Keyless Signing with Sigstore: Simplifying Artifact Security

In today's software landscape, managing keys securely is a daunting task. Keyless signing in Sigstore addresses this by associating identities with artifact signatures instead of relying on cryptographic keys. This approach not only simplifies the signing process but also enhances security by using short-lived certificates that bind ephemeral keys to trusted identities. By eliminating the need for developers to manage long-term keys, Sigstore makes the signing process more accessible and less error-prone.

The mechanics of keyless signing are straightforward yet powerful. When you sign an artifact, an in-memory public/private key pair is generated, and an identity token is retrieved. Sigstore's certificate authority verifies this token and issues a certificate that binds your identity to the public key. The private key is then destroyed shortly after signing, ensuring that it cannot be misused. This process is recorded in the Rekor transparency log, which timestamps the signing event and allows for public auditing. When a consumer wants to verify the artifact, Sigstore checks the signature against the timestamped entry in Rekor, confirming the authenticity of the software based on the verified identity of the signer.

In production, you need to ensure that your identity token is correctly configured. Use the --identity-token parameter to specify your token, and remember that it must contain the audience claim for Sigstore. Monitoring the Rekor log for unexpected signing events is crucial for maintaining trust in your artifacts. Be aware that while keyless signing simplifies many aspects of artifact security, it requires a solid understanding of how identity verification works and the implications of ephemeral keys.