Building Private Applications on the Personal Web

Users of the web trust third-party application providers with the safe keeping of their data. As the wealth of quality application services grows, so too does the volume of data that users disclose and entrust to others. This trust is precarious: services may go out of business or fail, while application provides may not take sufficient care of sensitive personal data, leading to data loss or unauthorized access. We argue for a web application model that treats personal data differently. We first observe that the best practical backup of a user’s data is to collect and store a complete log of their browserwebsite interactions, allowing them to search their browsing history for content and application state that they have viewed in the past. After showing that the collection and storage of this history is practical, we argue that many services that access personal data would be better implemented with access to the log, and in isolation from the Internet at large. This approach allows applications to be trusted with access to personal data without concerns over the leakage or unauthorized disclosure of that information. We describe the design and implementation of our system, and then evaluate the model’s potential with three useful applications: a search application working over all websites visited, a credit card fraud detection application, and a user self-profiling application.