Skip to content
GitLab
  • Menu
Projects Groups Snippets
  • Help
    • Help
    • Support
    • Community forum
    • Submit feedback
    • Contribute to GitLab
  • Sign in
  • Trac Trac
  • Project information
    • Project information
    • Activity
    • Labels
    • Members
  • Issues 246
    • Issues 246
    • List
    • Boards
    • Service Desk
    • Milestones
  • Monitor
    • Monitor
    • Metrics
    • Incidents
  • Analytics
    • Analytics
    • Value stream
  • Wiki
    • Wiki
  • Activity
  • Create a new issue
  • Issue Boards
Collapse sidebar
  • Legacy
  • TracTrac
  • Issues
  • #18191
Closed (moved) (moved)
Open
Created Jan 29, 2016 by cypherpunks@cypherpunks

.onion name collision

The output of SHA1 has a length of 160 bit. To make handling the URLs more convenient we only use the first half of the hash, so 80 bit remain. Taking advantage of the ​Birthday Attack, entropy can be reduced to 40 bit. That's why collisions could be found with moderate means. This is not a problem for Tor since all an attacker might be able to do is create two different public keys that match the same .onion name. He would not be able to impersonate already existing hidden services.

Why he would not be able? As I know, there is no built-in way to authenticate a HS if there is a collision: the legit and fake HSes will be indistinguishable from each other.

To upload designs, you'll need to enable LFS and have an admin enable hashed storage. More information
Assignee
Assign to
Time tracking