container-image-sigstore

Personal Container Image Signature Store

Setup

1. configure signature store location in /etc/containers/registries.d/fphammerle.yaml:

   docker:
   docker.io/fphammerle:
   sigstore: https://raw.githubusercontent.com/fphammerle/container-image-sigstore/master/docker.io
   quay.io/fphammerle:
   sigstore: https://raw.githubusercontent.com/fphammerle/container-image-sigstore/master/quay.io
   

2. download key

   $ gpg --recv-key 8D2902FE7DF47DDEDA2802F9456B9A0399A5DA2F
   $ gpg --export --armor --output /some/where/pgp/fphammerle 8D2902FE7DF47DDEDA2802F9456B9A0399A5DA2F
   

3. enable verification in policy.json:

   {
   "default": [
   {
     "type": "reject"
   }
   ],
   "transports": {
   "docker": {
     "docker.io/fphammerle": [
       {
         "type": "signedBy",
         "keyType": "GPGKeys",
         "keyPath": "/some/where/pgp/fphammerle",
         "signedIdentity": {"type": "matchRepoDigestOrExact"}
       }
     ],
     "quay.io/fphammerle": [
       {
         "type": "signedBy",
         "keyType": "GPGKeys",
         "keyPath": "/some/where/pgp/fphammerle",
         "signedIdentity": {"type": "matchRepoDigestOrExact"}
       }
     ]
   }
   }
   }
   

Verify with Podman

$ podman image trust show
default               reject
docker.io/fphammerle  signedBy  fabian@hammerle.me  https://raw.githubusercontent.com/fphammerle/container-image-sigstore/master/docker.io
quay.io/fphammerle    signedBy  fabian@hammerle.me  https://raw.githubusercontent.com/fphammerle/container-image-sigstore/master/quay.io
$ podman --log-level debug run --rm quay.io/fphammerle/systemctl-mqtt:0.5.0-amd64
[...]
DEBU[0000] Using registries.d directory /etc/containers/registries.d for sigstore configuration
DEBU[0000]  Using "docker" namespace quay.io/fphammerle
DEBU[0000]   Using https://raw.githubusercontent.com/fphammerle/container-image-sigstore/master/quay.io
[...]
DEBU[0002] GET https://raw.githubusercontent.com/fphammerle/container-image-sigstore/master/quay.io/fphammerle/systemctl-mqtt@sha256=34dcb878dbd66315de6fbf97ceb29e8fec549b7269c6c828c4c889a54a091f14/signature-1
DEBU[0002] GET https://raw.githubusercontent.com/fphammerle/container-image-sigstore/master/quay.io/fphammerle/systemctl-mqtt@sha256=34dcb878dbd66315de6fbf97ceb29e8fec549b7269c6c828c4c889a54a091f14/signature-2
DEBU[0002]  Requirement 0: allowed
DEBU[0002] Overall: allowed
[...]
DEBU[0004] Starting container 4e46cbe4e982ee84bcff54092146fb0442bb346e451cfb14e2e7f491bc886b88 with command [tini -- systemctl-mqtt --help]
[...]
$ podman --log-level debug run --rm quay.io/fphammerle/systemctl-mqtt:0.5.0-amd64-unsigned
[...]
DEBU[0000] Using registries.d directory /etc/containers/registries.d for sigstore configuration
DEBU[0000]  Using "docker" namespace quay.io/fphammerle
DEBU[0000]   Using https://raw.githubusercontent.com/fphammerle/container-image-sigstore/master/quay.io
[...]
DEBU[0002] GET https://raw.githubusercontent.com/fphammerle/container-image-sigstore/master/quay.io/fphammerle/systemctl-mqtt@sha256=34dcb878dbd66315de6fbf97ceb29e8fec549b7269c6c828c4c889a54a091f14/signature-1
DEBU[0002] GET https://raw.githubusercontent.com/fphammerle/container-image-sigstore/master/quay.io/fphammerle/systemctl-mqtt@sha256=34dcb878dbd66315de6fbf97ceb29e8fec549b7269c6c828c4c889a54a091f14/signature-2
DEBU[0002] Requirement 0: denied, done
DEBU[0002] Error pulling image ref //quay.io/fphammerle/systemctl-mqtt:0.5.0-amd64-unsigned: Source image rejected: Signature for identity quay.io/fphammerle/systemctl-mqtt:0.5.0-amd64 is not accepted
  Signature for identity quay.io/fphammerle/systemctl-mqtt:0.5.0-amd64 is not accepted
Error: unable to pull quay.io/fphammerle/systemctl-mqtt:0.5.0-amd64-unsigned: Source image rejected: Signature for identity quay.io/fphammerle/systemctl-mqtt:0.5.0-amd64 is not accepted

References

• containers/registries.d: sigstore configuration
• containers/policy.json: signedBy configuration
• containers/image: Signature access protocols
• How to sign and distribute container images using Podman
• Verifying signatures of Red Hat container images (archived)
• Red Hat: Signing Container Images
• Talk: A Docker image walks into a Notary
• Podman does not support Notary
• Skopeo does not support Notary
• Rui Marinho's Yubikey Handbook: Docker Content Trust
• CRI-O supports policy.json
• IBM: The top three ways to protect cloud native projects (archived)