Cryptographic hash functions are primarily used in password security and encryption. They are the fundamental building blocks that are used in many cryptographic algorithms and protocols. Most commonly know are MD5 (message digest 5, the iteration after 4) and SHA-256. Bitcoin uses the hashcash-SHA-256^2 proof of work function developed by Adam Back. Originally proposed as a way to prevent spam e-mail and anonymous remailers.
Hash functions take an input of arbitrary size and uses a mathematical transformation to create a deterministic output, one that is always the same for a given input, called a digest or hash. The size of the output is going to be fixes in length. In bitcoin (SHA-256) the hash is going to be 256-bit in length.
There is a difference between cryptographic hash functions and traditional hash functions. Cryptographic implies the hash function conforms to a certain set of design goals which enable it…
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