Economic Principle Oriented Security Management

Modern security management should be based upon economic principles. For this purpose organisations need data, tools and techniques for the cost-benefit-analysis of security investments as well as methods to integrate the results of that kind of analysis into their overall information security management systems. Our research in this area has three main goals:

1. Identifying methods for providing organisations with accurate data for evaluating security investments and building a system for the sharing of information security relevant data among organisations.
2. Evaluation and development of metrics, tools and techniques for an economically oriented security management.
3. Integrating economic principles into information security management and building a new process model for information security management.

Website Fingerprinting and User Linkability

It is rather easy to protect the confidentiality of the contents of messages using encryption techniques. It is fundamentally more difficult to hide the relationship between sender and receiver of messages, though, because addresses may be required for message routing and thus cannot be encrypted. Protecting communication relationships is especially important on the Internet and similar networks as destination addresses often reveal a lot about the actual contents of the messages.

Our goal is to protect users against traffic analysis attacks infringing users' privacy. Those attacks may allow a passive observer on a network to induce communication relationships and contents of messages via pattern matching and classification techniques from the data mining field. Such attacks may constitute a serious risk for users' privacy as they are difficult to detect and counter. We analyse the extent and risks of two particular attacks, namely website fingerprinting attacks, which allow the identification of websites retrieved over an encrypted line, and user linkability attacks, which enable an attacker to track individual users over multiple sessions solely based on the users' characteristic surfing behaviour. Early results indicate that both attacks can be perpetrated under certain circumstances successfully. We measure the effectiveness of the two attacks for various systems and circumstances using real-life datasets.

Designing and deploying countermeasures that protect users from such attacks is challenging: effective protection usually involves additional traffic or considerably delays, which is inacceptable in many cases. Wide-spread adoption of privacy-enhancing techniques depends on good usability and high efficiency, though. We approach this challenge from two sides: on the one hand we analyse the integration of protective measures like padding and dummy traffic into protocols and systems that already exist today; on the other hand we propose next generation systems that are incompatible with legacy technologies, but may offer superior privacy properties to their users.

gMix: A generic Open Source Framework for Mixes

Mixes are a technique to realize anonymous and unobservable communication. Numerous mixing strategies have been proposed since David Chaum suggested the basic mix concept in 1981. While some practical systems are available, the majority of the proposed mix techniques has never been deployed publically. Our goals are to

1. provide a comprehensive code repository of compatible and easily extensible mix implementations,
2. simplify the process of building new practical mix systems,
3. evaluate existing and new mixing strategies under the same conditions,
4. provide easily accessible solutions for educational purposes.

The implementations are organized in a framework. All source code is released under the GPLv3 on the project website [URL].