encrypted
Specifies whether the volume should be encrypted. Encrypted EBS volumes can only be attached to instances that support Amazon EBS encryption. For more information, see Supported instance types. If your AMI uses encrypted volumes, you can also only launch it on supported instance types.
If you are creating a volume from a snapshot, you cannot create an unencrypted volume from an encrypted snapshot. Also, you cannot specify a KMS key ID when using a launch configuration.
If you enable encryption by default, the EBS volumes that you create are always encrypted, either using the Amazon Web Services managed KMS key or a customer-managed KMS key, regardless of whether the snapshot was encrypted.
For more information, see Use Amazon Web Services KMS keys to encrypt Amazon EBS volumes in the Amazon EC2 Auto Scaling User Guide.