[chhs]

A v2 torrent allows clients to identify duplicate files across torrents via the "pieces root" entry in the metadata, so if they're downloading from torrent A and B, and each share file C, they can utilize peers from either swarm.

But there's no way for other clients to know that there exists another torrent containing the file they are interested in if they only have the metadata for torrent A. In other words, there's no lookup mechanism for a "pieces root" to know that torrent B exists and contains file C.

If you were to make a v2 torrent of your entire drive, other clients won't know to download from your torrent. They'd need to have the contents of the metadata to know it would contain a file they are interested in, and have no way of knowing which metadata contains the desired "pieces root" entries without downloading all of them.

I'm very interested in this problem space, if you are aware of clients/mechanisms that allow for this I would love to hear them.

[jychang]

I don't think you can solve this problem, without destroying the system by releasing too much data.

If I find a torrent of a file, and can look up all the seeders across all torrents for this file... then so can the FBI.

[londons_explore]

> there's no lookup mechanism for a "pieces root" t

I guess they'd just have to publish each pieces root in the DHT. And obviously you would let the user decide which directories to share...

I guess that'll have to wait for torrent v3...

[justshowpost]

This.

Also, advertising every file in torrent (of unsuspecting user) to entire world would be a HUGE privacy flaw.

[londons_explore]

But you already advertise (via the DHT, which offers no secrecy) the torrent file... and that contains all the data needed to get all the files within the torrent.

So this data is already being published, just in a less queryable form.