Quantum stream cipher based on optical communications

数学密码、Wyner方案、QKD和量子流密码安全机制的比较

Comparison of security mechanisms of Mathematical cipher, Wyner scheme, QKD, and Quantum stream cipher

本文比较了数学密码、Wyner方案、QKD和Y-00协议的安全机制，探讨其在光学量子领域中的不同原理和应用。

基于概率星座整形的量子噪声流密码安全性增强

Security Enhancement of Quantum Noise Stream Cipher Based on Probabilistic Constellation Shaping

提出基于概率星座整形的QNSC预编码方案，降低易截获密文比特概率，实验显示伊芙密文误码率安全性能提升100%。

Quantum Vernam Cipher

We discuss aspects of secure quantum communication by proposing and analyzing a quantum analog of the Vernam cipher (one-time-pad). The quantum Vernam cipher uses entanglement as the key to encrypt quantum information sent through an insecure quantum channel. First, in sharp contrast with the classical Vernam cipher, the quantum key can be recycled securely. We show that key recycling is intrinsic to the quantum cipher-text, rather than using entanglement as the key. Second, the scheme detects and corrects for arbitrary transmission errors, and it does so using only local operations and classi…

Towards Quantum Enigma Cipher III -Communication performance-

Cloud computing system based on data centers has recently attracted considerable attention. In that system, all data are communicated via a high speed optical network between a customer and data center or between data centers. There is a serious threat so called "Eavesdropper data center business", which means the eavesdropper can get all data from the transmission line and sell specific data selected by the protocol analyzer to malicious people who want to get the secret data. So we need to consider cyber attack against Layer-1 (physical layer). Quantum cryptography has been developed to prot…

Stream privacy amplification for quantum cryptography

Privacy amplification is the key step to guarantee the security of quantum communication. The existing security proofs require accumulating a large number of raw key bits for privacy amplification. This is similar to block ciphers in classical cryptography that would delay the final key generation since an entire block must be accumulated before privacy amplification. Moreover, any leftover errors after information reconciliation would corrupt the entire block. By modifying the security proof based on quantum error correction, we develop a stream privacy amplification scheme, which resembles t…

Quantum Noise Randomized Ciphers

We review the notion of a classical random cipher and its advantages. We sharpen the usual description of random ciphers to a particular mathematical characterization suggested by the salient feature responsible for their increased security. We describe a concrete system known as AlphaEta and show that it is equivalent to a random cipher in which the required randomization is effected by coherent-state quantum noise. We describe the currently known security features of AlphaEta and similar systems, including lower bounds on the unicity distances against ciphertext-only and known-plaintext atta…

集成QKD的量子噪声流密码：综述

QKD-Integrated Quantum Noise Stream Cipher: An Overview

本研究综述量子噪声流密码（QNSC）的原理、安全模型及与量子密钥分发（QKD）的集成，分析两层安全交互，调研相关实验进展，指出实用化全集成量子安全光通信网络的挑战与未来方向。

量子香农信息理论——通信、密码与传感器的设计

Quantum Shannon Information Theory -Design of communication, cipher and sensor-

本文探讨量子香农信息理论在通信、密码与传感器设计中的应用，指出其利用量子效应超越经典性能的潜力与局限，并介绍一种不降低性能的完美安全密码作为实例。

Potentially Information-theoretic Secure Y00 Quantum Stream Cipher with Limited Key Lengths beyond One-Time Pad

The previous work showed that the Y00 protocol could stay secure with the eavesdropper's guessing probability on the secret keys being strictly less than one under an unlimitedly long known-plaintext attack with quantum memory. However, an assumption that at least a fast correlation attack is completely disabled by irregular mapping. The present study shows that the Y00 protocol can be information-theoretic secure under any quantum-computational crypto-analyses if the Y00 system is well designed. The Y00 protocol directly encrypts messages with short secret keys expanded into pseudo-random run…

On the Key-Uncertainty of Quantum Ciphers and the Computational Security of One-way Quantum Transmission

We consider the scenario where Alice wants to send a secret (classical) $n$-bit message to Bob using a classical key, and where only one-way transmission from Alice to Bob is possible. In this case, quantum communication cannot help to obtain perfect secrecy with key length smaller then $n$. We study the question of whether there might still be fundamental differences between the case where quantum as opposed to classical communication is used. In this direction, we show that there exist ciphers with perfect security producing quantum ciphertext where, even if an adversary knows the plaintext …

Guessing probability under unlimited known-plaintext attack on secret keys for Y00 quantum stream cipher by quantum multiple hypotheses testing

Although quantum key distribution is regarded as promising secure communication, security of Y00 protocol proposed by Yuen in 2000 for the affinity to conventional optical communication is not well-understood yet; its security has been evaluated only by the eavesdropper's error probabilities of detecting individual signals or masking size, the number of hidden signal levels under quantum and classical noise. Our study is the first challenge of evaluating the guessing probabilities on shared secret keys for pseudorandom number generators in a simplified Y00 communication system based on quantum…

Coherent pulse position modulation quantum cipher supported by secret key

A quantum cipher supported by a secret key so called keyed communication in quantum noise (KCQ) is very attractive in implementing high speed key generation and secure data transmission. However, Yuen-2000 as a basic model of KCQ has a difficulty to ensure the quantitative security evaluation because all physical parameter for the cipher system is finite. Recently, an outline of a generalized scheme so called coherent pulse position modulation(CPPM) to show the rigorous security analysis is given, where the parameters are allowed to be asymptotical. This may open a new way for the quantum key …

Towards Quantum Enigma Cipher

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 q…

Measurement-device-independent QSDC protocol using Bell and GHZ states on quantum simulator

Secure cryptographic protocols are indispensable for modern communication systems. It is realized through an encryption process in cryptography. In quantum cryptography, Quantum Key Distribution (QKD) is a widely popular quantum communication scheme that enables two parties to establish a shared secret key that can be used to encrypt and decrypt messages. But security loopholes still exist in this cryptographic protocol, as an eavesdropper can in principle still intercept all the ciphertext to perform cryptanalysis and the key may get leaked to the eavesdropper, although it happens very rarely…

Y00协议中的结构脆弱性

Structural Vulnerability in Y00 Protocols

本文分析基于量子噪声的Y00流密码协议，揭示其存在可致密钥泄露的结构脆弱性，推导验证缺陷后推广至同类协议，提出物理态流密码的基本安全基准，强调严谨安全评估的重要性。