Hash

The result of mathematical operations carried out on the numeric representation of data—all data in a computer consists of numbers that are deciphered in order to create the words and images you see on a screen. This result has a fixed size and is a unique cryptographic fingerprint of the underlying data. A hash is a one-way function; this means that given the data, it is easy to verify that the hash is the correct one for that data. This is done by performing the pre-defined mathematical operations on the data that supposedly created the hash—if the result is the same, the data is the same. This is a key feature because it allows users to quickly confirm that no changes, at all, have been made. For example, even an additional space or empty line in a text would change its hash. At the same time, and this is what makes it aone-way function, it is almost impossible to recreatethe original data if all one has is the hash (i.e. reverse engineer it).