How to Configure AWS EBS Encryption for Data-at-Rest Security

November 30, 20235 min read

Ensuring data security is critical when operating in the cloud. Encrypting your AWS Elastic Block Store (EBS) volumes is a fundamental step you can take to secure your data. EBS encryption enables data-at-rest security by encrypting your volume data and any snapshots created from it.

Understanding AWS EBS Encryption

Before configuring encryption, it’s essential to understand how AWS EBS encryption works:

  • Encryption keys: EBS uses AWS Key Management Service (KMS) keys for encryption. You can either use the default AWS-managed CMK (Customer Master Key) or create your custom CMK.
  • Encryption process: Data is encrypted on the server side before being saved to the disk and decrypted when accessed.
  • Performance: The encryption/decryption process is seamless and has minimal impact on I/O performance.
  • Snapshots: Snapshots of encrypted volumes are also encrypted, and volumes restored from encrypted snapshots are encrypted as well.
  • Clusters and instances: Encryption is supported for both standalone EBS volumes and those used in a cluster or as instance stores for EC2 instances.

Configuring EBS Encryption

Step 1: Enable Default Encryption (Optional)

  1. Open the AWS Management Console.
  2. Navigate to the EBS Dashboard under the EC2 service.
  3. In the left navigation pane, click on Encryption Keys.
  4. You will see an option to “Always encrypt new EBS volumes”.
  5. Check this box to ensure that all new volumes created in the selected region are encrypted using the default AWS-managed CMK.

Note: Enabling default encryption doesn’t encrypt existing unencrypted volumes.

Step 2: Create a New Encrypted EBS Volume

  1. Access the EC2 Dashboard in the AWS Management Console.
  2. Navigate to the Volumes section.
  3. Click on the “Create Volume” button.
    • Volume Type: Choose your desired volume type (e.g., General Purpose SSD, Provisioned IOPS SSD).
    • Size: Specify the size of the EBS volume.
    • Availability Zone: Choose the Availability Zone where the EBS volume will be created.
    • Encryption:
      • Check the box labeled “Encrypt this volume”.
      • Under the “Master Key” drop-down, select the default AWS-managed CMK or a custom CMK that you have previously created.
  4. Click the “Create Volume” button once you have configured all the settings.
  5. Once the volume is created, you can attach it to an EC2 instance using the “Attach Volume” action.

Note: You can also encrypt a volume during the EC2 instance launch wizard by selecting an encrypted AMI or enabling encryption in the instance storage settings.

Step 3: Create a Custom KMS Key (Optional)

If you need a higher level of control over your encryption keys, you should create a custom CMK:

  1. Go to the AWS KMS Dashboard.
  2. Click on “Create a key”.
  3. Choose the “Symmetric” key type.
  4. Define aliases, descriptions, and tags.
  5. Determine key administrative and usage permissions.
  6. Review and create the key.
  7. After creating the key, you can select it when creating or configuring EBS volumes, as described in Step 2.

Important: Take note of your key policies and ensure that they grant necessary permissions to the correct users and roles.

Step 4: Encrypt an Unencrypted EBS Volume

To encrypt an existing unencrypted volume:

  1. Create a snapshot of the unencrypted EBS volume.
  2. Copy the snapshot and select the “Encrypt this snapshot” checkbox.
  3. Choose an encryption key (either the default AWS-managed key or a custom CMK).
  4. Create a new EBS volume from the encrypted snapshot.
  5. Attach the new encrypted volume to your EC2 instance in place of the old unencrypted volume.
  6. Clean up: Make sure to securely delete the old unencrypted volume and snapshots to maintain security.

Verifying Your Encryption

After configuring EBS encryption, verify that your volumes are encrypted:

  • In the EC2 Dashboard, go to the Volumes section. You can see the encryption status in the list of volumes.
  • Select a volume to check its details. Under the “Description” tab, it should indicate “Encrypted: Yes” along with the KMS key ID used for encryption.

By following these steps, you will enhance the security posture of your AWS EBS volumes by leveraging encryption to protect your sensitive data-at-rest.