Notation vs Sigstore

Notation is a command-line tool for signing and verifying container images and other artifacts in OCI registries, including software bills of materials. It implements the Notary Project specifications, which are intended to help secure software supply chains. Its signatures can move between OCI registries and be validated in connected, intermittently connected, or disconnected environments without additional server infrastructure. The specifications define signature envelopes using COSE or JWS. Notation can integrate with existing key management systems through a plugin model, with instructions for Azure Key Vault and AWS Signer. Developers and CI/CD pipelines can create signatures and store them alongside signed artifacts. The project provides a quick start for signing and validating a container image. Notation runs on Linux, macOS, and Windows and is free under the Apache 2.0 license. Cloud signing, trusted timestamping, and CI/CD signing are listed capabilities; a certificate is not provided. The specifications repository lists a 2023 security audit, and the project overview describes continuous fuzz testing across three repositories.

Sigstore is a free, open source project for signing and verifying software artifacts to improve supply chain security. It supports release files, container images, binaries, software bills of materials, and more. Signatures use temporary keys, so developers do not have to manage signing keys; events are recorded in a tamper-resistant public log for audit. Its components include Cosign, Fulcio, Rekor, OpenID Connect, and Policy Controller. Cosign signs and verifies artifacts and stores signatures in an OCI registry. Fulcio issues temporary certificates to authorized identities, while Rekor keeps signed metadata in a searchable ledger. OpenID Connect authenticates users through providers such as GitHub and Google. The trust root uses The Update Framework and is maintained by five keyholders from different companies and academic institutions. Sigstore provides GitHub Actions, documents GitLab CI installation, and offers official clients for Go, Java, JavaScript, Python, Ruby, and Rust. It supports API, Linux, macOS, Windows, and self-hosted environments. One integration caveat is that Cosign has no API stability guarantees, does not follow semantic versioning, and is not recommended for application integration because of its dependencies.