Как я НЕ взломал ED25519

В этой статье будет описано, как один чересчур поверивший в себя программист пытался взломать один из фундаментальных алгоритмов криптографии. Эта статья признана огородить других от подобных попыток или наоборот заинтересовать новых смельчаков для подобной авантюры. Сначала я опишу суть алгоритма на простом коде, затем перечислю методы и идеи, которыми я пытался его взломать.

https://habr.com/ru/articles/939686/

#curve25519 #ed25519 #python #хакинг #криптография #эллиптические_кривые #исследования_в_ит #математика #edwards_curve #уязвимости

Gibt es eine leicht erfassbare und verständliche Übersicht, welche Kryptoalgorithmen, Schlüssellängen, etc. nach dem #StandDerTechnik verwenden sollte? Ich stelle mir da eine Liste vor, die ich einem Admin in die Hand drücken kann und er macht nix falsch.

Das @bsi erstellt zwar (schwer verdauliche) Empfehlungen. Aber diese schwiegen sich aus zu üblichen Verfahren wie #Curve25519, die in RFCs beschrieben sind. Bei #telestrust gabs das mal - ist in neuen Versionen aber herausgefallen. Und die Zusammenstellung der #NIST verweist oft auf andere Dokumente.

@AG_KRITIS @kuketzblog

#InfoSec #Cryptographie #Kryptographie
#FollowerPower #PleaseBoost

@djb (Daniel J. Bernstein) tooted about a new blog post[1] he published. It's here:
https://blog.cr.yp.to/20250118-flight.html

It's interesting. He's a #mathematician and software guy that in more recent years has been known mostly for his work in #cryptography, #theoretical and #practical. You're probably using his #Curve25519 every day in your #communications.

I'm not a mathematician (by a long shot), but it's written in a pretty accessible manner - it's not #formulae and #turgid academic #prose.

The central point he's getting at, by my possibly-mistaken understanding of it, is that current "common sense" about when attacks against pre-quantum cryptography like #RSA (and therefore when post-quantum cryptography becomes critical) are badly mistaken - based on bad assumptions about how attacks work, how they're implemented, and on badly #extrapolating from those bad assumptions using logic that doesn't actually represent the way attacks are developed and become practical.

TL;DR is something along the lines of "#quantum cryptographic attacks against RSA will be practical sooner than most people think, and you should be deploying quantum-resistant cryptography now, not later".

It's worth reading if you're at all interested in #crypto and #security stuff.

He also mentions a project he's involved in that has been discussed separately, transparent post-quantum tunnelling for unmodified #server and #client #software. Link in post.

[1] Written more like a conference presentation, FWIW.

Coffee and elliptic curves

https://f.lapo.it/display/6a1cc041-1164-7767-4e2f-8f0061563271

Observation of today regarding Ed25519. I'm just trying to understand it on some level. Remember how did-keys have 44 significant "characters" in their base 58 encoding. This number 44 can be derived from 58**43 < 2**255 - 19 < 58**4, where 2**255 - 19 is the characteristic of the field the Curve25519 is considered over.

If my mathematical understanding is correct, there are always at most two points for a given y coordinate. So for the purposes of "representations" one can identify each point on Curve25519 with such a 44 character base 58 encoding.

Also please understand that figuring how numbers match is in no way mathematics. It just helps build a picture in my mind.

It’s 2023 and you’re designing a decentralised system based on public-key cryptography where a person’s identity(ies) are their public key(s).

Do you…

#cryptography #postQuantumCryptography #pqc #pq #ed25519 #curve25519 #x25519 #SmallWeb #Kitten