kmsKeyId

The AWS KMS key identifier for an encrypted CEV. A symmetric encryption KMS key is required for RDS Custom, but optional for Amazon RDS. If you have an existing symmetric encryption KMS key in your account, you can use it with RDS Custom. No further action is necessary. If you don't already have a symmetric encryption KMS key in your account, follow the instructions in Creating a symmetric encryption KMS key in the Key Management Service Developer Guide. You can choose the same symmetric encryption key when you create a CEV and a DB instance, or choose different keys.