Friday, June 17, 2005

Interesting. If you look at TorrentSpy right now, 2 seeders are supporting 143 downloaders.

If you're not up on the Bittorrent thing, allow me a massive geek out here. The idea is that one or more computers have the whole file: the "seed". The seeder sends one of the downloading computers a chunk of data. Then, chunk finished, the seeder sends a second computer a second chunk. Meanwhile, the first downloader uploads the chunk it has to, say, the second downloader, while the second downloader uploads its chunk to the first downloader. The seeder has now uploaded the two chunks once, but both downloaders have both chunks.

And so on: the seeder sends a third chunk to a third downloader, which shares it with the first two, in exchange for the first two chunks. The seeder is only responsible for getting each chunk it has to one downloading computer; the downloading computers copy these chunks amongst themselves. The protocol is careful to duplicate efficiently: each downloading computer asks for the rarest chunk of data from whoever has it. So, theoretically, two seeders would only need to upload half the file each to get all of the file into the common file-sharing ring; after that, they can ditch with no ill effect, because all the chunks of data are in play.

Under the old system (e.g. Napster), a central computer had to upload the file to each downloader requesting it. Under the Bittorrent protocol, one seed can service as many downloaders as there are, with no addition strain, so long as the seeder uploads each chunk of the file at least once.

The original Bittorrent protocol required one computer to "track" all the chunks, but the new (Beta) Bittorrent allows each computer to take no some of the tracking.

This has got to have the Chinese Communist Party having fits, if they get it. It is utterly subversive. There is no central hub you can shut down. The seeder can email a torrent file to a few friends, upload the data file, and then scram.

The Soviet dissidents used to get a copy of a banned book, type up their own copy, and then pass both copies along; this was called samizdat. With a lot of dedication and effort, valued books could slowly print themselves, multiplying at a binary rate. This allows effortless overnight multiplication of very large data files (a book is no more than 300KB; John's pilot is 450MB).

Needless to say this will also be a very good tool for terrorists, fanatics and crooks. Remember when Khomeini toppled the Shah by analog cassette tapes copied from tape player to tape player?

Anything that helps subvert oppressive authority can also be used to subvert legitimate authority. Well, you can't stop progress. Look how unsuccessful they've been at stopping public key encryption.

It's a brave new world we live in. Brace yourselves.

10:34 AM

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