do you think one way function is exist?

[Darelle]

all I know it's the mathematical function where it is easier to compute by a forward direction than in the opposite direction, so is it possible to make it easy to compute for one-to-one?

[Enthalpy]

We don't need to believe or think: they do exist and are used daily. Sha-1, Sha-256 and many more, like the common MD5 still used despite being broken.

http://en.wikipedia.org/wiki/Sha-1