How does an encrypted DynamoDB (the same question applies to RDS as well) query work?

Question

I am trying to understand whether the primary key is encrypted when I choose to encrypt in rest for AWS DynamoDB

1. If the primary key is encrypted, how does a primary-key look up get performed under the hood?

2. If the primary key is not encrypted, then I know how DynamoDB is implemented under the hood, but it seems that it's not entirely safe for some use cases. Any comment then?

Furthermore, if I choose to have a Global Secondary Index for my DynamoDB table, are the primary key of the Global Secondary Index table encrypted?

1. If not encrypted, I kinda understand how it works under the hood, but certainly some of my data get revealed in plain text;
2. If encrypted, I'd appreciate to understand how it works.

Answer 1

For DynamoDB encryption at rest, it means the table is encrypted on disk, not each of the attributes of the items in the table. This is true for any database talking about encryption at rest. That at rest means on disk. Now if you were to implement application data level encryption on your own, then what you are talking about would come into play.

One thing to know is that as of a few weeks ago, all DynamoDB tables are encrypted at rest by default.