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#hashing

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Joaquim Homrighausen

I want to convert UTF-8 encoded strings into some sort of irreversible hash *and* maintain correct sort order (or the ability to lexically compare strings).

If I say "Order-Preserving Hashing with Prefix-Free Encoding", what do you say? 🤔

The problem I foresee (with great wisdom 👀) is dictionary attacks, thus not being actually "irreversible".

#programming#sorting#hashing
Public
Habr

Merkle-tree: Как проверить целостность данных без полного доступа?

Хэширование — простой и надёжный способ проверить целостность данных. Но как быть, если нужно удостовериться, что часть данных принадлежит определённому набору ? Например, проверить отдельную транзакцию в блоке Bitcoin или чанк файла в BitTorrent? Для этого используется уникальная структура данных — Merkle-tree . В этой статье вы узнаете, как с её помощью решать задачи проверки данных без доступа к их полному объёму.

habr.com/ru/articles/873718/

ХабрMerkle-tree: Как проверить целостность данных без полного доступа?Когда речь заходит о проверке целостности и неизменяемости данных, на помощь приходит хэширование. Например, если мы хотим передать файл по сети и убедиться, что он дошел до получателя без изменений,...
#merkleproof#merkle_tree#merkle_patricia_tree
Replied in thread
Public
MidgePhoto

@spmatich @ibk @phoebematich

For medical records you can imagine we want to know, and show, that the record we see is the record that was made, all of it, and only it.

This may be accomplished by passing the (element of the) record through a #trapdoor #function, or #hashing #algorithm such as SHA1 (secure hash algorithm 1) and sending the hash somewhere else.

The hash is small, compared with the medical note, and tiny compared to a photograph.

…

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zirias (on snac)
Just started work on the planned "single instance mode" for #Xmoji.

The first commit is done, adding a class implementing the core functionality using a local #Unix #socket. Part of the job is deriving a unique name for that socket, where #hashing comes natural.

I had a similar class in #qXmoji (based on #Qt), and there you have #sha256 at your fingertips with QCryptographicHash, so I just used that. You need a string from that, and sure thing, there's a .toBase64() method. Well, a / doesn't play well for filenames, but then, there's .replace().

Without all these helpers from Qt, first thing I did now was searching the web for a "good" hash function, but there's certainly no need for a cryptographic one. I found #FNV1a. It's super easy to implement in #C. And for the base64 part, well, doing it myself, I can directly use a modified set of digits, without the /.

Now, here's the whole thing:
https://github.com/Zirias/xmoji/commit/db764e3184537d42b528e718bd4886495eb45544

I'd say that's a nice example how not having lots of "powerful" library functions readily available can lead to a much better (smaller, more efficient) solution. 😏

#X11 #emoji #keyboard #development
GitHubSingleInstance: Enforce single running instance · Zirias/xmoji@db764e3Add class to optionally enforce a single running instance per host and user. Use this during xmoji startup().
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Royce Williams

So ... due to an early obsession with historical BSD hashes ... I have significantly more bcrypt hashrate-per-watt cracking capacity than most solo shops. For bcrypt cost 12, it's about 34Kh/s straight wordlist -- the equivalent of about 17 4090s -- at only 1100W (these old Bitcoin FPGAs are very efficient for bcrypt specifically). And this capacity is intermittently idle, which is kinda a shame.

I haven't really put it out there as something I can help with if needed (outside of the Hashcat team). So ... feel free to ping me if you need bcrypts cracked/audited!

(Reasonable rates, but note that I do have a pretty firmly high bar for provenance / proof of authorization)

(Rat's nest of USB has been cleaned up a bit 😅)

A stack of 36 ZTEX FPGA boards in a couple of acrylic CD towers, fed through a rat's nest of USB hubs. A box fan sits in front. A John the Ripper sticker graces the edge of the outer stack. Some heatsinks are copper-colored and less than an inch high; others are black and taller.
#bcrypt#PasswordCracking#hashing
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