Protecting confidential data is a major challenge in the internet era. Standard cryptographic techniques are fast and scalable, but they are broken by quantum algorithms. Quantum cryptography is unclonable and more robust, but requires quantum installations that are more expensive, slower, and less scalable than classical optical networks.
Here we propose and demonstrate a perfect secrecy cryptography that provides a physical implementation to the Vernam cipher in classical optical channels. The proposed system exploits correlated chaotic wavepackets that are mixed in inexpensive and CMOS compatible silicon chips, which are irreversibly modified in time after and before every communication.
Each chip contains a biometric fingerprint of the user, and it is different for each user. The keys generated with this protocol are unique to the fingerprint chips, to the communication system that connects them and to random input conditions that the users choose independently on their respective ends. The chips have the capacity to generate 0.1 Tbit of different keys for every communication and for every $mm$ of length of the input channel. We theoretically and experimentally demonstrate that when the chips are changed, none of the keys can be recreated again, not even by the users. We discuss the security of this protocol in the case of an ideal attacker, who possess an unlimited power, who controls the communication channel, and who accesses the system before or after the communication, copying any of its part including the chips. The second law of thermodynamics and the exponential sensitivity of chaos unconditionally protect this scheme against any possible attack. Theory and measurements with classical telecommunication fibers show that the attacker always lies in a maximal entropy scenario, with average uncertainty per bit higher than 0.9899 bit and with the impossibility to obtain any information on the key being distributed to the users.
US Patent USPTO 16132017. Article in review