A function 
that maps an arbitrary length message 
to a fixed length message digest 
is a one-way hash function if
1. It is a one-way function.
2. Given 
and 
,
it is hard to find a message 
such that 
.
One-Way Hash Function
See also
Hash Function, One-Way Function, Trapdoor One-Way FunctionExplore with Wolfram|Alpha
References
Bakhtiari, S.; Safavi-Naini, R.; and Pieprzyk, J. Cryptographic Hash Functions: A Survey. Technical Report 95-09, Department of Computer Science, University of Wollongong, July 1995. ftp://ftp.cs.uow.edu.au/pub/papers/1995/tr-95-09.ps.Z.Referenced on Wolfram|Alpha
One-Way Hash FunctionCite this as:
Weisstein, Eric W. "One-Way Hash Function." From MathWorld--A Wolfram Web Resource. https://mathworld.wolfram.com/One-WayHashFunction.html