Sigstore
Sigstore is a free, open source project focused on software supply chain security.
What Sigstore is
Sigstore is a free, open source project focused on software supply chain security. Developers can use it to sign and verify release files, container images, binaries, software bills of materials, and other artifacts. Signing uses temporary keys, so developers do not need to manage signing keys themselves. Signing events are entered into a public, tamper-resistant log for auditing. Its components include Cosign, Fulcio, Rekor, OpenID Connect, and Policy Controller: Cosign handles artifact signatures and verification, Fulcio issues temporary certificates to authorized identities, and Rekor stores searchable signed metadata. OpenID Connect authenticates users through providers such as GitHub and Google. Sigstore provides GitHub Actions and documents installation for GitLab CI, alongside official clients for Go, Java, JavaScript, Python, Ruby, and Rust. The trust root uses The Update Framework and is maintained by five keyholders drawn from different companies and academic institutions. Sigstore supports Linux, macOS, Windows, API, and self-hosted environments. Community assistance is available through Slack and GitHub issues. One integration caveat is that Cosign has no API stability guarantees and is not recommended for application integration because of its dependencies.
Good
- Free and open source.
- Uses temporary signing keys.
- Public log supports auditing signing events.
- Official clients cover six programming languages.
- GitHub Actions and GitLab CI guidance are available.
Watch out
- Cosign has no API stability guarantees.
- Cosign is not recommended for application integration.
- Community support is through Slack and GitHub issues.
Who it suits
Sigstore suits developers and software providers seeking signing and verification workflows for software artifacts. It may also be relevant to package managers integrating signing into their tooling or registries.
Verdict
Sigstore combines artifact signing, identity-based certificates, and a public log in a free project. Developers planning application integrations should account for Cosign's stated API and dependency limitations.
Plans and prices
From Sigstore's own pricing page, checked 30 Sep 2026.
| Plan | Price | What it gives you |
|---|---|---|
| Free | Free | free to use for all developers and software providers |
| Public-good Sigstore service | Free | Public Fulcio certificate authority · Public Rekor transparency log · Public OIDC issuer |
The facts
Each one read from Sigstore's own pages, with the date it was checked.
What it does
- API coverage
- The documented API policy covers Fulcio and Rekor client APIs, Cosign features, the sigstore client library and the cosign OCI library.checked 15 Oct 2026
- API stability
- Sigstore classifies interfaces as Experimental, Beta or Generally Available, with best-effort deprecation notice periods of zero, two months or six months respectively.checked 15 Oct 2026
- Artifact coverage
- Sigstore supports signing and verifying release files, container images, binaries, software bills of materials and more.checked 30 Sep 2026
- CI integrations
- Sigstore provides GitHub Actions for generating signatures and installing Cosign, and documents GitLab CI installation.checked 30 Sep 2026
- Components
- Sigstore combines Cosign, Fulcio, Rekor, OpenID Connect and Policy Controller technologies.checked 30 Sep 2026
- Cosign
- Cosign is the command-line tool for signing and verifying containers and other artifacts, with signatures stored alongside artifacts in OCI registries.checked 15 Oct 2026
- Custom infrastructure
- Cosign can be configured to use privately operated Fulcio, Rekor, certificate-transparency and timestamp services with custom trust roots.checked 15 Oct 2026
- Documentation
- The project publishes user quickstarts, component documentation, developer documentation, certificate-authority material and troubleshooting guidance.checked 15 Oct 2026
- Ephemeral keys
- Its signing workflow uses short-lived or ephemeral keys, reducing the need for developers to manage persistent private keys.checked 15 Oct 2026
- Fulcio
- Fulcio is a free certificate authority that issues temporary certificates to authenticated identities and publishes certificate information through Rekor.checked 15 Oct 2026
- GitHub Actions integration
- Sigstore publishes a Python signing action and a Cosign installer action for CI workflows.checked 15 Oct 2026
- Governance
- Sigstore is operated as a public-good, nonprofit project within the Open Source Security Foundation ecosystem.checked 15 Oct 2026
- Identity
- Sigstore uses OpenID Connect to authenticate users through identity providers such as GitHub and Google.checked 30 Sep 2026
- Independent ecosystem evidence
- The Linux Foundation said Sigstore had been used by projects including Kubernetes and received support from Chainguard, Cisco, HPE, Google, Red Hat and VMware in 2021.checked 15 Oct 2026
- Independent usage evidence
- GitHub documents Sigstore Policy Controller deployment with two Helm charts and OCI-attached Sigstore Bundles for image attestations.checked 15 Oct 2026
- Integration limitation
- Cosign has no API stability guarantees, does not follow semantic versioning, and is not recommended for application integration because of its dependencies.checked 30 Sep 2026
- Keyless verification
- Verification checks the artifact signature, certificate identity, Sigstore trust root and Rekor inclusion proof together.checked 15 Oct 2026
- Key management
- Sigstore generates signatures with ephemeral signing keys, so developers do not need to manage keys.checked 30 Sep 2026
- Kubernetes policy
- The Policy Controller is a Kubernetes admission controller that can require valid container signatures or attestations before deployment.checked 15 Oct 2026
- Language clients
- Official language clients are available for Go, Java, JavaScript, Python, Ruby and Rust.checked 30 Sep 2026
- License
- Sigstore projects are required to use the Apache License 2.0 and include a compatible dependency-license check.checked 15 Oct 2026
- Limit: compromised publisher identity
- The Snyk incident involved a compromised maintainer token and malicious code inserted through a dependency, showing that valid provenance does not prove software is safe.checked 15 Oct 2026
The company
- Founded
- 2021checked 28 Sep 2026
- Independent company profile
- LinkedIn describes Sigstore as a London-based nonprofit public-good signing service with 2–10 employees and a 2021 founding year.checked 15 Oct 2026
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