S4 utilizes Tahoe-LAFS to securely store data on Amazon S3. You can access S4 using Gridsync or the Command Line Interface.
Tahoe-LAFS, the Least Authority File Store, is a free and open-source cloud storage system with verifiable end-to-end security. We use Tahoe-LAFS to provide client-side encryption and other features for our Simple Secure Storage Service – S4. This means you don’t have to rely on storage servers to provide confidentiality and integrity of your data.Tahoe-LAFS Website
This comic explains our Simple Secure Storage Service – S4 – works compared to other cloud storage options. This short series of illustrations was done by Sam Hester from The 23rd Story.
Magic Folders is a file-syncing utility that automatically keeps a folder’s contents up-to-date across multiple devices in our Simple Secure Storage Service – S4.Magic Folders Blog Post
Magic Wormhole allows us to send configuration information from our Simple Secure Storage Service – S4 – to Gridsync, and supports sharing files and folders.Magic Wormhole on GitHub