Online Anonymity & Privacy. Andrew Lewman The Tor Project

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1 Online Anonymity & Privacy Andrew Lewman The Tor Project

2 Outline Why anonymity? Crash course on Tor Future

3 Informally: anonymity means you can't tell who did what Who wrote this blog post? Who's been viewing my webpages? Who's been ing patent attorneys?

4 Formally: anonymity means indistinguishability within an anonymity set Alice1 Alice2 Alice4 Alice7 Alice6 Alice3 Alice5 Alice8 Bob... Attacker can't tell which Alice is talking to Bob!

5 Anonymity isn't cryptography: Cryptography just protects contents. Alice Hi, Bob! <gibberish> attacker Hi, Bob! Bob

6 Anonymity isn't steganography: Attacker can tell that Alice is talking; just not to whom. Bob1 Alice1 Alice2... AliceN Anonymity network Bob2 (Strong high-bandwidth steganography may not exist.)

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 ...since weak anonymity... isn't. You can't prove it was me! Proof is a very strong word. With statistics, suspicion becomes certainty. Will others parties have Promise you won't look! the ability and incentives Promise you won't remember! to keep their promises? Promise you won't tell! I didn't write my name on it! Not what we're talking about. Nope! (More info Isn't the Internet already anonymous? later.)

9 Anonymity serves different interests for different user groups. Anonymity It's privacy! Private citizens

10 Regular citizens don't want to be watched and tracked. Blogger Alice 8-year-old Alice Sick Alice Consumer Alice... Oppressed Alice I sell the logs. Hostile Bob Incompetent Bob Oops, I lost the logs. Indifferent Bob Name, address, age, friends, interests (medical, financial, etc), unpopular opinions, illegal opinions... Hey, they aren't my secrets. (the network can track too)

11 Anonymity serves different interests for different user groups. Anonymity Businesses It's network security! It's privacy! Private citizens

12 Businesses need to keep trade secrets. Oh, your employees are reading our patents/jobs page/product sheets? Competitor AliceCorp Competitor Hey, it's Alice! Give her the 'Alice' version! Compromised network Wanna buy a list of Alice's suppliers? What about her customers? What about her engineering department's favorite search terms?

13 Anonymity serves different interests for different user groups. It's traffic-analysis resistance! Governments Anonymity Businesses It's network security! Private citizens It's privacy!

14 Law enforcement needs anonymity to get the job done. Investigated suspect Officer Alice Witness/informer Alice Why is alice.localpolice.gov reading my website? Organized Crime Why no, alice.localpolice.gov! I would never sell counterfeits on ebay! Is my family safe if I go after these guys? Anonymous tips Are they really going to ensure my anonymity? Sting target

15 Governments need anonymity for their security Agent Alice Untrusted ISP Compromised service Coalition member Alice Shared network Defense in Depth What will you bid for a list of Baghdad IP addresses that get from.gov? What does the CIA Google for? Do I really want to reveal my internal network topology? What about insiders?

16 Anonymity serves different interests for different user groups. It's traffic-analysis resistance! Governments Blocked users Anonymity It's reachability! Businesses It's network security! Private citizens It's privacy!

17 You can't get anonymity on your own: private solutions are ineffective... Citizen Alice Alice's small anonymity net Officer Alice Municipal anonymity net AliceCorp AliceCorp anonymity net... Investigated suspect Competitor One of the 25 users on AliceNet. Looks like a cop. It's somebody at AliceCorp!

18 ... so, anonymity loves company! Citizen Alice Officer Alice... Shared anonymity net??? Investigated suspect??? Competitor??? AliceCorp

19 Current situation: Bad people on the Internet are doing fine Trojans Viruses Exploits Botnets Zombies Espionage DDoS Extortion Spam Phishing

20 IP addresses can be enough to bootstrap knowledge of identity. Alice x.x Hotlinked ad Amazon account Wikipedia post

21 Outline Why anonymity? Crash course on Tor Future

22 What is Tor? online anonymity software and network open source, freely available active research environment

23 The Tor Project, Inc. 501(c)(3) non-profit organization dedicated to the research and development of tools for online anonymity and privacy

24 Estimated 300,000 daily Tor users

25 The simplest designs use a single relay to hide connections. Alice1 E(B Bob1 ob3, X ) Alice2 E(Bob1, Y ) Alice3 ) Z 2, b o B E( Y Relay Z Bob2 X Bob3 (example: some commercial proxy providers)

26 But a single relay is a single point of failure. Alice1 E(B Bob1 ob3, X ) Alice2 E(Bob1, Y ) Alice3 ) Z 2, b o B E( Evil Relay Y Z Bob2 X Bob3 Eavesdropping the relay works too.

27 So, add multiple relays so that no single one can betray Alice. Bob Alice R1 R3 R5 R4 R2

28 A corrupt first hop can tell that Alice is talking, but not to whom. Bob Alice R1 R3 R5 R4 R2

29 A corrupt final hop can tell that somebody is talking to Bob, but not who. Bob Alice R1 R3 R5 R4 R2

30 Alice makes a session key with R1...And then tunnels to R2...and to R3 Bob Alice R1 R3 Bob2 R5 R4 R2

31 Who uses Tor? Normal people Law Enforcement Human Rights Activists Business Execs Militaries Abuse Victims

32 Tor doesn't magically encrypt the Internet Operating Systems and Applications leak your info Browser Plugins, Cookies, Extensions, Shockwave/Flash, Java, Quicktime, and PDF all conspire against you

33 Outline Why anonymity? Crash course on Tor Examples

34 Example 1: Pbd.ca

35 Example 2: cbc.ca

36 Advertising Network Reach Source:

37 IP Address Only?

38 IP Address Detail

39 Cookies

40 Cookie Details

41 Summary Privacy policies are prone to mistakes and equivalent to promises Not having the data, nor being able to get it, is privacy by design You are your data trail; increasingly others make decisions about you based upon your data trail.

42 Copyrights who uses tor? Matt Westervelt, CC-BY-SA danger!, hmvh, CC-BY-SA 300k, tochis, CC-BY-NC

Tor: a brief intro. Roger Dingledine The Tor Project

Tor: a brief intro. Roger Dingledine The Tor Project Tor: a brief intro Roger Dingledine The Tor Project https://torproject.org/ 1 What is Tor? Online anonymity 1) software, 2) network, 3) protocol Open source, freely available Community of researchers,