Azure Disk Encryption is a service that helps you encrypt your Windows and Linux IaaS virtual machine disks1. It uses BitLocker for Windows and DM-Crypt for Linux to provide volume encryption for the OS and data disks2. Azure Disk Encryption requires that you use a key encryption key in Azure Key Vault to encrypt the volume encryption key, which is then stored on the disk. You can use either a service-managed key or a customer-managed key in Azure Key Vault3. Azure Disk Encryption also supports encrypting virtual machine disks that are downloaded from Azure4.