There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

From the Publisher:
A valuable reference for the novice as well as for the expert who needs a wider scope of coverage within the area of cryptography, this book provides easy and rapid access of information and includes more than 200 algorithms and protocols; more than 200 tables and figures; more than 1,000 numbered definitions, facts, examples, notes, and remarks; and over 1,250 significant references, including brief comments on each paper.

Handbook of Applied Cryptography

We present Tor, a circuit-based low-latency anonymous communication service. This second-generation Onion Routing system addresses limitations in the original design by adding perfect forward secrecy, congestion control, directory servers, integrity checking, configurable exit policies, and a practical design for location-hidden services via rendezvous points. Tor works on the real-world Internet, requires no special privileges or kernel modifications, requires little synchronization or coordination between nodes, and provides a reasonable tradeoff between anonymity, usability, and efficiency. We briefly describe our experiences with an international network of more than 30 nodes. We close with a list of open problems in anonymous communication.

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Tor: the second-generation onion router

Advances in sensing and tracking technology enable location-based applications but they also create significant privacy risks. Anonymity can provide a high degree of privacy, save service users from dealing with service providers’ privacy policies, and reduce the service providers’ requirements for safeguarding private information. However, guaranteeing anonymous usage of location-based services requires that the precise location information transmitted by a user cannot be easily used to re-identify the subject. This paper presents a middleware architecture and algorithms that can be used by a centralized location broker service. The adaptive algorithms adjust the resolution of location information along spatial or temporal dimensions to meet specified anonymity constraints based on the entities who may be using location services within a given area. Using a model based on automotive traffic counts and cartographic material, we estimate the realistically expected spatial resolution for different anonymity constraints. The median resolution generated by our algorithms is 125 meters. Thus, anonymous location-based requests for urban areas would have the same accuracy currently needed for E-911 services; this would provide sufficient resolution for wayfinding, automated bus routing services and similar location-dependent services.

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Anonymous Usage of Location-Based Services Through Spatial and Temporal Cloaking

In the Hamadryas baboon, males are substantially larger than females. A troop of baboons is subdivided into a number of ‘one-male groups’, consisting of one adult male and one or more females with their young. The male prevents any of ‘his’ females from moving too far from him. Kummer (1971) performed the following experiment. Two males, A and B, previously unknown to each other, were placed in a large enclosure. Male A was free to move about the enclosure, but male B was shut in a small cage, from which he could observe A but not interfere. A female, unknown to both males, was then placed in the enclosure. Within 20 minutes male A had persuaded the female to accept his ownership. Male B was then released into the open enclosure. Instead of challenging male A , B avoided any contact, accepting A’s ownership.

Evolution and the Theory of Games

We introduce Self-Authenticating Traditional (SAT) domain names. SAT domains are traditional recognizable domains resolvable via the Domain Name System (DNS). They are also self-authenticating—they encode in the name itself a public key for authenticating the SAT domain. We present an implementation of our SAT domains for servers and a corresponding Firefox WebExtension that validates connections to them. SAT domains weave security directly into the fabric of the Web by building authentication into URLs themselves. Thus, by simply posting links to other SAT domains, a SAT site that a user trusts assures that user of the ability to make hijack-resistant connections to any of those domains. Because just the address attested in this way is sufficient for users to create a secure connection to a recognizable domain, we call this dirt simple trust. We present implemented examples of this and describe other channels to establish dirt simple trust. The public keys we embed in SAT domain names are in the format of Tor onion service keys. Specifically, a SAT domain includes the encoding of an onion service public key as a subdomain of a registered domain name. But the client can be ignorant of Tor and need not direct traffic over any onion routing network to obtain our protections. This makes SAT domains compatible with other browsers and standard routing infrastructure. Nonetheless, our extension also works in Tor Browser. We also explore systems developed and deployed by others that associate a self-authenticating domain with a traditional DNS domain using existing Web authentication mechanisms, but without building security in directly. Recently, major providers have deployed. onion alternative services to support load balancing and improved performance for Tor users. Though superficially similar to SAT domains, our analysis indicates that these alternative services are not actually self-authenticating. They also increase the effectiveness and impact of client tracking attacks acknowledged in the design of alternative services. We describe such attacks and describe another benefit of our WebExtension: it provides an interface allowing users to selectively block or permit alternative services.

Self-Authenticating Traditional Domain Names

Proceedings of the 5th International Conference on Financial Cryptography

Panel Introduction: Varieties of Authentication

Large market participants (LMPs) must often execute trades while keeping their intentions secret. Sometimes secrecy is required before trades are completed to prevent other traders from anticipating (and exploiting) the price impact of their trades. This is known as “front-running”. In other cases, LMPs with proprietary trading strategies wish to keep their positions secret even after trading because their strategies and positions contain valuable information. LMPs include hedge funds, mutual funds, and other specialized market players.

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Intention-Disguised algorithmic trading

Currently fielded anonymous communication systems either introduce too much delay and thus have few users and little security, or have many users but too little delay to provide protection against large attackers. By combining the user bases into the same network, and ensuring that all traffic is mixed together, we hope to lower delay and improve anonymity for both sets of users. Alpha-mixing is an approach that can be added to traditional batching strategies to let senders specify for each message whether they prefer security or speed. Here we describe how to add alpha-mixing to various mix designs, and show that mix networks with this feature can provide increased anonymity for all senders in the network. Along the way we encounter subtle issues to do with the attacker's knowledge of the security parameters of the users.

Paul Syverson

Papers

Self-Authenticating Traditional Domain Names

Proceedings of the 5th International Conference on Financial Cryptography

Panel Introduction: Varieties of Authentication

Intention-Disguised algorithmic trading

Blending different latency traffic with alpha-mixing