Most engineers treat container registries as glorified file servers, assuming that if a tag exists, it is the one they built. This is a dangerous oversight in any environment handling sensitive data. Relying on image tags alone provides no guarantee that the image running in your orchestration layer is the same bits-and-bytes package that passed your CI suite.

If you aren't cryptographically signing your container images, your data pipelines are vulnerable to man-in-the-middle attacks, registry poisoning, and unauthorized image swapping. Signing images with Sigstore Cosign allows you to attach a verifiable digital signature to your image in the container registry, ensuring that only trusted artifacts reach your production environment.

Prerequisites

To follow this tutorial, you need the following:

Docker: Version 20.10 or later.

Cosign: Installed via brew install cosign or the official binary from the Sigstore documentation .

A Container Registry: A registry that supports OCI artifacts (e.g., Docker…