摘自http://wiki.theory.org/BitTorrentSpecification,标题为Bittorrent Protocol Specification v1.0。它比http://www.bitconjurer.org/BitTorrent/protocol.html介绍的详细多了。
Bittorrent Protocol Specification v1.0
Identification
BitTorrent is a peer-to-peer file sharing protocol designed by Bram Cohen. Visit his pages at 
http://www.bitconjurer.org. BitTorrent is designed to facilitate file transfers among multiple peers across unreliable networks.
Purpose
The purpose of this specification is to document version 1.0 of the BitTorrent protocol specification in detail. Bram's protocol specification page http://www.bitconjurer.org/BitTorrent/protocol.html outlines the protocol in somewhat general terms, and lacks behaviorial detail in some areas. The hope is that this document will become a formal specification, written in clear, unambiguous terms, which can be used as a basis for discussion and implementation in the future.
This document is intended to be maintained and used by the BitTorrent development community. Everyone is invited to contribute to this document, with the understanding that the content here is intended to represent the current protocol, which is already deployed in a number of client implementations.
This is not the place to suggest feature requests. For that, please go to the mailing list.
Scope
This document applies to the first version (i.e. version 1.0) of the BitTorrent protocol specification. Currently, this applies to the torrent file structure, peer wire protocol, and the Tracker HTTP/HTTPS protocol specifications. As newer revisions of each protocol are defined, they should be specified on their own separate pages, not here.
Related Documents
http://www.bitconjurer.org/BitTorrent/protocol.html - The official protocol specification.
BitTorrentWishList - A wish list for developers and end users alike.
