Details
Customer-Supplied Encryption Keys (CSEK) are a feature in Google Cloud Storage and Google Compute Engine. If you supply your own encryption keys, Google uses your key to protect the Google-generated keys used to encrypt and decrypt your data. By default, Google Compute Engine encrypts all data at rest. Compute Engine handles and manages this encryption for you without any additional actions on your part. However, if you wanted to control and manage this encryption yourself, you can provide your own encryption keys.
Rationale:
By default, Google Compute Engine encrypts all data at rest. Compute Engine handles and manages this encryption for you without any additional actions on your part. However, if you wanted to control and manage this encryption yourself, you can provide your own encryption keys.
If you provide your own encryption keys, Compute Engine uses your key to protect the Google-generated keys used to encrypt and decrypt your data. Only users who can provide the correct key can use resources protected by a customer-supplied encryption key.
Google does not store your keys on its servers and cannot access your protected data unless you provide the key. This also means that if you forget or lose your key, there is no way for Google to recover the key or to recover any data encrypted with the lost key.
At least business critical VMs should have VM disks encrypted with CSEK.
Impact:
If you lose your encryption key, you will not be able to recover the data.
Solution
Currently there is no way to update the encryption of an existing disk. Therefore you should create a new disk with Encryption set to Customer supplied.
From Console:
Go to Compute Engine Disks by visiting: https://console.cloud.google.com/compute/disks.
Click CREATE DISK.
Set Encryption type to Customer supplied,
Provide the Key in the box.
Select Wrapped key.
Click Create.
From Command Line:
In the gcloud compute tool, encrypt a disk using the –csek-key-file flag during instance creation. If you are using an RSA-wrapped key, use the gcloud beta component:
gcloud (beta) compute instances create INSTANCE_NAME –csek-key-file
To encrypt a standalone persistent disk:
gcloud (beta) compute disks create DISK_NAME –csek-key-file
Default Value:
By default, VM disks are encrypted with Google-managed keys. They are not encrypted with Customer-Supplied Encryption Keys.
Supportive Information
The following resource is also helpful.
This security hardening control applies to the following category of controls within NIST 800-53: System and Communications Protection.This control applies to the following type of system GCP.