Torrent Files

Torrent files (aka metainfo files) contain a list of trackers and metadata for the file to download

• Use .torrent file extension
• Acts like a table of contents

Schema

• announce - URL of the tracker
• info - A dictionary with the following keys:
  • files: A list of dictionaries, with each dictionary corresponding to a file
    • Only exists when multiple files are being shared
    • Each of these dictionaries has 2 keys:
      • length - Size of the file in bytes
      • path - A list of strings (the components of the file path)
  • length - Size of the file in bytes
    • Only when one file is being shared
  • name - Suggested file name or directory name
  • piece length - Number of bytes per piece
    • Must be a power of 2
    • Must be at least 16KiB
  • pieces - A list of the hashes for every piece of the data
    • If the torrent contains multiple files, pieces formed by concatenating all files in the order they appear in the directory
    • The last piece may be shorter than the full piece length
    • BitTorrent uses SHA-1, which returns a 160-bit hash

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Information taken from How Does BitTorrent Work? A Plain English Guide