Skip to content
SPECIFICTION
Get listed

Sigstore

sigstore.dev

Free plan Open source WebWindowsmacOSLinuxAPISelf-hosted
Visit sigstore.dev
Spec score 8.3 #7 of 28 in Code Signing Software

What it is

Sigstore is a free, open source project for signing and verifying software artifacts to improve supply chain security. It supports release files, container images, binaries, software bills of materials, and more. Signatures use temporary keys, so developers do not have to manage signing keys; events are recorded in a tamper-resistant public log for audit. Its components include Cosign, Fulcio, Rekor, OpenID Connect, and Policy Controller. Cosign signs and verifies artifacts and stores signatures in an OCI registry. Fulcio issues temporary certificates to authorized identities, while Rekor keeps signed metadata in a searchable ledger. OpenID Connect authenticates users through providers such as GitHub and Google. The trust root uses The Update Framework and is maintained by five keyholders from different companies and academic institutions. Sigstore provides GitHub Actions, documents GitLab CI installation, and offers official clients for Go, Java, JavaScript, Python, Ruby, and Rust. It supports API, Linux, macOS, Windows, and self-hosted environments. One integration caveat is that Cosign has no API stability guarantees, does not follow semantic versioning, and is not recommended for application integration because of its dependencies.

Spec sheet

What it does
Sigstore helps developers sign and verify release files, container images, binaries and SBOMs to improve software supply-chain security.Read 15 Oct 2026 · openssf.org
Purpose
Sigstore is an open source project for improving software supply chain security.Read 30 Sep 2026 · docs.sigstore.dev
Support
Community support is provided through Slack and GitHub issues, with repository CODEOWNERS identifying project maintainers.Read 15 Oct 2026 · docs.sigstore.dev
License
Sigstore projects are required to use the Apache License 2.0 and include a compatible dependency-license check.Read 15 Oct 2026 · github.com
Founded
2021Read 28 Sep 2026 · sigstore.dev
API coverage
The documented API policy covers Fulcio and Rekor client APIs, Cosign features, the sigstore client library and the cosign OCI library.Read 15 Oct 2026 · docs.sigstore.dev
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.Read 15 Oct 2026 · docs.sigstore.dev
Artifact coverage
Sigstore supports signing and verifying release files, container images, binaries, software bills of materials and more.Read 30 Sep 2026 · docs.sigstore.dev
CI integrations
Sigstore provides GitHub Actions for generating signatures and installing Cosign, and documents GitLab CI installation.Read 30 Sep 2026 · docs.sigstore.dev
Components
Sigstore combines Cosign, Fulcio, Rekor, OpenID Connect and Policy Controller technologies.Read 30 Sep 2026 · docs.sigstore.dev
Cosign
Cosign is the command-line tool for signing and verifying containers and other artifacts, with signatures stored alongside artifacts in OCI registries.Read 15 Oct 2026 · docs.sigstore.dev
Custom infrastructure
Cosign can be configured to use privately operated Fulcio, Rekor, certificate-transparency and timestamp services with custom trust roots.Read 15 Oct 2026 · docs.sigstore.dev
Documentation
The project publishes user quickstarts, component documentation, developer documentation, certificate-authority material and troubleshooting guidance.Read 15 Oct 2026 · docs.sigstore.dev
Ephemeral keys
Its signing workflow uses short-lived or ephemeral keys, reducing the need for developers to manage persistent private keys.Read 15 Oct 2026 · openssf.org
Fulcio
Fulcio is a free certificate authority that issues temporary certificates to authenticated identities and publishes certificate information through Rekor.Read 15 Oct 2026 · docs.sigstore.dev
GitHub Actions integration
Sigstore publishes a Python signing action and a Cosign installer action for CI workflows.Read 15 Oct 2026 · github.com
Governance
Sigstore is operated as a public-good, nonprofit project within the Open Source Security Foundation ecosystem.Read 15 Oct 2026 · openssf.org
Identity
Sigstore uses OpenID Connect to authenticate users through identity providers such as GitHub and Google.Read 30 Sep 2026 · docs.sigstore.dev
Independent company profile
LinkedIn describes Sigstore as a London-based nonprofit public-good signing service with 2–10 employees and a 2021 founding year.Read 15 Oct 2026 · linkedin.com
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.Read 15 Oct 2026 · linuxfoundation.org
Independent usage evidence
GitHub documents Sigstore Policy Controller deployment with two Helm charts and OCI-attached Sigstore Bundles for image attestations.Read 15 Oct 2026 · docs.github.com
Integration limitation
Cosign has no API stability guarantees, does not follow semantic versioning, and is not recommended for application integration because of its dependencies.Read 30 Sep 2026 · docs.sigstore.dev
Key management
Sigstore generates signatures with ephemeral signing keys, so developers do not need to manage keys.Read 30 Sep 2026 · docs.sigstore.dev
Keyless verification
Verification checks the artifact signature, certificate identity, Sigstore trust root and Rekor inclusion proof together.Read 15 Oct 2026 · docs.sigstore.dev
Kubernetes policy
The Policy Controller is a Kubernetes admission controller that can require valid container signatures or attestations before deployment.Read 15 Oct 2026 · docs.sigstore.dev
Language clients
Official language clients are available for Go, Java, JavaScript, Python, Ruby and Rust.Read 30 Sep 2026 · docs.sigstore.dev
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.Read 15 Oct 2026 · security.snyk.io
Limit: provenance can look legitimate
Snyk reported a 2026 npm supply-chain attack in which attackers published packages carrying valid-looking Sigstore provenance badges.Read 15 Oct 2026 · security.snyk.io
OpenID Connect
Sigstore uses OIDC identity information to associate a signing event with an email address, service account or CI workflow.Read 15 Oct 2026 · docs.sigstore.dev
OpenSSF mission
OpenSSF states that its mission is to help the community secure the open-source software it depends on, and participation in its technical projects does not require membership funding.Read 15 Oct 2026 · openssf.org
Package-manager integration
Sigstore identifies open source package managers as primary stakeholders and describes workflows for integrating signing and verification into package tooling and registries.Read 30 Sep 2026 · docs.sigstore.dev
Python client
The sigstore-python project provides signing and verification commands, including verification modes for GitHub Actions identities.Read 15 Oct 2026 · github.com
Rekor
Rekor is an append-only transparency and timestamping log that records signed metadata and supports public searching.Read 15 Oct 2026 · docs.sigstore.dev
Release update
The sigstore Go client release v1.10.11 rolled back to a commit requiring Go 1.25.0, while a forthcoming v1.11.0 was planned to require Go 1.27.0.Read 15 Oct 2026 · github.com
SBOM and attestations
Cosign can create and verify in-toto attestations, while Rekor can store those attestations.Read 15 Oct 2026 · docs.sigstore.dev
Self-hosting
Sigstore provides scaffolding for running a full stack in Kubernetes, including KinD, and offers Google Cloud Terraform modules.Read 15 Oct 2026 · github.com
Staging limitation
The public staging environment has no SLO guarantees and weaker TUF root-key protection, so the documentation says not to use it in production.Read 15 Oct 2026 · docs.sigstore.dev
Transparency
Signing events are recorded in a tamper-resistant public log so developers can audit signing events.Read 30 Sep 2026 · docs.sigstore.dev
Trust root
The Sigstore trust root uses The Update Framework and is maintained through a rotation of five keyholders from different companies and academic institutions.Read 30 Sep 2026 · docs.sigstore.dev
Trust-root distribution
Fulcio roots, Rekor keys and related verification material are distributed through The Update Framework.Read 15 Oct 2026 · docs.sigstore.dev

Plans and prices

Free Free free to use for all developers and software providers Read 30 Sep 2026 · linuxfoundation.org
Public-good Sigstore service Free Public Fulcio certificate authority · Public Rekor transparency log · Public OIDC issuer Read 15 Oct 2026 · sigstore.dev

Every Sigstore plan and price →

Strong points and limits

Strong points

  • Free and open source
  • Temporary signing keys avoid key management
  • Public log supports auditing signing events
  • Official clients for six programming languages
  • GitHub Actions and documented GitLab CI installation

Limits

  • Cosign has no API stability guarantees
  • Cosign does not follow semantic versioning
  • Cosign is not recommended for application integration

Who it suits

Sigstore suits developers and software providers who need to sign and verify artifacts, including package managers integrating signing workflows. Its documented CI options and language clients offer routes for integrating it into development processes.

Verdict

Sigstore combines artifact signing, identity-based certificates, and a public log for verification and auditing. Cosign’s stated integration caveats matter for teams planning to build it into an application.

Where Specifiction places it

Alternatives to SigstoreAll alternatives →