TorrentFormat

TorrentFormat refers to the specific structure and content of a .torrent file, which is a metadata file used by the BitTorrent protocol. This file does not contain the actual content being shared, but rather information about that content, such as the names and sizes of files, and crucially, the cryptographic hashes of the individual pieces of the files. These hashes are essential for verifying the integrity of the downloaded data.

A .torrent file is essentially a dictionary, encoded using the bencode format. Key elements include the 'announce' URL, which points to a tracker server that helps peers find each other. It also contains a 'info' dictionary, which holds details about the files. For single-file torrents, 'info' includes the 'length' of the file and its 'piece length', along with a 'pieces' field containing the concatenated hashes of each piece. For multi-file torrents, 'info' includes a 'files' list, where each entry specifies the 'length' and 'path' of a file. The 'piece length' is also defined here, and the 'pieces' field similarly contains the concatenated hashes.

When a BitTorrent client opens a .torrent file, it uses the information within to connect to the tracker, download metadata, and begin requesting pieces of the actual data from other peers. The hashes stored in the .torrent file are then used to verify that each downloaded piece is complete and uncorrupted, ensuring the integrity of the final downloaded files.