tor2web esc2011
DESCRIPTION
Tor2web is a gate to Tor Hidden ServicesTRANSCRIPT
tor2web
Past, Present and Future of Tor Hidden Services
Sunday, September 4, 2011
What is tor2web?
• Gate to hidden services
• Allows people to access HTTP(s) Hidden Services without Tor
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Tradeoff
• --Client Anonymity
• ++Usability
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Tor Hidden Services
• am4wuhz3zifexz5u.onion
• Anonymity for the Server
• DoS protection
• End-To-End encryption
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Why use HS
• Avoid retaliation for what you publish
• Securely host and serve content
• Stealth Hidden Service
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Tor2web
• Works for HTTP(s) HS
• Promote Tor HS
• HS can impact the whole web!
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Tor2web 1.0
• Started by Aaaron Swartz in 2008
• Now part of GlobaLeaks
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Tor2web 1.0 Issues
• Exposed to abuse complaints
• Misuse of HS to spread illegal material
• No disclaimer
• This leads to Server Takedown
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First iteration
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Solved problems
• Tell the audience no content is hosted on the server
• Abuse and problem complaint form
• Dynamic URL rewriting
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Kharon
• Complementary to tor2web
• Firefox and Chrome plugin
• https://github.com/hellais/kharon
• rewrites hidden services to tor2web and i2p
• Done by evilaliv3, hellais and vecna
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Unsolved problems
• Responsibility not distributed
• Links directly serve the content
• High risk of takedown
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Future tor2web 3.0
• Discussed with Paul Syverson
• Further reduce the risk of takedown
• Distribute responsibility across multiple actors
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Scenarios
• Spammer links to *.tor2web.org site hosted on HS
• Illegal content hosting
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Definitions
NodeA
NodeB
Hidden Service
User
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Node A
• Landing page
• Accept disclaimer
• Does not serve content
• Generates a unique, temporary access URL for the User
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Properties of the URL
• Usable once
• Only Node A’s can make them
• Usable only by who generated it
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The unique URL
nonce
timestamp
the_user
onion_address
(maybe the IP)
H(
)
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The unique URL
NodeA
NodeB
Signed nonce
verifies the signature
User
Hash
computes the H(...)Sunday, September 4, 2011
Node B
NodeBUser
content
Node B is in different ISP and/or country
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What have we achieved?
• Distribute responsibility across two actors in two different jurisdictions
• Avoid direct serving of content
• URL’s are unique per user
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New problems
• How to handle caching?
• The issue is the delay in connecting to HS
• Cache is used only after connection has been established
• What are the flaws in this solution?
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Questions?
• Wiki: http://wiki.tor2web.org
• Mailing list: [email protected]
• IRC: #tor2web on irc.oftc.net
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Thanks for listening!
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