root-signing VS attestation

caveat, I am from the sigstore project.

GitLab are currently working with sigstore community to rig in their CI/CD as well and the root of CA of sigstore is community created and owned. This means any provider can trade an ODIC ID token for a sigstore certificate.

https://github.com/sigstore/root-signing

It's multi-pronged and I imagine adopters may use a subset of features. Broadly, I think folks are going to be interested in a) branch/tag/reference protection rules, b) file protection rules (monorepo or otherwise, though monorepos do pose a very apt usecase for gittuf), and c) general key management for those who primarily care about Git signing.

For those who care about a and b, I think the work we want to do to support [in-toto attestations](https://github.com/in-toto/attestation) for [SLSA's upcoming source track](https://github.com/slsa-framework/slsa/issues/956) could be very interesting as well.

I have. I actually worked a few desks down from dpc when he was creating it and we talked about it at length. I felt then and now that it has good goals but a very limiting implementation in that it does not pursue a portable spec and instead anchors a very opinionated format to git, and github, instead of cryptographic keys held in hardware owned controlled by reviewers. I want to see the same keys that sign git commits also sign reviews, for instance.

I think for broad adoption a review system should ask essentially the same questions as crev, but store them in a format like in-toto including signatures by the reviewers created with a user choice of pgp smartcards, ssh keys, or webauthn devices. These reviews would be anchored to hashes of a particular state of a particular tree of code and not to any type of VCS or distribution system. Important code is distributed via Perforce, mercurial subversion, and tar files depending if we are talking about big corps, or linux distro building blocks. A good OSS review system should be also be usable by teams in their internal proprietary codebases too if we wish to see wide adoption. Even for OSS we may wish to share some reviews as standalone objects privately while security embargos are in place, etc. Proofs should also be verified standalone easily from local cache, when github is down, when original repos vanish, etc.

Something that meets these broader needs will make it easy for large orgs with very different internal setups to participate and play nice with other supply chain efforts by the OpenSSF using in-toto for reproducible builds, etc.

My experience tells me we need something much more ambitious than crev, but crev proved to me many people have real interest in this problem which I really thank dpc for.

The biggest blocker for starting this project is the human review spec settling in in-toto https://github.com/in-toto/attestation/issues/77