Notation vs SignServer

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.

SignServer is a server-side platform that centrally manages signing keys and digitally signs code, documents, and timestamps. One installation can serve several signing workflows, including containers, firmware, IoT, and DevOps use cases. It can connect to CI/CD pipelines, firmware build processes, document workflow engines, identity platforms, and other applications through standard interfaces. Community is available as a Docker container, Helm chart, source code, or GitHub release, and is also listed on SourceForge. Its interfaces include SOAP, HTTP, REST, and the SignClient command-line interface, though Community REST lacks some endpoints. Community is released under LGPL V2.1 or later and is intended for learning, testing, and prototyping rather than production. The maker says it lacks production capabilities such as audit, compliance, SLA, high availability, and security features. Enterprise adds professional support with an SLA, security updates, and maintenance. The Community plan is free; the Enterprise Cloud trial is free for 30 days through AWS or Azure marketplaces. The maker recommends Hardware Security Modules for signing-key storage.