Distribution ensemble

In cryptography, a distribution ensemble or probability ensemble is a family of distributions or random variables X = { X i } i ∈ I where I is a (countable) index set, and each X i is a random variable, or probability distribution. Often I = N and it is required that each X n have a certain property for n sufficiently large.

A uniform ensemble U = { U n } n ∈ N is a distribution ensemble, uniformly distributed over strings of length n.