Overview of managed disk encryption options
There are several types of encryption available for your managed disks, including Azure Disk Encryption (ADE), Server-Side Encryption (SSE) and encryption at host.
Azure Disk Encryption helps protect and safeguard your data to meet your organizational security and compliance commitments. ADE encrypts the OS and data disks of Azure virtual machines (VMs) inside your VMs by using the DM-Crypt feature of Linux or the BitLocker feature of Windows. ADE is integrated with Azure Key Vault to help you control and manage the disk encryption keys and secrets. For full details, see Azure Disk Encryption for Linux VMs or Azure Disk Encryption for Windows VMs.
Azure Disk Storage Server-Side Encryption (also referred to as encryption-at-rest or Azure Storage encryption) automatically encrypts data stored on Azure managed disks (OS and data disks) when persisting on the Storage Clusters. When configured with a Disk Encryption Set (DES), it supports customer-managed keys as well. For full details, see Server-side encryption of Azure Disk Storage.
Encryption at host ensures that data stored on the VM host hosting your VM is encrypted at rest and flows encrypted to the Storage clusters. For full details, see Encryption at host - End-to-end encryption for your VM data.
Confidential disk encryption binds disk encryption keys to the virtual machine's TPM and makes the protected disk content accessible only to the VM. The TPM and VM guest state is always encrypted in attested code using keys released by a secure protocol that bypasses the hypervisor and host operating system. Currently only available for the OS disk. Encryption at host may be used for other disks on a Confidential VM in addition to Confidential Disk Encryption. For full details, see DCasv5 and ECasv5 series confidential VMs.
Encryption is part of a layered approach to security and should be used with other recommendations to secure Virtual Machines and their disks. For full details, see Security recommendations for virtual machines in Azure and Restrict import/export access to managed disks.
Here's a comparison of Disk Storage SSE, ADE, encryption at host, and Confidential disk encryption.
|Encryption at rest (OS and data disks)||Temp disk encryption||Encryption of caches||Data flows encrypted between Compute and Storage||Customer control of keys||Does not use your VM's CPU||Works for custom images||Enhanced Key Protection||Microsoft Defender for Cloud disk encryption status|
|Azure Disk Storage Server-Side Encryption at rest||✅||❌||❌||❌||✅ When configured with DES||✅||✅||❌||Unhealthy, not applicable if exempt|
|Azure Disk Encryption||✅||✅||✅||✅||✅||❌||❌ Does not work for custom Linux images||❌||Healthy|
|Encryption at Host||✅||✅||✅||✅||✅||✅||✅||❌||Unhealthy, not applicable if exempt|
|Confidential disk encryption||✅ For the OS disk only||❌||✅ For the OS disk only||✅ For the OS disk only||✅ For the OS disk only||❌||✅||✅||Unhealthy, not applicable if exempt|
For Encryption at host and Confidential disk encryption, Microsoft Defender for Cloud does not detect the encryption state. We are in the process of updating Microsoft Defender
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