Tor (The Onion Router, "The bulbous router") — set of proxy servers, the decentralized anonymizer. Thanks to Tor the user has an opportunity to maintain anonymity on the Internet. The name "bulbous router" was given because of the principle of network functioning: it is based on the basis of "levels", the same as the bulb consists of the leaves imposed at each other. How does Tor work?
Instruction
1. The Tor anonymous network consists of so-called "nod" (English nodes), also the term "rayleigh" (English relays) can be applied to designation of participants of network. Each rayleigh represents the proxy server capable to accept and send data. Any user, having configured the client of Tor, can turn the PC into a note, i.e. into an element of a chain of network. The package from the client to the server goes not directly, and through the chain consisting of three accidentally selected nod.
2. Approximate path which passes each package in the Tor anonymous network is schematically presented on an illustration:
3. When the user starts the client of the Tor anonymous network, the last is connected to the Tor servers and receives the list of all available nod. The rayleigh (about 5000) is in a random way selected from a large number only three. Further data transmission is carried out on these three accidental notes, and it is carried out consistently from more "top" rayleigh to more "lower".
4. Before sending a package to the first rayleigh in a chain, on client side there is a consecutive encryption of this package: in the beginning for the third note (red arrow), then for the second (a green arrow) and, at last, for the first (a blue arrow).
5. When the first rayleigh (R1) accepts a package, it makes interpretation of the most top level (blue arrow). Thereby the rayleigh obtains data on that, it is required to send a package far further. There is a relaying of a package, but already to two layers of encryption instead of three. Work of the second and third rayleigh happens the same way: each note receives a package, decrypts "the" layer and sends a package further. The last (the third, R3) the rayleigh in a chain delivers a package in a point of assignment (server) unencrypted. The answer from the server similarly passes on the same chain, but in the opposite direction.
6. Such approach provides more guarantees for anonymity, than traditional anonymizers. The anonymity is reached because primary source of a package disappears. Also the fact that all notes participating in transfer do not obtain information on the maintenance of a package, and only data on that from where the encrypted message came and to whom to transfer him further is important.
Both symmetric encryption, and asymmetric is applied to ensuring anonymity in Tor network. Each layer uses both methods that also favourably distinguishes Tor from other anonymizers.