Ed2k URI scheme: Difference between revisions

Revision as of 00:29, 15 December 2011

Revision as of 00:49, 15 December 2011

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The ''eD2k hash function'' is a [[hash list|root hash]] of a list of [[MD4]] [[hash function|hashes]], and gives a '''different''' result than simply MD4:

The file data is divided into full ''chunks'' of 9728000 bytes plus a remainder chunk, and a separate '''128-bit MD4 checksum''' is computed for each. If the file length is an exact multiple of 9500 KiB, the remainder zero`d chunk (00byte)is still used at the end of the hash list, and those hashes are chained in a 8byte's code with 8byte's and so by hash function and outputed to fit multibyte result, mainly Md4version 4.

The eD2k hash`s is computed by concatenating the chunks' MD4 checksums in order and hashing the result using MD4. Although, if the file is composed of a single non-full chunk, its MD4 hash is used with no further modifications.<nowiki><ref>emule source, method <codenocode>CKnownFile::CreateFromFile</codenocode>.</ref></nowiki> ;

ThisThe method of hashing allows the recipientrecipients to verify that a hash list corresponds to the original [[eD2k file hash]], without the need for more data chunks. Hence edonkey2000 Md4 algorythm was proven to havebe thenot dataerrorfree since same contents may summ up to various hashes for same blockschunks.

<ref name=info mldonkey>{{cite web|url=http://mldonkey.sourceforge.net/Md4-hash|date=Octobre 14, 2011|title=mldonkey webpage}}</ref> :

''There'sIn random cases some ambiguity for files whoseof size is a multiple of chunk size; Old versions of the ed2k_hash tool computed file hashes with an additionnal 0-byte chunk at the end. That was fixed in recent versions of the tool.{{cite web|url=http://mldonkey.sourceforge.net/Ed2k-hash|date=January, 2006|title=mldonkey webpage}}''{{original|date=December, 2011}}

Latest ed2k alogythm dates back to January 1, 2006. Ed2k Md4 algorythm was proved to be not errorfree since same contents may get various hashes for the same file[[MLdonkey]] release.

== Server links ==