Hello nusenu, DocTor and OrNetRadar detected that someone added 60 tor relays [1] with your email address in the contact info field on 2017-08-08 between 15:45 and 16:01 UTC. [1] https://nusenu.github.io/OrNetRadar/2017/08/08/a7.html <https://nusenu.github.io/OrNetRadar/2017/08/08/a7.html> Since tor relay contact information is not authenticated I was wondering if these are in fact your relays? (I guess they are) Yes indeed they are ours. We started them all at the same time to make it clear that they are all run but one group of researchers. You obviously don't have to answer but if you want to I'm curious: Are these just temporary relays and part of your research or are they here to stay to increase the capacity of the tor network for more than just a few weeks or months? I assume you are not planing to run them for a longer period of time (>6months), but if you do you: Please consider network diversity when adding that amount of tor relay capacity. All your relays are operated in AS "Online S.a.s" - which is already the second biggest AS in terms of tor network capacity. At this stage we are not planning to run it for more than 6 months or so (but this might change). We understand that your concern is primarily about capacity diversity not trust in "Online S.a.s" since anyway it's already the second largest provider for Tor relays. Our experiments are not related to the traffic (and since all our relays are part of the same family at most one of them would be used in any circuit). We are using Online S.a.s because it it is cheap (I guess it's the same reason why others use it). We will check in the next couple of days if there is an alternative low cost provider. We have also limited our bandwidth but can increase it if more people express interest and it can help (we didn’t want to look like we are trying to attract/intercept traffic). +-----------------------------+-------------+ | AS Name | CW Fraction | +-----------------------------+-------------+ | OVH SAS | 15.95 | | Online S.a.s. | 13.41 | | Hetzner Online GmbH | 7.74 | | Digital Ocean, Inc. | 6.65 | | myLoc managed IT AG | 2.63 | +-----------------------------+-------------+ Also the country (FR) is not ideal from a diversity point of view. :) 14 of our relays are in the Netherlands but will make sure to diversify if we have to restart them. thanks for running relays, nusenu Note: There is nothing wrong with adding 60 tor relays, especially with proper MyFamily configuration as you did. Thank you for the positive note and feedback!
On Thu, Aug 10, 2017 at 07:53:03PM -0400, privacy@ccs.neu.edu wrote:
We are using Online S.a.s because it it is cheap (I guess it's the same reason why others use it). We will check in the next couple of days if there is an alternative low cost provider.
If I understand the threat model for your "every relay encrypts its share, and then you do threshold decryption of the aggregate total" design, having even a few relays at some other ISP would make it a lot harder for the one ISP to attack all of the shares, right? Maybe you can spin up one relay at each research institution, for some diversity? :) That said, I'm not too worried here. The information you're protecting in this case isn't by itself that dangerous to publish, so the complicated privcount scheme is a great layer to add on top but the world doesn't end if it fails. So if you wanted to add some more relays to make the "distributed trust" angle more distributed, great, and if you don't, we can treat it as a good lesson to learn for next time.
We have also limited our bandwidth but can increase it if more people express interest and it can help (we didn???t want to look like we are trying to attract/intercept traffic).
Interesting question! I can see pros and cons. The two big topics are: 1) If you raise the bandwidth on each of them by enough, then they'll end up getting the Guard flag, so you'll attract clients directly, and your relays will be in a better position to attack them. 2) If you raise the bandwidth, then the total fraction of the Tor network that your relays handles go up. I'm tempted to say "as long as you stay at 2-3% of the total network you'll be fine", but the fact that they're all at an already overpopulated ISP makes me pause. --Roger
On Aug 11, 2017, at 4:50 AM, Roger Dingledine <arma@mit.edu> wrote:
On Thu, Aug 10, 2017 at 07:53:03PM -0400, privacy@ccs.neu.edu wrote:
We are using Online S.a.s because it it is cheap (I guess it's the same reason why others use it). We will check in the next couple of days if there is an alternative low cost provider.
If I understand the threat model for your "every relay encrypts its share, and then you do threshold decryption of the aggregate total" design, having even a few relays at some other ISP would make it a lot harder for the one ISP to attack all of the shares, right?
It is slightly different but basically the same spirit. We use a group key such that none of the three teams can decrypt alone. One key thing is that each relay only has the group public key and encrypts the counters. So the logged counters are encrypted and neither the ISP neither one/two of the teams can decrypt them. Another important point is that besides the encrypted counters the information available to the relays is the same as for any other relay running on the ISP. Here, whatever the ISP can do to our relays, he can also do to the other relays running on its infrastructure.
Maybe you can spin up one relay at each research institution, for some diversity? :)
Based on this discussion, we have started the process to move 20 relays to at least one of the institutions. Hopefully, this increase diversity in terms of capacity and trust.
That said, I'm not too worried here. The information you're protecting in this case isn't by itself that dangerous to publish, so the complicated privcount scheme is a great layer to add on top but the world doesn't end if it fails.
Yes.
So if you wanted to add some more relays to make the "distributed trust" angle more distributed, great, and if you don't, we can treat it as a good lesson to learn for next time.
Yes, we are working on it.
We have also limited our bandwidth but can increase it if more people express interest and it can help (we didn???t want to look like we are trying to attract/intercept traffic).
Interesting question! I can see pros and cons.
The two big topics are:
1) If you raise the bandwidth on each of them by enough, then they'll end up getting the Guard flag, so you'll attract clients directly, and your relays will be in a better position to attack them.
Yes, and we might ourselves become a more desirable target.
2) If you raise the bandwidth, then the total fraction of the Tor network that your relays handles go up.
I'm tempted to say "as long as you stay at 2-3% of the total network you'll be fine”,
That sounds good. We’ll keep it in mind.
but the fact that they're all at an already overpopulated ISP makes me pause.
Hopefully, the planned relays will help. In anycase, we will most likely keep the bandwidth low for now. Guevara
participants (2)
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privacy＠ccs.neu.edu -
Roger Dingledine