AWS Signer vs Sigstore

AWS Signer is a managed code-signing service for verifying code integrity and publisher trust. It supports signing AWS Lambda deployment packages, code for supported IoT devices, and OCI container images using Notation. Lambda verifies signatures and package integrity when signed code is deployed. For containers, Signer works with Notation in registries such as Amazon ECR, with signatures stored alongside images for verification.

Administrators control access to Signer resources and actions through AWS Identity and Access Management policies. Signing profiles can be managed in the Signer console, AWS CLI, or API. Signer manages certificates and keys for Lambda and container workflows; IoT workflows can use a code-signing certificate imported into AWS Certificate Manager. Documentation also lists integrations with AWS Certificate Manager and CloudTrail, plus Amazon EKS image verification. Notation CLI and Signer plugin installers are listed for Linux, macOS, and Windows. API actions have per-second quotas by account and Region, with no minimum request rate. Use with specified AWS services has no additional charge, though related charges may apply.

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.