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Notation

Notation is a built-in verifier to Ratify. Notation currently supports X.509 based PKI and identities, and uses a trust store and trust policy to determine if a signed artifact is considered authentic.

Configuration​

Kubernetes​

apiVersion: config.ratify.deislabs.io/v1beta1
kind: Verifier
metadata:
  name: verifier-notation
spec:
  name: notation
  artifactTypes: application/vnd.cncf.notary.signature
  parameters:
    verificationCertStores:  # maps a Trust Store to KeyManagementProvider resources with certificates 
      ca: # trust-store-type
        ca-certs: # name of the trustStore
          - <NAMESPACE>/<KEY MANAGEMENT PROVIDER NAME> # namespace/name of the key management provider CRD to include in this trustStore
    trustPolicyDoc: # policy language that indicates which identities are trusted to produce artifacts
      version: "1.0"
      trustPolicies:
        - name: default
          registryScopes:
            - "*"
          signatureVerification:
            level: strict
          trustStores: # trustStore must be trust-store-type:trust-store-name specified in verificationCertStores
            - ca:ca-certs
          trustedIdentities:
            - "*"
NameRequiredDescriptionDefault Value
verificationCertsnoAn array of string. Notation verifier will load all certificates from path specified in this array.""
verificationCertStoresnoDefines a collection of key management provider objects. This property supersedes the path defined in verificationCerts. CLI NOT supported.""
trustPolicyDocyesTrust policy is a policy language that indicates which identities are trusted to produce artifacts.""

There are two ways to configure verification certificates:

  1. verificationCerts: Notation verifier will load all certificates from path specified in this array.

  2. verificationCertStores: Defines a collection of Notary Project Trust Stores. Notary Project specification defines a Trust Policy, which is a policy construct to specify which identities and Trust Stores are trusted to produce artifacts in a verification. The name of KeyManagementProvider (KMP) resource(s) must be accurately provided. When a KMP name is specifed, the notation verifier will be configured to trust all certificates fetched from that particular KMP resource.

  • The Trust Stores currently supports three kinds of identities, additional identities may be supported in future:

    • Certificates: The x509/ca trust store contains named stores that contain Certificate Authority (CA) root certificates.
    • SigningAuthority Certificate: The x509/signingAuthority trust store contains named stores that contain Signing Authority's root certificates.
    • Timestamping Certificates: The x509/tsa trust store contains named stores that contain Timestamping Authority (TSA) root certificates.

NOTE 0: CLI is NOT SUPPORTED.

NOTE 1: verificationCertStore is able to reference a KeyManagementProvider to construct trust stores. When referencing a namespaced KMP resource, ensure to include the corresponding namespace prefix, while cluster-wide KMP should be referenced by its name directly. Refer to this section for more information.

NOTE 2: verificationCertStores supersedes verificationCerts if both fields are specified.

NOTE 3: verificationCertStores currently supported values for trust-store-type are ca, signingAuthority and tsa. For backward compatibility, users can either specify the truststore type or omit it, in which case it will default to the ca type.

WARNING!: Starting in Ratify v1.2.0, the KeyManagementProvider resource replaces CertificateStore. It is NOT recommended to use both CertificateStore and KeyManagementProvider resources together. If using helm to upgrade Ratify, please make sure to delete any existing CertificateStore resources. For self-managed CertificateStore resources, users should migrate to the equivalent KeyManagementProvider. If migration is not possible and both resources must exist together, please make sure to use DIFFERENT names for each resource type. Ratify is configured to prefer KMP resources when a matching CertificateStore with same name is found.

Sample Notation yaml spec:

apiVersion: config.ratify.deislabs.io/v1beta1
kind: Verifier
metadata:
  name: verifier-notation
spec:
  name: notation
  artifactTypes: application/vnd.cncf.notary.signature
  parameters:
    verificationCertStores:
      ca:
        ca-certs: 
          - gatekeeper-system/kmp-akv-ca
    trustPolicyDoc:
      version: "1.0"
      trustPolicies:
        - name: default
          registryScopes:
            - "*"
          signatureVerification:
            level: strict
          trustStores:
            - ca:ca-certs
          trustedIdentities:
            - "*"

In the example, the verifier's configuration references 2 KeyManagementProviders, kmp-akv-ca, kmp-akv-tsa. Here, ca:ca-certs is one of the trust stores specifing and the ca-certs suffix corresponds to the ca-certs certificate collection listed in the verificationCertStores section.

CLI​

Sample Notation CLI config:

{
    "store": {
        "version": "1.0.0",
        "plugins": [
            {
                "name": "oras",
            }
        ]
    },
    "policy": {
        "version": "1.0.0",
        "plugin": {
            "name": "configPolicy",
            "artifactVerificationPolicies": {
                "application/spdx+json": "all"
            }
        }
    },
    "verifier": {
        "version": "1.0.0",
        "plugins": [
            {
                "name": "notation",
                "artifactTypes": "application/spdx+json",
                "verificationCerts": [
                    "/usr/local/ratify-certs/notation/truststore"
                ],
                "trustPolicyDoc": {
                    "version": "1.0",
                    "trustPolicies": [
                        {
                            "name": "default",
                            "registryScopes": [
                                "*"
                            ],
                            "signatureVerification": {
                                "level": "strict"
                            },
                            "trustStores": [
                                "ca:ca-certs"
                            ],
                            "trustedIdentities": [
                                "*"
                            ]
                        }
                    ]
                }
            }
        ]
    }
}

Timestamping Configuration​

In the X.509 Public Key Infrastructure (PKI) system, digital signatures must be generated within the certificate’s validity period, as expired certificates compromise the signature’s trustworthiness. The RFC 3161 standard defines the internet X.509 PKI Time-Stamp Protocol (TSP), where a timestamp is issued by a trusted third party acting as a Time Stamping Authority (TSA). These trusted timestamps extend the trust of signatures created within certificates validity, enabling successful signature verification even after certificates have expired.

Kubernetes​

Sample Notation yaml spec with timestamping configuration:

apiVersion: config.ratify.deislabs.io/v1beta1
kind: Verifier
metadata:
  name: verifier-notation
spec:
  name: notation
  artifactTypes: application/vnd.cncf.notary.signature
  parameters:
    verificationCertStores:
      ca:
        ca-certs: 
          - gatekeeper-system/kmp-akv-ca
      tsa:
        tsa-certs: 
          - gatekeeper-system/kmp-akv-tsa
    trustPolicyDoc:
      version: "1.0"
      trustPolicies:
        - name: default
          registryScopes:
            - "*"
          signatureVerification:
            level: strict
            verifyTimestamp: "afterCertExpiry"   # Only verify timestamp countersignatures if any code signing certificate has expired. DEFAULT: `always`
          trustStores:
            - ca:ca-certs
            - tsa:tsa-certs                      # To enable timestamp verification, trust store type `tsa` MUST be configured.
          trustedIdentities:
            - "*"

To use the timestamping feature, you need to configure the trust store type accordingly. In the example, tsa:tsa-certs is the trust store specified for timestamp verification, and the tsa-certs suffix corresponds to the tsa-certs certificate collection listed in the verificationCertStores field.

CLI​

Sample Notation CLI config with timestamping configuration:

{
    "store": {
        "version": "1.0.0",
        "plugins": [
            {
                "name": "oras",
            }
        ]
    },
    "policy": {
        "version": "1.0.0",
        "plugin": {
            "name": "configPolicy",
            "artifactVerificationPolicies": {
                "application/spdx+json": "all"
            }
        }
    },
    "verifier": {
        "version": "1.0.0",
        "plugins": [
            {
                "name": "notation",
                "artifactTypes": "application/spdx+json",
                "verificationCerts": [
                    "/usr/local/ratify-certs/notation/truststore"
                ],
                "trustPolicyDoc": {
                    "version": "1.0",
                    "trustPolicies": [
                        {
                            "name": "default",
                            "registryScopes": [
                                "*"
                            ],
                            "signatureVerification": {
                                "level": "strict",
                                "verifyTimestamp": "afterCertExpiry"   // Only verify timestamp countersignatures if any code signing certificate has expired. DEFAULT: `always`
                            },
                            "trustStores": [
                                "ca:ca-certs",
                                "tsa:tsa-certs"                        // To enable timestamp verification, trust store type `tsa` MUST be configured.
                            ],
                            "trustedIdentities": [
                                "*"
                            ]
                        }
                    ]
                }
            }
        ]
    }
}