Acquia Key Provider
This module provides a secure way to store sensitive credentials for Acquia hosted applications. It integrates with a specialized directory on the Acquia platform that is excluded from backups, making it ideal for storing private information.
A specialized key provider for Acquia hosted applications.
Features
This module offers a first-class integration into the platform's recommended private information store within the filesystem. The short version is that each environment (dev, test, and prod for example) can have a special directory located at /mnt/gfs/[sitename].[env]/nobackup that is excluded from platform disaster recovery backups and is most suitable for storing sensitive credentials that would most commonly be used with the key module.
Why not use the File key provider instead?
There does not seem to be a common filesystem path between environments in the Acquia Cloud Next platform that can benefit from the nobackup directory security feature. The alternatives seem to be quite heavy-handed and either involve custom settings.php overrides or configuration splits.
Post-Installation
Place the proper key files within each directory within each environment via SSH. If a local development workflow is utilized, it may be required to temporarily mock the environment variables and filesystem a bit.