Why TOR does not guarantee anonymity

Why TOR does not guarantee anonymity

TOR uses servers called nodes between your computer and the target server you want to access.
For example, if you want to access http://www.google.com, we'll call it node E.
You are node A, and your data will go through node B also called the input node, then C and finally D which are all scattered somewhere in the world.
Until then it's simple, our IP address is hidden because Google will only see the IP address of the last node, which also called the output node, before reaching the target server. It will only see the IP address of node D.
The problem is that the data between the last node, so here D and the target server are not encrypted.
Google can see the data as plain text.
So there is no problem using a computer as an output node to sniff the traffic and analyze it before it reaches the server.
The solution is to use SSH to encrypt this data between the last node and the server, which is not done by default.

The NSA case

The NSA (National Security Agency) uses node servers too. It is therefore possible for them to analyze the traffic.
The traffic can be registered but they must know which server the data comes from.
That's why NSA servers synchronize with each other using a specific header or structure.
It is not 100% guaranteed that they will find the original computer but the possibility is not excluded either.

Finally, we remember when the FBI hit hard by hacking a website to inject malicious JavaScript code:
"A vulnerability in Firefox has been used by the FBI to stop an amateur child pornographer. The TOR network itself was not compromised, but JavaScript code was injected into some web pages visited by users. A malware was then executed to contaminate the computer of the victims. This same malware communicated outside Tor the real IP address of the target, this time to locate it without worries. "
This code was used to create a direct connection between the initial computer and the FBI server, thus directly giving the IP address of the wanted person.

Hard to say that this is a scandal, the FBI probably had a good reason to do so. That said, the individual who does not do anything wrong may feel spied out of proportion. Not to mention the fact that he finds himself surrounded by cyber criminals.

Anonymity is not guaranteed
You can use TOR as much as you want, if a malicious program runs on your computer, it will recover all your data without any problem.
It should not be forgotten either that TOR does not prevent other ways to retrieve data about you.