Performance and Security Improvements for Tor: a Survey
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Pairing-Based Onion Routing with Improved Forward Secrecy ∗
Pairing-Based Onion Routing with Improved Forward Secrecy ∗ Aniket Kate Greg M. Zaverucha Ian Goldberg David R. Cheriton School of Computer Science University of Waterloo Waterloo, ON, Canada N2L 3G1 {akate,gzaveruc,iang}@cs.uwaterloo.ca Abstract This paper presents new protocols for onion routing anonymity networks. We define a provably secure privacy-preserving key agreement scheme in an identity-based infrastructure setting, and use it to forge new onion routing circuit constructions. These constructions, based on a user’s selection, offer immediate or eventual forward secrecy at each node in a circuit and require significantly less computation and communication than the telescoping mechanism used by Tor. Further, the use of the identity-based infrastructure also leads to a reduction in the required amount of authenticated directory information. Therefore, our constructions provide practical ways to allow onion routing anonymity networks to scale gracefully. Keywords: onion routing, Tor, pairing-based cryptography, anonymous key agreement, forward secrecy 1 Introduction Over the years, a large number of anonymity networks have been proposed and some have been implemented. Common to many of them is onion routing [RSG98], a technique whereby a message is wrapped in multiple layers of encryption, forming an onion. As the message is delivered via a number of intermediate onion routers (ORs), or nodes, each node decrypts one of the layers, and forwards the message to the next node. This idea goes back to Chaum [Cha81] and has been used to build both low- and high-latency communication networks. A common realization of an onion routing system is to arrange a collection of nodes that will relay traffic for users of the system. -
Security Applications of Formal Language Theory
Dartmouth College Dartmouth Digital Commons Computer Science Technical Reports Computer Science 11-25-2011 Security Applications of Formal Language Theory Len Sassaman Dartmouth College Meredith L. Patterson Dartmouth College Sergey Bratus Dartmouth College Michael E. Locasto Dartmouth College Anna Shubina Dartmouth College Follow this and additional works at: https://digitalcommons.dartmouth.edu/cs_tr Part of the Computer Sciences Commons Dartmouth Digital Commons Citation Sassaman, Len; Patterson, Meredith L.; Bratus, Sergey; Locasto, Michael E.; and Shubina, Anna, "Security Applications of Formal Language Theory" (2011). Computer Science Technical Report TR2011-709. https://digitalcommons.dartmouth.edu/cs_tr/335 This Technical Report is brought to you for free and open access by the Computer Science at Dartmouth Digital Commons. It has been accepted for inclusion in Computer Science Technical Reports by an authorized administrator of Dartmouth Digital Commons. For more information, please contact [email protected]. Security Applications of Formal Language Theory Dartmouth Computer Science Technical Report TR2011-709 Len Sassaman, Meredith L. Patterson, Sergey Bratus, Michael E. Locasto, Anna Shubina November 25, 2011 Abstract We present an approach to improving the security of complex, composed systems based on formal language theory, and show how this approach leads to advances in input validation, security modeling, attack surface reduction, and ultimately, software design and programming methodology. We cite examples based on real-world security flaws in common protocols representing different classes of protocol complexity. We also introduce a formalization of an exploit development technique, the parse tree differential attack, made possible by our conception of the role of formal grammars in security. These insights make possible future advances in software auditing techniques applicable to static and dynamic binary analysis, fuzzing, and general reverse-engineering and exploit development. -
Into the Reverie: Exploration of the Dream Market
Into the Reverie: Exploration of the Dream Market Theo Carr1, Jun Zhuang2, Dwight Sablan3, Emma LaRue4, Yubao Wu5, Mohammad Al Hasan2, and George Mohler2 1Department of Mathematics, Northeastern University, Boston, MA 2Department of Computer & Information Science, Indiana University - Purdue University, Indianapolis, IN 3Department of Mathematics and Computer Science, University of Guam, Guam 4Department of Mathematics and Statistics, University of Arkansas at Little Rock, AK 5Department of Computer Science, Georgia State University, Atlanta, GA [email protected], [email protected], [email protected], [email protected], [email protected], [email protected], [email protected], [email protected] Abstract—Since the emergence of the Silk Road market in Onymous" in 2014, a worldwide action taken by law enforce- the early 2010s, dark web ‘cryptomarkets’ have proliferated and ment and judicial agencies aimed to put a kibosh on these offered people an online platform to buy and sell illicit drugs, illicit behaviors [5]. Law enforcement interventions such as relying on cryptocurrencies such as Bitcoin for anonymous trans- actions. However, recent studies have highlighted the potential for Onymous, along with exit scams and hacks, have successfully de-anonymization of bitcoin transactions, bringing into question shut down numerous cryptomarkets, including AlphaBay, Silk the level of anonymity afforded by cryptomarkets. We examine a Road, Dream, and more recently, Wall Street [6]. Despite these set of over 100,000 product reviews from several cryptomarkets interruptions, new markets have continued to proliferate. The collected in 2018 and 2019 and conduct a comprehensive analysis authors of [7] note that there appears to be a consistent daily of the markets, including an examination of the distribution of drug sales and revenue among vendors, and a comparison demand of about $500,000 for illicit products on the dark web, of incidences of opioid sales to overdose deaths in a US city. -
Consensgx: Scaling Anonymous Communications Networks With
Proceedings on Privacy Enhancing Technologies ; 2019 (3):331–349 Sajin Sasy* and Ian Goldberg* ConsenSGX: Scaling Anonymous Communications Networks with Trusted Execution Environments Abstract: Anonymous communications networks enable 1 Introduction individuals to maintain their privacy online. The most popular such network is Tor, with about two million Privacy is an integral right of every individual in daily users; however, Tor is reaching limits of its scala- society [72]. With almost every day-to-day interaction bility. One of the main scalability bottlenecks of Tor and shifting towards using the internet as a medium, it similar network designs originates from the requirement becomes essential to ensure that we can maintain the of distributing a global view of the servers in the network privacy of our actions online. Furthermore, in light to all network clients. This requirement is in place to of nation-state surveillance and censorship, it is all avoid epistemic attacks, in which adversaries who know the more important that we enable individuals and which parts of the network certain clients do and do not organizations to communicate online without revealing know about can rule in or out those clients from being their identities. There are a number of tools aiming to responsible for particular network traffic. provide such private communication, the most popular In this work, we introduce a novel solution to this of which is the Tor network [21]. scalability problem by leveraging oblivious RAM con- Tor is used by millions of people every day to structions and trusted execution environments in order protect their privacy online [70]. -
Doswell, Stephen (2016) Measurement and Management of the Impact of Mobility on Low-Latency Anonymity Networks
Citation: Doswell, Stephen (2016) Measurement and management of the impact of mobility on low-latency anonymity networks. Doctoral thesis, Northumbria University. This version was downloaded from Northumbria Research Link: http://nrl.northumbria.ac.uk/30242/ Northumbria University has developed Northumbria Research Link (NRL) to enable users to access the University’s research output. Copyright © and moral rights for items on NRL are retained by the individual author(s) and/or other copyright owners. Single copies of full items can be reproduced, displayed or performed, and given to third parties in any format or medium for personal research or study, educational, or not-for-profit purposes without prior permission or charge, provided the authors, title and full bibliographic details are given, as well as a hyperlink and/or URL to the original metadata page. The content must not be changed in any way. Full items must not be sold commercially in any format or medium without formal permission of the copyright holder. The full policy is available online: http://nrl.northumbria.ac.uk/policies.html MEASUREMENT AND MANAGEMENT OF THE IMPACT OF MOBILITY ON LOW-LATENCY ANONYMITY NETWORKS S.DOSWELL Ph.D 2016 Measurement and management of the impact of mobility on low-latency anonymity networks Stephen Doswell A thesis submitted in partial fulfilment of the requirements of the University of Northumbria at Newcastle for the degree of Doctor of Philosophy Research undertaken in the Department of Computer Science and Digital Technologies, Faculty of Engineering and Environment October 2016 Declaration I declare that the work contained in this thesis has not been submitted for any other award and that it is all my own work. -
Threat Modeling and Circumvention of Internet Censorship by David Fifield
Threat modeling and circumvention of Internet censorship By David Fifield A dissertation submitted in partial satisfaction of the requirements for the degree of Doctor of Philosophy in Computer Science in the Graduate Division of the University of California, Berkeley Committee in charge: Professor J.D. Tygar, Chair Professor Deirdre Mulligan Professor Vern Paxson Fall 2017 1 Abstract Threat modeling and circumvention of Internet censorship by David Fifield Doctor of Philosophy in Computer Science University of California, Berkeley Professor J.D. Tygar, Chair Research on Internet censorship is hampered by poor models of censor behavior. Censor models guide the development of circumvention systems, so it is important to get them right. A censor model should be understood not just as a set of capabilities|such as the ability to monitor network traffic—but as a set of priorities constrained by resource limitations. My research addresses the twin themes of modeling and circumvention. With a grounding in empirical research, I build up an abstract model of the circumvention problem and examine how to adapt it to concrete censorship challenges. I describe the results of experiments on censors that probe their strengths and weaknesses; specifically, on the subject of active probing to discover proxy servers, and on delays in their reaction to changes in circumvention. I present two circumvention designs: domain fronting, which derives its resistance to blocking from the censor's reluctance to block other useful services; and Snowflake, based on quickly changing peer-to-peer proxy servers. I hope to change the perception that the circumvention problem is a cat-and-mouse game that affords only incremental and temporary advancements. -
Changing of the Guards: a Framework for Understanding and Improving Entry Guard Selection in Tor
Changing of the Guards: A Framework for Understanding and Improving Entry Guard Selection in Tor Tariq Elahi†, Kevin Bauer†, Mashael AlSabah†, Roger Dingledine‡, Ian Goldberg† †University of Waterloo ‡The Tor Project, Inc. †{mtelahi,k4bauer,malsabah,iang}@cs.uwaterloo.ca ‡[email protected] ABSTRACT parties with anonymity from their communication partners as well Tor is the most popular low-latency anonymity overlay network as from passive third parties observing the network. This is done for the Internet, protecting the privacy of hundreds of thousands by distributing trust over a series of Tor routers, which the network of people every day. To ensure a high level of security against cer- clients select to build paths to their Internet destinations. tain attacks, Tor currently utilizes special nodes called entry guards If the adversary can anticipate or compel clients to choose com- as each client’s long-term entry point into the anonymity network. promised routers then clients can lose their anonymity. Indeed, While the use of entry guards provides clear and well-studied secu- the client router selection protocol is a key ingredient in main- rity benefits, it is unclear how well the current entry guard design taining the anonymity properties that Tor provides and needs to achieves its security goals in practice. be secure against adversarial manipulation and leak no information We design and implement Changing of the Guards (COGS), a about clients’ selected routers. simulation-based research framework to study Tor’s entry guard de- When the Tor network was first launched in 2003, clients se- sign. Using COGS, we empirically demonstrate that natural, short- lected routers uniformly at random—an ideal scheme that provides term entry guard churn and explicit time-based entry guard rotation the highest amount of path entropy and thus the least amount of contribute to clients using more entry guards than they should, and information to the adversary. -
A Framework for Identifying Host-Based Artifacts in Dark Web Investigations
Dakota State University Beadle Scholar Masters Theses & Doctoral Dissertations Fall 11-2020 A Framework for Identifying Host-based Artifacts in Dark Web Investigations Arica Kulm Dakota State University Follow this and additional works at: https://scholar.dsu.edu/theses Part of the Databases and Information Systems Commons, Information Security Commons, and the Systems Architecture Commons Recommended Citation Kulm, Arica, "A Framework for Identifying Host-based Artifacts in Dark Web Investigations" (2020). Masters Theses & Doctoral Dissertations. 357. https://scholar.dsu.edu/theses/357 This Dissertation is brought to you for free and open access by Beadle Scholar. It has been accepted for inclusion in Masters Theses & Doctoral Dissertations by an authorized administrator of Beadle Scholar. For more information, please contact [email protected]. A FRAMEWORK FOR IDENTIFYING HOST-BASED ARTIFACTS IN DARK WEB INVESTIGATIONS A dissertation submitted to Dakota State University in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Cyber Defense November 2020 By Arica Kulm Dissertation Committee: Dr. Ashley Podhradsky Dr. Kevin Streff Dr. Omar El-Gayar Cynthia Hetherington Trevor Jones ii DISSERTATION APPROVAL FORM This dissertation is approved as a credible and independent investigation by a candidate for the Doctor of Philosophy in Cyber Defense degree and is acceptable for meeting the dissertation requirements for this degree. Acceptance of this dissertation does not imply that the conclusions reached by the candidate are necessarily the conclusions of the major department or university. Student Name: Arica Kulm Dissertation Title: A Framework for Identifying Host-based Artifacts in Dark Web Investigations Dissertation Chair: Date: 11/12/20 Committee member: Date: 11/12/2020 Committee member: Date: Committee member: Date: Committee member: Date: iii ACKNOWLEDGMENT First, I would like to thank Dr. -
Optical Onion Routing
Optical Onion Routing Anna Engelmann and Admela Jukan Technische Universitat¨ Carolo-Wilhelmina zu Braunschweig, Germany Email: fa.engelmann, [email protected] Abstract—As more and more data is transmitted in the depend on number and dependability of volunteer systems, configurable optical layer, – whereby all optical switches forward the privacy features in optical network need to be approached packets without electronic layers involved, we envision privacy as differently: for instance, it is a telecom operator that should the intrinsic property of future optical networks. In this paper, we be able offer a private optical communication service as a propose Optical Onion Routing (OOR) routing and forwarding value added feature. For instance, for some client networks techniques, inspired by the onion routing in the Internet layer, - an optical network can grant anonymous access to third-party the best known realization of anonymous communication today, – but designed with specific features innate to optical networks. servers in the cloud, whereby the traffic contents and the origin We propose to design the optical anonymization network system of requests can remain secret for both the attacker as well as with a new optical anonymization node architecture, including the cloud provider. In designing an anonymous optical network the optical components and their electronic counterparts to akin to Tor, however, several obstacles need to be overcome, realize layered encryption. We propose modification to the secret since the main features need to be primarily implemented in key generation using Linear Feedback Shift Register (LFSR), – photonics, i.e., without intervention of electronics, such as able to utilize different primitive irreducible polynomials, and encryption, traffic routing, and session key distribution. -
Walking Onions: Scaling Anonymity Networks While Protecting Users
Walking Onions: Scaling Anonymity Networks while Protecting Users Chelsea H. Komlo Nick Mathewson Ian Goldberg University of Waterloo The Tor Project University of Waterloo Abstract Anonymity networks in practice [13] have prevented these Scaling anonymity networks offers unique security chal- attacks by requiring all participants to share a globally consis- lenges, as attackers can exploit differing views of the net- tent view of the entire state of the network, and giving clients work’s topology to perform epistemic and route capture at- complete control over selecting relays for their paths. While tacks. Anonymity networks in practice, such as Tor, have this approach prevents the described attacks, requiring a glob- opted for security over scalability by requiring participants ally consistent view results in quadratic bandwidth growth as to share a globally consistent view of all relays to prevent the number of clients increases [26], because the number of these kinds of attacks. Such an approach requires each user relays must also increase to provide more capacity, and all to maintain up-to-date information about every relay, causing parties must download information about all relays. While the total amount of data each user must download every epoch today’s Tor network requires only approximately half a per- to scale linearly with the number of relays. As the number cent of its total bandwidth to serve network state [39, 41], of clients increases, more relays must be added to provide increasing the number of clients and relays by one order of bandwidth, further exacerbating the total load on the network. magnitude would result in the consumption of roughly five In this work, we present Walking Onions, a set of proto- percent of the network’s (ten times larger) total bandwidth cols improving scalability for anonymity networks. -
A Secure Environment for Untrusted Helper Applications (Confining the Wily Hacker)
The following paper was originally published in the Proceedings of the Sixth USENIX UNIX Security Symposium San Jose, California, July 1996. A Secure Environment for Untrusted Helper Applications (Confining the Wily Hacker) Ian Goldberg, David Wagner, Randi Thomas, and Eric Brewer Computer Science Division University of California, Berkeley For more information about USENIX Association contact: 1. Phone: 510 528-8649 2. FAX: 510 548-5738 3. Email: [email protected] 4. WWW URL: http://www.usenix.org A Secure Environment for Untruste d Help er Applications Con ningtheWilyHacker Ian Goldb erg David Wagner Randi Thomas Er ic A. Brewer fiang,daw,randit,[email protected] University of California, Berkeley cious programs to spawn pro ce ss e s andto read or Ab stract wr iteanunsusp ecting us er's le s [15,18,19,34,36]. Whatisnee ded in thi s new environment, then, i s Manypopular programs, suchasNetscap e, us e un- protection for all re source s on a us er's system f rom trusted help er applications to pro ce ss data f rom the thi s threat. network. Unfortunately,theunauthenticated net- workdatathey interpret could well have b een cre- Our aim i s tocon netheuntrusted software anddata ated byanadversary,andthehelp er applications are by monitor ingand re str ictingthe system calls it p er- 1 usually to o complex to b e bug-f ree. Thi s rai s e s s ig- forms. We builtJanus , a s ecure environment for ni cant s ecur ity concer ns. Therefore, it i s de s irable untrusted help er applications, bytaking advantage to create a s ecure environmenttocontain untrusted of the Solar i s pro ce ss tracing f acility. -
Effective Attacks and Provable Defenses for Website Fingerprinting
Effective Attacks and Provable Defenses for Website Fingerprinting Tao Wang, University of Waterloo; Xiang Cai, Rishab Nithyanand, and Rob Johnson, Stony Brook University; Ian Goldberg, University of Waterloo https://www.usenix.org/conference/usenixsecurity14/technical-sessions/presentation/wang_tao This paper is included in the Proceedings of the 23rd USENIX Security Symposium. August 20–22, 2014 • San Diego, CA ISBN 978-1-931971-15-7 Open access to the Proceedings of the 23rd USENIX Security Symposium is sponsored by USENIX Effective Attacks and Provable Defenses for Website Fingerprinting Tao Wang1 Xiang Cai2 Rishab Nithyanand2 Rob Johnson2 Ian Goldberg1 1University of Waterloo 2Stony Brook University t55wang,iang @cs.uwaterloo.ca xcai,rnithyanand,rob @cs.stonybrook.edu { } { } Abstract When a client browses the web, she reveals her desti- Website fingerprinting attacks allow a local, passive nation and packet content to intermediate routers, which eavesdropper to identify a user’s web activity by lever- are controlled by ISPs who may be susceptible to ma- aging packet sequence information. These attacks break licious attackers, eavesdroppers, and legal pressure. To the privacy expected by users of privacy technologies, protect her web-browsing privacy, the client would need including low-latency anonymity networks such as Tor. to encrypt her communication traffic and obscure her In this paper, we show a new attack that achieves sig- destinations with a proxy such as Tor. Website finger- nificantly higher accuracy than previous attacks in the printing refers to the set of techniques that seek to re- same field, further highlighting website fingerprinting as identify these clients’ destination web pages by passively a genuine threat to web privacy.