I want to make an electronically cryptography on physical layer in the network cables.
consider a hard device which code (encrypt) the data electronically at the source system and decrypt it electronically again at the target system via changing the bits through physical layer by a electronic circuit.
what is the voltage in STP and UTP cables for data transmission?! in which voltage interval the '1' is represented?! and through which voltage the '0' is represented!? how can I read more and start studying about this problem and find standards protocols for data transmission in physical layer?! do you know some same project?!
thanks.