In order to understand how Tor Network works, you first need to have basic picture of how the regular network works, or even more basic – how the internet works.
If a Person A, for example, wants to send a message to a Person B, or just wants to access a webpage hosted on Person’s B computer, the Person A will then have to make a data package which will include: the message and the IP address of both the sender and the recipient.
The data package will then travel from Person’s A computer carrying the information to Person’s B computer through a series of routers connected to each other, and making the global network, aka – the internet.
One major disadvantage of this system is that anyone who has access to any of the routers can intercept the data package, read the Person’s A message, as well as both sender’s and recipient’s IP addresses.
Understandably, if the Person A is sending some personal or confidential information, he definitely doesn’t want the contents of the message to be revealed by a wrong person; or even have his identity revealed by wrong people.
This is when The Onion Router Network, otherwise known as the Tor Network, comes in handy.
How does Tor work?
Tor Network consists of a series of trusted routers called nodes. In order to use Tor Network, you need to download TOR browser bundle and extract it on your computer.
Now let’s get back to our Person A – let’s assume he’s downloaded the Tor browser, configured it correctly and now he’s ready to send that same message to the Person B. Tor browser will automatically connect to Tor Network and use its nodes as some sort of secret or hidden network of tunnels.
As in the previous case, sending a message will create the data package. Only, this time, before the message is sent it goes through three mathematical encryptions.
And, what exactly is the mathematical encryption?
You can imagine mathematical encryption like putting a certain message in a box together with its encryption key. The end result – you get a totally different message or a messy code. To decipher the message you simply use the key and reverse the process; meaning that the person who wants to read the message will need the encrypted message and its decryption key. Otherwise it would be hard, almost impossible to decipher it, because the key is made of a series of complex mathematical operations.
Tor browser, however, takes things on a whole new level encrypting a message three times! Each time using a different encryption key.
Basically, the whole process looks like this: it simply takes the original message and encrypts it – it now becomes the encrypted message #1. Then, it takes the message #1 and encrypts it again, this time using a different encryption key – we get message #2. It does the same for the third time using new encryption key and the final product of this process is message #3.
Now, the Person’s A initial data package contains the encrypted message #3 and information about the sender and the recipient. And while the sender IS the Person A, the recipient is NOT the Person B, but the first node, otherwise known as the entry node.
The entry node, receives the decryption key for message #2, decrypts it and the product is message #2, which contains the sender’s address – the entry node, and the recipient address – the second node, also known as the middle node.
The middle node gets its own decryption key for message #2, decrypts it and the final product is message #1, which contains the senders address which is the middle node, and the recipient address which is the third node, also known as the exit node.
When the message #1 reaches the exit node; the exit node decrypts it and the final product is the original message. NOW the recipient is the Person B and the exit node is really the sender.
The whole process of revealing the encrypted information layer by layer resembles onion peeling, hence the term The Onion Router.
To get more information on how it all works, below is an infographic for your reference, courtesy of Tor official website:
This isn’t something new – it existed even before the computers did. As a matter of fact, during the World War II, the German military was sending encrypted messages to communicate overseas using just the radio transmission.
Advantages of using Tor browser
The main advantage of this complex system is that the Person A can send his message to the Person B without the possibility to be tracked down. Because, if someone tries to intercept the message on its way to the Person B, the interceptor would need to have the access to ALL three nodes in order to track down the sender; for, each node only leads to its recipient and its sender. Meaning, the exit node leads to the Person B and the middle node; the middle node leads to the exit node and the entry node; and the entry node leads to the middle node and the Person A.
In short, there is very little chance for anyone to be able to track all three nodes. Optionally, a sender can use more than three nodes.
Who else uses Tor Network?
Tor Network is a great tool for keeping anonymity and privacy intact. Many non- governmental organizations use Tor for communicating when they are outside of their counties. People who have bans on some portions of the internet use it too, like people in China and Syria. Journalists also use Tor for interviewing the confidential sources, so-called whistleblowers, whose anonymity is essential.
But, according to some studies, the main usage of Tor Network lies in obtaining and distributing of illegal pornography and drugs, unfortunately. That’s the main reason for all the negative connotations surrounding the Tor Network.
Disadvantages of using Tor browser
There are, however, a few disadvantages in using the Tor Network.
First of all, speed. The maximum speed between each of the nodes is less than 256 Kbps, and the latency is way too high. This basically means that you are getting anonymity at the expense of speed. The other disadvantage concerns some troubles involving the exit nodes. Many of them are unreliable; and if you are sending confidential information in your message, it can be easily compromised. As mentioned earlier, if someone succeeds in accessing all three nodes and the decryption keys, sender’s identity can be tracked down. So, many users recommend using VPN with Tor Network.