I am novice to Tor, but before using it I have gone through lot of websites. An article explained that Tor is dangerous the following reason:

  1. Consider an IP which was assigned by Tor to user X and he used it for an illegal activity then he closes his Tor circuit after accomplishing it,
  2. Later an innocent Y comes in and is assigned the same IP by Tor,
  3. If user X is a government suspect and the IP he got at the time of doing illegal activity ( was targeted by the NSA, what would happen to Y when Y retains that IP for a day? Could he be arrested by the NSA because of having though he claim himself as innocent?

This lead the article's author to conclude that Tor is dangerous.

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    Political nitpicking: The NSA doesn't have the authority to make arrests. They do not care about crime either, only about national security. When the NSA has evidence you are a threat to national security, then they might send the FBI (when you are in the US), the CIA (when outside the US) or TSA (when about to cross the US border) after you. – Philipp Sep 20 '15 at 13:52
  • I've edited your post to make it more clear. I also restricted it to the main question (the danger of sharing his IP with a malicious user, actually how Tor is made users X and Y could even share the same IP at the same moment ;) ). Regarding your other question, the anonymity provided by Tor, you could find more information in already answered questions: How does Tor guarantee anonymity of Tor network?, How much can I trust Tor?. – WhiteWinterWolf Sep 20 '15 at 13:52
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    By the way, when talking about an article content, do not hesitate to link it :). – WhiteWinterWolf Sep 20 '15 at 13:56
  • Hi white! many thanks for editing my question and I wasn't mean X & Y sharing same IP I meant after X closed his TOR Circuit X is no longer belongs to that IP later Y open TOR in somewhere around the world there might be possibility of Y getting same IP – RaGa__M Sep 20 '15 at 13:59
  • WBT, how can I move this question? – RaGa__M Sep 20 '15 at 14:06

Regarding the question "Can you be arrested?", yes, you can be arrested all the time. In most countries you can be arrested for looking funny at a police officer. In most countries you will also be released as soon as they have no reason to suspect you anymore. Interesting questions would be would a prosecutor charge you and would those charges hold up in a court. But these are 1. questions for Law Stackexchange and 2. doesn't seem to be what you actually want to know. Your actual question seems to be How likely would it be that I am mistaken for a different Tor user?

Someone who is smart enough to deanonymize Tor users should be smart enough to have a basic understanding of how Tor works. Tor circuits only live for 10 minutes and many users share the same exit node. Deanonymizing a user which accesses service A and seeing that the same exit node also accessed service B is very weak evidence that both accesses came from the same user. When there are more than 10 minutes between both events, its practically no evidence at all.

  • Hi Philip thanks for your reply,I remember I could switch my identity in orbot by swiping the orbot interface screen but in TOR browser I ought to close firefox and open it for getting new IP and so the tor circuit as well am I correct? Though don't you think 10 minutes is enough for NSA to know person Y is beyond – RaGa__M Sep 20 '15 at 14:34
  • And one more thing what would happen when NSA start deanonymyzing process a bit late I.e after X left and Y got – RaGa__M Sep 20 '15 at 14:41
  • @RichardGeorge As I already commented on the question itself: you should stop being so fixated on the NSA specifically. 1. they only care about national security, not petty crime and 2. they aren't the only organization in the world trying to deanonymize TOR users. It's the FBI (or your national equivalent) you should be afraid of. – Philipp Sep 20 '15 at 14:46
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    @RichardGeorge To get a new identity in TOR Browser, click on the onion-icon next to the address bar and select "new identity". Restarting TOR browser also works. – Philipp Sep 20 '15 at 14:48
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    @RichardGeorge yes, "new identity" is the userfriendly description of "build a new TOR circuit" – Philipp Sep 20 '15 at 14:54

There is no risk that you get mistaken for 'the previous user who used this IP address'. Tor is not something like DHCP. There is no mapping between 'users' and 'IP addresses'. At any given time, multiple clients all use the same exit node. Also, the government / the NSA know how Tor works. When they see suspicious traffic from an exit node, they know it can be from any Tor client around the world.


Later an innocent Y comes in ...

It all depends on which precise later we are talking about. According to the official manual, MaxCircuitDirtiness parameter is configured to 10 minutes by default. Also, given the fact Tor does not store your IP address, we can say Tor is not dangerous in the context you are describing.

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