this post was submitted on 05 Oct 2026
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Programming
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I've never heard of anyone relying on git's sha1 hashed for security
I have. In some languages you can use git repos as dependencies. It's good practice to use hashes instead if tags because tags are not immutable. SHA1 hashes are better than tags but better hases would be even better.
Also traceability. You can build a chain from your commit over ci to the artifact if you do it right. If you can change the files to a hash you can destroy that trust chain. Sha256 makes that impossible.
People use the hashes in ways you might not. It wasn't meant as a trust anchor but it became one. And that is now being addressed. I also think that the git maintainers have put a lot of thought into backward compatability and making the change as painless as possible.
Good practice != Something that ensures security. As I said, it's an even better practice to just host your own fork if what you want is security. The reason to use git hashes is mostly so you don't have to trust the author following semver in there version number. It's a matter of ensuring that your code will always compile, not a security feature.
Have you read the article? Your arguments derive from an assumption of "sha1 is mutable, sha256 is immutable". First of all, every hashing algorithm is going to have collisions, that's an unavoidable "feature" of hashes. And sha1 is in no way "mutable", it takes a great amount of effort (and money) to generate a collision. Furthermore, those collisions are not arbitrary. You have to calculate them beforehand. As the article says: what is more likely? Paying 40k€ in compute time to generate a single collision? Or just paying an open source maintainer 40k€ to let you do 1 new commit that most people are going to download anyway?
Yes I read the article. I don't agree with all the conclusions.
Now is the best time to change to a new algo. SHA1 is not completely broken yet. It most probably will be at some point.
Also AFAIK they will have compatibility tools for SHA1 repos in git. I don't see the big deal with the path they chose.
We will probably nor agree on that one. I think the hashes are important and that they are mutable right new with effort and later without. It's okay that we don't agree though. The git maintainers have made their decision anyways.