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parkman

Using info hash to download files

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Hi, I am new to the forum so I would just like to say hello to every-one. I hope that I have not posted this question in the wrong place.

As a user of utorrent for quite a long time I have always used either magnet links or just downloaded files with a torrent link. I have never used the info hash links and i would admit to not really understanding how to use them. Would some-one be kind enough to write an example of how to use the links, with a sort of "blow by blow" account. When I find an info hash on a website relating to, say, a film, what do I do with the info hash ? I know that I need to enter it in utorrent somewhere and then download files but as I said earlier I honestly don't really know how to do this, or where to copy the information.

I have seen some information on the web but it generally seems to be directed to people who already know the basics. I would just like to get to know the basics, first.

Any assistance would be very welcome,

parkman

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The answer to "Using info hash to download files" is, ... You don't.

The infohash is a MD5 schecksum used to verify the the file(s) are the correct ones and have not been altered since the hash was created.

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Hi, thanks for the reply ciaobaby. The only problem is, as happens on many forums, the reply is a bit smart. I have already said that I have never used info hash to download files, and that I don't really know what the idea of info hash is, and I don't mind admitting to being ignorant of the use of info hash; but I don't need to be told in a smart way that I don't use the info hash to download files. I asked for some assistance because I don't know how they work. That is supposed to be the idea of forums - to ask for advice and assistance if you don't have the answers yourself, not get smart answers from other users. Thanks for replying, Perhaps some-one else out there may have a more constructive answer.

parkman

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Hi, torrents have an infohash that represents the torrent as a whole with all its files (it's actually a hash of the "info" section of the original torrent file), and is calculated using SHA1 encryption. There is also a "hashtable" that has an SHA1 hash for each piece of the file and the pieces are verified as the finish downloading, and are discarded if they fail to match the hash, indicating something wrong was transmitted to you.

You said you already use magnet links -- well - then you already download torrents using their infohash, since that is how Magnet URNs are used with Bittorrent.

A Bittorrent magnet URN, at minimum, looks like this:

magnet:?xt=urn:btih:[infohash here, no brackets]

Here is a magnet link as advertised for the current release of Arch Linux:

magnet:?xt=urn:btih:e940a7a57294e4c98f62514b32611e38181b6cae&dn=archlinux-2013.01.04-dual.iso&tr=udp://tracker.archlinux.org:6969&tr=http://tracker.archlinux.org:6969/announce

The above link works with uTorrent, but it is not an example of a trackerless magnet link (one of the main unique features of using Magnet links to begin with).

It can be shortened to:

magnet:?xt=urn:btih:e940a7a57294e4c98f62514b32611e38181b6cae

magnet:?xt=urn:btih:e940a7a57294e4c98f62514b32611e38181b6cae

in order to "go trackerless". Notice how the only info uTorrent is provided is the infohash.

THIS is how you download using only an infohash. You type a link like this, with the deseired hash, either into a browser window and submit it or in uTorrent you can use File>Add torrent from URL (or the equivalent Ctrl-U) and submit it there.

LT

edit: corrected to indicate the correct hash algorithm, SHA1.

edit: clarified that an infohash is a hash of part of a torrent file. I learn as I go :)

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Hi Lovetour, very many thanks for a decent and informative post. I often wondered whether I was better using the info hash text to download, than a magnet connection. Sometimes I have noticed that there might be an info hash tag on a torrent download site, when there might be no magnet link. I will try using the information that you have described as an alternative, just to see how it works.

Very many thanks again,

parkman

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