cosign – sign and verify software artifacts with Sigstore

cosign is a command-line utility for signing and verifying software artifacts. It is part of the Sigstore project and is particularly well suited to container images and other artifacts stored in OCI registries. The software provides a way for developers, release engineers and organisations to establish who produced an artifact and check that it has not subsequently been altered.

One of cosign’s main approaches is keyless signing. Instead of maintaining a long-lived private signing key, a user authenticates through an OpenID Connect identity provider and obtains a short-lived signing certificate from Sigstore’s Fulcio certificate authority. Information about the signing event can be recorded in Sigstore’s transparency infrastructure. Verification can then check both the signature and the expected identity of the signer. This makes cosign useful in automated build and release pipelines where traditional key management can introduce significant operational overhead.

cosign is not limited to keyless workflows. It can create and use encrypted key pairs, work with hardware-backed keys and key management services, and integrate with an organisation’s existing public key infrastructure. It supports signing and verification of container images as well as arbitrary files and blobs. Signatures can be associated with artifacts in OCI registries, allowing integrity information to travel alongside the software it describes. Verification policies can constrain expected certificate identities and issuers rather than merely checking whether any valid signature exists.

This is free and open source software.

Key Features

• Signs and verifies container images and other software artifacts.
• Supports identity-based keyless signing with Sigstore.
• Works with conventional public and private key pairs.
• Supports hardware-backed keys, key management services and existing PKI.
• Stores signatures alongside artifacts in OCI registries.
• Verifies expected certificate identities and OIDC issuers.
• Supports signing and verification of arbitrary files and blobs.
• Works with software supply-chain attestations and Sigstore bundles.
• Integrates with transparency infrastructure for auditable signing events.
• Designed for automated build, release and deployment workflows.

Website: github.com/sigstore/cosign
Support:
Developer: Sigstore
License: Apache License 2.0

cosign is written in Go. Learn Go with our recommended free books and free tutorials.

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