PrivaTegrity allows smart phones to send and receive messages, with little extra bandwidth or battery usage, while achieving anonymity for senders and recipients among all messages sent globally in batches defined by each one-second time interval. To learn anything about which inputs correspond with which outputs of the batch of messages, the entire cascade of ten mix servers, each preferably operating independently in a different country, would have to be compromised. None of the real-time computation, neither by the mixes nor smartphones, uses public-key operations—achieving orders of magnitude performance improvement over comparable earlier work.

PrivaTegrity also takes a new approach to user identification, requiring each user to provide a small amount of different identifying information to each mix node. Each node would require its own particular type of identification. Answers to personal history questions or even photos may be requested by some nodes and mobile phone numbers or email addresses confirmed by other nodes. Comparatively little is revealed to each node individually, but if ever aggregated the user identification should become very effective. The mix nodes can obligate themselves contractually to trace and aggregate only according to a published policy, resulting in accountability and even identification of users who violate that policy.

Untraceable communication is fundamental to freedom of inquiry, freedom of expression, and increasingly to online privacy generally, including person-to-person communication. To address these needs a system should support, ideally within a combined anonymity set, the most common use cases: chat, photo/video sharing, feed following, searching, posting, payments, all with various types of potentially pseudonymous authentication. Rather than layering such services on top of its mixing and allowing widely varying payload sizes, PrivaTegrity integrates such services directly into its mixing with standardized formats and payload sizes. It includes what aims to be a comprehensive range of lightweight services efficiently supporting the above use cases, bringing much of them into the same anonymity sets as those for chat messages.

Widely recognized as the inventor of digital cash, David Chaum is also known for other fundamental innovations in cryptography, including privacy technology and secure election systems. With a PhD in Computer Science from UC Berkeley, he taught at NYU Graduate School of Business and the University of California, lead a number of breakthrough projects as well as founded the International Association for Cryptologic Research, the cryptography group at the Center for Mathematics and Computer Science in Amsterdam, DigiCash, the Voting Systems Institute, and the Spectoccular Technology Fund.

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