TOR https://media.defcon.org/DEF%20CON%2025/DEF%20CON - - PowerPoint PPT Presentation

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TOR https://media.defcon.org/DEF%20CON%2025/DEF%20CON - - PowerPoint PPT Presentation

Sep 13, 2023 620 likes •970 views

TOR https://media.defcon.org/DEF%20CON%2025/DEF%20CON %2025%20presentations/DEFCON-25-Roger-Dingledine-Next- Generation-Tor-Onion-Services-UPDATED.pdf https://metrics.torproject.org/ https://compass.torproject.org/

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TOR

https://media.defcon.org/DEF%20CON%2025/DEF%20CON %2025%20presentations/DEFCON-25-Roger-Dingledine-Next- Generation-Tor-Onion-Services-UPDATED.pdf https://metrics.torproject.org/ https://compass.torproject.org/ https://www.torproject.org/about/overview.html.en

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Threat Model

Alice Bob Anonymity Network

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Anonymity serves different interests for different users

  • private citizens
  • privacy
  • businesses
  • network security
  • governments
  • traffic-analysis resistance
  • human rights activists
  • reachability
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Simple design

Relay

Joey Phoebe Rachel Ross Chandler Monica

E(X,Chandler) E(Y,Ross) E(Z,Monica) Y X Z

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Single Point of Failure

EVIL RELAY

Joey Phoebe Rachel Ross Chandler Monica

E(X,Chandler) E(Y,Ross) E(Z,Monica) Y X Z

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Question

  • In the last example, let’s say Jane is a local

business’ website run completely over http.

  • If Alice entered in her username/password into the

website, which users along the circuit could read her password?

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Usage Statistics

1 000 000 2 000 000 3 000 000 Jul−2017 Oct−2017

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

Directly connecting users

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Network Size

2000 4000 6000 Jul−2017 Oct−2017

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

Relays Bridges

Number of relays

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Types of Relays

2000 4000 6000 Jul−2017 Oct−2017

The Tor Project − https://metrics.torproject.org/ Relay flags

Running Exit Fast Guard Stable

Number of relays with relay flags assigned

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Bandwidth

50 100 150 200 2010 2011 2012 2013 2014 2015 2016 2017 2018

The Tor Project − https://metrics.torproject.org/ Bandwidth (Gbit/s)

Advertised bandwidth Bandwidth history

Total relay bandwidth

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Anonymity vs Security

  • Anonymity: safety in numbers
  • diversity in users
  • diversity in relays
  • Security: safety in heterogeneity
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Anonymity vs Security

  • Open source
  • Public design documents
  • Design peer reviewed
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Onion Services

  • Authenticated
  • End-to-end encryption
  • Limit surface area
  • No need to “exit” from TOR
  • No need for anybody to know where it is or who

runs it

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29

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30

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Onion keys are getting bigger

  • From 16 characters:
  • the first 80 bits of the SHA-1 of the 1024 RSA key
  • … to 52 characters:
  • ED25519 public key base32 encoded
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