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Verifying Sigstore Bundles as an End User

May 2, 2025 · Zach Steindler (GitHub)

There’s a mnemonic for quickly determining if a bicycle is safe to ride: “ABC” for checking the air in the tires, ensuring the brakes are functional, and checking the chain. It doesn’t definitively answer the question “is this bike safe?” but it does give you a quick starting point for your assessment. Let’s say you download some software and it comes with a Sigstore bundle. Similarly, there isn’t a quick, definitive answer to “is this software safe to use?

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Using rekor-monitor to Scan Your Transparency Logs

Nov 21, 2024 · Linus Sun (Google)

Overview As part of the tool suite within Sigstore that focuses on providing transparency in the software supply chain, Rekor, Sigstore’s signature transparency log, and Fulcio’s certificate transparency log provides discoverability and auditability for signed artifact metadata and code-signing certificates. These immutable read-only logs help secure the software supply chain by making it easier to show what actions have been performed by a compromised identity. A variety of different improvements have recently been integrated into rekor-monitor to make it easier to use.

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PyPI's Sigstore-powered attestations are now generally available

Nov 14, 2024 · William Woodruff (Trail of Bits), Dustin Ingram (Google), Hayden Blauzvern (Google)

Check out the PyPI blog and Trail of Bits blog for more user-facing and technical details, respectively! Over the past year, the Google Open Source Security Team and Trail of Bits have worked together to implement PEP 740, a Python packaging standard that allows users to upload Sigstore-based attestations to the Python Package Index. Today we’re pleased to announce that attestation support on PyPI is generally available, meaning that project maintainers can submit attestations for both PyPI and downstream users to verify.

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cosign Verification of npm Provenance, GitHub Artifact Attestations, and Homebrew Provenance

Aug 27, 2024 · Zach Steindler (GitHub)

One of the features of the cosign v2.4.0 release allows you to verify attestations in the bundle format used by npm provenance, GitHub Artifact Attestations, and Homebrew provenance. This is part of all Sigstore clients supporting the bundle format as outlined in the community roadmap. We’ll show how to perform that verification for each ecosystem, and explain some of the details involved. You’ll notice these examples follow the same general pattern of getting an artifact to verify, getting the bundle that contains the signed attestation about that artifact, and then providing a verification policy to cosign via command line flags.

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Homebrew's Sigstore-powered provenance is in beta

May 14, 2024 · William Woodruff (Trail of Bits), Hayden Blauzvern (Google)

Last November, Alpha-Omega and Trail of Bits announced a collaboration to bring build provenance to homebrew-core. Today, we are pleased to announce that the core of that work is live and in public beta: homebrew-core is now using Sigstore to cryptographically attest to all bottles built in the official Homebrew CI. This is aligned with Sigstore’s mission: to support frictionless and transparent provenance on all artifact registries. Homebrew’s build provenance follows last year’s npm provenance feature, making Homebrew the second major packaging ecosystem to adopt Sigstore!

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npm's Sigstore-powered provenance goes GA

Oct 3, 2023 · The Sigstore Technical Steering Committee

Last week saw the GA release of npm CLI’s native Sigstore functionality, a project over a year in the making. This is a tremendous milestone for the adoption of Sigstore in open source projects and represents huge progress in effecting a cultural shift toward expecting provenance to exist for software components. It also helps move npm toward the best practices articulated by the OpenSSF’s Securing Open Source Repos Working Group in their document “Build Provenance for All Package Registries”.

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Sigstore Support in npm launches for Public Beta

Apr 19, 2023 · The Sigstore Technical Steering Committee

We’re thrilled to announce that the npm project has launched a public beta, bundling Sigstore support directly into the npm Command-Line Interface (CLI). This innovation brings strong origin guarantees to the npm ecosystem and marks the first time that a large package registry technology is using public software signatures to attest to a package’s originating source code and build instructions. Sigstore is an OpenSSF project that enables developers to validate that the software they are using is exactly what it claims to be using cryptographic digital signatures and transparency log technologies.

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Cosign 2.0 Released!

Feb 23, 2023 · Hayden Blauzvern

Cosign 2.0 has arrived! Cosign 2.0 follows Sigstore’s General Availability launch, which offers production grade stable services for artifact signing and verification. Cosign’s most significant change is to no longer require COSIGN_EXPERIMENTAL=1, since the Sigstore services are now stable! By default, Cosign will fetch an identity-based certificate from Fulcio when a signing key is not provided, and upload the signature and signing key to Rekor to provide transparency. The following is the list of breaking changes:

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Cosign and Policy-controller with GKE, Artifact Registry and KMS

Feb 10, 2023 · Mathieu Benoit

As soon as I came back from KubeCon NA 2022, my first ever in-person KubeCon, I felt re-energized. What a community, full of people eager to share knowledge and expertise with each others, so inspiring. I mostly attended sessions about security best practices for containers and Kubernetes (that’s what excites me these days!). Secure Software Supply Chain (S3C) was almost mentioned everywhere, for good reasons. Sigstore as a new standard for signing, verifying and protecting software, got its first own SigstoreCon as co-located event and hit the General Availability (GA) milestone.

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Sigstore January Roundup

Feb 1, 2023 · Sigstore

This month, we are thrilled to have announced the 1.0 release of sigstore-python. This project started a year ago to provide a Sigstore-compatible client similar to cosign, but built entirely with Python and easily adoptable by the Python ecosystem. A big thank you to all the contributors and maintainers for making it to 1.0! Read more Latest Blog Posts Thank you to Andrew, Felix and Zachary for contributing the following blog posts this month.

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