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PyPI now supports digital attestations

(blog.pypi.org)
218 points miketheman | 6 comments | 14 Nov 24 14:25 UTC | HN request time: 0s | source | bottom
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belval ◴[14 Nov 24 16:05 UTC] No.42137562[source]▶
I have a bit of uneasiness about how this is heavily pushing GitHub actions as the correct way to publish to PyPI. I had to check PEP740 to make sure it was not directly supported by Microsoft.

> The generation and publication of attestations happens by default, and no changes are necessary for projects that meet all of these conditions: publish from GitHub Actions; via Trusted Publishing; and use the pypa/gh-action-pypi-publish action to publish.

If you then click on "The manual way" it adds a big disclaimer:

> STOP! You probably don't need this section; it exists only to provide some internal details about how attestation generation and uploading work. If you're an ordinary user, it is strongly recommended that you use one of the official workflows described above.

Where the only official workflow is "Use GitHub Actions".

I guess I am an idealist but as a maintainer this falls short of my expectations for the openness of Python and PyPI.

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woodruffw ◴[14 Nov 24 16:12 UTC] No.42137628[source]▶
> Where the only official workflow is "Use GitHub Actions".

The standard behind this (PEP 740) supports anything that can be used with Trusted Publishing[1]. That includes GitLab, Google Cloud, ActiveState, and can include any other OIDC IdP if people make a good case for including it.

It's not tied to Microsoft or GitHub in any particular way. The only reason it emphasizes GitHub Actions is because that's where the overwhelming majority of automatic publishing traffic comes from, and because it follows a similar enablement pattern as Trusted Publishing did (where we did GitHub first, followed by GitLab and other providers).

[1]: https://docs.pypi.org/trusted-publishers/

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silverwind ◴[14 Nov 24 16:15 UTC] No.42137658[source]▶
Why does this need to allowlist CI providers in first place? Why not publish an open interface any CI provider can integrate against?
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woodruffw ◴[14 Nov 24 16:20 UTC] No.42137727[source]▶
Because the security benefit of Trusted Publishing via OIDC versus normal API tokens is marginal at small scales, in two senses:

1. The primary benefit of Trusted Publishing over a manual API token is knowing that the underlying OIDC IdP has an on-call staff, proper key management and rotation policies, etc. These can be guaranteed for GitHub, GitLab, etc., but they're harder to prove for one-off self-hosted CI setups. For the latter case, the user is no better off than they would be with a manual API token, which is still (and will always be) supported.

2. If the overwhelming majority of traffic comes from a single CI/CD provider, adding more code to support generic OIDC IdPs increases PyPI's attack surface for only marginal user benefit.

There also is no "open interface" for PyPI to really use here: this is all built on OIDC, but each OIDC provider needs to have its unique claims mapped to something intelligible by PyPI. That step requires thoughtful, manual, per-IdP consideration to avoid security issues.

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freeone3000 ◴[14 Nov 24 19:36 UTC] No.42140243{4}[source]▶
I think I would be better off with API key + PGP than API key alone. And that’s being phased out?
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1. woodruffw ◴[14 Nov 24 20:20 UTC] No.42140749{5}[source]▶
You can no longer upload a PGP signature to PyPI, if that's what you mean. That was phased out last year (to virtually no complaint since nobody was actually verifying any of the signatures, much less attempting to confirm that their keys were discoverable[1]).

[1]: https://blog.yossarian.net/2023/05/21/PGP-signatures-on-PyPI...

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2. guappa ◴[14 Nov 24 21:43 UTC] No.42141554[source]▶
> to virtually no complaint since nobody was actually verifying any of the signatures

And this is in no way a consequence of pypi stopping to host public keys right? Say the whole story at least… Say that there used to be a way to verify the signatures but you dropped it years ago and since then the signatures have been useless.

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3. woodruffw ◴[14 Nov 24 22:24 UTC] No.42141856[source]▶
If it did, it was well before I ever began to work on PyPI. By the time I came around, PGP signature support was vestigial twice over and the public key discovery network on the Internet was rapidly imploding.

(But also: having PyPI be the keyserver defeats the point, since PyPI could then trivially replace my package's key. If that's the "whole story," it's not a very good one.)

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4. freeone3000 ◴[14 Nov 24 23:16 UTC] No.42142309{3}[source]▶
This attestation doesn’t change a ton with that, though. The point is to provide chain of custody — it got to my computer, from pypi, from ???. The PGP signature, much like a self-signed android app, verifies that it continues to be the same person.
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5. guappa ◴[15 Nov 24 08:21 UTC] No.42144900{3}[source]▶
It was a plural you. I have no idea who you personally are.
6. woodruffw ◴[15 Nov 24 14:02 UTC] No.42147013{4}[source]▶
The critical difference with this architecture is that it doesn’t require key discovery or identity mapping: those are properties of the key infrastructure, similarly to the Web PKI.

Your self-signed app analogy is apt: self-signing without a strong claimant identity proof is a solution, but a much weaker one than we wanted.