Managing the lifecycle of cryptographic keys is a critical aspect of strong security posture, especially in cloud environments like AWS. While AWS Key Management Service (KMS) simplifies many aspects of key management, handling keys that you import yourself requires a slightly different approach compared to those generated within KMS. A key best practice for security and compliance is regularly rotating your encryption keys.
For keys created directly in AWS KMS, the service offers automated rotation every year, handled seamlessly in the background. However, this automatic rotation feature is not available for imported key material. If you use keys generated outside of KMS and imported into the service, the responsibility for rotating the underlying cryptographic material falls on you.
This doesn’t mean imported keys can’t be rotated. Instead, it means you need a deliberate strategy. The process typically involves creating new key material externally, securely transferring it, and then updating the existing KMS key to use this fresh material. This manual effort can be time-consuming and requires careful planning to avoid disrupting operations that rely on the key.
The need often arises to rotate imported keys on-demand, perhaps driven by a security incident, a change in policy, or specific compliance requirements that mandate rotation outside of a fixed schedule. Achieving this requires a well-defined procedure. This process essentially involves preparing new key material, re-importing it under the same KMS Key ID (using appropriate API calls like ImportKeyMaterial), and potentially updating any aliases or application configurations that point to the key. It’s crucial to ensure minimal downtime and proper handling of data encrypted with the old material (AWS KMS handles decryption with previous material versions automatically for the same Key ID).
Implementing a reliable process for on-demand rotation of imported keys ensures that your security practices remain robust and adaptable, meeting both best practices and dynamic compliance needs without relying on AWS’s automatic rotation for natively generated keys. This proactive management of your imported cryptographic assets is key to maintaining a strong security foundation in AWS.
Source: https://aws.amazon.com/blogs/security/how-to-use-on-demand-rotation-for-aws-kms-imported-keys/
