AWS KMS Key Rotation

TL;DR

This guide shows you how to automatically rotate your AWS KMS data keys for improved security. We’ll use the built-in key rotation feature, which simplifies the process and ensures your encryption is always using fresh keys.

Prerequisites

• An existing AWS KMS customer master key (CMK).
• Permissions to manage KMS keys (kms:DescribeKey, kms:EnableKeyRotation, kms:RotateKey).

Steps

1. Check Key Rotation Status

   First, verify if key rotation is already enabled. Use the AWS CLI or console:

   aws kms describe-key --key-id  --query 'KeyMetadata.EnableKeyRotation'

   If the output is true, skip to step 4.

2. Enable Key Rotation

   If key rotation isn’t enabled, enable it using the AWS CLI:

   aws kms enable-key-rotation --key-id 

   Alternatively, you can do this through the AWS Management Console. Navigate to your KMS key, then choose Key rotation and click Enable key rotation.

3. Understand Rotation Period

   By default, KMS rotates keys every 365 days. You can’t change this period directly. The rotation happens automatically after the initial enablement.

4. Initiate Manual Key Rotation (Optional)

   To force a key rotation immediately (for testing or compliance), use:

   aws kms rotate-key --key-id 

   This creates a new key version. Note that this is not usually necessary as automatic rotation will occur.

5. Verify Key Rotation

   Check the key versions associated with your CMK to confirm the rotation:

   aws kms list-key-versions --key-id 

   You should see multiple key versions, including a new one created after enabling or initiating rotation. The Used column will indicate which version is currently in use.

6. Update Applications (If Necessary)

   Most AWS services automatically handle key rotation when using KMS for encryption. However, if you’re directly integrating with the KMS API, ensure your application code supports multiple key versions and can retrieve the correct one for decryption.