[Cryptography] Solving Matt's hash problem

[Kyle Butt]

On November 12, 2022 5:18:33 AM MST, John Levine <johnl at iecc.com> wrote:
>In Matt Levine's long article about cryptocurrencies, he describes in
>accurate detail how hashing works, and mentions in an aside that he
>cannot include the hash of the article in the article itself, you (the
>reader) figure out why.
>
>I know this is a preimage problem, but is there anything about making
>the hash itself part of the input that would make it harder or easier
>to solve?

This is known as a "Hash quine". They exist at least for gifs and MD5

https://www.rogdham.net/2017/03/12/gif-md5-hashquine.en

Presumably you could use the same technique of commenting out blocks of data in other file formats. I haven't seen a demonstration, but it could be possible for HTML.