How Tor Browser knows that a directory server is legit? Does it have their certificates hardcoded?

  • Yes, exactly : the certificates are hardcoded into your Tor binary client, not Tor Browser - the Tor Browser is just a modified Firefox
    – Alexey Vesnin
    Apr 7, 2016 at 14:30

1 Answer 1


I assume that you downloaded a valid copy of Tor or Tor Browser. The source code contains information about all current directory authorities. (config.c). Currently there are nine authorities which you can also find within Atlas.

This file contains an IP address as well as the fingerprint of the authorities. When the client connects to the authorities it will check the fingerprint. It is not possible for an attacker to reproduce this fingerprint. Here are some further discussions about what happens when nodes are compromised or taken down.

  • why? "It is not possible for an attacker to reproduce this fingerprint"
    – 장석인
    Oct 4, 2016 at 0:29

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