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Ed2k-hash: Difference between revisions
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== What's an ed2k hash? == | == What's an ed2k hash? == | ||
In short, a hash is a checksum. It is used to detect errors in data by checking the integrity of the message/file. There are various different hash algorithms used for differing purposes, some that are focused more on security and some on speed. AniDB sports both kinds; CRC is not particularly secure at all, while MD5, SHA-1 and the MD4/ed2k hashes are much more secure from a cryptographic standpoint. They are not | In short, a hash is a checksum. It is used to detect errors in data by checking the integrity of the message/file. There are various different hash algorithms used for differing purposes, some that are focused more on security and some on speed. AniDB sports both kinds; CRC is not particularly secure at all, while MD5, SHA-1 and the MD4/ed2k hashes are much more secure from a cryptographic standpoint. They are not fail-safe though, but having more than one hash makes it exponentially harder to counterfeit a file. You might be able to fool one of the hashes, but generally not two, or as is the case with most of the files found in AniDB: four hashes! | ||
The ed2k hash is based on the ''md4 algorithm'', but rather than providing a single hash of the entire file, it breaks the file up into 9500kb ''chunks'' and produces a final hash based on the md4 sums of the chunks. While md4 longer considered secure from a cryptographic perspective, for the purpose of uniquely identifying files it's more than adequate. It is often listed as part of an ''ed2k link'', which also includes a size in bytes, and a name. | The ed2k hash is based on the ''md4 algorithm'', but rather than providing a single hash of the entire file, it breaks the file up into 9500kb ''chunks'' and produces a final hash based on the md4 sums of the chunks. While md4 longer considered secure from a cryptographic perspective, for the purpose of uniquely identifying files it's more than adequate. It is often listed as part of an ''ed2k link'', which also includes a size in bytes, and a name. | ||
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If you have the file(s) on your hard disk or on CD you can use all kinds of tools to generate the ed2k-hash and other additional info: | If you have the file(s) on your hard disk or on CD you can use all kinds of tools to generate the ed2k-hash and other additional info: | ||
* [[Avdump]] is the preferred tool as it can automatically creq files. | * [[Avdump]] is the preferred tool as it can automatically creq files. | ||
* [[ | * [[AniDB O'Matic]] by BennieB/PetriW can generate ed2k-hashes. It generates ed2k-hashes, md5, sha-1, crc32 in one go and also lists stuff like codec, resolution, bitrates, ... | ||
* [http://ed2k-tools.sourceforge.net/index.shtml ed2k_hash] another tool which is commandline based (current Windows and OSX versions have a GUI as well) and also available for Unix operating systems (Linux/BSD/etc). | * [http://ed2k-tools.sourceforge.net/index.shtml ed2k_hash] another tool which is commandline based (current Windows and OSX versions have a GUI as well) and also available for Unix operating systems (Linux/BSD/etc). | ||
* [http://malich.content.no-ip.org/filehash/filehash-0.5.3.zip Filehash] a little Java program written by Malich. For further info on it read [http://forum.anidb.net/viewtopic.php?t=77 here] | * [http://malich.content.no-ip.org/filehash/filehash-0.5.3.zip Filehash] a little Java program written by Malich. For further info on it read [http://forum.anidb.net/viewtopic.php?t=77 here] | ||