Criptocurrency/ bitCoin

https://www.youtube.com/watch?v=kubGCSj5y3k&feature=youtu.be
Hash function - Wikipedia

https://en.wikipedia.org/wiki/Hash_function
A hash function is any function that can be used to map data of arbitrary size to data of fixed size. The values returned by a hash function are called hash values, hash codes, digests, or simply hashes. One use is a data structure called a hash table, widely used in computer software for rapid data lookup. Hash functions ...