The most commonly used mathematics today

What is the most used piece of mathematics in the present day?

 

The answer is a cryptography technique used to keep all of the world's banking details secure.

The technique takes an input call it a and is for example your PIN and then puts it through a function which outputs a generator to the power of a modulo a large prime.

a->g^(a)

This function has the property that if you steal the data g^(a) it is very difficult to get the original a out. This is obviously a very useful property for protecting private information.

So when you input your PIN a, g^(a) is computed then this is compared to a stored list of g^(a) before access is given.