Cryptography Tutorials - Herong's Tutorial Examples - v5.40, by Dr. Herong Yang
What Is MD5 Message Digest Algorithm?
This section describes what is MD5 - a message digest algorithm which takes as input a message of arbitrary length and produces as output a 128-bit 'fingerprint'.
Based on the MD5 RFC document, MD5 is message-digest algorithm, which takes as input a message of arbitrary length and produces as output a 128-bit "fingerprint" or "message digest" of the input. It is conjectured that it is computationally infeasible to produce two messages having the same message digest, or to produce any message having a given pre-specified target message digest.
MD5 was designed by Ronald Rivest in 1991 to replace an earlier hash function, MD4. MD5 is more secure than MD4. However a number of weaknesses have been found in recent years. The most recent paper published in this area shows that a collision of MD5 can be found within one minute on a standard notebook PC, using a method called tunneling.
Despite its weaknesses, MD5 is widely used in digital signature processes. It's been implemented in many programming languages.
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