Atomic Charge is a seeding-only BitTorrent client.

The torrent protocol is designed to negotiate peers for file transfer (via trackers or DHT) dynamically. This guarantees a fair distribution of the pieces among all peers. Atomic Charge sends to a single peer exclusively.

Say you have downloaded a file from a torrent and want a friend of yours to receive it too. Instead of initiating a direct connection to your friend you can augment her torrent download -- and hers only. Thereby she will fetch the file from your uplink and the swarm. All you need for this to work is a common torrent file, its finished files, your friend's IP and her listening port.

Example:

• You download beach_party.torrent, containing beachparty.avi.
• Your friend expresses interest in the file.
• Your friend connects to the torrent, downloading the file with the same speed as you did.
• Your friend tells you his torrent client is listening on the default port, 6881, from his IP 10.11.12.13.

• You start charging your friend:

  ./atomic_charge.py beach_party.torrent beachparty.avi 10.11.12.13 6881

• Your friend receives the file much faster. Yay!

The unfair game resulting from this behaviour stems directly from a flaw in the torrent protocol: peers announce their download status to other peers in a private connection. The swarm does not necessarily receive full, let alone consistent, data; clients accept pieces (parts of a file) from any interesting peer. The peer to peer nature of the torrent protocol allows you to communicate with a single peer only if you chose so.