The MD5 (Message-Digest algorithm 5) algorithm was created by a professor named Ronald L. Rivest of MIT. Using this algorithm you are able to calculate a hash value or digest of any message. A digest works as a fingerprint for the text that you apply the algorithm on. A fingerprint has the length of 128-bit and is often written as a charactersting of 32 hex digits. The internals is specified in rfc1321. The beautiful thing about this hash value is that it is almost impossible to produce two messages that will result in the same digest or hash siquence of bits. Thus it is often used when comparing large amounts of data.
It is widely used by publishers of downloadable material on the internet to ensure the authenticy of the downloaded content. To do so the publisher supplies the hash value together with the download link to the file. The user is then able to compare the two values after download by calculating the MD5 hash value of the downloaded file. There are some utilities avaliable on the Internet for free download that will calculate these digests.
RSA's MD5 disclaimer
Public Information Sources
MD5 - Wikipedia, the free
I have collected a short list of MD5 tools and utilities on this page so that you can download the one that suits your task at hand.
- md5: Command Line Message Digest Utility.
Visual Basic (VB)
Java Script (JScript)