AKS Double Encryption

I have been living in a world of compliance these past few weeks, specifically NIST 800-171. Azure provides an initiative for NIST and one of the checks is to make sure your disks have both a platform and customer managed key. I recently ran into a scenario where you have an application that is StatefulSet in Azure Kubernetes. Let’s talk a bit more around this and NIST.

The Azure Policy was in non compliance for my disks because they were just a managed platform key. Researching the AKS docs, I found an article for using a customer managed key, but this still is not what I need as I need double encryption to meet compliance. After some research in the Kubernetes SIGs repo, I found the Azure Disk CSI driver doc and check it out:

It looks like this document was modified back in May adding support for this feature, so recently new. Upgrade the driver to 1.18 or above and double encryption support should be there.

To implement, create a new storage class that references your disk encryption set id with double encryption.

kind: StorageClass
apiVersion: storage.k8s.io/v1  
  name: byok-double-encrpytion
provisioner: disk.csi.azure.com 
reclaimPolicy: Retain
allowVolumeExpansion: true
  skuname: Premium_LRS
  kind: managed
  diskEncryptionType: EncryptionAtRestWithPlatformAndCustomerKeys
  diskEncryptionSetID: "/subscriptions/<sub>/resourceGroups/<rg>/providers/Microsoft.Compute/diskEncryptionSets/<dek-name>"

Apply this snippet above and reference the storage class in your deployment yaml to have double encryption. This will tick that NIST compliance checkbox for AKS disks.

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