Tor (The Onion Router) is a collection of proxy servers, a decentralized anonymizer. Thanks to Tor, the user has the ability to remain anonymous on the Internet. The name "onion router" was given because of the principle of the network: it is built on the basis of "levels", just as an onion consists of superimposed leaves. How does Tor work?
Instructions
Step 1
The anonymous Tor network consists of so-called "nodes", and the term "relays" can also be used to refer to network participants. Each relay is a proxy server capable of receiving and sending data. Any user, having configured the Tor client, can turn their PC into a node, i.e. to the chain element. The packet from the client to the server does not go directly, but through a chain consisting of three randomly selected nodes.
Step 2
The approximate path that each packet takes in the Tor anonymous network is shown schematically in the illustration:
Step 3
When the user starts the Tor anonymous network client, the latter connects to the Tor servers and gets a list of all available nodes. Out of a large number of relays (about 5000), only three are randomly selected. Further data transmission is carried out through these three random nodes, and it is carried out sequentially from the "upper" relay to the "lower" one.
Step 4
Before sending a packet to the first relay in the chain, on the client side, this packet is sequentially encrypted: first for the third node (red arrow), then for the second (green arrow), and finally for the first (blue arrow).
Step 5
When the first relay (R1) receives a packet, it decrypts the topmost level (blue arrow). Thus, the relay receives data on where to send the packet further. The packet is relayed, but with two layers of encryption instead of three. The second and third relays work in a similar way: each node receives a packet, decrypts its "own" layer and sends the packet further. The last (third, R3) relay in the chain delivers the packet to the destination (server) unencrypted. The response from the server similarly follows the same chain, but in the opposite direction.
Step 6
This approach provides more guarantees for anonymity than traditional anonymizers. Anonymity is achieved by hiding the primary source of the package. It is also important that all the nodes participating in the transfer do not receive information about the contents of the packet, but only data about where the encrypted message came from and to whom to transfer it further.
To ensure anonymity, the Tor network uses both symmetric encryption and asymmetric encryption. Each layer uses both methods, which also distinguishes Tor from other anonymizers.
