans from new tariffs on Canada
But does America have a trade imbalance with Canada?

Yes, because Canada has a lot of cheap oil which America wants. If you deduct oil, the trade deficit runs the other way.

cperciva··on FDA authorizes first wearable device that monitors ketone and blood sugar levels
whether or not (say) that coffee you just drank took you out of the fasted state

A cup of coffee has zero carbohydrates, trace lipids, and about half a gram of protein. That's not going to pull anyone out of a fasting state.

Now, if you're talking about a cup of flavoured milk, that's a different question...

cperciva··on US Military newspaper editor voices censorship fears after being fired
The oath isn't legally binding, but the law is. Committing war crimes is illegal even if the civilian government orders it.
cperciva··on I close SSH port 22 (and what I use instead)
This is what spiped is for.
cperciva··on Breaking the WAL
Typo in the post: "SQL 3.51.2" should presumably be "SQLite 3.51.2".
cperciva··on Postmortem for Kernel Soundness Bug #14576
A counterexample of the form "X cycles to X after N steps" is easy to check. A counterexample of the form "starting with X we keep going up forever" is hard to check in finite time.
cperciva··on Delayed Gratification – Proud to Be 'Last to Breaking News'
I'm guessing you want https://www.daemonology.net/hn-weekly/ then?
cperciva··on A single underscore led to an innocent Halifax man's conviction
... how did that happen? Yes thanks.
cperciva··on Financing the AI boom: from cash flows to debt [pdf]
You're right, I was remembering the peak and duration of the railway boom but of course it wasn't at the peak for the entire duration.
cperciva··on Financing the AI boom: from cash flows to debt [pdf]
Yes. In inflation adjusted dollars spending on AI dwarfs previous "megaprojects". But as a fraction of GDP it's fairly modest -- comparable to the Apollo Project.

It's a sign of how much the economy has grown that under "1% of GDP for a few years" now is far bigger than "over 10% of GDP for a few decades" was in the late 1800s.

cperciva··on Aluminum foil (2021)
the oxide to pure aluminum ratio is high

For some definition of high? Standard foil is around 20 um thick while the oxide layer only goes about 10 nm deep.

cperciva··on New serious vulnerabilities spiked around release of Claude Mythos Preview
I've seen plenty of people saying "Mythos isn't all that exceptional, lots of LLMs can find security vulnerabilities" -- and indeed there is some evidence for that; it sounds like Anthropic was taken somewhat by surprise at how easily a simple prompt managed to get Mythos to deliver exploits and didn't distinguish immediately between the effectiveness of Mythos and the effectiveness of the prompt.

But the claim of "LLMs aren't making a difference in vulnerability discovery" has been laughable to anyone who has been reading security advisories for the past 3 months. Just look at the Credits lines.

cperciva··on New serious vulnerabilities spiked around release of Claude Mythos Preview
This is hardly news? We've known for months that a flood of AI-assisted vulnerabilities was coming; I posted on Twitter in March calling 2026 the year of a million CVEs: https://x.com/i/status/2035045573116789002
cperciva··on For first time, a cell built from scratch grows and divides
This was CVE-2005-0109.
cperciva··on For first time, a cell built from scratch grows and divides
Frankly, there's no way any arch venue at the time would have done anything beyond rejecting it with "caches make RSA fast, what's the problem?"

Security wasn't something CPU designers paid much attention to, and cryptography wasn't something they were even particularly aware of. Even seven years ago, when an Intel VP was giving a talk at re:Invent about "processor technologies for improving security in virtual machines", my question to him about cache collision side channel attacks was met with "what's a side channel attack?"

cperciva··on For first time, a cell built from scratch grows and divides
They publish lots of papers about side channel attacks, including very hardware based ones like power consumption analysis.

It just happened that "leak information into microarchitectural state and then retrieve it" didn't exist as a subfield until my work (and the OST work a few weeks behind mine).

cperciva··on For first time, a cell built from scratch grows and divides
My paper demonstrating a side channel attack on RSA via hyperthreading was rejected from the crypto preprint archive on the basis that it was "not cryptography".

(Reviewers at J.Crypto subsequently sat on it for a year and then suggested I submit it to a journal on CPU microarchitecture instead.)

Novel research is uniquely susceptible to "cool but it's not part of our field", because that critique is entirely correct until the research gets published!

cperciva··on Ask HN: What are you working on? (June 2026)
FreeBSD 15.1! Scheduled to be announced 2026-06-16 00:00 UTC; just need to get some release documentation polished now.
cperciva··on World Capitals Voronoi
Square root of the population is because that's what it takes to normalize large vs small countries. Imagine slicing a country into quarters; each slice has a quarter of the population and half the radius.
cperciva··on World Capitals Voronoi
It would be interesting to see a map which was not minimizing [distance to capital] but instead minimized [distance to capital]/sqrt([national population]). The latter would be more robust against Sybil attacks.
cperciva··on How much do amd64 microarchitecture levels help in Go?
arguably the whole scheme should be replaced by finer-grained feature detection.

This seems like a strange thing to say. Fine grained feature detection was around long before "microarchitecture levels" and never went away. The microarchitecture levels were introduced because they were easier to use.

cperciva··on Google will pay SpaceX $920M per month for compute
True. The amount of free float increasing dramatically will probably also depress the share price.
cperciva··on Google will pay SpaceX $920M per month for compute
Now with this incredible deal, SpaceX is now GAAP profitable under the existing rules, and they get to join the index next year without a rule change.

Didn't they also run up against a "minimum free float" rule?

cperciva··on Conventional Commits encourages focus on the wrong things
That information should still be in the commit messages. "No functional change intended." appears widely in FreeBSD commit logs when code is being refactored (or, rarely, restyled).

And the issue isn't whether you can remember what you changed yesterday; this is largely about making sure other developers can quickly identify relevant commits. If you're a solo non-OSS developer, this is entirely relevant to you.

cperciva··on Claude Code and Codex Can Have Real-Time Conversation via Git
I've done this with code review. "Another LLM reviewed the attached code and produced the attached report. What do you think?"

Lots of "the other LLM clearly hallucinated this part". To be fair, it has never accused the other, err, itself, of being incompetent; it accepts that hallucinating is just something which happens.

cperciva··on Having your insulin pump die while you're on vacation
Is that true for every type and format

Yes, OTC for everything. I've heard that some pharmacists ask more questions about types which are commonly abused by body builders but that's about the extent of it.

Funny story since you mention cats: My brother's cat was diabetic and prescribed long acting insulin which cost $250/vial. I looked it up and... apparently it was just relabeled lantus, because of course nobody is going to waste money on a separate manufacturing line. Ended up buying it from my local pharmacy, without a prescription, instead of using the vet prescription.

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