Bricklayer function

In cryptography, the bricklayer function is a part of a round function that can be decomposed into identical independent Boolean operations on the partitioned pieces of its input data,^[2] so called bundles.^[3] The term was introduced by Daemen and Rijmen in 2001.^[1]

The SubBytes transformation of the Advanced Encryption Standard is a notable^[1] example of a bricklayer function: each 8-bit bundle of the 128-bit state is undergoing the same S-box transformation independently

If the underlying function transforming the bundle is nonlinear, it is traditionally called an S-box. If the function is linear, Daemen and Rijmen use for it the term D-box (after diffusion).^[2]