In testing and supporting Cloud Storage products, we describe FESF’s ability to interoperate with a given Cloud Storage product as being one of three levels:
Level 1 Interoperability (L1): FESF and the Cloud Storage product can be installed on the same system without affecting system stability. That is, systems don’t crash or exhibit unusual behaviors as a result of both products being installed simultaneously. However, regardless of the Solution policy implemented, it is not necessarily possible for FESF to encrypt files that are stored in directories that are serviced by the Cloud Storage product.
Level 2 Interoperability (L2): In addition to stability coexisting with a given Cloud Storage product, FESF can encrypt local copies of files that are stored in the cloud by that product. In products that use placeholder technologies (that is, where some subset of files stored in the cloud are represented by a “marker file” locally and are only fully recalled from the cloud when requested by the user), files will be encrypted by FESF when they are recalled from the cloud and stored on the local system.
Level 3 Interoperability (L3): FESF supports encrypting both local files and files that are stored in the cloud. This means that FESF encrypted files that are recalled from the cloud can be successfully decrypted and stored locally (in either encrypted or decrypted form) depending on the Solution policy.
We strive to ensure that all common Cloud Storage products can coexist on the same system as FESF, and thereby achieve L1 interoperability. It is sometimes hard to even achieve this level of interoperability, but it remains our goal.
Almost everyone would agree that it’s better for FESF to be interoperable with a product at L2 than at L1. At L1, the best we can say is that the two products coexist peacefully. At L2 end-users can decide (depending on the capabilities of your Solution, of course) if they want their cloud files to be encrypted when they are stored on their local system. However, it’s not always possible (barring major changes in the Cloud Storage product itself) for a Cloud Storage product that’s interoperable with FESF at L1 today to be interoperable with FESF at L2 tomorrow.
Also, it’s not clear that L3 interoperability is necessarily useful in all cases. When files are stored encrypted in the cloud (the defining attribute of L3 interoperability) users can’t access them using browser-based tools such as Microsoft Office online. The ability to use these tools is one of the prime motivating factors for many end-users deciding to put their files in the cloud.
Further, it’s not always possible for FESF to provide L3 interoperability with a given Cloud Storage product.