Enhancing the privacy of web-based communication.

A profiling adversary is an adversary whose goal is to classify a population of users into categories according to messages they exchange. This adversary models the most common privacy threat against web based communication.We propose a new encryption scheme, called stealth encryption, that protects users from profiling attacks by concealing the semantic content of plaintext while preserving its grammatical structure and other non-semantic linguistic features, such as word frequency distribution. Given English plaintext, stealth encryption produces ciphertext that cannot efficiently be distinguished from normal English text (our techniques apply to other languages as well).