# What is the purpose of having a one-way function also be a permutation on it's on domain?

From a cryptographic sense, what value is added from setting the domain to be the image in the mapping?

• Welcome to Cryptography.SE! Dec 19 '17 at 9:07

• Yes. But for small domain ( e.g $\{0,1\}^{256}$ ), a public OWP is much harder to construct than a public OWF. If one has such OWP, I want to know ! Thus I asked.