Private Document Editing with some Trust
Document editing has migrated in the last decade from a mostly
individual activity to a shared activity among multiple persons. The
World Wide Web and other communication means have contributed to this
evolution. However, collaboration via the web has shown a tendency to
centralize information, making it accessible to subsequent uses and
abuses, such as surveillance, marketing, and data theft.
Traditionally, access control policies have been enforced by a central
authority, usually the server hosting the content, a single point of
failure. We describe a novel scheme for collaborative editing in which
clients enforce access control through the use of strong encryption.
Encryption keys are distributed as the portion of a URI which is not
shared with the server, enabling users to adopt a variety of document
security workflows. This system separates access to the information (``the key'') from the
responsibility of hosting the content (``the carrier of the vault''),
allowing privacy-conscious editors to enjoy a modern collaborative editing
experience without relaxing their requirements.
The paper presents CryptPad, an open-source reference implementation
which features a variety of editors which employ the described access control
methodology. We will detail approaches for implementing a variety of features
required for user productivity in a manner that satisfies user-defined
Published:Proceedings of the ACM Symposium on Document Engineering 2018, Halifax, August 2018