The 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.

Note: All slides are made public by the authors who created the slides. The slides may be downloaded for informational purposes only. The reproduction, reuse or reposting of these slides is expressly prohibited. 1 ● Online Anonymity – Open Source – Open Network ● Community of researchers, developers, users and relay operators. ● U.S. 501(c)(3) non- profit organization

Note: All slides are made public by the authors who created the slides. The slides may be downloaded for informational purposes only. The reproduction, reuse or reposting of these slides is expressly prohibited. 2 Estimated 2,000,000+ daily Tor users Note: All slides are made public by the authors who created the slides. The slides may be downloaded for informational purposes only. The reproduction, reuse or reposting of these slides is expressly prohibited. 3 Threat model: what can the attacker do?

Alice Anonymity network Bob watch Alice!

watch (or be!) Bob!

Control part of the network!

Note: All slides are made public by the authors who created the slides. The slides may be downloaded for informational purposes only. The reproduction, reuse or reposting of these slides is expressly prohibited. 4 Anonymity isn't encryption: Encryption just protects contents.

“Hi, Bob!” “Hi, Bob!” Alice attacker Bob

Note: All slides are made public by the authors who created the slides. The slides may be downloaded for informational purposes only. The reproduction, reuse or reposting of these slides is expressly prohibited. 5 Anonymity serves different interests for different user groups.

Anonymity

“It's privacy!” Private citizens

Note: All slides are made public by the authors who created the slides. The slides may be downloaded for informational purposes only. The reproduction, reuse or reposting of these slides is expressly prohibited. 6 Anonymity serves different interests for different user groups.

Anonymity Businesses

“It's network security!”

“It's privacy!” Private citizens

Note: All slides are made public by the authors who created the slides. The slides may be downloaded for informational purposes only. The reproduction, reuse or reposting of these slides is expressly prohibited. 7 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

Note: All slides are made public by the authors who created the slides. The slides may be downloaded for informational purposes only. The reproduction, reuse or reposting of these slides is expressly prohibited. 8 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

Note: All slides are made public by the authors who created the slides. The slides may be downloaded for informational purposes only. The reproduction, reuse or reposting of these slides is expressly prohibited. 9 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)

Note: All slides are made public by the authors who created the slides. The slides may be downloaded for informational purposes only. The reproduction, reuse or reposting of these slides is expressly prohibited. 10 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

Note: All slides are made public by the authors who created the slides. The slides may be downloaded for informational purposes only. The reproduction, reuse or reposting of these slides is expressly prohibited. 11 ... 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

Note: All slides are made public by the authors who created the slides. The slides may be downloaded for informational purposes only. The reproduction, reuse or reposting of these slides is expressly prohibited. 12 So, add multiple relays so that no single one can betray Alice.

Alice Bob

R1 R3

R4 R5 R2

Note: All slides are made public by the authors who created the slides. The slides may be downloaded for informational purposes only. The reproduction, reuse or reposting of these slides is expressly prohibited. 13 Alice makes a session key with R1 ...And then tunnels to R2...and to R3

Alice Bob

R1 R3 Bob2

R4 R5 R2

Note: All slides are made public by the authors who created the slides. The slides may be downloaded for informational purposes only. The reproduction, reuse or reposting of these slides is expressly prohibited. 14 Note: All slides are made public by the authors who created the slides. The slides may be downloaded for informational purposes only. The reproduction, reuse or reposting of these slides is expressly prohibited. 15 Note: All slides are made public by the authors who created the slides. The slides may be downloaded for informational purposes only. The reproduction, reuse or reposting of these slides is expressly prohibited. 16 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.

Note: All slides are made public by the authors who created the slides. The slides may be downloaded for informational purposes only. The reproduction, reuse or reposting of these slides is expressly prohibited. 17 Transparency for Tor is key

● Open source / free software ● Public design documents and specifications ● Publicly identified developers ● Not a contradiction: privacy is about choice!

Note: All slides are made public by the authors who created the slides. The slides may be downloaded for informational purposes only. The reproduction, reuse or reposting of these slides is expressly prohibited. 18 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.

Note: All slides are made public by the authors who created the slides. The slides may be downloaded for informational purposes only. The reproduction, reuse or reposting of these slides is expressly prohibited. 19 20 Note: All slides are made public by the authors who created the slides. The slides may be downloaded for informational purposes only. The reproduction, reuse or reposting of these slides is expressly prohibited. 21 Note: All slides are made public by the authors who created the slides. The slides may be downloaded for informational purposes only. The reproduction, reuse or reposting of these slides is expressly prohibited. Note: All slides are made public by the authors who created the slides. The slides may be downloaded for informational purposes only. The reproduction, reuse or reposting of these slides is expressly prohibited. 22 Directly connecting users from Russia

300000 -

200000 -

100000 -

o- ' I I I I Mar-2015 Jun-2015 Sep-2015 Dec-2015 Mar-2016 The Tor Project - ://metrics.torproject.org/

Note: All slides are made public by the authors who created the slides. The slides may be downloaded for informational purposes only. The reproduction, reuse or reposting of these slides is expressly prohibited. 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 24 Note: All slides are made public by the authors who created the slides. The slides may be downloaded for informational purposes only. The reproduction, reuse or reposting of these slides is expressly prohibited. Directly connecting users from the Islamic Republic of Iran

12000-

10000-

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6000-

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0- 1 I I I I Dec-2010 Jan-2011 Feb-2011 Mar-2011 Apr-2011

The Tor Project - https://metrics.torproject.org/

Note: All slides are made public by the authors who created the slides. The slides may be downloaded for informational purposes only. The reproduction, reuse or reposting of these slides is expressly prohibited. Pluggable transports

Note: All slides are made public by the authors who created the slides. The slides may be downloaded for informational purposes only. The reproduction, reuse or 26 reposting of these slides is expressly prohibited. 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

Note: All slides are made public by the authors who created the slides. The slides may be downloaded for informational purposes only. The reproduction, reuse or reposting of these slides is expressly prohibited. 27 Note: All slides are made public by the authors who created the slides. The slides may be downloaded for informational purposes only. The reproduction, reuse or reposting of these slides is expressly prohibited. 28 Note: All slides are made public by the authors who created the slides. The slides may be downloaded for informational purposes only. The reproduction, reuse or reposting of these slides is expressly prohibited. 29 Note: All slides are made public by the authors who created the slides. The slides may be downloaded for informational purposes only. The reproduction, reuse or reposting of these slides is expressly prohibited. 30 Note: All slides are made public by the authors who created the slides. The slides may be downloaded for informational purposes only. The reproduction, reuse or 31 reposting of these slides is expressly prohibited. Note: All slides are made public by the authors who created the slides. The slides may be downloaded for informational purposes only. The reproduction, reuse or reposting of these slides is expressly prohibited. 32 33 Note: All slides are made public by the authors who created the slides. The slides may be downloaded for informational purposes only. The reproduction, reuse or reposting of these slides is expressly prohibited. Note: All slides are made public by the authors who created the slides. The slides may be downloaded for informational purposes only. The reproduction, reuse or reposting of these slides is expressly prohibited. 34 Note: All slides are made public by the authors who created the slides. The slides may be downloaded for informational purposes only. The reproduction, reuse or 35 reposting of these slides is expressly prohibited. 36 Note: All slides are made public by the authors who created the slides. The slides may be downloaded for informational purposes only. The reproduction, reuse or reposting of these slides is expressly prohibited. Note: All slides are made public by the authors who created the slides. The slides may be downloaded for informational purposes only. The reproduction, reuse or 37 reposting of these slides is expressly prohibited. “Still the King of high secure, low latency Anonymity”

Contenders for the throne: ● None

Note: All slides are made public by the authors who created the slides. The slides may be downloaded for informational purposes only. The reproduction, reuse or reposting of these slides is expressly prohibited. 38 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 Note: All slides are made public by the authors who created the slides. The slides may be downloaded for informational purposes only. The reproduction, reuse or reposting of these slides is expressly prohibited. 39 Note: All slides are made public by the authors who created the slides. The slides may be downloaded for informational purposes only. The reproduction, reuse or reposting of these slides is expressly prohibited. 40 Note: All slides are made public by the authors who created the slides. The slides may be downloaded for informational purposes only. The reproduction, reuse or reposting of these slides is expressly prohibited. 41 Arms races ● Censorship arms race is bad ● Surveillance arms race is worse – And centralization of the Internet makes it worse still

Note: All slides are made public by the authors who created the slides. The slides may be downloaded for informational purposes only. The reproduction, reuse or reposting of these slides is expressly prohibited. 42 Note: All slides are made public by the authors who created the slides. The slides may be downloaded for informational purposes only. The reproduction, reuse or reposting of these slides is expressly prohibited. 43 Onion Service

44

Note: All slides are made public by the authors who created the slides. The slides may be downloaded for informational purposes only. The reproduction, reuse or reposting of these slides is expressly prohibited. Note: All slides are made public by the authors who created the slides. The slides may be downloaded for informational purposes only. The reproduction, reuse or reposting of these slides is expressly prohibited. 45 Note: All slides are made public by the authors who created the slides. The slides may be downloaded for informational purposes only. The reproduction, reuse or 46 reposting of these slides is expressly prohibited. Note: All slides are made public by the authors who created the slides. The slides may be downloaded for informational purposes only. The reproduction, reuse or reposting of these slides is expressly prohibited. 47 Note: All slides are made public by the authors who created the slides. The slides 48 may be downloaded for informational purposes only. The reproduction, reuse or reposting of these slides is expressly prohibited. Note: All slides are made public by the authors who created the slides. The slides may be downloaded for informational purposes only. The reproduction, reuse or reposting of these slides is expressly prohibited. 49 SecureDrop

Today, 30+ organizations use SecureDrop https://securedrop.org/directory

Note: All slides are made public by the authors who created the slides. The slides may be downloaded for informational purposes only. The reproduction, reuse or reposting of these slides is expressly prohibited. 50 Ricochet

Note: All slides are made public by the authors who created the slides. The slides may be downloaded for informational purposes only. The reproduction, reuse or 51 reposting of these slides is expressly prohibited. Tor isn't foolproof

● Opsec mistakes ● Browser metadata fingerprints ● Browser exploits ● Traffic analysis

Note: All slides are made public by the authors who created the slides. The slides may be downloaded for informational purposes only. The reproduction, reuse or reposting of these slides is expressly prohibited. 52 ooni.torproject.org

Note: All slides are made public by the authors who created the slides. The slides may be downloaded for informational purposes only. The reproduction, reuse or reposting of these slides is expressly prohibited. 53 explorer.ooni.torproject.org

● I

Note: All slides are made public by the authors who created the slides. The slides may be downloaded for informational purposes only. The reproduction, reuse or reposting of these slides is expressly prohibited. 54