One-Way Function

Related Concepts

Public Key Cryptography; Trapdoor One-Way Function

Definition

Informally, a one-way function is a function for which computation in one direction is straightforward, while computation in the reverse direction is far more difficult.

Background

The seminal paper of Diffie and Hellman [1] was the first to set down the potential of one-way functions in the development of public-key cryptography. The interesting, and important, feature of the one-way function is the asymmetry in computational effort required to perform a function evaluation and its reverse.

Theory

While the informal definition gives the flavour of the one-way function, it is typically described in a more formal, though still not rigorous, way [3,  4] as a function f with domain X and range (codomain) Y, where f(x) is “easy” to compute for all $x \in X$; but for “virtually all” elements $y \in Y$, it is “computationally infeasible” to find an x such that $f(x) = y$. The function fis a one-way...