Pre-image Resistance

      Pre-image resistance is one of the necessary fundamental properties of a sound/adequate Hashing function. 

     In cryptography, a pre-image attack is basically the reverse engineering of a hashing function. It is the ability to deduce an input based on it output through the application of possible inputs when measured against the outputs. Similar to a Brute Force attack, pre-images are a series of messages that are rapidly put through a hashing function in search of a specified output. In order for a hashing function to be considered secure, it must be robust enough to deter such malicious attempts.