[the8472]

> The protocol should prioritize donors with high bandwidth over vast storage space.

If you're doing this in bittorrent then you might want a client that's configured to optimize for a different goal than most torrent clients.

Potential goals, somewhat conflicting:

A) keep data with a low mirroring degree available. either this needs to be centrally coordinated or some sort of randomized algorithm where clients pick underseeded torrents but not everyone picks the same

B) bandwidth matching. to not consume more resources than are provided a client maybe should only download 1 piece of data for every N times it uploaded any piece. This is much less greedy than what you'd have in a normal torrent client but ensures that caches themselves don't take up much bandwidth compared to users who actually want to download something. Otherwise a misconfigured cache (e.g. behind NAT) could accidentally always download data without ever giving much back.