One-way functions are mathematical models for encryption
. The one-way function can be easily computed in one direction, but requires a great deal of computation for the inverse. If the one-way function of x yields the value y, with y = f(x), then it is not possible to infer x directly from y in the reverse direction. This is not a problem for simple mathematical operations such as multiplication and division, but it is for more complex contexts. In the one-way function, the encryption is not done with secret keys but with publicly known keys. Since the inversion can only be done with considerable computational effort, it is extremely difficult for attackers to determine the encrypted plaintext
from the one-way function. One-way functions are used for the encryption of passwords, in hash functions, and in public key methods.