A randomness test for block ciphers

This paper describes a randomness test which can be used to measure the cryptographic strength of a block cipher or its underlying cryptographic primitive(s). Cryptographic strength in the context of this paper is related to the ability of the round function to produce a random output which in turn is defined as the distance between a theoretical calculation and an experimental measure. The measurements are based on the diffusion characteristic of the cipher. Potentially, the test for randomness proposed in this paper could be used as a distinguisher based on diffusion.