International Association
for Cryptologic Research

In this paper, we introduce the concept of the derivative of sequence of numbers and define new statistical indices by which we discoverd new properties of randomly generated number sequences.

We also build a test for pseudo random generators based on these properties and use it to confirm the weakness of RC4 key scheduling algorithm that has been reported in the litterature.

In this rescpect we publish a new RC4\'s key scheduling algorithm that don\'t have this weakness.