How does Rekor work?

How Rekor fits into supply-chain provenance

Rekor is not the signer and not the verifier. It is the public log that records supply-chain artefact metadata, usually signatures and attestations, so a consumer can later prove that a record existed at a given point in time and was not silently rewritten. That makes Rekor useful for provenance checks, auditability, and detecting gaps between what was signed and what was actually logged.

For teams adopting transparency logging, the key design idea is separation of duties: signing creates the trust claim, while logging makes that claim independently observable. Software Supply Chain Security Guide is the best broader starting point when you need to place Rekor alongside signing, provenance, SBOMs, and release controls rather than treating it as a standalone product feature.

In practice, Rekor works best when the artefact identity, the signature material, and the logged record can all be correlated by verifiers without depending on a single internal system of record. If that correlation is weak, the log may still exist, but it will not meaningfully improve trust because you cannot reliably answer whether the artefact you received is the artefact that was logged.

What verifiers actually check

A verifier uses Rekor to confirm two things: first, that a signed object was submitted to the log, and second, that the log entry still matches the public record. That is why Rekor supports transparency rather than secrecy. It helps consumers detect inconsistent provenance, missing log entries, or records that do not line up with the claimed release artefact.

The useful security property here is tamper evidence. Rekor does not replace the signature itself, and it does not prove the software is safe. It provides an additional independent checkpoint that can expose a broken release pipeline, a missing attestation, or an attempt to circulate an artefact that was never properly recorded.

For people building verification workflows, the strongest use case is to treat a missing or mismatched Rekor entry as a supply-chain exception, not as a paperwork issue. If a release process says logging is mandatory, then an absent entry is a control failure worth investigating before distribution expands.

Where Rekor changes the trust model

Rekor changes trust by reducing reliance on private assertions about what was built, signed, or released. Instead of asking recipients to accept a vendor statement at face value, it gives them a public artefact trail that can be checked independently. That is especially valuable when software comes through multiple systems, automated pipelines, or third-party build services.

It is also helpful when provenance quality matters more than raw execution. A software package can be perfectly signed and still be hard to trust if the surrounding records are incomplete, inconsistent, or impossible to audit later. Rekor makes those gaps visible, which is why it is often used as a control around release integrity rather than as a replacement for build hardening.

Because the log is append-only, its value depends on immutable history and reliable inclusion proofs. If the workflow allows artefacts to be signed but not logged, or logged under inconsistent naming and metadata, the trust improvement drops quickly. Rekor is strongest when it is embedded in a release process that treats logging as a required step, not an optional one.

Practitioner Guidance

What to verify: Check that your verification process confirms both the signature and the Rekor inclusion evidence, not just one of them. If the release pipeline can produce signatures without producing a usable log entry, treat that as an operational defect that weakens provenance assurance.

What to prioritise: Focus first on the artefacts whose compromise would matter most, such as release binaries, container images, and provenance attestations. Those are the records where a missing or inconsistent transparency trail creates the biggest downstream trust gap.

Common mistake: Teams sometimes assume a transparency log makes the artefact trustworthy by itself. It does not. The log is evidence of recording and consistency, while the underlying signing and build controls still have to establish whether the artefact should be trusted at all.

Practitioner takeaway: Use Rekor as a verifiable record of provenance, then make missing or inconsistent entries operationally meaningful by tying them to release approval, exception handling, and distribution controls.

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