@Alaa Elrayes,Thanks for posting in Q&A.
From your description, I know you want to encrypt Linux devices without re-installation to meet the compliance policy.
Based on my research, if you already have Ubuntu installed without any encryption, then full disk encryption with LUKS may not be an option.
And if you use the encryptsetup tool to only encrypt Home folder, but not encrypt the writable fixed disks on this computer, it may not meet the compliance policy settings. Therefore, it is suggested that you re-install the Linux devices and encrypt Linux devices during the installation to meet the compliance policy.
Hopa above information can be helpful.
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