Verify Docker images

As of v10.10, CloudBees CD/RO’s Docker images are signed to allow you to verify their origin and authenticity. Verifying the origin and authenticity of Docker images is an optional step in the installation process. However, it is suggested to help prevent you from installing possibly malicious images.

To verify the CloudBees CD/RO Docker images, you must download Cosign verification software. Cosign is a component of the Sigstore solution, a collection of projects designed to make software signatures easier. For the following task, cosign verify is used.

To verify the authenticity of CloudBees CD/RO Docker images:

To verify the Docker image against the CloudBees public key, run:

cosign verify --key https://cdn.cloudbees.com/keyring/cloudbees.pub docker.io/cloudbees/<product-docker-repo>:<image-tag>▼

(OPTIONAL) The previous step used:
- cosign verify --key https://cdn.cloudbees.com/keyring/cloudbees.pub
  
  Alternatively, you can use a local copy of cloudbees.pub:
- cosign verify --key path/to/local/cloudbees.pub
  
  To save a local copy of cloudbees.pub, run:
  wget https://cdn.cloudbees.com/keyring/cloudbees.pub
  ▼

Confirming and troubleshooting Docker image verification

This section describes positive and negative examples of Docker image verification.

The following is a positive example of cosign verify used to verify the CloudBees public key against the cbflow-web Docker image for tag 9.1.0.138283_1.0.3_20191027:

cosign verify --key https://cdn.cloudbees.com/keyring/cloudbees.pub docker.io/cloudbees/cbflow-web:9.1.0.138283_1.0.3_20191027

Verification for index.docker.io/cloudbees/cbflow-web:9.1.0.138283_1.0.3_20191027 --
The following checks were performed on each of these signatures:
  - The cosign claims were validated
  - The signatures were verified against the specified public key

[{"critical":{"identity":{"docker-reference":"index.docker.io/cloudbees/cbflow-web"},"image":{"docker-manifest-digest":"sha256:c3d278d7d47ae6da3611418148af6591b192a82195237e8aef72d0e0a179c2bf"},"type":"cosign container image signature"},"optional":null}]▼

The following is a negative example of cosign verify unable to verify the key against the signature:

cosign verify --key cosign.pub docker.io/cloudbees/cbflow-web:9.1.0.138283_1.0.3_20191027
Error: no matching signatures:
invalid signature when validating ASN.1 encoded signature
main.go:62: error during command execution: no matching signatures:
invalid signature when validating ASN.1 encoded signature▼

This is typically caused by an incorrect public key path or URL being passed to cosign verify. In this example, the cosign.pub key was used instead of cloudbees.pub or https://cdn.cloudbees.com/keyring/cloudbees.pub.

The following is a negative example of cosign verify unable to locate the specified Docker image:

cosign verify --key https://cdn.cloudbees.com/keyring/cloudbees.pub docker.io/cloudbees/cbflow-web:9.2.0.138283_1.0.3_20191027
Error: entity not found in registry
main.go:62: error during command execution: entity not found in registry▼

This is typically caused by an incorrect Docker image repo URL or tag being passed. In this example, the image tag 9.2.0.138283_1.0.3_20191027 does not exist for cbflow-web.

If the image you are trying to verify is not validated as authentic, and you have confirmed you are using the correct key, repo URL, and image tag, please contact CloudBees Support.