Sigstore

The primary CLI tool for the Sigstore project, enabling keyless signing and verification of container images, blobs, and other artifacts. Cosign generates a short-lived signing key pair, binds the signature to an OIDC identity (e.g., a GitHub Actions workflow), and records the event in a transparency log. The private key is discarded immediately after signing, eliminating the long-term key management burden. Verification uses the public key from the certificate, validated against the transparency log.

• Signs and verifies OCI images, blobs, and in-toto attestations
• Supports hardware tokens and KMS for existing key workflows
• Integrates natively with Kubernetes admission controllers via policy-controller

An append-only, immutable ledger that records signed metadata about software artifacts. Rekor provides a tamper-resistant record of signing events, enabling anyone to verify that a signature was created and logged at a specific point in time. By checking the log, verifiers can detect if a signing identity was compromised and used retroactively. Rekor stores signed checkpoints and supports Merkle tree-based consistency proofs.

• Cryptographically verifiable append-only data structure
• Enables detection of unauthorized signing events
• Public instance available at rekor.sigstore.dev

A root Certificate Authority that issues short-lived code-signing certificates bound to OpenID Connect identities. Fulcio authenticates the signer via an OIDC provider (Google, GitHub, Microsoft) and issues an X.509 certificate valid for only 10 minutes. This ephemeral nature eliminates the need for manual key distribution or revocation—the certificate expires before an attacker can realistically exploit a compromised key.

• Issues certificates after successful OIDC authentication
• Certificates include the signer's verified identity in the SAN field
• No long-lived secrets to manage or revoke

The mechanism that ties a digital signature to a real-world identity without requiring pre-shared secrets. Sigstore leverages OpenID Connect tokens from trusted providers (GitHub Actions, Google Cloud, SPIFFE) to authenticate the signer. The OIDC token contains claims like issuer, subject, and audience, which Fulcio embeds into the issued certificate. Verification policies can then enforce that only specific identities from specific issuers may sign.

• No API keys or static credentials required
• Supports custom OIDC providers and SPIFFE workloads
• Enables fine-grained policy: 'Only the GitHub repo X can sign image Y'

A framework for cryptographically asserting claims about the software supply chain, fully integrated with Sigstore. In-toto attestations are signed, verifiable statements about how an artifact was produced—covering build steps, source repositories, and test results. Sigstore's Cosign can generate and verify in-toto attestations, linking them to container images via the OCI registry. This creates a verifiable chain of custody from source code to deployed artifact.

• Predicate types: SLSA Provenance, SPDX SBOM, Vulnerability Scan
• Attestations stored alongside images in OCI registries
• Enables policy enforcement: 'Only deploy images with a verified SLSA Level 3 attestation'

A Kubernetes admission controller that enforces signature and attestation policies at deployment time. Policy Controller validates that container images are signed by trusted identities and possess required attestations before allowing them to run in a cluster. It integrates with Sigstore's verification libraries to check Rekor transparency logs and Fulcio certificates in real-time, blocking non-compliant workloads.

• Native Kubernetes dynamic admission control
• Policies defined as Custom Resources using CUE or Rego
• Prevents deployment of unsigned or unattested images