supergeek
A cryptographic hash function is a mathematical algorithm that maps data of arbitrary size to a bit array of a fixed size (the "hash).

Cryptographic hash functions

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A cryptographic hash function is a mathematical algorithm that maps data of arbitrary size to a bit array of a fixed size (the “hash). It is a one-way function, that is, a function that is practically infeasible to invert or reverse the computation.

Certain properties of cryptographic hash functions impact the security of password storage.

  • Non-reversibility, or one-way function
    A good hash should make it very hard to reconstruct the original password from the output or hash
  • Diffusion, or avalanche effect
    A change in just one bit of the original content will result in a change to half the bits of its hash. In other words, when the original content is changed slightly, the output of enciphered text will change significantly and unpredictably
  • Collision resistance
    It’s almost impossible to find two different source contents that hash to the same enciphered text
  • Determinism
    A given original content will always generate the same hash value
  • Non-predictable
    The hash value can not be reconstructed from the source content

We have elected to put our money and faith in a mathematical framework that is free of politics and human error.

Tyler Winklevoss
American cryptocurrency and Bitcoin investor