DOCSLIB.ORG

The Tor Project

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
The Tor Project The Tor Project Our mission is to be the global resource for technology, advocacy, research and education in the ongoing pursuit of freedom of speech, privacy rights online, and censorship circumvention. 1 ● Online Anonymity – Open Source – Open Network ● Community of researchers, developers, users and relay operators. ● U.S. 50 !c)!#" non$ profit or&anization 2 Estimated 2,000,000 to 8,000,000 daily Tor users 3 Threat model: what can the attacker do? Alice Anonymity network Bob watch Alice! watch (or be!) Bob! Control part of the network! 4 Anonymity isn't encryption: Encryption just protects contents. “Hi, Bob!” “Hi, Bob!” Alice <gibberish> attacker Bob 5 6 Anonymity serves different interests for different user groups. Anonymity “It's privacy!” Private citizens 7 Anonymity serves different interests for different user groups. Anonymity Businesses “It's network security!” “It's privacy!” Private citizens 8 Anonymity serves different interests for different user groups. “It's traffic-analysis resistance!” Governments Anonymity Businesses “It's network security!” “It's privacy!” Private citizens 9 Anonymity serves different interests for different user groups. Human rights “It's reachability!” “It's traffic-analysis activists resistance!” Governments Anonymity Businesses “It's network security!” “It's privacy!” Private citizens 10 The simplest designs use a single relay to hide connections. Alice1 Bob1 E(B ob3 ” ,“X “Y ”) Relay Alice2 E(Bob1, “Y”) “Z” Bob2 ”) “X , “Z ” ob2 Alice3 E(B Bob3 (example: some commercial proxy providers) 11 But a central relay is a single point of failure. Alice1 Bob1 E(B ob3 ” ,“X “Y ”) Evil Alice2 E(Bob1, “Y”) Relay “Z” Bob2 ”) “X , “Z ” ob2 Alice3 E(B Bob3 12 ... or a single point of bypass. Alice1 Bob1 E(B ob3 ” ,“X “Y ”) Irrelevant Alice2 E(Bob1, “Y”) Relay “Z” Bob2 ”) “X , “Z ” ob2 Alice3 E(B Bob3 Timing analysis bridges all connections through relay ⇒ An attractive fat target 13 So, add multiple relays so that no single one can betray Alice. Alice Bob R1 R3 R4 R5 R2 14 Alice makes a session key with R1 ...And then tunnels to R2...and to R3 Alice Bob R1 R3 Bob2 R4 R5 R2 15 16 17 18 19 Tor's safety comes from diversity ● #1: Diversity of relays. The more relays we have and the more diverse they are, the fewer attackers are in a position to do traffic confirmation. (Research problem: measuring diversity over time) ● #2: Diversity of users and reasons to use it. 50000 users in Iran means almost all of them are normal citizens. 20 Transparency for Tor is key ● Open source / free software ● Public design documents and specifications ● Publicly identified developers ● Not a contradiction: privacy is about choice! 21 But what about bad people? ● Remember the millions of daily users. ● Still a two-edged sword? ● Good people need Tor much more than bad guys need it. 22 23 24 25 26 Alice Alice Alice Blocked Alice User Alice R3 Blocked Alice R4 User Bob Alice Blocked R2 User Alice R1 Blocked Alice User Alice Alice Blocked Alice User Alice Alice 28 Pluggable transports 30 Pluggable transports ● Flashproxy (Stanford), websocket ● FTEProxy (Portland St), http via regex ● Stegotorus (SRI/CMU), http ● Skypemorph (Waterloo), Skype video ● uProxy (Google), webrtc ● ScrambleSuit (Karlstad), obfs-based ● Telex (Michigan/Waterloo), traffic divert 31 32 33 35 36 37 38 39 “Still the King of high secure, low latency Internet Anonymity” Contenders for the throne: ● None 40 Alice Alice Alice Blocked Alice User Alice R3 Blocked Alice R4 User Bob Alice Blocked R2 User Alice R1 Blocked Alice User Alice Alice Blocked Alice User Alice Alice 41 42 44 Arms races ● Censorship arms race is bad ● Surveillance arms race is worse – And centralization of the Internet makes it worse still 45 46 Onion Service 47 Onion service properties ● Self authenticated ● End-to-end encrypted ● Built-in NAT punching ● Limit surface area ● No need to “exit” from Tor 48 49 50 q 51 52 53 SecureDrop Today, 30+ organizations use SecureDrop https://securedrop.org/directory 54 Ricochet 55 OnionShare 56 Tor isn't foolproof ● Opsec mistakes ● Browser metadata fingerprints ● Browser exploits ● Traffic analysis 57 How can you help? ● Run a relay (or a bridge) ● Teach your friends about Tor, and privacy in general ● Help find -- and fix – bugs ● Work on open research problems (petsymposium.org) ● donate.torproject.org 58 Relay operator meetup, today 15:00 today in room H.3244 59 ooni.torproject.org 60 explorer.ooni.torproject.org ● I 61.
Load more

Recommended publications
  • Arxiv:1907.07120V1 [Cs.CY] 16 Jul 2019 1 Introduction That China Hindered Access to I2P by Poisoning DNS Resolu- Tions of the I2P Homepage and Three Reseed Servers
    Measuring I2P Censorship at a Global Scale Nguyen Phong Hoang Sadie Doreen Michalis Polychronakis Stony Brook University The Invisible Internet Project Stony Brook University Abstract required flexibility for conducting fine-grained measurements on demand. We demonstrate these benefits by conducting an The prevalence of Internet censorship has prompted the in-depth investigation of the extent to which the I2P (invis- creation of several measurement platforms for monitoring ible Internet project) anonymity network is blocked across filtering activities. An important challenge faced by these different countries. platforms revolves around the trade-off between depth of mea- Due to the prevalence of Internet censorship and online surement and breadth of coverage. In this paper, we present surveillance in recent years [7, 34, 62], many pro-privacy and an opportunistic censorship measurement infrastructure built censorship circumvention tools, such as proxy servers, virtual on top of a network of distributed VPN servers run by vol- private networks (VPN), and anonymity networks have been unteers, which we used to measure the extent to which the developed. Among these tools, Tor [23] (based on onion rout- I2P anonymity network is blocked around the world. This ing [39,71]) and I2P [85] (based on garlic routing [24,25,33]) infrastructure provides us with not only numerous and ge- are widely used by privacy-conscious and censored users, as ographically diverse vantage points, but also the ability to they provide a higher level of privacy and anonymity [42]. conduct in-depth measurements across all levels of the net- In response, censors often hinder access to these services work stack.
    [Show full text]
  • Hacking the Web
    Hacking the Web (C) 2009-2020 Arun Viswanathan Ellis Horowitz Marco Papa 1 Table of Contents } General Introduction } Authentication Attacks } Client-Side Attacks } Injection Attacks } Recent Attacks } Privacy Tools 2 (C) 2009-2020 Arun Viswanathan Ellis Horowitz Marco Papa Why secure the Web? } The Web has evolved into an ubiquitous entity providing a rich and common platform for connecting people and doing business. } BUT, the Web also offers a cheap, effective, convenient and anonymous platform for crime. } To get an idea, the Web has been used for the following types of criminal activities (source: The Web Hacking Incidents Database (WHID) http://projects.webappsec.org/w/page/13246995/Web-Hacking-Incident-Database) } Chaos (Attack on Russian nuclear power websites amid accident rumors (5Jan09) } Deceit (SAMY XSS Worm – Nov 2005) } Extortion (David Aireys domain hijacked due to a CSRF (cross site request forgery) flaw in Gmail – 30Dec2007) } Identity Theft (XSS on Yahoo! Hot jobs – Oct 2008) } Information Warfare (Israeli Gaza War - Jan 2009 / Balkan Wars – Apr 2008 ) } Monetary Loss (eBay fraud using XSS) } Physical Pain (Hackers post on epilepsy forum causes migraines and seizures – May 2008) } Political Defacements (Hacker changes news release on Sheriffs website – Jul 2008) (Obama, Oreilly and Britneys Twitter accounts hacked and malicious comments posted – Jan 09) } Chinese Gaming sites hacked (Dec. 2011) 3 Copyright(C) 2009 (c) -20092020- 2019Arun Arun Viswanathan Viswanathan Ellis HorowitzEllis Horowitz Marco Marco Papa Papa
    [Show full text]
  • Tor and Circumvention: Lessons Learned
    Tor and circumvention: Lessons learned Nick Mathewson The Tor Project https://torproject.org/ 1 What is Tor? Online anonymity 1) open source software, 2) network, 3) protocol Community of researchers, developers, users, and relay operators Funding from US DoD, Electronic Frontier Foundation, Voice of America, Google, NLnet, Human Rights Watch, NSF, US State Dept, SIDA, ... 2 The Tor Project, Inc. 501(c)(3) non-profit organization dedicated to the research and development of tools for online anonymity and privacy Not secretly evil. 3 Estimated ~250,000? daily Tor users 4 Anonymity in what sense? “Attacker can’t learn who is talking to whom.” Bob Alice Alice Anonymity network Bob Alice Bob 5 Threat model: what can the attacker do? Alice Anonymity network Bob watch Alice! watch (or be!) Bob! Control part of the network! 6 Anonymity isn't cryptography: Cryptography just protects contents. “Hi, Bob!” “Hi, Bob!” Alice <gibberish> attacker Bob 7 Anonymity isn't just wishful thinking... “You can't prove it was me!” “Promise you won't look!” “Promise you won't remember!” “Promise you won't tell!” “I didn't write my name on it!” “Isn't the Internet already anonymous?” 8 Anonymity serves different interests for different user groups. Anonymity “It's privacy!” Private citizens 9 Anonymity serves different interests for different user groups. Anonymity Businesses “It's network security!” “It's privacy!” Private citizens 10 Anonymity serves different interests for different user groups. “It's traffic-analysis resistance!” Governments Anonymity Businesses “It's network security!” “It's privacy!” Private citizens 11 Anonymity serves different interests for different user groups.
    [Show full text]
  • 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.
    [Show full text]
  • Array AG 9.4 CLI Handbook
    Array AG 9.4 CLI Handbook Copyright Statement Copyright Statement Copyright©2000-2018 Array Networks, Inc., 1371 McCarthy Blvd, Milpitas, California 95035, USA. All rights reserved. This document is protected by copyright and distributed under licenses restricting its use, copying, distribution, and compilation. No part of this document can be reproduced in any form by any means without prior written authorization of Array Networks. Documentation is provided “as is” without warranty of any kind, either express or implied, including any kind of implied or express warranty of non-infringement or the implied warranties of merchantability or fitness for a particular purpose. Array Networks reserves the right to change any products described herein at any time, and without notice. Array Networks assumes no responsibility or liability arising from the use of products described herein, except as expressly agreed to in writing by Array Networks. The use and purchase of this product does not convey a license to any patent copyright, or trademark rights, or any other intellectual property rights of Array Networks. Warning: Modifications made to the Array Networks unit, unless expressly approved by Array Networks, could void the user’s authority to operate the equipment. Declaration of Conformity We, Array Networks, Inc., 1371 McCarthy Blvd, Milpitas, CA 95035, 1-866-692-7729; declare under our sole responsibility that the product(s) Array Networks, Array Appliance complies with Part 15 of FCC Rules. Operation is subject to the following two conditions: (1) this device can not cause harmful interference, and (2) this device must accept any interference received, including interference that can cause undesired operation.
    [Show full text]
  • Tor: the Second-Generation Onion Router (2014 DRAFT V1)
    Tor: The Second-Generation Onion Router (2014 DRAFT v1) Roger Dingledine Nick Mathewson Steven Murdoch The Free Haven Project The Free Haven Project Computer Laboratory [email protected] [email protected] University of Cambridge [email protected] Paul Syverson Naval Research Lab [email protected] Abstract Perfect forward secrecy: In the original Onion Routing We present Tor, a circuit-based low-latency anonymous com- design, a single hostile node could record traffic and later munication service. This Onion Routing system addresses compromise successive nodes in the circuit and force them limitations in the earlier design by adding perfect forward se- to decrypt it. Rather than using a single multiply encrypted crecy, congestion control, directory servers, integrity check- data structure (an onion) to lay each circuit, Tor now uses an ing, configurable exit policies, anticensorship features, guard incremental or telescoping path-building design, where the nodes, application- and user-selectable stream isolation, and a initiator negotiates session keys with each successive hop in practical design for location-hidden services via rendezvous the circuit. Once these keys are deleted, subsequently com- points. Tor is deployed on the real-world Internet, requires promised nodes cannot decrypt old traffic. As a side benefit, no special privileges or kernel modifications, requires little onion replay detection is no longer necessary, and the process synchronization or coordination between nodes, and provides of building circuits is more reliable, since the initiator knows a reasonable tradeoff between anonymity, usability, and ef- when a hop fails and can then try extending to a new node.
    [Show full text]
  • Piracy Versus Privacy: an Analysis of Values Encoded in the Piratebrowser
    International Journal of Communication 9(2015), 818–838 1932–8036/20150005 Piracy Versus Privacy: An Analysis of Values Encoded in the PirateBrowser BALÁZS BODÓ University of Amsterdam, Institute for Information Law The Netherlands The PirateBrowser is a Web browser that uses Tor privacy-enhancing technology to circumvent nationally implemented Internet filters blocking access to The Pirate Bay. This article analyzes the possible consequences of a mass influx of copyright pirates into the privacy domain. The article addresses the effects of the uptake of strong privacy technologies by pirates on copyright enforcement and on free speech and privacy technology domains. Also discussed are the norms and values reflected in the specific design choices taken by the developers of the PirateBrowser. Keywords: piracy, privacy, Tor, privacy-enhancing technologies, policy Introduction Tor (The Onion Router), “endorsed by Egyptian activists, WikiLeaks, NSA, GCHQ, Chelsea Manning, Snowden” (Dingledine & Appelbaum, 2013), is a volunteer network of computers that relays Web traffic through itself to provide anonymous, unobserved, and uncensored access to the Internet. It has about 4,000 relays and about 1,000 exit nodes. Tor users connect to the network, and their Web traffic is channeled through the internal relays to reach its final destination through one of the exit nodes. This arrangement makes the identification and surveillance of Tor users difficult. Anonymity is promised by the difficulty of tracing the Web traffic that appears on the exit node back to the individual who initiated the traffic, as long as there is a sufficient number of internal hops in between. Protection from surveillance is granted by the fact that each link in the communication chain is encrypted.
    [Show full text]
  • Jacob Appelbaum, Wikileaks Activist and Tor Project Leader, Travels to Beijing to Work with Artist/Activist Ai We
    Breaking News: Jacob Appelbaum, Wikileaks activist and Tor Project leader, travels to Beijing to work with artist/activist Ai Weiwei for Rhizome's Seven on Seven conference at the New Museum. Laura Poitras documents the pair in her first film since Citizenfour, premiering excerpts at the event on May 2. On Saturday, April 19, Jacob Appelbaum—notable Wikileaks and Tor Project activist—traveled to Beijing for five days to take part in a collaboration with dissident artist Ai Weiwei, at the invitation of art- meets-tech organization Rhizome, on the occasion of the seventh Seven on Seven conference at the New Museum. Director Laura Poitras, whose portrait of Edward Snowden won the 2015 Academy Award for Documentary Feature, filmed the duo's work. Seven on Seven is an annual signature conference with a unique format that pairs artists and technologists together to make something new in 24 hours. The pair worked to create an artwork that underscores their mutual concerns with privacy, surveillance, and their state-restricted movement. Excerpts of the short film documenting this collaboration—Poitras' first since Citizenfour—will be premiered at the event, held at New Museum in New York on May 2, and the final film will be released online later in May. The Appelbaum/Ai collaboration was organized by Heather Corcoran, Executive Director of Rhizome, who said: “It was important to bring together these two courageous people who are disseminating their messages using art and technology, respectively, and facing similar levels of scrutiny and hardship as a result. It represents the best that Rhizome achieves with Seven on Seven, which brings the worlds of technology and art into closer proximity, to share strategies for thinking critically about digital culture and communicating those ideas.
    [Show full text]
  • A Privacy Threat for Internet Users in Internet-Censoring Countries
    A Privacy Threat for Internet Users in Internet-censoring Countries Feno Heriniaina R. College of Computer Science, Chongqing University, Chongqing, China Keywords: Censorship, Human Computer Interaction, Privacy, Virtual Private Networks. Abstract: Online surveillance has been increasingly used by different governments to control the spread of information on the Internet. The magnitude of this activity differs widely and is based primarily on the areas that are deemed, by the state, to be critical. Aside from the use of keywords and the complete domain name filtering technologies, Internet censorship can sometimes even use the total blocking of IP addresses to censor content. Despite the advances, in terms of technology used for Internet censorship, there are also different types of circumvention tools that are available to the general public. In this paper, we report the results of our investigation on how migrants who previously had access to the open Internet behave toward Internet censorship when subjected to it. Four hundred and thirty-two (432) international students took part in the study that lasted two years. We identified the most common circumvention tools that are utilized by the foreign students in China. We investigated the usability of these tools and monitored the way in which they are used. We identified a behaviour-based privacy threat that puts the users of circumvention tools at risk while they live in an Internet-censoring country. We also recommend the use of a user-oriented filtering method, which should be considered as part of the censoring system, as it enhances the performance of the screening process and recognizes the real needs of its users.
    [Show full text]
  • Security Analysis of Instant Messenger Torchat
    TALLINN UNIVERSITY OF TECHNOLOGY Faculty of Information Technology Department of Informatics Chair of Software Engineering Security Analysis of Instant Messenger TorChat Master's Thesis Student: Rain Viigipuu Student code: 072125 Supervisor: Alexander Norta, PhD External Supervisor: Arnis Parˇsovs, MSc TALLINN 2015 Abstract TorChat is a peer-to-peer instant messenger built on top of the Tor network that not only provides authentication and end-to-end encryption, but also allows the communication parties to stay anonymous. In addition, it prevents third parties from even learning that communication is taking place. The aim of this thesis is to document the protocol used by TorChat and to analyze the security of TorChat and its reference implementation. The work shows that although the design of TorChat is sound, its implementation has several flaws, which make TorChat users vulnerable to impersonation, communication confirmation and denial-of-service attacks. 2 Contents 1 Introduction 6 2 Tor and Hidden Services 8 2.1 Hidden Services . .9 2.1.1 Hidden service address . 11 3 TorChat 12 3.1 Managing Contacts and Conversations . 12 3.2 Configuration Options . 16 4 TorChat Protocol 17 4.1 Handshake . 17 4.2 File Transfers . 18 4.3 Protocol Messages . 19 4.3.1 not implemented . 19 4.3.2 ping . 20 4.3.3 pong . 21 4.3.4 client . 22 4.3.5 version . 22 4.3.6 status . 22 4.3.7 profile name . 23 4.3.8 profile text . 23 4.3.9 profile avatar alpha . 24 4.3.10 profile avatar . 24 4.3.11 add me.............................
    [Show full text]
  • The Potential Harms of the Tor Anonymity Network Cluster Disproportionately in Free Countries
    The potential harms of the Tor anonymity network cluster disproportionately in free countries Eric Jardinea,1,2, Andrew M. Lindnerb,1, and Gareth Owensonc,1 aDepartment of Political Science, Virginia Tech, Blacksburg, VA 24061; bDepartment of Sociology, Skidmore College, Saratoga Springs, NY 12866; and cCyber Espion Ltd, Portsmouth PO2 0TP, United Kingdom Edited by Douglas S. Massey, Princeton University, Princeton, NJ, and approved October 23, 2020 (received for review June 10, 2020) The Tor anonymity network allows users to protect their privacy However, substantial evidence has shown that the preponder- and circumvent censorship restrictions but also shields those ance of Onion/Hidden Services traffic connects to illicit sites (7). distributing child abuse content, selling or buying illicit drugs, or With this important caveat in mind, our data also show that the sharing malware online. Using data collected from Tor entry distribution of potentially harmful and beneficial uses is uneven, nodes, we provide an estimation of the proportion of Tor network clustering predominantly in politically free regimes. In particular, users that likely employ the network in putatively good or bad the average rate of likely malicious use of Tor in our data for ways. Overall, on an average country/day, ∼6.7% of Tor network countries coded by Freedom House as “not free” is just 4.8%. In users connect to Onion/Hidden Services that are disproportion- countries coded as “free,” the percentage of users visiting Onion/ ately used for illicit purposes. We also show that the likely balance Hidden Services as a proportion of total daily Tor use is nearly of beneficial and malicious use of Tor is unevenly spread globally twice as much or ∼7.8%.
    [Show full text]
  • Monitoring the Dark Web and Securing Onion Services
    City University of New York (CUNY) CUNY Academic Works Publications and Research Queensborough Community College 2017 Monitoring the Dark Web and Securing Onion Services John Schriner CUNY Queensborough Community College How does access to this work benefit ou?y Let us know! More information about this work at: https://academicworks.cuny.edu/qb_pubs/41 Discover additional works at: https://academicworks.cuny.edu This work is made publicly available by the City University of New York (CUNY). Contact: [email protected] Monitoring the Dark Web Schriner 1 John Schriner Monitoring the Dark Web Contrary to what one may expect to read with a title like Monitoring the Dark Web, this paper will focus less on how law enforcement works to monitor hidden web sites and services and focus more on how academics and researchers monitor this realm. The paper is divided into three parts: Part One discusses Tor research and how onion services work; Part Two discusses tools that researchers use to monitor the dark web; Part Three tackles the technological, ethical, and social interests at play in securing the dark web. Part One: Tor is Research-Driven Tor (an acronym for 'the onion router' now stylized simply 'Tor') is an anonymity network in which a user of the Tor Browser connects to a website via three hops: a guard node, a middle relay, and an exit node. The connection is encrypted with three layers, stripping a layer at each hop towards its destination server. No single node has the full picture of the connection along the circuit: the guard knows only your IP but not where the destination is; the middle node knows the guard and the exit node; the exit node knows only the middle node and the final destination.
    [Show full text]