On Wed, Oct 14, 2020, 11:03 PM Karl <[1]gmkarl@gmail.com> wrote:

   On Wed, Oct 14, 2020, 10:48 PM Peter Fairbrother <[2]peter@tsto.co.uk>
   wrote:

     On 14/10/2020 23:59, Karl wrote:
     >
     >
     > On Wed, Oct 14, 2020, 6:34 PM Peter Fairbrother wrote:
     >     To put some BOTE numbers on that, suppose you want to provide
     for 1
     >     million concurrent users. You have about 150 TB per month user
     traffic
     >     to play with (500 x 1TB, ~3 hops), 150 MB per month per user,
     or 450
     >     Baud.
     >
     >
     > Could you explain your math here?  How did 500TB/3 (am I wrong?)
     become
     > 150MB?
     There are 500 raspberry pi's, each on the end of a 1TB/month link.
     That's 500 TB/month total traffic, but dividing by 3 we get
     approximately 150 TB/month user traffic.

   How about more routers if there are more users?

     With a million users at any time that's 150TB user traffic per
     month:
     divided by 1 million users that's 150MB per user per month.
     As they are concurrent users (the total number of users is higher,
     but
     at any time 1 million users are using the service) that is 150
     million
     bytes per month per user divided by 2,592,000 seconds per month,
     which
     is 58 bytes per second per user or 463.32 baud.
     Looked at another way, if people always used an anonymity service
     the
     hops would multiply their traffic by say 5 times (3 times as in TOR
     is
     not enough). Covertraffic and file size

   I'm curious why you believe it to be not enough (two seems good enough
   to my quick guesses if traffic is constant, but I can't think worth
   beans); I'm happy to look at a reference.

   I thought about this a bit, realised some strong danger of only two
   hops, and realised that more hops are needed if an adversary is running
   many nodes.  Brings ideas of blockchains, trust metrics,
   friend-to-friend networks.
   Bandwidth is /5.

     padding traffic would at least
     double that, so we would need at least 10 times the normal traffic
     the
     users created.

   I propose constant rate: cover traffic reduces as legitimate traffic
   increases.  Would this work, do you think?

     And you ned a lot of traffic through your anonymisation network to
     get
     decent anonymity, you need a large anonymity set.
     Web traffic is expensive - making it at least ten times more
     expensive
     is not on, especially if nine tenths of it has to be paid for by
     someone
     else.
     That's not counting the servers etc - getting a pi to handle 386
     kB/s
     [1] of anonymity traffic is not trivial, I don't even think it is
     possible.

   Mmm might need good bare metal algorithms.  Easier to use the client
   device which has more CPU.

     [...]
     > Enforcing TLS is much more reasonable nowadays.  (You could add a
     plugin
     > to use http tricks to hide file sizes.). Not what I would focus on
     once
     > it gets nonsimple.
     A good proportion of TOR traffic will be protected by TLS anyway,
     especially those sites which you might not want other people to know
     you
     are accessing.
     Visible file sizes are the main anonymity weakness in TOR.
     If you suspect someone you compare the file sizes of the traffic
     through
     their system with traffic through the exit nodes.

   Wouldn't using chaff to make your transfer rate relatively constant
   close almost all of this anonymity attack surface?

     In the UK at least it is legally fairly easy for the cops to demand
     that
     info (and most ISPs are legally required to obtain and store that
     data
     anyway) - getting everyone's traffic info where the cops have no
     suspect
     is a little harder, but not impossible.
     Of course the ordinary cops don't use that power, and the people who
     do
     use it don't want it known that they can do it, so you will find
     that
     they make up stories about reused passwords and the like being the
     source of their information.
     Peter Fairbrother
     [1] 1TB/month divided by 2,592,000s/month

References

   1. mailto:gmkarl@gmail.com
   2. mailto:peter@tsto.co.uk