Basic Cryptography: Hash Function
Lawrence E. Hughes · Apress eBooks · 2022
The algorithms in this chapter are very different from those in the previous chapter (symmetric key encryption). A Hash Function is a one-way process (there is no way to recover the original information from a message digest). There is no key (a given plaintext will always produce exactly the same message digest). With symmetric key cryptography, the output is roughly the same size as the input. With a hash function, the output is always a fixed length (based on the algorithm used, e.g. 256 bits for SHA2-256). Hash functions are used in very different ways than encryption algorithms.