Magnet link

from Wikipedia, the free encyclopedia

A magnet link is a URI standard for hyperlinks that refer to files. It contains at least one unique identifier ( hash value ) of the target file, on the basis of which the location of the linked file can be resolved by means of a (possibly decentralized) database. Magnet links allow you to refer to one or more files without having to worry about where they are stored or the reference becoming invalid. They are used in particular in connection with peer-to-peer networks. Magnet links should therefore be viewed more as URNs and less as URLs , as they do not identify the location but the content.

Clear description

A magnet link is comparable to an ISBN (book number) in the sense that only certain content is identified (a “resource”). Two different files practically never have the same magnet link, but the same file that is found in different places on the Internet always has the same hash sum in its magnet link (and thus the central identification block in the link is identical). It's the same as with ISBNs: two different books never have the same ISBN, but a particular book always has the same location-independent identifier.

use

In contrast to the ISBN (book numbers), magnet links are automatically generated from the file content. No central organization is required to assign numbers. For this reason, they serve as a “guaranteed valid” search term in peer-to-peer networks, which guarantees that nothing other than the file intended by the link distributor is actually downloaded.

Another advantage of using magnetic links is their ease of use and platform independence . The same Magnet-Link can be used for download in a wide variety of applications on almost any operating system . Because magnet links are short and precise, they can easily be named in e-mails with the help of copy-and-paste or inserted as lines of text when chatting , which is not so easy with BitTorrent files , for example . They can also be used on the Internet instead of normal URLs in websites and simply integrated with the help of the HTML link code.

technical description

Unlike other types of links ( e.g. HTTP or FTP ), the magnet link is not a Uniform Resource Locator (URL), but a different type of Uniform Resource Identifier (URI), called Uniform Resource Name (URN), because it does not designate the location of the resource so that it can be obtained directly. In peer-to-peer networks this means that the resource must first be searched for in order to find one or more so-called “sources” from which the file can be obtained. For this reason, use file sharing user mainly magnet links, the only one hash value to identify include the file. However, that is not the only option. Storage locations or alternative HTTP , FTP and other Internet sources can also be specified in order to avoid or limit the search effort. Here is an example of a fully qualified magnet link:

Magnet-icon.gif magnet:?xt=urn:sha1:YNCKHTQCWBTRNJIV4WNAE52SJUQCZO5C

In this example, the reference only contains a SHA1 hash value that uniquely identifies a file or resource. It does not describe where this resource can be found. A suitable search system is required to be able to access the file, for example the computer network of a peer-to-peer program.

Magnet-icon.gif magnet:?xt=urn:bitprint:XZBS763P4HBFYVEMU5OXQ44XK32OMLIN.HGX3CO3BVF5AG2G34MVO3OHQLRSUF4VJXQNLQ7A
&xt=urn:ed2khash:aa52fb210465bddd679d6853b491ccce
&xl=6745696
&dn=Shareaza_2.4.0.0.exe
&as=http://www.freebase.be/g2/dlcount.php?sha1=XZBS763P4HBFYVEMU5OXQ44XK32OMLIN

This example is a complete magnet link that contains SHA1, TTH and eD2k hash values ​​as well as the size and name of a file. The link also uses the Freebase.be cache, which is not unlike a BitTorrent tracker , in order to be able to find sources for the download more quickly.

Various parameters in the form of name-value pairs are permitted in the Magnet-Link system. Here are the most important:

  • xtstands for " exact topic " and is followed by a URI.
  • xsstands for “ exact substitute ” and is followed by a URL, thus corresponds to the classic hyperlink .
  • asstands for “ acceptable substitute ” and can xsspecify alternatives .
  • ktstands for “ keyword topic ” and means that resources with this file name are to be searched for using keywords. The keywords are separated with plus signs.
  • dnstands for " display name " and typically indicates the file name, more precisely a name under which the resource is presented.
  • mtstands for “ manifest topic ” and uses a URL to indicate the location of a list (ie a file) in which the actual links are then located.

The Magnet-URI standard was further developed in the encrypting e-mail client and instant messenger GoldBug into a format in order to be able to pass on encryption values ​​similar to a sheet of blood values. A magnetic URI to enter an encrypted chat room then sees e.g. B. as in this format: 

magnet:?rn=Spot-On_Developer_Channel_Key&xf=10000&xs=Spot-On_Developer_Channel_Salt&ct=aes256&hk=Spot-On_Developer_Channel_Hash_Key&ht=sha512&xt=urn:buzz

Overview of Magnet URI standards for cryptographic values

Abbreviation example designation
rn & rn = Spot-On_Developer_Channel_Key Room name
xf & xf = 10000 Exact Frequency
xs & xs = Spot-On_Developer_Channel_Salt Exact Salt
ct & ct = aes256 Cipher Type
hk & hk = Spot-On_Developer_Channel_Hash_Key Hash key
ht & ht = sha512 Hash type
xt = urn: buzz & xt = urn: buzz Magnet for IRC chat
xt = urn: starbeam & xt = urn: starbeam Magnet for sending files
xt = urn: institution & xt = urn: institution Magnet for the e-mail inbox

This standard for cryptographic values ​​is used to exchange symmetric keys for group chat or e-mail inboxes in the p2p network or for encrypted file transfers.

Distribution of files

To distribute a file using magnet links, the distributing user creates the magnet link, usually a P2P client. He then distributes this link, for example, via websites, email or chat. If the receiving user uses the link, his client usually resolves it without the need for a central server using distributed hash tables and / or network searches. If at least one file location is found, the download can begin.

Programs

A small selection of programs that can use Magnet URI links:

Individual evidence

  1. ↑ Note: Line breaks have been added to the link text for better formatting.

Web links