Classical cryptography can be formulated twice in purely abstract algebraic terms

This paper seeks to present and justify 2 theses: that cryptography can be reduced to a purely categorical formulation, specifically that it can be reduced to the study of a single family of sets of functors; and that cryptography can be reduced to a purely 2-adic formulation, specifically it can be reduced to the study of functions Z m 2 → Z n 2 .