[simplicialset]

It's probably easier with quantum computers: https://eprint.iacr.org/2020/213.pdf.

[thfuran]

How would that appreciably help? There are so many more 4kb strings than sha1 hash values that finding collisions barely matters.

[simplicialset]

Data generated by people isn't random, it has statistical regularities that can be used to narrow down the search space and since quantum computers are better at certain kinds of search problems it will be easier to find fragments of files based on just the hashes of the content.