Q:

Identifying torrented files by reversing info_hash

I've been lead to believe that if you decode the info_hash in a tracker GET request, you are left with the SHA1 hash of the file that is being downloaded.  That makes sense to me but I'm not getting results here.  Does anybody have any experience with this?
info_hash=%ab%10o%22%a8%b0%e2%a4p%27%e2U%d3j%d1F%a0%f7%05%27

This is what I'm currently working with.  Clearly this is URL encoded yet URL decode gives me absolutely nothing to work with.  Where am I going wrong here?
Any help is appreciated.

A:

Nope, you can't easily get the file hash from the infohash. 

The “infohash” is the SHA1 Hash over the part of a torrent file that
  includes:

ITEM:  length(size) and path (path with filename)
Name: The name to search for
Piece length: The length(size) of a single piece
Pieces: SHA1 Hash of EVERY piece of this torrent
Private: flag for restricted access

(See https://stackoverflow.com/questions/28348678/what-exactly-is-the-info-hash-in-a-torrent-file)
If you have all the other components (such as the name of the torrent), you can combine it with the data in each file you are checking, hash the whole thing, and then check if the result is the correct infohash. 

