I need to implement IPSEC and MACSEC transformations on ethernet packets (i.e. I don't need to deal with setting up parameters, security associations, or key exchange issues, just do the transformations on the packets when that is already known. Also I can nick GCM/AES implementations so I don't have to implement the actual ciphering either.)
Unfortunately I am just too stupid to understand the specifications.
Does anyone know of a nice simple explanation, designed for an idiot, with diagrams and concrete examples, of what the transformations are supposed to look like?