Talk:Md5sum

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[edit] What MD5 stands for

What does md5 stand for?

From MD5: MD5 (Message-Digest algorithm 5)

Also see RFC 1321. --Teratornis 19:26, 22 January 2007 (UTC)

[edit] Qualifying the "exact copy" claim

Two non-identical files have a very low but non-zero probability of generating the same MD5 hash. I clarified this in Md5sum#Usage, which previously stated that if two copies of a file produce the same MD5 hash, they must be identical. That is virtually always true but is not absolutely guaranteed to be true. This is trivially easy to recognize from the fact that there are more possible files than MD5 hashes, because MD5 hashes have a fixed length, and files can be of any length. See RFC 1321 for more about the computational effort of constructing two non-identical files with the same MD5 hash (and thus something about the probability that two randomly-chosen non-identical files will have the same MD5 hash). --Teratornis 19:26, 22 January 2007 (UTC)