A cryptographic hash function takes an input and returns a fixed size string that corresponds to it, called a hash. Cryptographic hashes have a lot of uses, some of which are: detecting data changes, storing or generating passwords, making unique keys in databases and ensuring message integrity. This video will mostly cover detecting file changes, but I hope it gets your mind going in the right direction for how hashes can be used. Specifically covered will be tools for creating MD5 hashes in Windows and Linux.
 

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