I use the exact same mechanism for four years now to locally distribute content among digital signage devices. The advantage of that scheme is that pairs that e

I use the exact same mechanism for four years now to locally distribute content among digital signage devices. The advantage of that scheme is that pairs that exactly know (by hash) which content they want to retrieve can do so from other pairs that already have the content locally available. All without revealing anything about the content to pairs that don't know the hash. I'm sure the same mechansim has been used before elsewhere?