Symbols and customized cryptography
Cryptography, in the mathematical sense, is used in many domains but semiotics (the theory of symbols) is a more powerful personalized approach to encoding messages. The mathematics bounds the subject to be used only via rigid analytical systems and not fluid malleable ones. I’ve found the latter to be more interesting in terms of application and what happens in the real world. It can be as simple as creating a new domain specific language or reinterpreting old symbols via existing texts.