A measure of the uncertainty associated with a random variable.

Entropy

https://en.wikipedia.org/wiki/Entropy_(information_theory)

In information theory, the entropy of a random variable is the average level of "information",

"surprise", or "uncertainty" inherent in the variable's possible outcomes. The concept of information

entropy was introduced by Claude Shannon in his 1948 paper "A Mathematical Theory of

Communication".

Incorrect answers:

Diffusion - transposition processes used in encryption functions to increase randomness.

Whitening - technique intended to increase the security of an iterated block cipher. It consists of

steps that combine the data with portions of the key.

Collision - situation where two different inputs yield the same output.