Cosign

Cosign is an open-source tool developed as part of the Sigstore project, designed to simplify code signing and enhance transparency for containers and other software artifacts. It aims to make signatures an invisible part of the infrastructure, providing developers with a straightforward way to sign and verify their software. Cosign supports various signing methods, including "Keyless signing" with the Sigstore public good Fulcio certificate authority and Rekor transparency log, hardware and KMS signing, and signing with Cosign-generated encrypted keypairs. It facilitates container signing, verification, and storage within an OCI registry, and also allows users to bring their own Public Key Infrastructure (PKI). This tool is crucial for developers and organizations looking to secure their software supply chain by ensuring the authenticity and integrity of their deployed artifacts. By integrating with Sigstore's transparency logs, Cosign provides an immutable record of signing events, making it difficult for malicious actors to tamper with software without detection. Its ease of use, especially with the default keyless signing, lowers the barrier to entry for robust software supply chain security practices.