Envelope Encryption is an approach/process used within many applications to encrypt data. Using this approach your data is protected two-fold.
For more information please see the below links :
#NOTE To build the vault sub module you need to have vault in your PATH. You can download Vault from https://www.vaultproject.io/downloads.html , unzip it and add to your /usr/bin directory.
To build the aws sub module you need to have proper ~/.aws/credentials and a correct ARN in the test file.