One-Way Function

A one-way function f:X→Y is a function where it is easy to compute y∈Y for a given x∈X such that f(x)=y but it is computationally infeasible to compute x∈X for a given y∈Y such that f(x)=y

References

A. Menzes, P. van Oorschot, and S. Vanstone, Handbook of Applied Cryptography. CRC Press, 1996.