#STEVEN L. TRIBLER TORRENT#

torrent file size within reason for large files, the piece size can be increased, meaning each hash represents a larger portion of the file. In most cases, the piece hashes is the bulk of the size of. torrent file/metadata (in the info-dictionary). In BitTorrent v1, pieces are hashed and the resulting hashes are included in the. More on this later, under backwards compatibility. It means that fundamentally a v2 torrent will be identified by a different hash than a v1 torrent, which would always create a separate swarm, even when sharing the same files. This was one of the original rationales for creating a v2 protocol to begin with. To handle this, DHT- and tracker announces and lookups for v2 torrents use the SHA-256 info-hash truncated to 20 bytes. In BitTorrent v2, the info-dictionary is also computed by SHA-256, which poses a compatibility challenge with the DHT and trackers, which have protocols that expect 20 byte hashes. One consequence of this is that hashes are 32 bytes instead of 20 bytes. The hash function for piece data was changed to SHA-256. This post describes the new features of the BitTorrent v2 protocol. Given a new hash function would not be backwards compatible, a few other changes were proposed as well, while we were taking the compatibility hit anyway.

What is BitTorrent v2?īitTorrent v2 kick-started with an effort to transition away from SHA-1 as the hash function for pieces, shortly after google announced having produced a collision.

BiglyBT also has an implementation of BitTorrent v2 to be released in the near future. The libtorrent support for bittorrent v2 was mostly implemented by Steven Siloti. Most of the specification work of BEP 52 was done by the8472. One of them is support for BitTorrent v2. Libtorrent-2.0 has just been released with a few major new features.

Steven l. tribler