| 1. |
- Berthold, Stefan
(författare)
-
Inter-temporal Privacy Metrics
- 2014
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Informational privacy of individuals has significantly gained importance after information technology has become widely deployed. Data, once digitalised, can be copied, distributed, and long-term stored at negligible costs. This has dramatic consequences for individuals that leave traces in the form of personal data whenever they interact with information technology, for instance, computers and phones; or even when information technology is recording the personal data of aware or unaware individuals. The right of individuals for informational privacy, in particular to control the flow and use of their personal data, is easily undermined by those controlling the information technology.The objective of this thesis is to study the measurement of informational privacy with a particular focus on scenarios where an individual discloses personal data to a second party which uses this data for re-identifying the individual within a set of other individuals. We contribute with privacy metrics for several instances of this scenario in the publications included in this thesis, most notably one which adds a time dimension to the scenario for modelling the effects of the time passed between data disclosure and usage. The result is a new framework for inter-temporal privacy metrics.
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| 2. |
- Berthold, Stefan, 1982-
(författare)
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Towards Inter-temporal Privacy Metrics
- 2011
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Informational privacy of individuals has significantly gained importance after information technology has become widely deployed. Data, once digitalised, can be copied and distributed at negligible costs. This has dramatic consequences for individuals that leave traces in form of personal data whenever they interact with information technology. The right of individuals for informational privacy, in particular to control the flow and use of their personal data, is easily undermined by those controlling the information technology. The objective of this thesis is the measurement of informational privacy with a particular focus on scenarios where an individual discloses personal data to a second party, the data controller, which uses this data for re-identifying the individual within a set of others, the population. Several instances of this scenario are discussed in the appended papers, most notably one which adds a time dimension to the scenario for modelling the effects of the time passed between data disclosure and usage. This extended scenario leads to a new framework for inter-temporal privacy metrics. The common dilemma of all privacy metrics is their dependence on the information available to the data controller. The same information may or may not be available to the individual and, as a consequence, the individual may be misguided in his decisions due to his limited access to the data controller’s information when using privacy metrics. The goal of this thesis is thus not only the specification of new privacy metrics, but also the contribution of ideas for mitigating this dilemma. However a solution will rather be a combination of technological, economical and legal means than a purely technical solution.
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| 3. |
- Adestam, Johan, 1982-
(författare)
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Den dokumentvillkorade garantin
- 2014
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Den dokumentvillkorade garantin, som i praktiken vanligen betecknas som självständig, känneteck-nas av att villkoren i utfästelsen väsentligen endast innefattar villkor som refererar till att vissa angivna dokument presenteras för garanten. Dokumentvillkorade garantier förekommer vanligtvis i avtalsstrukturer som involverar ett flertal olika avtal och parter. De typer av avtal som omfattas av sådana avtalsstrukturer ger upphov till speciella rättsliga frågor. Avhandlingen belyser ett antal sådana frågor ur ett svenskt perspektiv, genom att beskriva rättsnormers utformning och tillämpning på olika typer av fall. Särskild vikt läggs vid att upprätthålla ett språkbruk som möjliggör att detta sker på ett motsägelsefritt och rättvisande sätt.En fråga av grundläggande betydelse är hur garantier kan klassificeras på ett sätt som bidrar till att besvara nyss nämnda typ av frågor. En sådan klassifikation, baserad på garantiers innehåll, klargör vad som skiljer den dokumentvillkorade garantin från andra typer av garantier. När det gäller den rättsliga relationen mellan parterna till ett avtal i vilket det föreskrivs att den ena parten, gäldenären, ska låta ombesörja att det ställs ut en garanti till motparten, berörs i synnerhet frågan under vilka omständigheter motparten är fri att begära fullgörelse av garantin och frågan under vilka omständigheter det uppkommer en återkravsrätt för gäldenären gentemot motparten (beneficienten). I fråga om den rättsliga relationen mellan garanten och beneficienten behandlas särskilt frågorna hur man genom tolkning avgör om en garanti är dokumentvillkorad eller inte, hur dokumentvillkoren i en dokumentvillkorad garanti ska tolkas och i vilken mån det finns speciella rättsnormer tillämpliga på dokumentvillkorade garantier. Ytterligare en fråga rör tillämpningen av den tvingande regeln om rättsmissbruk, enligt vilken beneficienten saknar rätt till fullgörelse av garanten om det föreligger rättsmissbruk. Såvitt avser den rättsliga relationen mellan uppdragsgivare och uppdragstagare i uppdrag som relaterar till utfärdandet av en dokumentvillkorad garanti berörs i synnerhet frågan under vilka omständigheter en uppdragstagare har regressrätt gentemot sin uppdragsgivare. En fråga av allmän betydelse är vad som i olika avseenden krävs för att intresset av att uppdragstagare till sådana uppdrag inte ska ha incitament att undersöka svårbedömda omständigheter ska tillgodoses.
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| 4. |
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| 5. |
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| 6. |
- Brunström, Anna, et al.
(författare)
-
Proceedings of the 2nd International Workshop on Security and Communication Networks (IWSCN 2010)
- 2010
-
Bok (refereegranskat)abstract
- This publication contains the Proceedings of the 2nd International Workshop on Security and Communication Networks (IWSCN 2010) that will be held on May 2628, 2010 in Karlstad, Sweden. IWSCN 2010 brings together researchers, developers, practitioners, and users interested in the area of security and communication networks. The workshop focuses on how to design, build, and evaluate future networks that are secure, reliable, and provide high and predictable performance. The aim of the workshop is to serve as a forum for presenting current and future work, as well as to exchange research ideas in these fields.Papers containing research contributions focusing on aspects of security and communication networks were solicited for submission to IWSCN 2010. A total of 40 papers were received, representing authors from 20 different countries and 5 different continents. Each paper was reviewed by at least three members of the technical program committee. After a thorough review process, 13 papers were selected for presentation at the workshop, giving an acceptance rate of 32.5%. In addition to the technical papers, two keynote presentations on The Changing Performance Goals in Internet Video Streaming and Dependable Protocols for Wireless Sensor Networks will be provided by Carsten Griwodz from the Simula Research Laboratory AS in Norway and Levente Buttyán from Budapest University of Technology and Economics in Hungary, respectively. Furthermore, a tutorial on Penetration Testing from an Attacker Perspective will be given by Vesa Virta from the National Defence Radio Establishment in Sweden.IWSCN 2010 is organized by the Department of Computer Science at Karlstad University and is supported by the Euro-NF and Newcom++ EU Networks of Excellence, and IEEE Sweden Section. The workshop is sponsored by Compare Karlstad Foundation, Coromatic, and TeliaSonera, and we thank them for their support. We also gratefully thank all authors, members of the program committee, and the local organizing committee for contributing to the scientific quality of the workshop
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| 7. |
- Elgebrant, Emil, 1969-
(författare)
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Ägande & värde av utsläppsrätter och andra liknande handelsobjekt : en sakrättslig, redovisningsrättslig och skatterättslig studie
- 2012
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The objective of the dissertation is to examine national legal issues arising with the enactment of emissions allowances, electricity certificates and other similar trading objects. Several of the issues identified in this dissertation have their origins in the same problems that arose with the enactment of the legislation regarding promissory notes in the 1910’s and the legislation concerning the digitalization/dematerialization of financial instruments in the 1980’s. Simply stated, the fundamental problem is what has the legislator created? The dissertation’s interdisciplinary character has facilitated an approximation of issues that have arisen, which would not have been possible through studies solely of individual legal areas. This method has proven itself to be particularly relevant as new legal figures are introduced in an existing legal system. A starting point for any study of the trading object is that it is an independent legal object, separate from any authorization to emit, etc. This means that the trading object does not consist of any right to act in a certain manner (emit, etc.). A legal classification of the trading object has shown itself to be difficult to achieve within all of the studied legal areas. The private law conceptual apparatus and its categorizations of property have been debated in this dissertation from different perspectives. How the economic value of the trading object is treated in a legal context has shown itself to be dependent upon which legal context is intended, and how the trading object is classified in this context. The trading object’s private law character and its ability to be owned has certain significance for the accounting, income, and VAT law classifications of the trading object. The legal classification of the trading objects raises, to a great extent, a general and fundamental classification problem
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| 8. |
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| 9. |
- Korling, Fredric, 1976-
(författare)
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Rådgivningsansvar – särskilt avseende finansiell rådgivning och investeringsrådgivning
- 2010
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The liability incurred with respect to advisory services, particularly with respect to financial and investment advice, is the subject of this thesis. A number of factors that have influenced developments within the societal and regulatory environments in which advisory services are provided, primarily with respect to financial advice, are examined. The legal regulation of financial markets is extensive as is also self-regulation. Despite the extensive legislation, no universal definition of advisory services has been established. The thesis examines how advisory services relate to information, marketing and sales, as well as how they are defined in penal, public and private law. Professional liability, as well a contractual and tort liability, are also explored with respect to advisory services.The regulations in the financial market have the purpose of strengthening investor protection. Information obligations are often used in order to ensure that investors become sufficiently aware as to the products and services that the investor purchases and accompanying risks. Many investors, however, have difficulties processing financial information. In addition, investors act irrationally.The criticism of the regulations today is that they, in too great an extent, are based on that investors act rationally, when there is very much research that indicates the contrary. Another criticism is that the legislation on financial advice lack clarity in several aspects and that this deficiency is not cured by the preparatory works, for example on the important question on the boundary between advisory services and selling. The legislation would considerably benefit from definitions of advisory services being put into concrete form, in order to therewith facilitate understanding for both investors and advisers as well as supervisory governmental agencies. The situation today is unsatisfactory, not in the least with respect to the requirements of foreseeability and legal certainty.
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| 10. |
- Larson, Ulf, 1975, et al.
(författare)
-
A Structured Approach to Selecting Data Collection Mechanisms for Intrusion Detection
- 2011
-
Ingår i: Privacy, Intrusion Detection, and Response: Technologies for Protecting Networks. - : IGI Global. - 9781609608361 ; , s. 1-39
-
Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- This chapter aims at providing a clear and concise picture of data collection forintrusion detection. It provides a detailed explanation of generic data collectionmechanism components and the interaction with the environment, from initial triggeringto output of log data records. Taxonomies of mechanism characteristics anddeployment considerations are provided and discussed. Furthermore, guidelinesand hints for mechanism selection and deployment are provided. The guidelinesare aimed to assist intrusion detection system developers, designers, and operatorsin selecting mechanisms for resource efficient data collection.
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| 11. |
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| 12. |
- Larson, Ulf, 1975, et al.
(författare)
-
Guidance for Selecting Data Collection Mechanisms for Intrusion Detection
- 2014
-
Ingår i: Handbook of Research on Emerging Developments in Data Privacy. - : IGI Global. - 9781466673830 ; , s. 340-370
-
Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- This chapter aims at providing a clear and concise picture of data collection for intrusion detection. It provides a detailed explanation of generic data collection mechanism components and the interaction with the environment, from initial triggering to output of log data records. Taxonomies of mechanism characteristics and deployment considerations are provided and discussed. Furthermore, guidelines and hints for mechanism selection and deployment are provided. Finally, this chapter presents a set of strategies for determining what data to collect, and it also discusses some of the challenges in the field. An appendix providing a classification of 50 studied mechanisms is also provided. This chapter aims at assisting intrusion detection system developers, designers, and operators in selecting mechanisms for resource efficient data collection.
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| 13. |
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| 14. |
- Lindskog, Stefan, et al.
(författare)
-
NEWCOM++ DRA.2: Advanced algorithms and metrics for wireless secrecy and security
- 2010
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- The report deals with Advanced Algorithms and Metrics for Wireless Secrecy and Security developed within the framework of Newcom++ (contrarily to the first report which was an overview of existing results). As far as wireless secrecy is concerned, the notion of information theoretic secrecy capacity is extended to different types of channels such as the interference channel, the relay channel as well as the wiretap frequency selective channel. Practical algorithms are derived in the case of multi-carrier channels such as the OFDM case through the notion of Vandermonde precoding. In the second part of the report, Wireless security focuses on Wireless Sensor Networks. After an overview of different wireless technologies, a risk analysis approach is proposed together with a taxonomy of wireless security attacks and descriptions of threats and known vulnerabilities in wireless networks in general. Finally, a framework that enables a formal reasoning and description of a WSN system is provided
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| 15. |
- Lindskog, Stefan, et al.
(författare)
-
NEWCOM++ DRA.3: Final report about security in wireless networks
- 2010
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- The report deals with advanced schemes for Wireless Secrecy and Security evaluation tools developed within the framework of Newcom++. As far as wireless secrecy is concerned, different cases are treated, namely the multi-antenna fading case, the frequency selective channel case (with OFDM modulation) and the the relay channel case. Besides the major information theoretic consideration related to capacity issues, physical layer coding, Secure Lossy Source Coding as well as classical precoding (through beamforming) schemes are analyzed. The second part of the report is dedicated to security evaluation tools and provides a framework for a formal reasoning and description of wireless sensor networks (WSN). Some input models for the design and evaluation of WSN security are provided, especially for 6LoWPAN Networks. The report finishes with an important contribution related to a Penetration Testing tool developed for 6LoWPAN
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| 16. |
- Lindskog, Stefan, et al.
(författare)
-
Performance Evaluation of IKEv2 Authentication Methods in Next Generation Wireless Networks
- 2010
-
Ingår i: Journal of Security and Communication Networks. - : Wiley InterScience. - 1939-0122. ; 3:1, s. 83-98
-
Tidskriftsartikel (refereegranskat)abstract
- Secure communications have a key role in future networks and applications. Information security provisions such as authorization, authentication, and encryption must be added to current communications protocols. To accomplish this, each protocol must be reexamined to determine the impact on performance of adding such security services. This paper presents an experimental evaluation of the performance costs of a wide variety of authentication methods over IKEv2 in real and partly emulated scenarios of next generation wireless networks. The studied methods are pre-shared keys (PSKs), extensible authentication protocol (EAP) using MD5, SIM, TTLS-MD5, TLS, and PEAP-MSCHAPv2. For the EAP-based methods, RADIUS is used as the authentication, authorization, and accounting (AAA) server. Different lengths of certificate chains are studied in case of the TLS-based methods, i.e., TTLS-MD5, TLS, and PEAP-MSCHAPv2. The paper first presents a brief overview of the considered authentication methods. Then, a comparison of the costs for message transfers and computations associated with the authentication methods is provided. The measurement results are verified through a simple analysis, and interpreted by discussing the main contributing factors of the costs. The measurement results illustrate the practical costs involved for IKEv2 authentication, and the implications of the use of different methods are discussed
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| 17. |
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| 18. |
- Lindskog, Stefan, et al.
(författare)
-
Security Solution Suitability Analysis using Modified Multiplicative Analytic Hierarchy Process
- 2010
-
Konferensbidrag (refereegranskat)abstract
- Tackling security and performance issues in ubiquitous computing has turned out to be a challenging task due to the heterogeneity of both the environment and the applications. Services must satisfy several constraints caused by the security, performance, and other requirements of applications, users and providers. This paper introduces a new formalized decision model for security solution suitability analysis. It supports the design of dynamic security services and can be used by security managers making runtime decisions. Our solution improves previously proposed AHP-based decision models. The MAHP decision engine is applied using a new approach. Furthermore, we extend the MAHP algorithm to handle the non-fulfillment of requirements. This results in more accurate decisions, and better fulfillment of the design criteria. The use of the proposed decision model is illustrated through an IKEv2 authentication method selection problem
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| 19. |
- Lindskog, Stefan, et al.
(författare)
-
Using System Call Information to Reveal Hidden Attack Manifestations
- 2010
-
Ingår i: Proceedings of the 1st International Workshop on Security and Communication Networks, IWSCN 2009. - Piscataway, NJ, USA : IEEE. - 9788299710510
-
Konferensbidrag (refereegranskat)abstract
- We investigate how system call-based intrusion detectors can be made more resistant against mimicry attacks. We show that by including extra information such as system call arguments, return values, and identity of the user responsible for the calls, the attackers options of constructing successful attacks are significantly reduced, in particular with respect to the use of no-op system calls. For our investigation, we add extra information to two system call-based detection algorithms one distance-based and one sequence-based that normally operate on system call names only. We then create two mimicry attacks which avoid detection by the original detectors but are revealed when the extra information is used. Our investigation shows that by providing the extra information to the detector the attackers options of constructing successful and undetected attacks decreases drastically
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| 20. |
- Lundin, Reine, 1974-, et al.
(författare)
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An Investigation of Entropy of Selectively Encrypted Bitmap Images
- 2012
-
Ingår i: Computational Aspects of Social Networks (CASoN), 2012 Fourth International Conference on. - : IEEE. - 9781467347938 - 9781467347921 ; , s. 238-243
-
Konferensbidrag (refereegranskat)abstract
- Selective encryption is a concept in which the main goal is to reduce computational cost while providing confidentiality by encrypting only chosen parts of the information to be protected. Previous work on selective encryption has mainly been aimed towards multimedia applications in order to reduce the overhead induced by encryption while still making the information perceptually secure to a desired protection level. This was accomplished by utilizing the fact that different parts of the information have different impacts on our perception senses, i.e., eyes and ears. How computationally secure the information is when using selective encryption has however only briefly been mentioned or rudimentarily analyzed. In this paper, we therefore investigate the security implications of selective encryption by generalizing the work on entropy of selectively encrypted strings to several dimensions and applying it to bitmap images. The generalization is done by constructing information neighborhoods that capture and model information dependencies in several dimensions.
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| 21. |
- Lundin, Reine, 1974-, et al.
(författare)
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Changes in Guesswork over Time in Multi-processor Attacks
- 2012
-
Ingår i: Journal of Information Assurance and Security. - Atlanta, GA, USA : Dynamic Publishers Incorporation. - 1554-1010. ; 7, s. 145-150
-
Tidskriftsartikel (refereegranskat)abstract
- More and more effort is being spent on security improvements in today's computer networking environments. However, due to the nature of computer security there is still a lack of good quantitative assessment methods. Inventing and developing new ways of measuring security are therefore needed in order to more exact describe, assess, and improve security of computer environments. One existing quantitative security measure is guesswork. Guesswork gives the average number of guesses in a brute force attack when breaking an encrypted message. In the current definition of guesswork it is assumed that the attacker uses a single processor when breaking an encrypted message. However, an intelligent and motivated attacker will likely use several processors that can work in parallel to break an encrypted message. This paper formally investigates how guesswork changes over time in multi-processor attacks. The result is applied on three probability distributions, the English alphabet, the geometric, and the truncated geometric to illustrate some behaviors.
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| 22. |
- Lundin, Reine, 1974-, et al.
(författare)
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Entropy of Selectively Encrypted Strings
- 2011
-
Ingår i: Information Security Theory and Practice. - : Springer Berlin/Heidelberg. - 9783642210402 ; , s. 234-243
-
Konferensbidrag (refereegranskat)abstract
- A feature that has become desirable for low-power mobile devices with limited computing and energy resources is the ability to select a security configuration in order to create a trade-off between security and other important parameters such as performance and energy consumption. Selective encryption can be used to create this trade-off by only encrypting chosen units of the information. In this paper, we continue the investigation of the confidentiality implications of selective encryption by applying entropy on a generic selective encryption scheme. By using the concept of run-length vector from run-length encoding theory, an expression is derived for entropy of selectively encrypted strings when the number of encrypted substrings, containing one symbol, and the order of the language change
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| 23. |
- Lundin, Reine, 1974-, et al.
(författare)
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Extending the Definition of Guesswork
- 2010
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Ingår i: Sixth International Conference on Information Assurance and Security (IAS), 2010. - Atlanta, GA, USA : IEEE. - 9781424474073 ; , s. 191-196
-
Konferensbidrag (refereegranskat)abstract
- To be able to perform an analytical and more exact description of security, quantitative security measures are desirable. In this paper, we continue our investigation of the quantitative security measure guesswork, which gives the average number of guesses in an optimal brute force attack. The definition of guesswork is extended to joint and conditional guesswork. We show that joint guesswork is always at least equal to the marginal guessworks, and that conditioning reduces guesswork. Hence, guesswork possesses the same two properties as entropy, i.e., joint entropy is always at least equal to the marginal entropies, and conditioning reduces entropy. However, unlike entropy, guesswork does not possess the chain rule property. For entropy, this rule states that joint entropy is equal to marginal entropy plus the corresponding conditional entropy
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| 24. |
- Lundin, Reine, 1974-
(författare)
-
Guesswork and Entropy as Security Measures for Selective Encryption
- 2012
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- More and more effort is being spent on security improvements in today's computer environments, with the aim to achieve an appropriate level of security. However, for small computing devices it might be necessary to reduce the computational cost imposed by security in order to gain reasonable performance and/or energy consumption. To accomplish this selective encryption can be used, which provides confidentiality by only encrypting chosen parts of the information. Previous work on selective encryption has chiefly focused on how to reduce the computational cost while still making the information perceptually secure, but not on how computationally secure the selectively encrypted information is. Despite the efforts made and due to the harsh nature of computer security, good quantitative assessment methods for computer security are still lacking. Inventing new ways of measuring security are therefore needed in order to better understand, assess, and improve the security of computer environments. Two proposed probabilistic quantitative security measures are entropy and guesswork. Entropy gives the average number of guesses in an optimal binary search attack, and guesswork gives the average number of guesses in an optimal linear search attack. In information theory, a considerable amount of research has been carried out on entropy and on entropy-based metrics. However, the same does not hold for guesswork.In this thesis, we evaluate the performance improvement when using the proposed generic selective encryption scheme. We also examine the confidentiality strength of selectively encrypted information by using and adopting entropy and guesswork. Moreover, since guesswork has been less theoretical investigated compared to entropy, we extend guesswork in several ways and investigate some of its behaviors.
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| 25. |
- Lundin, Reine, 1974-, et al.
(författare)
-
Guesswork Changes in Multi-processor Attacks
- 2011
-
Ingår i: Proceedings of the 7th International Conference on Information Assurance and Security (IAS 2011). - : IEEE Press. - 9781457721540 ; , s. 145-150
-
Konferensbidrag (refereegranskat)abstract
- More and more effort is being spent on security improvements in today's computer networking environments. However, due to the nature of computer security there is still a lack of good quantitative assessment methods. Inventing and developing new ways of measuring security are therefore needed in order to more exact describe, assess, and improve security of computer environments. One existing quantitative security measure is guesswork. Guesswork gives the average number of guesses in a brute force attack when breaking an encrypted message. In the current definition of guesswork it is assumed that the attacker uses a single processor when breaking an encrypted message. However, an intelligent and motivated attacker will likely use several processors that can work in parallel to break an encrypted message. This paper formally investigates how guesswork changes over time in multi-processor attacks. The result is applied on three probability distributions, the English alphabet, the geometric, and the truncated geometric to illustrate some behaviors.
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| 26. |
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| 27. |
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| 28. |
- Lundin, Reine, 1974-, et al.
(författare)
-
Security Implications of Selective Encryption
- 2010
-
Ingår i: MetriSec'10. - New York : ACM. - 9781450303408
-
Konferensbidrag (refereegranskat)abstract
- To be able to perform an analytical and more exact description of security, quantitative security measures are desirable. Two proposed quantitative security measures are entropy and guesswork. When breaking an encrypted message, entropy measures the average number of guesses in an optimal binary search attack, whereas guesswork measures the average number of guesses in an optimal linear search attack. In this paper, we continue to investigate the security implications of a generic selective encryption procedure. That is, how entropy and guesswork changes with the number of encrypted units, i.e., the encryption level. This is done for languages up to thesecond order by deriving equations for entropy of selectively encrypted messages and then transferring the result to guesswork through an equation relating the two measures. Furthermore, unlike entropy, guesswork does not possess the chain rule, however, through the equation relating entropy and guesswork an equation connecting the different guessworks is derived.
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| 29. |
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| 30. |
- Pulls, Tobias
(författare)
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Privacy-Preserving Transparency-Enhancing Tools
- 2012
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Transparency is a key principle in democratic societies. For example, the public sector is in part kept honest and fair with the help of transparency through different freedom of information (FOI) legislations. In the last decades, while FOI legislations have been adopted by more and more countries worldwide, we have entered the information age enabled by the rapid development of information technology. This has led to the need for technological solutions that enhance transparency, for example to ensure that FOI legislation can be adhered to in the digital world. These solutions are called transparency-enhancing tools (TETs), and consist of both technological and legal tools. TETs, and transparency in general, can be in conflict with the privacy principle of data minimisation.The goal of transparency is to make information available, while the goal of data minimisation is to minimise the amount of available information. This thesis presents two privacy-preserving TETs: one cryptographic system forenabling transparency logging, and one cryptographic scheme for storing the data for the so called Data Track tool at a cloud provider. The goal of the transparency logging TET is to make data processing by data controllers transparent to the user whose data is being processed. Our work ensures that the process in which the data processing is logged does not leak sensitive information about the user, and thatthe user can anonymously read the information logged on their behalf. The goal of the Data Track is to make it transparent to users which data controllers they have disclosed data to under which conditions. Furthermore, the Data Track intends to empower users to exercise their rights, online and potentially anonymously, with regard to their disclosed data at the recipient data controllers. Our work ensures that the data kept by the Data Track can be stored at acloud storage provider, enabling easy synchronisation across multiple devices, while preserving the privacy of users by making their storage anonymous toward the provider and by enabling users to hold the provider accountable for the data it stores.
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| 31. |
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| 32. |
- Rajiullah, Mohammad, et al.
(författare)
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Performance Analysis and Improvement of PR-SCTP for Small Messages
- 2013
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Ingår i: Computer Networks. - Elsevier : Elsevier BV. - 1389-1286. ; 57:18, s. 3967-3986
-
Tidskriftsartikel (refereegranskat)abstract
- PR-SCTP, a partially reliable extension of SCTP, provides a flexible QoS trade-off between timeliness and reliability for application traffic. However, the performance of PR-SCTP can be reduced due to certain traffic characteristics and network scenarios. Previously, we proposed a NR-SACK based optimization for PR-SCTP. In this work we extensively evaluate and analyze the performance of PR-SCTP with NR-SACKs using different network scenarios. Moreover, we compare the performance of our NR-SACK based PR-SCTP with existing transport protocols for syslog traffic. In the evaluation, we use real syslog traces from an operational syslog system. The results indicate that NR-SACKs based PR-SCTP significantly improves the overall message transfer delay as compared to SCTP and TCP.
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| 33. |
- Rajiullah, Mohammad, et al.
(författare)
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Priority Based Delivery of PR-SCTP Messages in a Syslog Context
- 2011
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Ingår i: Access networks. - : Springer. - 9783642209307 ; , s. 299-310
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Konferensbidrag (refereegranskat)abstract
- Unquestionably, syslog provides the most popular and easily manageable computer system logging environment. In a computer network, syslog messages are used for several purposes such as for optimizing system performance, logging user's actions and investigating malicious activities. Due to all these essential utilities, a competent transport service for syslog messages becomes important. Most of the current syslog implementations use either the unreliable UDP protocol or the more costly reliable TCP protocol. Neither of these protocols can provide both timeliness and reliability, while transporting inherently prioritized syslog messages in a congested network. In this paper, we both propose and evaluate the use of PR-SCTP, an existing partial reliability extension of the SCTP transport protocol, as a candidate transport service for the next generation syslog standard. In our emulation based experimental results, PR-SCTP shows better performance than TOP in terms of average delay for message transfer. Furthermore, PR-SCTP exhibits less average packet loss than UDP. In both cases, PR-SCTP exploits priority properties of syslog messages during loss recovery.
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| 34. |
- Rajiullah, Mohammad, 1981-, et al.
(författare)
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Syslog Performance : Data Modeling and Transport
- 2011
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Ingår i: Proceedings of the 3rd International Workshop on Security and Communication Networks (IWSCN 2011). - Norway : IEEE Press. ; , s. 31-37
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Konferensbidrag (refereegranskat)abstract
- Syslog is one of the basic methods for event logging in computer networks. Log messages that are generated by syslog can be used for a number of purposes, including optimizing system performance, system auditing, and investigating malicious activities in a computer network. Considering all these attractive uses, both timeliness and reliability is needed when syslog messages are transported over a network. The unreliable transport protocol UDP was specified in the original syslog specification; later a reliable transport service based on TCP was also proposed. However, TCP is a costly alternative in terms of delay. In our previous work, we introduced the partially reliable extension of SCTP, PR-SCTP, as a transport service for syslog, trading reliability against timeliness by prioritizing syslog messages. In this work, we first model syslog data using real syslog traces from an operational network. The model is then used as input in the performance evaluation of PR-SCTP. In the experiments, real congestion is introduced in the network by running several competing flows. Although PR-SCTP clearly outperformed TCP and SCTP in our previous work, our present evaluations show that PR-SCTP performance is largely influenced by the syslog data size characteristics
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| 35. |
- Winter, Philipp
(författare)
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Enhancing Censorship Resistance in the Tor Anonymity Network
- 2014
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- BaksidestextThe Tor network was originally designed as low-latency anonymity network.However, as the years progressed, Tor earned a reputation as also being a useful tool to circumvent Internet censorship. At times, the network counted 30,000 users only from China. Censors reacted by tightening their grip on the national communication infrastructure. In particular, they developed techniques to prevent people from being able to access the Tor network. This arms race now counts several iterations and no end is in sight.This thesis contributes to a censorship-resistant Tor network in two ways. First, it analyses how existing censorship systems work. In particular, the Great Firewall of China is analysed in order to obtain an understanding of its capabilities as well as to explore circumvention opportunities. Second, this thesis proposes practical countermeasures to circumvent Internet censorship. In particular, it presents a novel network protocol which is resistant to the Great Firewall's active probing attacks.
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| 36. |
- Winter, Philipp, et al.
(författare)
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How China Is Blocking Tor
- 2012
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Not only the free web is victim to China’s excessive censorship, but also the Tor anonymity network: the Great Firewall of China prevents thousands of potential Tor users from accessing the network. In this paper, we investigate how the blocking mechanism is implemented, we conjecture how China’s Tor blocking infrastructure is designed and we propose countermeasures. Our work bolsters the understanding of China’s censorship capabilities and thus paves the way towards more effective evasion techniques.
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| 37. |
- Winter, Philipp, et al.
(författare)
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How the Great Firewall of China is Blocking Tor
- 2012
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Konferensbidrag (refereegranskat)abstract
- Internet censorship in China is not just limited to the web: the Great Firewall of China prevents thousands of potential Tor users from accessing the network. In this paper, we investigate how the blocking mechanism is implemented, we conjecture how China's Tor blocking infrastructure is designed and we propose circumvention techniques. Our work bolsters the understanding of China's censorship capabilities and thus paves the way towards more effective circumvention techniques.
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| 38. |
- Winter, Philipp
(författare)
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Measuring and circumventing Internet censorship
- 2014
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- An ever increasing amount of governments, organisations, and companies employ Internet censorship in order to filter the free flow of information. These efforts are supported by an equally increasing number of companies focusing on the development of filtering equipment.Only what these entities consider right can pass the filters. This practice constitutes a violation of the Universal Declaration of Human Rights and hampers progress. This thesis contributes novel techniques to measure and to circumvent Internet censorship. In particular, we 1) analyse how the Great Firewall of China is blocking the Tor network by using active probing techniques as well as side channel measurements, we2) propose a concept to involve users in the process of censorship analysis, we 3) discuss the aptitude of a globally-deployed network measurement platform for censorship analysis, and we 4) propose a novel circumvention protocol. We attach particular importance to practicality and usability. Most of the techniques proposed in this thesis were implemented and some of them are deployed and used on a daily basis. We demonstrate that the measurement techniques proposed in this thesis are practical and useful by applying them in order to shed light on previously undocumented cases of Internet censorship. We employed our techniques in three countries and were able to expose previously unknown censorship techniques and cooperation between a corporation and a government for the sake of censorship. We also implemented a circumvention protocol which was subsequently deployed and is used to evade the Great Firewall of China.
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| 39. |
- Winter, Philipp, 1986-, et al.
(författare)
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Spoiled Onions : Exposing Malicious Tor Exit Relays
- 2014
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Ingår i: Privacy Enhancing Technologies. - Cham : Springer. - 9783319085067 - 9783319085050 ; , s. 304-331
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Konferensbidrag (refereegranskat)abstract
- Tor exit relays are operated by volunteers and together push more than 1 GiB/s of network traffic. By design, these volunteers are able to inspect and modify the anonymized network traffic. In this paper, we seek to expose such malicious exit relays and document their actions. First, we monitored the Tor network after developing two fast and modular exit relay scanners-one for credential sniffing and one for active MitM attacks. We implemented several scanning modules for detecting common attacks and used them to probe all exit relays over a period of several months. We discovered numerous malicious exit relays engaging in a multitude of different attacks. To reduce the attack surface users are exposed to, we patched Torbutton, an existing browser extension and part of the Tor Browser Bundle, to fetch and compare suspicious X. 509 certificates over independent Tor circuits. Our work makes it possible to continuously and systematically monitor Tor exit relays. We are able to detect and thwart many man-in-the-middle attacks, thereby making the network safer for its users. All our source code is available under a free license.
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| 40. |
- Winter, Philipp, et al.
(författare)
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Spoiled Onions: Exposing Malicious Tor Exit Relays
- 2014
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Several hundred Tor exit relays together push more than 1 GiB/s of network traffic. However, it iseasy for exit relays to snoop and tamper with anonymised network traffic and as all relays are runby independent volunteers, not all of them are innocuous.In this paper, we seek to expose malicious exit relays and document their actions. First, wemonitored the Tor network after developing a fast and modular exit relay scanner. We implementedseveral scanning modules for detecting common attacks and used them to probe all exit relays over aperiod of four months. We discovered numerous malicious exit relays engaging in different attacks.To reduce the attack surface users are exposed to, we further discuss the design and implementationof a browser extension patch which fetches and compares suspicious X.509 certificates overindependent Tor circuits.Our work makes it possible to continuously monitor Tor exit relays. We are able to detect andthwart many man-in-the-middle attacks which makes the network safer for its users. All our code isavailable under a free license.
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