What I want to know is the percentage risk of x malicious nodes to deanonymize a user by controlling the full circuit.
‐‐‐‐‐‐‐ Original Message ‐‐‐‐‐‐‐ On Friday, October 8, 2021 7:35 AM, grarpamp <[email protected]> wrote: > > How can I calculate how much impact X honest Tor relays have? > > Is it better to calculate with bandwidth consumed (250Gbps), despite the > > number of relays (~7000)? > > Basically, I want to get the mathematical equation to this statement: > > I run X Tor relays at Y Mb/s each and by doing so I secure Z % of the Tor > > network! > > Starting thoughts: > > > > - Each “normal” route has three nodes involved: Guard, Middle, Exit > > - I am aware of guard pinning and vanguard protection for middle relay > > pinning > > > > - Maybe it is easier to assume an infinite usage time of the network to > > eliminate guard and vanguard pinning > > > > - I guess the best is to assume a scenario with 1%, 5%, 10%, etc. > > dishonest > > relays > > > > > > My take on this: > > Tor has approximately 7000 relays. > > If I consider a number of 5% malicious relays, this would be: 350 > > My calculation: > > (1/(7000/350))(1/(7000/349))(1/(7000/348)) > > = 0.000123931 > > = 0.0123931% > > > 1. Is my approach correct? > > Generically, assuming you're only running the > exit use case, not the HS onion case. > > You'll probably want to consider some adjustments... > > - There's not 7k exits, only ~1k, but it's a ratio term > so then it only matters if you're expecting different > densities of bad/good across each of the guard/mid/exit roles. > > - There's not 7k guards, only ... . > - tor only uses family, /nn cidr blocks, etc once in a circuit... > effect is not 7k nodes, but G groups made up of 1-N nodes. > Read torspec, scrape consensus, determine the resultant > number G that tor actually gives itself to choose from. > > - Some nodes are down, sleeping, busy, filtered, etc. > - Not all exits serve the clearnet ports you want. > - Circuits expire, nodes rotate, etc. > > > 2. Not every relay has the same bandwidth. How could I change the > > calculation to make it more realistic? > > > > Read torspec, scrape consensus, determine how tor is > allocating clients across its bandwidth gravity well, etc. > See also... > https://metrics.torproject.org/ > > > 3. How can I add the effect of guard fixation? > > 4. How can I include the effect of mid-node fixation by the vanguard? > > You didn't really define exactly what attack ("dishonesty") > you're trying to model, so these settings could render you > anywhere from safe, to having no effect and thus still being > subject to the exploit. > > See also... > https://anonbib.freehaven.net/ > https://git.torproject.org/torspec/
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