How does end-to-end encryption between Client and Hidden Service work?

I am trying to understand more about TOR and how it works and found something about a end-to-end encryption between the client and the hidden service, but nothing good, that explains how it works.

  • 2
    Both parties perform an authenticated key exchange, so the circuit between the client and service is encrypted with a secret known only to those two parties like any form of end-to-end encrypted tunnel. What specifically about it do you want to know?
    – cacahuatl
    Feb 5, 2018 at 23:54
  • @cacahuatl my guess would be how it compares to https sites that use trusted certs.
    – james-see
    Jul 5, 2018 at 12:54

1 Answer 1


A Tor onion service host chooses several Tor nodes to serve as the host's introduction points. The host builds circuits to those nodes, and tells the nodes to use those circuits to forward introduction requests from clients to the onion service. When a client wants to connect to the onion service, the client first chooses a Tor node at random to be its "rendezvous point", and the client builds a circuit to that rendezvous point. The client then builds an anonymous circuit to one of the onion service's introduction points. The onion service makes an anonymous circuit to the rendezvous point and completes the cryptographic handshake. The rendezvous point connects the two circuits, and the cryptographic handshake gives the two parties a shared key, which proves to the client that it is indeed talking to the onion service host. Once the two circuits are joined, the client can send Tor RELAY cells to the onion service host with end-to-end encryption.

Tor Rendezvous Specification - Version 3 Tor: Onion Service Protocol - Step 5: The rendezvous point simply relays (end-to-end encrypted) messages from client to service and vice versa.
Tor's Fall Harvest: the Next Generation of Onion Services
index: torspec - Onion Service Version 2 Specifications
index: torspec - Onion Service Version 3 Specifications
Tor: The Second-Generation Onion Router - Section 5 - Rendezvous Points and hidden services

  • This is a link only answer.
    – cacahuatl
    Feb 6, 2018 at 14:16

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