Sorry, no.

When I check out code from a git repository in a pipeline using a git hash, I expect the code to be exactly what has been reviewed by me under that hash.

Everything else would just be a crazy invitation to make supply chain attacks uncircumventable.

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kazinator 6 hours ago | parent [-]

And so if you don't trust the server that is hosted on or the security of the transport mechanism like TLS/SSL, such that the content may be manipulated by adversaries, you think that git hashes are good enough?

Well, what about someone who is fetching the commit from that server for the first time and has nothing to compare the hash against?

Oh, that would never be a problem for widely disseminated, popular, open source project, so it doesn't matter.

	▲	kstrauser 16 minutes ago \| parent \| next [-]
		Rumor has it that GitHub has a flat namespace for commits. They don't store "user1/repo1/abcd1234" in one file and "user2/repo2/abcd1234" in another. Both references point to the same commit in a global shared space. If the hashes are truly unique, then that never matters, because the odds are approximately 0.000000000...000 of you and I accidentally generating the same commit. However, if I see that you pushed commit abcd134, and then I can build and push a colliding commit, and the backend doesn't check uniqueness before writes because the odds are infinitesimal that it'd ever matter, than voila, I've updated your repo by writing to my own. Or if first writer wins, and I know that you have a popular non-GitHub repo that you're about to migrate into it, then I could pre-poison the namespace by writing my own version of a commit that I see you already have in Codeberg or Savannah or wherever. I don't swear that this is how GitHub actually works, but I've had knowledgeable friends swear up and down that it is. And honestly, it'd make sense. They could shard storage by the first 4 digits of the hash or something, and that'd be vastly more efficient if all commits were writing to the same space.
	▲	crote 6 hours ago \| parent \| prev \| next [-]
		Dealing with potentially-hostile hosts is quite common, actually. See for example how most Linux mirrors work, or Subresource Integrity with HTML. Turns out securing a service to transfer a single hash is a lot easier than securing a service to transfer gigabytes of data. Even if I don't fully trust Github, it is still incredibly convenient to be able to upload my code there and then send someone an email telling them to fetch commit `123abc` from some repo link. As long as my email isn't compromised, that should be secure.
	▲	PunchyHamster 3 hours ago \| parent \| prev [-]
		I mean, Git commit signing should be used more often... then you can actually trust the person signing, not the distribution method But you still need SHA256 for that