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What is an MD5 Calculation?


A digital fingerprint that speaks to the uniqueness of an individual file’s contents, regardless of file renaming.


It is created using a mathematical algorithm. When an MD5 hash is created, the algorithm is applied against the contents of the file. The Message Digest 5 (MD5) was developed in 1991 and generates a 128-bit hash value. Another commonly used hash algorithm is Secure Hash Algorithm (SHA) developed in 1995 by the US Government . SHA  generates a 160-bit hash value.


If the file is renamed, the MD5 hash value remains constant. It is this quality that allows for searching for deliberate renaming of files.




Contacts.xls could be changed to Mom.jpg.  If the contents of the file had remained unchanged, the hash value aids the forensics examiner in finding the file and the fact that it had been renamed.










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