The Onion Router Hao-Lun Hsu Taiwan Evolutionary Intelligence Laboratory 2017/3/13 Group Meeting Presentation

Outline Dark Web Onion Router Structure of the Internet Content of dark web Onion Router Onion routing Security issue

Dark Web The Internet was not designed with things like anonymity and privacy. In 1960s, U.S. navy (Naval Research Laboratory) began to develop The Onion Router (Tor). Onion Routing is a system that allows for bi-directional communications over the Internet where the source and destination cannot be determined by a mid-point. Tor的project負責人曾說： 不能只有美國政府在用這套系統，不然的話下次有人看到一條匿名的連線就會說”噢，又一個CIA探員在偷看我”

Structure of Internet Deep Web/ Surface Web = 500 I2P Freenet Source: https://www.youtube.com/watch?v=mUP0tx7Ib2w

Content of Dark Web Hidden Services: .onion e.g. http://zqktlwi4fecvo6ri.onion/ Black market e.g. Drug Market Google會鎖 因為會判定為DDoS

Onion Router Randomly selects 3 nodes from a list provided by a "directory node“. These nodes are arranged into a path, called a “circuit”. No node in a circuit can tell whether the node before it is the originator or another intermediary like itself. Random select 但是有congestion control Lannister Stark Baratheon Bolton Targaryen

Stark Baratheon Lannister Bolton Targaryen

Stark Baratheon Lannister Bolton Targaryen

Stark Baratheon Lannister Bolton Targaryen

Stark Baratheon Lannister Bolton Targaryen

Stark Baratheon Lannister Bolton Targaryen

Stark Baratheon Lannister Bolton Targaryen

Stark Baratheon Lannister Bolton Targaryen

Stark Baratheon Lannister 外部攻擊者必須 Bolton Targaryen

Onion Router Each node only knows its next node and previous node. The three nodes change every 10 minutes. Unless all three nodes are compromised, the user cannot be traced. (Usually, the three nodes are in three different countries) If the three nodes are compromised unfortunately, tracing the user is still hard since there are too many users.

Connection Establishment

Security Issue Exit node vulnerability Time analysis attack SSL connection between exit node and destination server Time analysis attack NSA: 木馬將Tor導向NSA控制的節點

Pros & Cons Pros Cons Real anonymity Slow (high latency) Rely on SSL connection between nodes and between a node and the destination

Reference Roger Dingledine, Nick Mathewson, Paul Syverson, Tor: The Second-Generation Onion Router Wikipedia: https://en.wikipedia.org/wiki/Onion_routing https://en.wikipedia.org/wiki/Tor_(anonymity_network) https://www.torproject.org/ https://read01.com/5BoQzE.html https://www.youtube.com/watch?v=mUP0tx7Ib2w https://www.youtube.com/watch?v=l5FRYpPwpJ0 https://www.youtube.com/watch?v=a_4aiwVdEOg https://www.youtube.com/watch?v=LAcGiLL4OZU http://iguang.tw/u/4219580/article/320257.html https://plus.google.com/+GhostAssassin/posts/CTqfYy1xVdw https://plus.google.com/+GhostAssassin/posts/eSdPCiPjnhn