Goals ===== Security goals -------------- * **Client-side encryption:** Before any data is synced to the cloud, it should be encrypted on the client device. * **Encrypted local storage:** Any data cached in the client should be stored in an encrypted format. * **Resistant to offline attacks:** Data stored on the server should be highly resistant to offline attacks (i.e. an attacker with a static copy of data stored on the server would have a very hard time discerning much from the data). * **Resistant to online attacks:** Analysis of storing and retrieving data should not leak potentially sensitive information. * **Resistance to data tampering:** The server should not be able to provide the client with old or bogus data for a document. Synchronization goals --------------------- * **Consistency:** multiple clients should all get sync'ed with the same data. * **Selective sync:** the ability to partially sync data. For example, so a mobile device doesn’t need to sync all email attachments. * **Multi-platform:** supports both desktop and mobile clients. * **Quota:** the ability to identify how much storage space a user is taking up. * **Scalable cloud:** distributed master-less storage on the cloud side, with no single point of failure. * **Conflict resolution:** conflicts are flagged and handed off to the application logic to resolve. Usability goals * **Availability:** the user should always be able to access their data. * **Recovery:** there should be a mechanism for a user to recover their data should they forget their password. Known limitations ----------------- These are currently known limitations: * The server knows when the contents of a document have changed. * There is no facility for sharing documents among multiple users. * Soledad is not able to prevent server from withholding new documents or new revisions of a document. * Deleted documents are never deleted, just emptied. Useful for security reasons, but could lead to DB bloat. Non-goals --------- * Soledad is not for filesystem synchronization, storage or backup. It provides an API for application code to synchronize and store arbitrary schema-less JSON documents in one big flat document database. One could model a filesystem on top of Soledad, but it would be a bad fit. * Soledad is not intended for decentralized peer-to-peer synchronization, although the underlying synchronization protocol does not require a server. Soledad takes a cloud approach in order to ensure that a client has quick access to an available copy of the data.