If piracy is moral and ethical and enables us to share knowledge, why do private trackers gatekeep this knowledge? It goes against the principles of piracy. Do they do it just to feel superior about bring in a sekrit club?
It's fairly trivial to craft a dummy file that has the same hash as any given file, the chance of that happening randomly is infinitesimal, hence the usefulness of hashing, but it has been done in the past as a way to poison torrents.
Huh, there has been a detected SHA1 hash collision in 2017. But unless your malicious actor is the NSA it’s unlikely they would be able to crack the hash