Sigstore is an open standard and set of tools for signing, verifying, and proving the provenance of software artifacts. It provides keyless signing with short-lived certificates and a transparency log to secure the software supply chain.
Sigstore
Sigstore is an open-source project and emerging standard for signing, verifying, and proving the provenance of software artifacts. Backed by the Open Source Security Foundation, it removes the traditional burden of managing long-lived signing keys by issuing short-lived certificates tied to an existing identity, then recording every signature in a public transparency log.
- Keyless signing - Developers sign using an OIDC identity (a Google, GitHub, or corporate login) rather than holding and protecting private keys.
- Short-lived certificates - Fulcio issues ephemeral certificates that exist only long enough to sign, shrinking the window for key compromise.
- Transparency log - Rekor records signatures in a tamper-evident, publicly auditable log so anyone can verify what was signed and when.
- Provenance and attestations - It integrates with SLSA and in-toto to attach verifiable build provenance to artifacts.
In API operations, Sigstore matters most in the delivery pipeline behind the API: signing the container images, SDKs, and CLI binaries a provider ships so consumers can verify they are running authentic, untampered code. As software supply-chain attacks and agent-driven toolchains raise the stakes, keyless signing with a public log is one of the cheaper, more machine-verifiable trust signals a producer can add — a supply-chain complement to runtime signals like security.txt.
Open source tools that implement this standard
Harvested from this standard's own governing organisation, with the license read from each repository rather than assumed. The role is what the tool does to the specification, from the shared vocabulary — so an agent holding one of these documents can resolve straight from a goal to a tool.
| Tool | Role | License | What it does |
|---|---|---|---|
| Cosign | signs |
Apache-2.0 | Signs and verifies containers, blobs and SBOMs with keyless signing backed by OIDC identity and a public transparency log — no ... |
| Rekor | stores |
Apache-2.0 | The immutable, append-only transparency log that records signing events, so a signature can be verified after the short-lived c... |
| Gitsign | signs |
Apache-2.0 | Signs Git commits and tags with Sigstore keyless signing, requiring no GPG key. |
| Fulcio | issues |
Apache-2.0 | The certificate authority that issues short-lived signing certificates bound to an OIDC identity — what makes keyless signing p... |
| sigstore-python | signs |
Apache-2.0 | A Sigstore client for Python, used for signing and verifying Python package releases. |
| sigstore-js | signs |
Apache-2.0 | The Sigstore client for JavaScript, underneath npm's provenance and attestation support. |
| Sigstore Policy Controller | verifies |
Apache-2.0 | A Kubernetes admission controller that enforces signature and attestation policy on images before they are allowed to run. |
