Towards Quantum Enigma Cipher

TL;DR

This paper proposes a novel quantum detection-based encryption method that leverages quantum noise to surpass traditional cryptographic limits, offering potentially higher security and speed for direct encryption.

Contribution

It introduces a new approach to generate inherent ciphertext accuracy differences using quantum detection principles, advancing quantum cipher technology beyond existing protocols.

Findings

Quantum noise can be exploited to enhance encryption security.

The proposed method surpasses the Shannon limit of cryptography.

Potential for high-speed, secure quantum communication.

Abstract

This research note suggests a new way to realize a high speed direct encryption based on quantum detection theory. The conventional cipher is designed by a mathematical algorithm and its security is evaluated by the complexity of the algorithm for cryptanalysis and ability of computers. This kind of cipher cannot exceed the Shannon limit of cryptography,and it can be decrypted with probability one in principle by trying all the possible keys against the data length equal to the secret key length. A cipher with quantum effect in physical layer may exceed the Shannon limit of cryptography. The quantum stream cipher by $\alpha/\eta$ or Yuen-2000 protocol (Y-00) which operates at Gbit/sec is a typical example of such a cipher. That is, ciphertext of mathematical cipher with a secret key is masked by quantum noise of laser light when an eavesdropper observes optical signals as a ciphertext of the mathematical cipher, while the legitimate receiver does not suffer the quantum noise effect. As a result, the inherent difference of accuracy of ciphertext between eavesdropper and legitimate receiver arises. This is a necessary condition to exceed the Shannon limit of cryptography. In this note, we present a new method to generate an inherent difference of accuracy of the ciphertext, taking into account a fundamental properties of quantum detection schemes.