> This has been in LimeWire for a while. All users set the same
> non-standard connect string.
Except that you can't revoke one person's access without resetting the
connect string for the entire network.
What I'm thinking of is a paid gateway to a filesharing node. There is an
application-level requirement that the specific user account isn't known
to the server.
An example solution that's not quite right is a secret sharing threshold
scheme. There's a file which is split into K chunks, and any of N (where
N is a constant that's less than K) chunks can be combined to reassemble
the file. For the challenge, the server would emit a version of the file
as reassembled with N-1 chunks. The user would add their one chunk,
pushing the total reassembly up to the threshold, but not allowing the
server to know which of the missing N-K-1 chunks was used to do it.
Hm. This is a traditional secret sharing threshold scheme where N happens
to be 1. That's gibberish, but it's just an example to clarify what I'm