---
title: Verify Signed Kubernetes Artifacts
content_type: task
min-kubernetes-server-version: v1.26
weight: 420
---

<!-- overview -->

{{< feature-state state="beta" for_k8s_version="v1.26" >}}

## {{% heading "prerequisites" %}}

You will need to have the following tools installed:

- `cosign` ([install guide](https://docs.sigstore.dev/cosign/system_config/installation/))
- `curl` (often provided by your operating system)
- `jq` ([download jq](https://jqlang.github.io/jq/download/))

## Verifying binary signatures

The Kubernetes release process signs all binary artifacts (tarballs, SPDX files,
standalone binaries) by using cosign's keyless signing. To verify a particular
binary, retrieve it together with its signature and certificate:

```bash
URL=https://dl.k8s.io/release/v{{< skew currentPatchVersion >}}/bin/linux/amd64
BINARY=kubectl

FILES=(
    "$BINARY"
    "$BINARY.sig"
    "$BINARY.cert"
)

for FILE in "${FILES[@]}"; do
    curl -sSfL --retry 3 --retry-delay 3 "$URL/$FILE" -o "$FILE"
done
```

Then verify the blob by using `cosign verify-blob`:

```shell
cosign verify-blob "$BINARY" \
  --signature "$BINARY".sig \
  --certificate "$BINARY".cert \
  --certificate-identity krel-staging@k8s-releng-prod.iam.gserviceaccount.com \
  --certificate-oidc-issuer https://accounts.google.com
```

{{< note >}}
Cosign 2.0 requires the `--certificate-identity` and `--certificate-oidc-issuer` options.

To learn more about keyless signing, please refer to [Keyless Signatures](https://docs.sigstore.dev/cosign/signing/overview/).

Previous versions of Cosign required that you set `COSIGN_EXPERIMENTAL=1`.

For additional information, please refer to the [sigstore Blog](https://blog.sigstore.dev/cosign-2-0-released/)
{{< /note >}}

## Verifying image signatures

For a complete list of images that are signed please refer
to [Releases](/releases/download/).

Pick one image from this list and verify its signature using
the `cosign verify` command:

```shell
cosign verify registry.k8s.io/kube-apiserver-amd64:v{{< skew currentPatchVersion >}} \
  --certificate-identity krel-trust@k8s-releng-prod.iam.gserviceaccount.com \
  --certificate-oidc-issuer https://accounts.google.com \
  | jq .
```

### Verifying images for all control plane components

To verify all signed control plane images for the latest stable version
(v{{< skew currentPatchVersion >}}), please run the following commands:

```shell
curl -Ls "https://sbom.k8s.io/$(curl -Ls https://dl.k8s.io/release/stable.txt)/release" \
  | grep "SPDXID: SPDXRef-Package-registry.k8s.io" \
  | grep -v sha256 | cut -d- -f3- | sed 's/-/\//' | sed 's/-v1/:v1/' \
  | sort > images.txt
input=images.txt
while IFS= read -r image
do
  cosign verify "$image" \
    --certificate-identity krel-trust@k8s-releng-prod.iam.gserviceaccount.com \
    --certificate-oidc-issuer https://accounts.google.com \
    | jq .
done < "$input"
```

Once you have verified an image, you can specify the image by its digest in your Pod
manifests as per this example:

```console
registry-url/image-name@sha256:45b23dee08af5e43a7fea6c4cf9c25ccf269ee113168c19722f87876677c5cb2
```

For more information, please refer
to the [Image Pull Policy](/docs/concepts/containers/images/#image-pull-policy)
section.

## Verifying Image Signatures with Admission Controller

For non-control plane images (for example
[conformance image](https://github.com/kubernetes/kubernetes/blob/master/test/conformance/image/README.md)),
signatures can also be verified at deploy time using
[sigstore policy-controller](https://docs.sigstore.dev/policy-controller/overview)
admission controller.

Here are some helpful resources to get started with `policy-controller`:

- [Installation](https://github.com/sigstore/helm-charts/tree/main/charts/policy-controller)
- [Configuration Options](https://github.com/sigstore/policy-controller/tree/main/config)

## Verify the Software Bill Of Materials

You can verify the Kubernetes Software Bill of Materials (SBOM) by using the
sigstore certificate and signature, or the corresponding SHA files:

```shell
# Retrieve the latest available Kubernetes release version
VERSION=$(curl -Ls https://dl.k8s.io/release/stable.txt)

# Verify the SHA512 sum
curl -Ls "https://sbom.k8s.io/$VERSION/release" -o "$VERSION.spdx"
echo "$(curl -Ls "https://sbom.k8s.io/$VERSION/release.sha512") $VERSION.spdx" | sha512sum --check

# Verify the SHA256 sum
echo "$(curl -Ls "https://sbom.k8s.io/$VERSION/release.sha256") $VERSION.spdx" | sha256sum --check

# Retrieve sigstore signature and certificate
curl -Ls "https://sbom.k8s.io/$VERSION/release.sig" -o "$VERSION.spdx.sig"
curl -Ls "https://sbom.k8s.io/$VERSION/release.cert" -o "$VERSION.spdx.cert"

# Verify the sigstore signature
cosign verify-blob \
    --certificate "$VERSION.spdx.cert" \
    --signature "$VERSION.spdx.sig" \
    --certificate-identity krel-staging@k8s-releng-prod.iam.gserviceaccount.com \
    --certificate-oidc-issuer https://accounts.google.com \
    "$VERSION.spdx"
```