OpenPubkey vs SignServer

OpenPubkey binds a user or workload identity established through OpenID Connect to a public key, so the identity can sign messages or artifacts. A PK Token represents control of an OIDC identity and its related private key at a particular time, provided the verifier trusts the identity provider. The project lists Google, Azure/Microsoft, Okta, OneLogin and Keycloak as compatible without changes to those providers; however, its client and verifier currently create and verify tokens from Google for users and GitHub for workloads. Current workload identity use requires GQ signatures. For user identity, they are unnecessary when the PK Token is not public. GQ signatures allow the identity provider’s signature to be stripped from an ID Token while preserving proof of that signature, preventing use against OIDC resource providers. OpenPubkey says it needs no additional certificate authority because the OpenID Provider fulfills that role. Public PK Tokens can reveal claims from an OIDC ID Token, potentially including a name or email address. The project is free under the Apache 2.0 license and is a Linux Foundation project; its repository says it is being prepared for version 1.0. The project directs technical questions to GitHub issues and offers a community Slack channel.

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.