Author | Lightnews

Nils Fleischhacker @cryptomaeher.bsky.social · 16h

Unfortunately I don't think you have time for that talk.

Nils Fleischhacker @cryptomaeher.bsky.social · 19h

Mathematicians always claim to love blackboards. But what they don't want you to know is that most of those boards are green.

Nils Fleischhacker @cryptomaeher.bsky.social · 1d

It's an extremely information dense language.

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Nils Fleischhacker @cryptomaeher.bsky.social · 1d

If I didn't know any better I'd say that's a mallard duck and not a dodo 🤔

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Nils Fleischhacker @cryptomaeher.bsky.social · 2d

How many do you need to redeem your free coffee?

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Nils Fleischhacker @cryptomaeher.bsky.social · 2d

Well, I'm certainly better now than I was. I'm finally allowed to walk without crutches again. Starting physio on Friday and cleared for crossing on a stationary bike, so things are looking up.
Will probably need to wait another four weeks before I can start running again.

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Nils Fleischhacker @cryptomaeher.bsky.social · 2d

Broke my foot trying to evade a dog that lunged at me. Spent six weeks on crutches. Missed three races including the Frankfurt Marathon because of it. (Technically I will be missing the third one in three weeks.) Still pretty pissed about it.

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Nils Fleischhacker @cryptomaeher.bsky.social · 2d

I'M ALLOWED TO WALK! Now to find out if I remember how.

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Nils Fleischhacker @cryptomaeher.bsky.social · 2d

Operating system or headwear?

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Nils Fleischhacker @cryptomaeher.bsky.social · 5d

That actually makes a lot of sense. We agreed on a time, not on a time of day. This maintains the same time difference at all times. The fact that that's necessary is still definitely evidence that timezones and DST are cursed.

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Nils Fleischhacker @cryptomaeher.bsky.social · 5d

TIL that while we managed to agree with the Brits on a *date* to change the clocks, we apparently couldn't agree on a time. 🤦‍♂️ Timezones are truly cursed and DST even more so.

Matt Gray @mattgrayy.es · 6d

That time of year I have to check which 1:45am it is

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Nils Fleischhacker @cryptomaeher.bsky.social · 10d

We also want people to stop using something literally called Secure Hash Algorithm because it's not secure. 🤷‍♂️

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Nils Fleischhacker @cryptomaeher.bsky.social · 10d

I still expect dlog to be broken classically before anyone builds a cryptographically relevant quantum computer.

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Reposted by Nils Fleischhacker

ePrint Updates @eprint.ing.bot · 12d

What is Cryptography Hiding from Itself? (Diego F. Aranha, Nikolas Melissaris) ia.cr/2025/1951

Abstract. The European Commission’s 2022 proposal for a regulation on child sexual abuse material, popularly labelled ChatControl, obliges online services to detect, report, and remove prohibited content, through client-side scanning.
This paper examines the proposal as a case of undone science in computer security ethics: a domain where technical feasibility and rights-compatibility questions remain systematically underexplored. Combining legal analysis with philosophy of technology, the paper argues that client-side scanning transforms end-to-end encryption from a right to secrecy into a conditional privilege of use. By integrating Isaiah Berlin’s concept of negative liberty, Langdon Winner’s account of the politics of artifacts, and David Hess’s notion of undone science, the analysis traces how design choices become moral constraints.
The discussion situates the European debate within broader concerns about proportionality, epistemic selectivity, and the governance of digital infrastructures. Ultimately, the study shows that the controversy over ChatControl is not only about privacy or child protection but about the epistemic norms that define what counts as legitimate technological knowledge.

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Nils Fleischhacker @cryptomaeher.bsky.social · 12d

Just scale the last two pages to 50% and include them on one page in landscape. The beauty of the ISO A Series.

Reposted by Nils Fleischhacker

ePrint Updates @eprint.ing.bot · 14d

Guaranteeing a Dishonest Party’s Knowledge (Or: Setup Requirements for Deniable Authentication) (Nils Fleischhacker, Guilherme Rito) ia.cr/2025/1922

Abstract. Deniable authentication is a very desirable guarantee for secure messaging — and in particular Off-The-Record messaging: it allows a sender Alice to authenticate her messages while retaining plausible deniability on whether she authenticated any of her messages.

While deniable authentication is not achievable in standard Public-Key Infrastructures, Dodis et al. (TCC ’09) have shown that it is achievable in so-called Key-Registration with Knowledge setups. These guarantee: 1. dishonest parties’ key-pairs are honestly generated; and 2. dishonest parties have access to their secret keys. However, these are expensive assumptions, and it is unclear how securely realize them in practice.

In this paper we study the weakest setup requirements that are sufficient to enable deniable authentication. One of our main findings is that deniable authentication does require an expensive — but not necessarily impractical — Key-Registration procedure. Roughly, this procedure must guarantee that if a user’s key registration is successful, then the user can extract by themselves valid secret keys from their interaction with the registration authority. We show this setup is sufficient by capturing it via an appropriate security model and then proving the anonymity of a ring signature based on it. On the other hand, we explain why this setup seems inherently necessary by listing a series of attacks that void deniability as soon as a user manages to successfully register a public key for which it can convincingly claim it does not know a valid (corresponding) secret key.

The requirements we identify for key-registration protocols are expensive, but not necessarily impractical. Our second main contribution is showing how to amortize the per-user Key-Registration cost, which brings deniable authentication guarantees a step closer to practicality.

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Nils Fleischhacker @cryptomaeher.bsky.social · 19d

"By standard hybrid argument"

Matteo Panella @matteo.panella.boo · 19d

In honour of spooky month, share a 4 word horror story that only someone in your profession would understand.

"NFS needed for HA"

Queen Olivia III @queenoliviaiii.com · 20d

In honour of spooky month, share a 4 word horror story that only someone in your profession would understand.

“The tapes wouldn’t start”

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Nils Fleischhacker @cryptomaeher.bsky.social · 26d

No German government in the last 20 years was in any way a principled opponent of surveillance.

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Nils Fleischhacker @cryptomaeher.bsky.social · 26d

I'm a bit confused where anyone got the idea that Germany had any kind of principled position on this.

Signal @signal.org · 28d

We are alarmed by reports that Germany is on the verge of a catastrophic about-face, reversing its longstanding and principled opposition to the EU’s Chat Control proposal which, if passed, could spell the end of the right to privacy in Europe. signal.org/blog/pdfs/ge...

signal.org

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Nils Fleischhacker @cryptomaeher.bsky.social · 28d

It's a big red button. The required action seems very clear.

Nils Fleischhacker @cryptomaeher.bsky.social · 28d

Very helpful. 👍

I mean telling me *what* I need to do would be even more helpful, but you know. 🤷‍♂️

Anyway, apparently I no longer have access to my emails on my phone. Well, we had a good run.

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Nils Fleischhacker @cryptomaeher.bsky.social · Sep 26

What? No I'm not hopping around on one leg because I can't carry anything when waking with crutches. I'm doing single leg plyometrics!

Nils Fleischhacker @cryptomaeher.bsky.social · Sep 17

And these thrombosis prevention drugs should not be combined with caffeine? WTF is this shit? 🤬

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Nils Fleischhacker @cryptomaeher.bsky.social · Sep 17

Well, Shit.

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Nils Fleischhacker @cryptomaeher.bsky.social · Sep 16

People always say that, but honestly the owners wouldn't be a problem if dogs weren't naturally aggressive little shits that needed extensive training just to ignore people.

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