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I personally believe that Tor is compromised. I have been saying this for several years. The amount of bandwidth it consumes, and the reliance on honest entranc

I personally believe that Tor is compromised. I have been saying this for several years. The amount of bandwidth it consumes, and the reliance on honest entrance and exit nodes, means it is assured that three-letter agencies run the whole network. I’m confident the government can demask users on demand as needed. I would love a counterpoint to my opinion but given that public honest nodes have trivial donations I don’t understand who can afford to support this network other than incentivized agencies.

nabla9 8y ago
How does Tor rely on honest exit nodes?
- zcid 8y ago
  Basically, if you control the entry and exit nodes of a user, you can correlate their traffic. So, if a group had control of large numbers of servers, eventually (faster or slower depending on what proportion of tor servers they controll) they would be able to view a targeted user's traffic.
Retric 8y ago
That’s not nessisarily relevant. In WWII most codes where cracked, but little of this information was used as the assumption was keeping the secret is generally more valuable than using the information. If in practice those agencies leave users alone then the polite fiction provides very useful cover. Sure, if you’re trying to sell a stolen nuclear weapon then don’t use it. But for stolen credit cards it’s probably very safe in practice.
- a11595 8y ago
  It is absolutely relevant, it is your point that is not. Random drug dealers are not the Germans, and there is no war. They arrest shady people using tor all the time, and if tor is compromised, they can use parallel construction to hide their use of tor.
- dta5003 8y ago
  This is where "parallel construction" comes into play. https://en.wikipedia.org/wiki/Parallel_construction https://en.wikipedia.org/wiki/Parallel_construction The entity using the information works backwards to construct a plausible fake chain of events which is acceptable to a court and hides the true source of the information.
devwastaken 8y ago
I've wondered the same. bandwidth is still very expensive at scale. How TOR exit nodes could afford it years ago is a mystery to me. There's some ISP's that host their own in europe, but aren't there still expensive charges when all that bandwidth goes out of their network?
- throwaway2048 8y ago
  It is extraordinarily cheap at scale, you can buy a gigabit port that you can blast at 1000mbit all day, every day, forever for around $300 a month (which comes out to about 300 TB of traffic in a month). If you stick with providers like AWS or Amazon, sure its absurdly expensive, but its yet another way they have a huge amount of markup.
jstanley 8y ago
This doesn't matter. If you use your residential internet connection you're definitely not anonymous. If you use Tor you're maybe not anonymous. That's still better.
- seibelj 8y ago
  Tor has convinced the average user that it is a black box that protects them and this is gravely untrue. It may be safer than your residential ISP but the level of security it claims to provide is simply false. Like I said, I would appreciate someone explaining why I’m wrong but I’ve been closely following Tor for years and I haven’t seen anything to refute my opinion.
  - jstanley 8y ago
    Sure, maybe you're right. Maybe Tor is compromised. I'm not saying you're wrong. I don't know. But what are you going to do? Not use Tor? That's surely worse.
    - artursapek 8y ago
      His point is that Tor is a honey pot because people will use it for stuff that they wouldn't even do on their residential internet. It's not an argument of better or worse.
  - gye 8y ago
    Where does Tor claim to do more than it can? Can you point at any specific statement? Compared to anything else in that space, I always liked how Tor does not promise magic, but is actually pretty open about its weaknesses. Most of what comes up as "new discovery of a weakness" is actually already covered in the original design paper and FAQ.
  - kodablah 8y ago
    > Like I said, I would appreciate someone explaining why I’m wrong but I’ve been closely following Tor for years and I haven’t seen anything to refute my opinion. That's gonna be tough, as the network would be broken if we could show you're wrong. Anonymity means you don't know. I've also been closely following for years and haven't seen anything to support your opinion. I believe most Tor nodes are run by aliens and haven't seen anything to refute it. Not saying you shouldn't be cautious about anonymity, aliens, or whatever, but to tell everyone it's non-anonymous, intergalactic, etc and wait to be convinced by your own standards you're wrong doesn't help the practical user. Curious though, if a popular non-nefarious app that used Tor were to emerge and communicated only on onion services (i.e. no exit nodes) and most users (i.e. non-mobile) were also relays, do you think that would help reduce the percentage of surveillance relays enough to feel comfortable? Or are there any ways that you could feel comfortable in a popular, anonymous, distributed network environment that most participants weren't surveillers?
arkadiyt 8y ago
One possible counterpoint is that the FBI took over and ran a child pornography onion service in 2015 [1] in order to deliver malware to visitors and demask them. This suggests that at least the FBI does not have the capability to demask users on demand. [1]: https://motherboard.vice.com/en_us/article/qkj8vv/the-fbis-unprecedented-hacking-campaign-targeted-over-a-thousand-computers https://motherboard.vice.com/en_us/article/qkj8vv/the-fbis-u...
- ng12 8y ago
  Couldn't it have been parallel construction? They wanted convictions without revealing that Tor has been compromised.
  - rictic 8y ago
    There were strong suspicions of parallel construction in the Silk Road case, where the US government was able to track down the Silk Road's servers despite its use of TOR. One article: https://krebsonsecurity.com/2014/10/silk-road-lawyers-poke-holes-in-fbis-story/ https://krebsonsecurity.com/2014/10/silk-road-lawyers-poke-h...
    - EGreg 8y ago
      Read Tarbell’s deposition https://archive.org/stream/pdfy-LsKJJAOvP4fDfuhV/Ulbricht%20Criminal%20Complaint_djvu.txt https://archive.org/stream/pdfy-LsKJJAOvP4fDfuhV/Ulbricht%20... Or TLDR read some news article from the time http://mag.newsweek.com/2013/10/11/crossing-swords-with-pirates-in-cyberspace.html http://mag.newsweek.com/2013/10/11/crossing-swords-with-pira...
- nickpsecurity 8y ago
  Well, they also lied they couldn't break into that iPhone to try to get a court ruling that made it unnecessary to use expensive contractors or secret exploits. They lied that cryptography is blocking them a lot in general when the data shows that's rare. The NSA also had attacks on most mobile OS's, backdoors in ISP's, and so on feeding stuff to FBI who supposedly had no such capabilities. Btw, the big ISP's being backdoored with high-bandwidth, Tor nodes on same networks drawing people to use them is about the worst-case scenario for Tor. Global visibility into traffic patterns on top of huge, attack budget for partial or full defeats of the technology. Plus lots of storage to keep as much encrypted traffic as they can as long as they can. That lets them hit today's systems or encrypted data with future attacks. I assume NSA sees it all. I assume the FBI gets a part of it which will grow over time, concealing how they got the information. I did anonymous activities using equipment bought in cash over WiFi and HTTPS-looking connections to blend in with the less-interesting crowd. If worried about publicity, use cantennas so folks can't see your face on camera. Preferably suburban areas with more empty space and trees than cameras. Maybe Tor, too, but just don't use it anywhere near devices or a residence that's obviously yours.
jchw 8y ago
If you are using Tor for unencrypted connections to the internet, then sure, the security is going to depend entirely on the honesty of the nodes. But what about when no exit nodes are involved, when you connect to hidden services? And if your underlying connection is properly encrypted, then the most that could be divuldged is metadata. You'd have to believe the U.S. government has also broken popular crypto, and I believe that if that were the case we would've never seen things like Dual EC DRGB. Even powerful quantum computers could only weaken cryptographic algorithms, if my understanding of Shor's algorithm is accurate, so you could always use paranoid-sized keys or post-quantum cryptographic algorithms. The folks that work on and support Tor are by all accounts some fairly intelligent people. It is obviously very possible the whole network is compromised, but it would be very impressive if it was compromised and nobody ever found out. I think software like Tor-based IM is still useful even in the event that the network is compromised to some degree.
- seibelj 8y ago
  You should operate on the assumption that a significant fraction of the Tor nodes are hostile. The value is simply too high not to operate that way. Given that, I would at a minimum route your network through an anonymous VPN (or two) before touching the Tor network. It all depends on your opsec requirements but don’t be a naïve fool - Tor is not a magic anonymity service. It has pros and cons like everything else.
  - metildaa 8y ago
    Where can I get such an "anonymous" vpn? The VPN providers are selling the traffic logs and/or charging you in a traceable way, while Tor literally routes you through multiple VPN servers (aka Tor Relays) to mitigate this risk.
    - toufiqbarhamov 8y ago
      Pay for your VPN with privacy coins or run your own VPN. Of course the unethical and illegal method is to compromise a number of systems to route traffic, but obviously that’s problematic.
nickysielicki 8y ago
Timing attacks especially. https://security.stackexchange.com/questions/147402/how-do-traffic-correlation-attacks-against-tor-users-work https://security.stackexchange.com/questions/147402/how-do-t... The referenced Tor Project blog post, "One cell is enough to break Tor's anonymity", was written in 2009, prior to any Snowden revelations about the scale and scope of state-level actors to see the entirety of the global networks. AFAIK, Tor still refuses to have nodes add random delays and random padding, etc. to make this style of analysis more difficult, but I am just going off what I researched a few years ago, so I could be wrong.
- gye 8y ago
  Tor already "pads" to cell size. There is ongoing work towards better padding. Look at WTF-PAD for more. It is surprisingly difficult to improve padding effectively, and you just can't add delays to TCP streams. Tor is not "refusing to add" either of those things. A more recent and thorough real world analysis of the traffic correlation problem is https://www.freehaven.net/anonbib/#ccs2013-usersrouted https://www.freehaven.net/anonbib/#ccs2013-usersrouted . In general, that site has a lot of great papers on these topics.
  - nickysielicki 8y ago
    > you just can't add delays to TCP streams. Why not? I'm talking about shuffling queues such that it cannot be determined that a given node is relaying traffic in the order that it receives it. This is how most packet shaping works, no? At a minimum, I would expect Tor to be more secure by having nodes: * Not process traffic in the order in which its received, obfuscating the cause-and-effect of a packet being received and a packet going out * Pad traffic substantially with garbage such that the outgoing size cannot be associated with whatever came in, potentially splitting packets in half so that they can appear smaller than they actually are, forking around many different nodes. * Sending lots of random garbage traffic between relays such that input and output is meaningless overall, perhaps relaying packets to several nodes needlessly, when only a single node is instructed to actually do something with it. To my knowledge, Tor doesn't do any of this and has explicitly ruled out the possibility because they're more concerned with usability than security. And maybe that's the right call to make in the end, I don't know enough to say. I'm just saying that it's possible to imagine a system like Tor that is more secure than Tor, and that's something worth talking about. I'll check that link out, thanks for posting it.
usernymous 8y ago
I don't really know whether the government of my country knows I use TOR (i use obfs4) and whether he can "correlate" sites i visit. If i'm of such interest to him, he can knock at my door and get all my computers : i will give him without any resistance. Because the fact is that i use TOR to be anonymous and escape data mining by dangerous Big Companies : i can elect a government and should give him access to part of my data needed to be a citizen of my country, but i never elect thoses dangerous companies that steal and sell data, violate privacy, accumulate large data set about us behind our backs to cross-annalyse and compute who know why we didn't ask or envisage ... Governments are supposed to be accountable, companies are not unless we publicly discover they did something wrong.
gye 8y ago
This can be refuted pretty easily, on various grounds. One, you are assuming that all parties interested in deanonymizing Tor collaborate. As you say: agencies, not agency. The design makes sure that you do not need to trust any node in particular. The damage individual nodes can do are small and basically amount to temporary denial of service for non-exits (which clients will quickly route around) and messing with your traffic as exit (which becomes less and less of a problem as everything moves to e2e, and https is improved/hardened with key pinning etc). The remaining problem is statistical correlation, where studies show it is actually not trivial to perform and takes time and repetitive behavior. Your argument also assumes that everyone is immediately fucked when one powerful adversary can break the anonymity. This will very rarely be the case in real scenarios, where "the NSA" will just not care about you, but plenty of other actors might. By spreading not necessarily false but very simplified claims, you are drawing users who don't know better to systems where they will be clearly much worse off! The list of relays is public. There are actually surprisingly few exits that carry most of the traffic, which yes, is a weakness, but that weakness is still stronger than anything else you could compare it to. You can look at the large operators like universities and nonprofits like www.torservers.net, their relays, and you will see that it does not take that big of a budget to run the majority of all exits in terms of total capacity. Is is much easier even to contribute high bandwidth entry nodes -- again, feel free to check the largest non-exits in terms of capacity, and investigate the motives. It's all public information.
- seibelj 8y ago
  My understanding is that Tor is not a permissioned network. This means that anyone can run a node without asking for anyone’s approval. If this is the case, a trivial amount of money in terms of the USA defense budget ($100mil - $1 bil) could be spent to selectively reveal entities that the gov finds worthy of arrest. Everyone be careful, nothing is as simple as it seems. Notice how I’m responding to an anonymous user. This is expected.
  - gye 8y ago
    Again, very simplified. The design makes sure everyone knows about the same network. The network is being monitored by independent folks constantly, and you cannot just ramp up lots of capacity without anyone noticing. Not only the current state, all past states of the network are recorded. You also make it sound like there would be an alternative design, like a closed set of operators. Now, that would obviously be worse than an open system. All you need is two non collaborating entities in your path. Note how I am trying to convince you with facts, whereas you point to my preference of anonymity as something that makes them less worthwhile. Such ad hominem attacks should be avoided in serious discussions, thanks. I value my anonymity.
EGreg 8y ago
Any network where a single server somewhere runs a domain is not going to be reliable. People can use timing attacks to figure out who is running what. SAFE Network is much better, as was stuff like Freenet and PerfectDark.
LMYahooTFY 8y ago
So if you've been following Tor closely for years, you've presumably decided you don't trust Roger Dingledine? I say this partly as an appeal to his authority (which I'll argue is not insignificant), but I don't mean it in an aggressive way. I don't know him personally, and I can't say very precisely how much trust I have in his claims. With that said, he's claimed that he personally knows a substantial number of relay operators by volume, and there is significant pressure from certain levels of the US executive branch on the Tor Project to either compromise or abandon development of the Tor network in order to stop child porn. Of course, he could be entirely unaware that the relay operators he knows are compromised or are simply federal agents, or he could be himself. But I think these, among other pieces of information, must be contended with to develop a theory that tor is entirely compromised. For instance, there are claims that people within the intelligence community use and rely on tor for their own work.
laser 8y ago
Definitely could be, but they must have gone through the trouble of setting up a larger number of little nodes if that's the case, as a lot of the largest exit nodes on the network have known operators. For example, as of a few weeks ago, a friend/grad students put up a top 5 (by bandwidth) in the US in the Media Lab at MIT, and a different friend ran a top 10 out of an MIT dorm room a few years ago before eventually getting shut down by admins. Fortunately, this one will likely stay up as it's under Joi Ito's purview now.
jerheinze 8y ago
> I personally believe that Tor is compromised. I have been saying this for several years. The amount of bandwidth it consumes, and the reliance on honest entrance and exit nodes You obviously never bothered to look at who runs relays: https://metrics.torproject.org/rs.html https://metrics.torproject.org/rs.html Plus Tor's threat model already assumes that some nodes are compromised: https://www.torproject.org/projects/torbrowser/design/#adversary-positioning https://www.torproject.org/projects/torbrowser/design/#adver... And as others pointed out, the oft-stated "using Tor is better than not" applies.
belorn 8y ago
There are multiple counterpoints but most can be summed up that there is no strong argument in favor or either so that one has to fall back on a personal default. Bandwidth consumption in Tor is not that big at 300Gbit/s. While its not perfectly comparable, a 1gbit/s connection residential connection cost about $100 a month. Imagining 300 users, or rather 7000 servers, is really not that big for a community project by volunteers. Naturally this finding is a double edge sword, as it also mean it is not costly for a nation to become the majority owner of all servers if they wanted to. Bandwidth is cheap. It is so cheap that one ISP has started to roll out 10Gbit/s for residential use. 7000 nodes are nothing for high bandwidth nations, and its not without reason that some over represented nations in the Tor network match those that subsidized broadband infrastructure. Sweden is about as big as UK but with 1/6 of the population. Germany is twice the size of US (https://metrics.torproject.org/bubbles.html#country https://metrics.torproject.org/bubbles.html#country). I do not think cost is relevant to the question. Any agencies of any nation could afford it. The question really is if they would bother, and if they could continuously do it stealthy enough to not rouse suspicion. Its rather know that the hardest security to do is to run operation security continuously without mistakes. In additional we have leaks from inside (Snowden, Manning), internal politics, and I personally do not think it is likely that they would have managed to run perfectly stealthy for 16 years. I would give them the benefit of the doubt that any given year they could take over it, but once they do it won't take too long until it is detected.

nabla9 8y ago

How does Tor rely on honest exit nodes?

zcid 8y ago
Basically, if you control the entry and exit nodes of a user, you can correlate their traffic. So, if a group had control of large numbers of servers, eventually (faster or slower depending on what proportion of tor servers they controll) they would be able to view a targeted user's traffic.

Retric 8y ago

That’s not nessisarily relevant. In WWII most codes where cracked, but little of this information was used as the assumption was keeping the secret is generally more valuable than using the information. If in practice those agencies leave users alone then the polite fiction provides very useful cover. Sure, if you’re trying to sell a stolen nuclear weapon then don’t use it. But for stolen credit cards it’s probably very safe in practice.

a11595 8y ago
It is absolutely relevant, it is your point that is not. Random drug dealers are not the Germans, and there is no war. They arrest shady people using tor all the time, and if tor is compromised, they can use parallel construction to hide their use of tor.
dta5003 8y ago
This is where "parallel construction" comes into play. https://en.wikipedia.org/wiki/Parallel_construction https://en.wikipedia.org/wiki/Parallel_construction The entity using the information works backwards to construct a plausible fake chain of events which is acceptable to a court and hides the true source of the information.

devwastaken 8y ago

I've wondered the same. bandwidth is still very expensive at scale. How TOR exit nodes could afford it years ago is a mystery to me. There's some ISP's that host their own in europe, but aren't there still expensive charges when all that bandwidth goes out of their network?

throwaway2048 8y ago
It is extraordinarily cheap at scale, you can buy a gigabit port that you can blast at 1000mbit all day, every day, forever for around $300 a month (which comes out to about 300 TB of traffic in a month). If you stick with providers like AWS or Amazon, sure its absurdly expensive, but its yet another way they have a huge amount of markup.

jstanley 8y ago

This doesn't matter. If you use your residential internet connection you're definitely not anonymous. If you use Tor you're maybe not anonymous. That's still better.

seibelj 8y ago
Tor has convinced the average user that it is a black box that protects them and this is gravely untrue. It may be safer than your residential ISP but the level of security it claims to provide is simply false. Like I said, I would appreciate someone explaining why I’m wrong but I’ve been closely following Tor for years and I haven’t seen anything to refute my opinion.
- jstanley 8y ago
  Sure, maybe you're right. Maybe Tor is compromised. I'm not saying you're wrong. I don't know. But what are you going to do? Not use Tor? That's surely worse.
  - artursapek 8y ago
    His point is that Tor is a honey pot because people will use it for stuff that they wouldn't even do on their residential internet. It's not an argument of better or worse.
- gye 8y ago
  Where does Tor claim to do more than it can? Can you point at any specific statement? Compared to anything else in that space, I always liked how Tor does not promise magic, but is actually pretty open about its weaknesses. Most of what comes up as "new discovery of a weakness" is actually already covered in the original design paper and FAQ.
- kodablah 8y ago
  > Like I said, I would appreciate someone explaining why I’m wrong but I’ve been closely following Tor for years and I haven’t seen anything to refute my opinion. That's gonna be tough, as the network would be broken if we could show you're wrong. Anonymity means you don't know. I've also been closely following for years and haven't seen anything to support your opinion. I believe most Tor nodes are run by aliens and haven't seen anything to refute it. Not saying you shouldn't be cautious about anonymity, aliens, or whatever, but to tell everyone it's non-anonymous, intergalactic, etc and wait to be convinced by your own standards you're wrong doesn't help the practical user. Curious though, if a popular non-nefarious app that used Tor were to emerge and communicated only on onion services (i.e. no exit nodes) and most users (i.e. non-mobile) were also relays, do you think that would help reduce the percentage of surveillance relays enough to feel comfortable? Or are there any ways that you could feel comfortable in a popular, anonymous, distributed network environment that most participants weren't surveillers?

arkadiyt 8y ago

One possible counterpoint is that the FBI took over and ran a child pornography onion service in 2015 [1] in order to deliver malware to visitors and demask them. This suggests that at least the FBI does not have the capability to demask users on demand. [1]: https://motherboard.vice.com/en_us/article/qkj8vv/the-fbis-unprecedented-hacking-campaign-targeted-over-a-thousand-computers https://motherboard.vice.com/en_us/article/qkj8vv/the-fbis-u...

ng12 8y ago
Couldn't it have been parallel construction? They wanted convictions without revealing that Tor has been compromised.
- rictic 8y ago
  There were strong suspicions of parallel construction in the Silk Road case, where the US government was able to track down the Silk Road's servers despite its use of TOR. One article: https://krebsonsecurity.com/2014/10/silk-road-lawyers-poke-holes-in-fbis-story/ https://krebsonsecurity.com/2014/10/silk-road-lawyers-poke-h...
  - EGreg 8y ago
    Read Tarbell’s deposition https://archive.org/stream/pdfy-LsKJJAOvP4fDfuhV/Ulbricht%20Criminal%20Complaint_djvu.txt https://archive.org/stream/pdfy-LsKJJAOvP4fDfuhV/Ulbricht%20... Or TLDR read some news article from the time http://mag.newsweek.com/2013/10/11/crossing-swords-with-pirates-in-cyberspace.html http://mag.newsweek.com/2013/10/11/crossing-swords-with-pira...
nickpsecurity 8y ago
Well, they also lied they couldn't break into that iPhone to try to get a court ruling that made it unnecessary to use expensive contractors or secret exploits. They lied that cryptography is blocking them a lot in general when the data shows that's rare. The NSA also had attacks on most mobile OS's, backdoors in ISP's, and so on feeding stuff to FBI who supposedly had no such capabilities. Btw, the big ISP's being backdoored with high-bandwidth, Tor nodes on same networks drawing people to use them is about the worst-case scenario for Tor. Global visibility into traffic patterns on top of huge, attack budget for partial or full defeats of the technology. Plus lots of storage to keep as much encrypted traffic as they can as long as they can. That lets them hit today's systems or encrypted data with future attacks. I assume NSA sees it all. I assume the FBI gets a part of it which will grow over time, concealing how they got the information. I did anonymous activities using equipment bought in cash over WiFi and HTTPS-looking connections to blend in with the less-interesting crowd. If worried about publicity, use cantennas so folks can't see your face on camera. Preferably suburban areas with more empty space and trees than cameras. Maybe Tor, too, but just don't use it anywhere near devices or a residence that's obviously yours.

jchw 8y ago

If you are using Tor for unencrypted connections to the internet, then sure, the security is going to depend entirely on the honesty of the nodes. But what about when no exit nodes are involved, when you connect to hidden services? And if your underlying connection is properly encrypted, then the most that could be divuldged is metadata. You'd have to believe the U.S. government has also broken popular crypto, and I believe that if that were the case we would've never seen things like Dual EC DRGB. Even powerful quantum computers could only weaken cryptographic algorithms, if my understanding of Shor's algorithm is accurate, so you could always use paranoid-sized keys or post-quantum cryptographic algorithms. The folks that work on and support Tor are by all accounts some fairly intelligent people. It is obviously very possible the whole network is compromised, but it would be very impressive if it was compromised and nobody ever found out. I think software like Tor-based IM is still useful even in the event that the network is compromised to some degree.

seibelj 8y ago
You should operate on the assumption that a significant fraction of the Tor nodes are hostile. The value is simply too high not to operate that way. Given that, I would at a minimum route your network through an anonymous VPN (or two) before touching the Tor network. It all depends on your opsec requirements but don’t be a naïve fool - Tor is not a magic anonymity service. It has pros and cons like everything else.
- metildaa 8y ago
  Where can I get such an "anonymous" vpn? The VPN providers are selling the traffic logs and/or charging you in a traceable way, while Tor literally routes you through multiple VPN servers (aka Tor Relays) to mitigate this risk.
  - toufiqbarhamov 8y ago
    Pay for your VPN with privacy coins or run your own VPN. Of course the unethical and illegal method is to compromise a number of systems to route traffic, but obviously that’s problematic.

nickysielicki 8y ago

Timing attacks especially. https://security.stackexchange.com/questions/147402/how-do-traffic-correlation-attacks-against-tor-users-work https://security.stackexchange.com/questions/147402/how-do-t... The referenced Tor Project blog post, "One cell is enough to break Tor's anonymity", was written in 2009, prior to any Snowden revelations about the scale and scope of state-level actors to see the entirety of the global networks. AFAIK, Tor still refuses to have nodes add random delays and random padding, etc. to make this style of analysis more difficult, but I am just going off what I researched a few years ago, so I could be wrong.

gye 8y ago
Tor already "pads" to cell size. There is ongoing work towards better padding. Look at WTF-PAD for more. It is surprisingly difficult to improve padding effectively, and you just can't add delays to TCP streams. Tor is not "refusing to add" either of those things. A more recent and thorough real world analysis of the traffic correlation problem is https://www.freehaven.net/anonbib/#ccs2013-usersrouted https://www.freehaven.net/anonbib/#ccs2013-usersrouted . In general, that site has a lot of great papers on these topics.
- nickysielicki 8y ago
  > you just can't add delays to TCP streams. Why not? I'm talking about shuffling queues such that it cannot be determined that a given node is relaying traffic in the order that it receives it. This is how most packet shaping works, no? At a minimum, I would expect Tor to be more secure by having nodes: * Not process traffic in the order in which its received, obfuscating the cause-and-effect of a packet being received and a packet going out * Pad traffic substantially with garbage such that the outgoing size cannot be associated with whatever came in, potentially splitting packets in half so that they can appear smaller than they actually are, forking around many different nodes. * Sending lots of random garbage traffic between relays such that input and output is meaningless overall, perhaps relaying packets to several nodes needlessly, when only a single node is instructed to actually do something with it. To my knowledge, Tor doesn't do any of this and has explicitly ruled out the possibility because they're more concerned with usability than security. And maybe that's the right call to make in the end, I don't know enough to say. I'm just saying that it's possible to imagine a system like Tor that is more secure than Tor, and that's something worth talking about. I'll check that link out, thanks for posting it.

usernymous 8y ago

I don't really know whether the government of my country knows I use TOR (i use obfs4) and whether he can "correlate" sites i visit. If i'm of such interest to him, he can knock at my door and get all my computers : i will give him without any resistance. Because the fact is that i use TOR to be anonymous and escape data mining by dangerous Big Companies : i can elect a government and should give him access to part of my data needed to be a citizen of my country, but i never elect thoses dangerous companies that steal and sell data, violate privacy, accumulate large data set about us behind our backs to cross-annalyse and compute who know why we didn't ask or envisage ... Governments are supposed to be accountable, companies are not unless we publicly discover they did something wrong.

gye 8y ago

This can be refuted pretty easily, on various grounds. One, you are assuming that all parties interested in deanonymizing Tor collaborate. As you say: agencies, not agency. The design makes sure that you do not need to trust any node in particular. The damage individual nodes can do are small and basically amount to temporary denial of service for non-exits (which clients will quickly route around) and messing with your traffic as exit (which becomes less and less of a problem as everything moves to e2e, and https is improved/hardened with key pinning etc). The remaining problem is statistical correlation, where studies show it is actually not trivial to perform and takes time and repetitive behavior. Your argument also assumes that everyone is immediately fucked when one powerful adversary can break the anonymity. This will very rarely be the case in real scenarios, where "the NSA" will just not care about you, but plenty of other actors might. By spreading not necessarily false but very simplified claims, you are drawing users who don't know better to systems where they will be clearly much worse off! The list of relays is public. There are actually surprisingly few exits that carry most of the traffic, which yes, is a weakness, but that weakness is still stronger than anything else you could compare it to. You can look at the large operators like universities and nonprofits like www.torservers.net, their relays, and you will see that it does not take that big of a budget to run the majority of all exits in terms of total capacity. Is is much easier even to contribute high bandwidth entry nodes -- again, feel free to check the largest non-exits in terms of capacity, and investigate the motives. It's all public information.

seibelj 8y ago
My understanding is that Tor is not a permissioned network. This means that anyone can run a node without asking for anyone’s approval. If this is the case, a trivial amount of money in terms of the USA defense budget ($100mil - $1 bil) could be spent to selectively reveal entities that the gov finds worthy of arrest. Everyone be careful, nothing is as simple as it seems. Notice how I’m responding to an anonymous user. This is expected.
- gye 8y ago
  Again, very simplified. The design makes sure everyone knows about the same network. The network is being monitored by independent folks constantly, and you cannot just ramp up lots of capacity without anyone noticing. Not only the current state, all past states of the network are recorded. You also make it sound like there would be an alternative design, like a closed set of operators. Now, that would obviously be worse than an open system. All you need is two non collaborating entities in your path. Note how I am trying to convince you with facts, whereas you point to my preference of anonymity as something that makes them less worthwhile. Such ad hominem attacks should be avoided in serious discussions, thanks. I value my anonymity.

EGreg 8y ago

Any network where a single server somewhere runs a domain is not going to be reliable. People can use timing attacks to figure out who is running what. SAFE Network is much better, as was stuff like Freenet and PerfectDark.

LMYahooTFY 8y ago

So if you've been following Tor closely for years, you've presumably decided you don't trust Roger Dingledine? I say this partly as an appeal to his authority (which I'll argue is not insignificant), but I don't mean it in an aggressive way. I don't know him personally, and I can't say very precisely how much trust I have in his claims. With that said, he's claimed that he personally knows a substantial number of relay operators by volume, and there is significant pressure from certain levels of the US executive branch on the Tor Project to either compromise or abandon development of the Tor network in order to stop child porn. Of course, he could be entirely unaware that the relay operators he knows are compromised or are simply federal agents, or he could be himself. But I think these, among other pieces of information, must be contended with to develop a theory that tor is entirely compromised. For instance, there are claims that people within the intelligence community use and rely on tor for their own work.

laser 8y ago

Definitely could be, but they must have gone through the trouble of setting up a larger number of little nodes if that's the case, as a lot of the largest exit nodes on the network have known operators. For example, as of a few weeks ago, a friend/grad students put up a top 5 (by bandwidth) in the US in the Media Lab at MIT, and a different friend ran a top 10 out of an MIT dorm room a few years ago before eventually getting shut down by admins. Fortunately, this one will likely stay up as it's under Joi Ito's purview now.

jerheinze 8y ago

> I personally believe that Tor is compromised. I have been saying this for several years. The amount of bandwidth it consumes, and the reliance on honest entrance and exit nodes You obviously never bothered to look at who runs relays: https://metrics.torproject.org/rs.html https://metrics.torproject.org/rs.html Plus Tor's threat model already assumes that some nodes are compromised: https://www.torproject.org/projects/torbrowser/design/#adversary-positioning https://www.torproject.org/projects/torbrowser/design/#adver... And as others pointed out, the oft-stated "using Tor is better than not" applies.

belorn 8y ago

There are multiple counterpoints but most can be summed up that there is no strong argument in favor or either so that one has to fall back on a personal default. Bandwidth consumption in Tor is not that big at 300Gbit/s. While its not perfectly comparable, a 1gbit/s connection residential connection cost about $100 a month. Imagining 300 users, or rather 7000 servers, is really not that big for a community project by volunteers. Naturally this finding is a double edge sword, as it also mean it is not costly for a nation to become the majority owner of all servers if they wanted to. Bandwidth is cheap. It is so cheap that one ISP has started to roll out 10Gbit/s for residential use. 7000 nodes are nothing for high bandwidth nations, and its not without reason that some over represented nations in the Tor network match those that subsidized broadband infrastructure. Sweden is about as big as UK but with 1/6 of the population. Germany is twice the size of US (https://metrics.torproject.org/bubbles.html#country https://metrics.torproject.org/bubbles.html#country). I do not think cost is relevant to the question. Any agencies of any nation could afford it. The question really is if they would bother, and if they could continuously do it stealthy enough to not rouse suspicion. Its rather know that the hardest security to do is to run operation security continuously without mistakes. In additional we have leaks from inside (Snowden, Manning), internal politics, and I personally do not think it is likely that they would have managed to run perfectly stealthy for 16 years. I would give them the benefit of the doubt that any given year they could take over it, but once they do it won't take too long until it is detected.