Amazon ElastiCache for Redis encryption at rest is now available in the AWS GovCloud (US) Regions (encryption at rest is already available in all commercial regions). Customers are increasingly moving sensitive workloads to Amazon ElastiCache for Redis, such as financial and healthcare data, whose compliance regulations mandate data encryption. You can now enable encryption at rest in AWS GovCloud (US) regions using either the default (service managed) encryption at rest or your own symmetric customer managed AWS KMS keys in AWS Key Management Service (KMS). When you enable encryption at rest, Amazon ElastiCache for Redis encrypts all data on disk including service backups stored in Amazon S3.
Source:: Amazon AWS