How does API Gateway encrypt its cache?

Hello folks,

I have been looking into AWS documentation that explains how the API Gateway encrypts its cache when cache encryption is enabled. The only article I was able to find around this topic is from 2017 (https://forums.aws.amazon.com/thread.jspa?threadID=260950) and it states the following:

*Under the hood we use KMS to generate cipher texts for encrypting cache values. Keys are rotated hourly and stored in a local cache.

Regards, xxx*

Can someone confirm this is still the case and/or point me to any official AWS documentation that explains the cache encryption mechanism in detail?