Document verification steps for capi images

Document verification of CAPI images with cosign.

Signed-off-by: Anurag <[email protected]>

Author: kranurag7

docs/book/src/SUMMARY.md

@@ -40,6 +40,7 @@
             - [Deploying Runtime Extensions](./tasks/experimental-features/runtime-sdk/deploy-runtime-extension.md)
         - [Ignition Bootstrap configuration](./tasks/experimental-features/ignition.md)
     - [Running multiple providers](./tasks/multiple-providers.md)
+    - [Verification of Container Images](./tasks/verify-container-images.md)
 - [Security Guidelines](./security/index.md)
     - [Pod Security Standards](./security/pod-security-standards.md)
 - [clusterctl CLI](./clusterctl/overview.md)

docs/book/src/tasks/verify-container-images.md

@@ -0,0 +1,55 @@
+# Verification of CAPI artifacts
+
+## Requirements 
+You will need to have the following tools installed:
+- cosign [(install guide)](https://docs.sigstore.dev/system_config/installation/)
+- jq [(download jq)](https://stedolan.github.io/jq/download/)
+
+## CAPI Images
+Each [release](https://github.com/kubernetes-sigs/cluster-api/releases) of the Cluster API project includes the following container images:
+- cluster-api-controller
+- kubeadm-bootstrap-controller
+- kubeadm-control-plane-controller
+- clusterctl
+
+## Verifying Image Signatures
+All of the four images are hosted by [registry.k8s.io](https://registry.k8s.io). In order to verify the authenticity of the images, you can use `cosign verify` command with the appropriate image name and version: 
+
+```bash
+$ cosign verify registry.k8s.io/cluster-api/cluster-api-controller:v1.5.0 --certificate-identity [email protected] --certificate-oidc-issuer https://accounts.google.com | jq .
+```
+```text
+Verification for registry.k8s.io/cluster-api/cluster-api-controller:v1.5.0 --
+The following checks were performed on each of these signatures:
+  - The cosign claims were validated
+  - Existence of the claims in the transparency log was verified offline
+  - The code-signing certificate was verified using trusted certificate authority certificates
+[
+  {
+    "critical": {
+      "identity": {
+        "docker-reference": "registry.k8s.io/cluster-api/cluster-api-controller"
+      },
+      "image": {
+        "docker-manifest-digest": "sha256:f34016d3a494f9544a16137c9bba49d8756c574a0a1baf96257903409ef82f77"
+      },
+      "type": "cosign container image signature"
+    },
+    "optional": {
+      "1.3.6.1.4.1.57264.1.1": "https://accounts.google.com",
+      "Bundle": {
+        "SignedEntryTimestamp": "MEYCIQDtxr/v3uRl2QByVfYo1oopruADSaH3E4wThpmkibJs8gIhAIe0odbk99na5GBdYGjJ6IwpFzhlTlicgWOrsgxZH8LC",
+        "Payload": {
+          "body": "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",
+          "integratedTime": 1690304684,
+          "logIndex": 28719030,
+          "logID": "c0d23d6ad406973f9559f3ba2d1ca01f84147d8ffc5b8445c224f98b9591801d"
+        }
+      },
+      "Issuer": "https://accounts.google.com",
+      "Subject": "[email protected]",
+      "org.kubernetes.kpromo.version": "kpromo-v4.0.3-5-ge99897c"
+    }
+  }
+]
+```