W3Bcrypt: Encryption as a Stylesheet

While web-based communications (e.g., webmail or web chatrooms) are increasingly protected by transport-layer cryptographic mechanisms, such as the SSL/TLS protocol, there are many situations where even the web server (or its operator) cannot be trusted. The end-to-end (E2E) encryption of data becomes increasingly important in these trust models to protect the confidentiality and integrity of the data against snooping and modification.

We introduce W3Bcrypt, an extension to the Mozilla Firefox platform that enables application-level cryptographic protection for web content. In effect, we view cryptographic operations as a type of style to be applied to web content, similar to and along with layout and coloring operations. Among the main benefits of using encryption as a stylesheet are (a) reduced workload on the web server, (b) targeted content publication, and (c) greatly increased privacy. This paper discusses our implementation for Firefox, although the core ideas are applicable to most current browsers.