Algorithms For Dummies

Creating and Using One-Way Functions

A one-way function is a function that is easy to use to obtain an answer in one 

direction, but nearly impossible to use with the inverse of that answer. In other 

words, you use a one-way function to create something like a hash that would 

appear as part of a solution for cryptography, personal identification, authentica-

tion, or other data security needs.

The existence of a one-way function is less mystery and more a matter of proof. 

Many telecommunications, e-commerce, and e-banking systems currently rely 

on functions that are purportedly one way, but no one truly knows whether they 

really are one way. The existence of a one-way function is currently a hypothesis, 

not a theory (see an explanation of the difference between the two at 

http://www.

diffen.com/difference/Hypothesis_vs_Theory

). If someone were able to prove 

that a one-way function exists, data security issues would be easier to solve from 

a programming perspective.

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