Understanding the Torrent File Format and Bencoding

Build Your Own Redis / DNS / BitTorrent / SQLite - with CodeCrafters.

In this video, I delved into the intricacies of dot torrent files, essential for downloading files from the torrent network. Explaining the life cycle and contents of these files, I highlighted their critical role in peer-to-peer sharing. Emphasizing the importance of seeders in keeping torrents alive, I compared the unique incentivization model of BitTorrent with traditional blockchain networks. Furthermore, I elucidated the structure of dot torrent files, including crucial elements like announce URLs, file information, and encoding. Lastly, I outlined the b encoding format used in torrent files, encouraging viewers to explore parsing techniques.

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[joshiatharva]

Great video Arpit! After watching your video I tried writing a bencode encoder and decoder using Javascript. If anyone needs a reference, I've added a medium link in my about section. Thanks!

[japanijoota]

Hi arpit, first of all thank you for making this in depth series.
I created a python script which takes torrent file as an argument and prints its contents after decoding it.
I tested a bunch of torrent files, even the official ubuntu 24.04 torrent file, but I did not find md5sum in any of those.
I also looked at the specification, there is no mention of md5sum in that document. I don't think it is there. I guess it makes sense too, since we are calculating sha1 already, there is no need for much weaker md5sum.
also, in most torrent files, alongside "announce", there is also a key called "announce-list" which contains a list of trackers

[Vikasc]

Hi Arpit,

Great content, thank youuu
Trying to find the Handwritten notes on the site, i couldn't.
Can you please share the link, would be really helpful.
Thanks

[vikassrivastava]

Was about to login, got this video notification, now will login after watching this video 😅

[gunahawk]

Hi bro, iam planning to learn backend then lld and hld, but since iam from python background do you think is it better to learn fastapi ( mircroservices) than django?

[suhanimittal]

Hi, what if at any point of time that tracker is down... wouldn't it be single point of failure?

[JardaniJovonovich]

So, as far as I understand, the torrent file would contain the metadata and the entire data of the file but in Bencoded form as an array of pieces.
So, the torrent client doesn't need seeders to be online, right? Of course, if seeders are online, download might be faster but if they are not then the download speed takes a hit, correct?

[jivanmainali]

but how does client knows where to get torrent file from ??

[deezydoezeet]

I have been nerd-sniped. Now I want to go write the bencode decoder

[adityaparasar]

I recently found your youtube channel, this playlist, this cannel is a gem 😍
Love n respect 🖤🫡