SignServer vs Sigstore

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.

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.