Feature/lab8

[Lisoon22]

Goal

Complete Lab 8 by signing an immutable Juice Shop image digest with Cosign, demonstrating that a substituted image cannot be verified, attaching SBOM and provenance attestations, and implementing signed release-blob verification.

Changes

• Added the public Cosign verification key:

  • labs/lab8/keys/cosign.pub

• Started a local OCI Distribution registry on localhost:5000.

• Pushed Juice Shop v20.0.0 into the local registry.

• Resolved the immutable manifest digest directly from the Registry HTTP API using the Docker-Content-Digest response header.

• Signed the registry-resident immutable digest with Cosign v3.

• Verified the original image signature using the public key.

• Pushed an unrelated Alpine image under a deceptive Juice Shop tag.

• Confirmed that the substituted image digest did not have a valid Juice Shop signature.

• Reverified the original immutable digest successfully.

• Attached and verified a CycloneDX SBOM attestation.

• Extracted the verified SBOM predicate and compared it with the source SBOM.

• Attached and verified a minimal SLSA provenance attestation.

• Added the bonus blob-signing demonstration:

  • signed a release archive;
  • verified the original archive;
  • modified the archive;
  • confirmed that the modified blob failed verification.

• Added submissions/lab8.md with all command output and security analysis.

• Excluded the private Cosign key and regenerable result files from Git.

Testing

The full workflow was executed with:

./scripts/lab8_install_arch.sh
sudo systemctl start docker
./scripts/lab8_run_all.sh

The registry digest was resolved through:

curl -fsS \
  -D - \
  -o /dev/null \
  -H 'Accept: application/vnd.oci.image.index.v1+json, application/vnd.oci.image.manifest.v1+json, application/vnd.docker.distribution.manifest.list.v2+json, application/vnd.docker.distribution.manifest.v2+json' \
  http://127.0.0.1:5000/v2/juice-shop/manifests/v20.0.0

The original signed image was verified with the committed public key.

The substituted image was tested separately and correctly failed verification because it resolved to a different immutable digest without a matching signature.

The SBOM attestation was verified and decoded into:

labs/lab8/results/sbom-from-attestation.json

The provenance attestation was verified and included:

• an explicit builder ID;
• a SLSA provenance build type;
• source repository and commit information;
• build parameters and materials.

The bonus release archive was verified before modification and rejected after additional bytes were appended.

Artifacts & Screenshots

Committed:

• labs/lab8/keys/cosign.pub
• submissions/lab8.md

Generated locally but intentionally not committed:

• labs/lab8/keys/cosign.key
• labs/lab8/results/
• labs/lab8/.cosign-home/
• local OCI registry storage;
• generated signatures, bundles, and decoded predicates.

Checklist

• PR title clearly describes the Lab 8 changes
• Only the public Cosign key was committed
• The private Cosign key was excluded
• Regenerable signing and verification evidence was excluded
• Submission exists at submissions/lab8.md
• Commit is SSH-signed

Lab Checklist

• Task 1 — local OCI registry started
• Task 1 — Juice Shop image pushed successfully
• Task 1 — registry-resident immutable digest signed
• Task 1 — original digest verification succeeded
• Task 1 — substituted image verification failed correctly
• Task 1 — original digest succeeded again after the negative test
• Task 2 — CycloneDX SBOM attestation attached
• Task 2 — SBOM attestation verified and decoded
• Task 2 — SLSA provenance attestation attached and verified
• Bonus — release blob signed with a Cosign bundle
• Bonus — original blob verification succeeded
• Bonus — modified blob verification failed correctly