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

The semiconductor industry is fully globalized and integrated circuits (ICs) are commonly defined, designed and fabricated in different premises across the world. This reduces production costs, but also exposes ICs to supply chain attacks, where insiders introduce malicious circuitry into the final products. Additionally, despite extensive post-fabrication testing, it is not uncommon for ICs with subtle fabrication errors to make it into production systems. While many systems may be able to tolerate a few byzantine components, this is not the case for cryptographic hardware, storing and computing on confidential data. For this reason, many error and backdoor detection techniques have been proposed over the years. So far all attempts have been either quickly circumvented, or come with unrealistically high manufacturing costs and complexity. 
This paper proposes Myst, a practical high-assurance architecture, that uses commercial off-the-shelf (COTS) hardware, and provides strong security guarantees, even in the presence of multiple malicious or faulty components. The key idea is to combine protective-redundancy with modern threshold cryptographic techniques to build a system tolerant to hardware trojans and errors. To evaluate our design, we build a Hardware Security Module that provides the highest level of assurance possible with COTS components. Specifically, we employ more than a hundred COTS secure crypto-coprocessors, verified to FIPS140-2 Level 4 tamper-resistance standards, and use them to realize high-confidentiality random number generation, key derivation, public key decryption and signing. Our experiments show a reasonable computational overhead (less than 1% for both Decryption and Signing) and an exponential increase in backdoor-tolerance as more ICs are added.

A Touch of Evil: High-Assurance Cryptographic Hardware from Untrusted Components

Private keyword search is a technique that allows for searching and retrieving documents matching certain keywords without revealing the search criteria. We improve the space efficiency of the Ostrovsky et al. Private Search [9] scheme, by describing methods that require considerably shorter buffers for returning the results of the search. Our basic decoding scheme recursive extraction, requires buffers of length less than twice the number of returned results and is still simple and highly efficient. Our extended decoding schemes rely on solving systems of simultaneous equations, and in special cases can uncover documents in buffers that are close to 95% full. Finally we note the similarity between our decoding techniques and the ones used to decode rateless codes, and show how such codes can be extracted from encrypted documents. © IFCA/Springer-Verlag Berlin Heidelberg 2007.

Space-efficient private search with applications to rateless codes

We show that Alice and Bob can communicate covertly and anonymously, despite Eve having access to the traffic data of most machines on the Internet. Our protocols take advantage of small amounts of shared state that exist in many TCP/IP stacks, and use them to construct a covert channel. Techniques inspired from Direct Sequence Spread Spectrum (DSSS) are used to make sure that the communication is covert and resistant to noise. We implement a prototype based on ICMP Echo (ping) to illustrate the practicality of our approach and discuss how a more complex protocol would modulate information through the use of TCP features to make communication detection very difficult. The feasibility of covert communications despite stringent traffic data retention, has far reaching policy consequences. © 2011 Springer-Verlag.

Covert communications despite traffic data retention

We show two ways of recovering all matching documents, in the Ostrovsky
et al. Private Search, while requiring considerably shorter buffers.
Both schemes rely on the fact that documents colliding in a buffer
position provide the sum of their plaintexts. Efficient decoding
algorithms can make use of this property to recover documents never
present alone in a buffer position.

/pdf/improving-the-decoding-efficiency-of-private-search-4bhzh044lp.pdf

Improving the Decoding Efficiency of Private Search

Privacy-preserving metering with low overhead is described. In an embodiment consumption of a resource such as electricity, car insurance, cloud computing resources is monitored by a meter and bills are created in a manner which preserves privacy of a customer but at the same reduces bandwidth use between a meter and a provider of the resource. For example, fine grained meter readings which describe customer behavior are kept confidential without needing to send large cryptographic commitments to meter readings from a meter to a provider. In an example, meter readings are encrypted and sent from a meter to a provider who is unable to decrypt the readings. In examples a cryptographic signature is generated to commitments to the meter readings and only the signature is sent to a provider thus reducing bandwidth. For example, a customer device is able to regenerate the commitments using the signature.

George Danezis

Papers

A Touch of Evil: High-Assurance Cryptographic Hardware from Untrusted Components

Space-efficient private search with applications to rateless codes

Covert communications despite traffic data retention

Improving the Decoding Efficiency of Private Search

Privacy-Preserving Metering with Low Overhead