Encourage a storage server configuration that enables Zcash shielded donations to storage servers

[exarkun]

Copying some motivation from ​https://tahoe-lafs.org/trac/tahoe-lafs/ticket/2264:

why not add incentive for people to participate (i.e. seed) in the network by using bitcoin as inter-node payment system? A client could (auto)setup a wallet containing an amount of coins which could be used to automatically pay servers which store data correctly. This of course will throw up a whole range of problems including the possibility of scamming. The payment model could be somewhat exponential; 1MB for example would cost nothing or something close to that whilst 100GB would cost one a reasonable amount of coins. I believe in order to get reasonable scalability in a network such as LAFS, the goodfeel coming from being part of a network is not enough to compensate for the time and money spent on participating. Especially if LAFS wants to handle data bigger than say a gigabyte.

The basic motivation here seems to have remained valid. However, time has slipped somewhat into the future. These days, it would make sense to implement this idea using Zcash shielded transactions to support properly anonymous exchanges.

One very simple step in this direction (by no means a complete solution) is this documentation-only hack:

Suggest (in the Tahoe-LAFS documentation in a position such that a user configuring a storage server will encounter it) that storage server operators set their storage server nickname to a string of the form zcash:z... where z... is a Zcash shielded address.

Suggest (in the Tahoe-LAFS documentation in a position such that users configuring or operating a client) that clients inspect their web ui (or the equivalent JSON endpoint) to discover the nicknames of storage servers they rely on and, when encountering a nickname like zcash:z... and feeling like supporting the efforts of that server, sending some Zcash from a shielded payer address to the indicated shielded receiver address.

This is all documentation. It's just to put the idea of one way consumers can support providers and to get Zcash folks thinking about Tahoe-LAFS and vice versa. No doubt it would be fantastic to have a more streamlined workflow in the future if this proves to be an area of interest - but that is out of scope for this ticket.

[exarkun]

See ​https://github.com/tahoe-lafs/tahoe-lafs/pull/506

[exarkun]

Fixed in ​https://github.com/tahoe-lafs/tahoe-lafs/commit/844a5ff06410d289677787417ec65acc9550d73f