[tor-dev] Proposal: Merging Hidden Service Directories and Introduction Points

Nicholas Hopper hopper at cs.umn.edu
Mon Jul 20 18:42:04 UTC 2015

Hi Aaron,

On Fri, Jul 17, 2015 at 4:54 PM, A. Johnson
<aaron.m.johnson at nrl.navy.mil> wrote:
>> This proposal doubles the default number of IPs and reduces the "cost"
>> of being an IP since the probability of being selected is no longer
>> bandwidth-weighted.  Is this a fair tradeoff for the performance
>> improvement?
> That seems easy to fix. Make the number of Introduction Points the same as it was before and make them be selected in a bandwidth-weight way. There is no cost to this. You need IPs to be online, and so whatever number was used in the past will yield the same availability now. And bandwidth-weighting should actually improve both performance and security.

Is it obvious how to build a bandwidth-weighted DHT that is stable
across changes in the consensus?  One advantage of using the hash ring
is that the loss of an HSDir causes only local changes in the
topology, so if the client is using a different version of the
consensus they can still locate one of the responsible HSDirs.  (Note:
I do not claim this cannot be done; it just seems like an important
detail to sort out...)

Nicholas Hopper
Associate Professor, Computer Science & Engineering
University of Minnesota

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