Physical Turing Machines and the Formalization of Physical Cryptography
Physical Cryptography (PhC) is a recently emerging form of cryptography and security. Central to this young field are not the mathematical properties of certain cryptographic functions (such as non-invertability, pseudo-randomness, etc.). Instead, PhC tries to exploit the analog properties of unclonable, randomly structured physical systems for cryptographic and security purposes. There are two potential advantages that result from this paradigm shift: first of all, it can enable a better protection of secret keys in cryptographic hardware. Instead of storing secret keys in vulnerable non-volatile digital memory, the keys are derived from, or hidden in, the analog characteristics of a randomly structured medium. Second, the new paradigm can sometimes avoid the classical, unproven computational assumptions like the purported hardness of the factoring and discrete logarithm problem.