https://en.wikipedia.org/wiki/Magnet_URI_scheme
https://ru.wikipedia.org/wiki/Magnet-%D1%81%D1%81%D1%8B%D0%BB%D0%BA%D0%B0

https://en.wikipedia.org/wiki/Magnet_URI_scheme#Clients

bit torrent info hash
https://ru.wikipedia.org/wiki/Magnet-%D1%81%D1%81%D1%8B%D0%BB%D0%BA%D0%B0#BTIH_(BitTorrent_Info_Hash)
magnet:?xt=urn:btih: