What Does MD5 Mean?

MD5 is a type of algorithm that is known as a cryptographic hash algorithm. MD5 produces a hash value in a hexadecimal format. This competes with other designs where hash functions take in a certain piece of data, and change it to provide a key or value that can be used in place of the original value.


Techopedia Explains MD5

With the development of various hash algorithms, experts have noted that engineers found MD5 to have serious weaknesses in terms of not being "collision resistant." A collision happens when two hash values are found to be similar or the same. To work correctly, each individual hash value has to be unique. Because this functionality is needed for popular authentication protocols like Secure Sockets Layer (SSL), MD5 has often been replaced with other types of hash algorithms.

Security engineers and others are familiar with long lists of hash algorithms with different properties. MD5 and other types of hash algorithms are often referred to as "message digest" functions.The idea here is that a hash "digests" an original value and outputs a replacement value that is significantly different from the original. Hashes have several main uses in security and database efficiency, related to the use of replacement values in searches and in data storage.


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Margaret Rouse
Technology Expert

Margaret is an award-winning technical writer and teacher known for her ability to explain complex technical subjects to a non-technical business audience. Over the past twenty years, her IT definitions have been published by Que in an encyclopedia of technology terms and cited in articles by the New York Times, Time Magazine, USA Today, ZDNet, PC Magazine, and Discovery Magazine. She joined Techopedia in 2011. Margaret's idea of a fun day is helping IT and business professionals learn to speak each other’s highly specialized languages.