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

2 1 The innovative transport systems and the CityMobil project 10 1.1 The research questions 10 2 The state of art in the field of automatic transport systems 12 2.1 Case studies and demand studies for innovative transport systems 12 3 The design and implementation of surveys 14 3.1 Definition of experimental design 14 3.2 Questionnaire design and delivery 16 3.3 First analyses on the collected sample 18 4 Calibration of Logit Multionomial demand models 21 4.1 Methodology 21 4.2 Calibration of the “full” model. 22 4.3 Calibration of the “final” model 24 4.4 The demand analysis through the final Multinomial Logit model 25 5 The analysis of interaction between the demand and socioeconomic attributes 31 5.1 Methodology 31 5.2 Application of Mixed Logit models to the demand 31 5.3 Analysis of the interactions between demand and socioeconomic attributes through Mixed Logit models 32 5.4 Mixed Logit model and interaction between age and the demand for the CTS 38 5.5 Demand analysis with Mixed Logit model 39 6 Final analyses and conclusions 45 6.1 Comparison between the results of the analyses 45 6.2 Conclusions 48 6.3 Answers to the research questions and future developments 52

The European commission

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.

/pdf/tor-the-second-generation-onion-router-2qfrg0ppqb.pdf

Tor: the second-generation onion router

Social Network Analysis

National Institute of Standards and Technology における超伝導研究及び生活

We present attacks on the anonymity and pseudonymity provided by a "lonely hearts" dating service and by the HushMail encrypted email system. We move on to discuss some generic attacks upon anonymous systems based on the engineering reality of these systems rather than the theoretical foundations on which they are based. However, for less sophisticated users it is social engineering attacks, owing nothing to computer science, that pose the biggest day-to-day danger. This practical experience then permits a start to be made on developing a security policy model for pseudonymous communications.

/pdf/real-world-patterns-of-failure-in-anonymity-systems-4croxl0ykz.pdf

Real World Patterns of Failure in Anonymity Systems

We present a traffic analysis of the ADU anonymity scheme presented at ESORICS 2008, and the related RADU scheme. We show that optimal attacks are able to de-anonymize messages more effectively than believed before. Our analysis applies to single messages as well as long term observations using multiple messages. The search of a "better" scheme is bound to fail, since we prove that the original Crowds anonymity system provides the best security for any given mean messaging latency. Finally we present D-Crowds, a scheme that supports any path length distribution, while leaking the least possible information, and quantify the optimal attacks against it. © 2009 Springer Berlin Heidelberg.

https://lirias.kuleuven.be/bitstream/123456789/244798/2/article-1233.pdf

The wisdom of Crowds: attacks and optimal constructions

Privacy protecting metering is described such as for electricity, gas or water metering, metering use of cloud computing resources, traffic congestion charging and other metering applications. In examples, fine grained user consumption data is kept private and not disclosed to a provider of a resource consumed by the user. In examples, a bill generator receives certified meter readings and a certified pricing policy and generates a bill which omits fine grained user consumption data. For example, the bill generator generates a zero knowledge proof that the bill is correct and sends that proof to a provider together with the bill. In examples a provider is able to check that the bill is correct using the zero knowledge proof without finding out the user's private consumption data. In an embodiment the pricing policy is stored as signed rows of a table to enable efficient generation of the zero knowledge proof.

Privacy-preserving metering

Universal Re-encryption allows El-Gamal ciphertexts to be re-encrypted without knowledge of their corresponding public keys. This has made it an enticing building block for anonymous communications protocols. In this work we analyze four schemes related to mix networks that make use of Universal Re-encryption and find serious weaknesses in all of them. The Universal Re-encryption of signatures is open to existential forgery, and the two mix schemes can be fully compromised by an passive adversary observing a single message close to the sender. The fourth scheme, the rWonGoo anonymous channel, turns out to be less secure than the original Crowds scheme, on which it is based. Our attacks make extensive use of unintended 'services' provided by the network nodes acting as decryption and re-routing oracles. Finally, our attacks against rWonGoo demonstrate that. anonymous channels are not automatically composable: using two of them in a careless manner makes the system more vulnerable to attack.

Breaking Four Mix-related Schemes Based on Universal Re-encryption

Privacy-preserving billing protocols are useful in settings where a meter measures user consumption of some service, such as smart metering of utility consumption, pay-as-you-drive insurance and electronic toll collection. In such settings, service providers apply fine-grained tariff policies that require meters to provide a detailed account of user consumption. The protocols allow the user to pay to the service provider without revealing the user’s consumption measurements. Our contribution is twofold. First, we propose a general model where a meter can output meter readings to multiple users, and where a user receives meter readings from multiple meters. Unlike previous schemes, our model accommodates a wider variety of smart metering applications. Second, we describe a protocol based on polynomial commitments that improves the efficiency of previous protocols for tariff policies that employ splines to compute the price due.

/pdf/privacy-preserving-smart-metering-revisited-26tubeee3w.pdf

George Danezis

Papers

Real World Patterns of Failure in Anonymity Systems

The wisdom of Crowds: attacks and optimal constructions

Privacy-preserving metering

Breaking Four Mix-related Schemes Based on Universal Re-encryption

Privacy-preserving smart metering revisited