No Arabic abstract
Privacy amplification is an indispensable step in the post-processing of quantum key distribution, which can be used to compress the redundancy of shared key and improve the security level of the key. The commonly used privacy amplification is based on the random selection of universal hash functions, which needs the help of an additional random source, while it does not exist in general. In this paper, we propose a privacy amplification scheme based on composite coding, which is an extension of quantum CSS codes to classical linear codes. Compared with the universal hashing function, the proposed scheme does not need other random sources, and the randomness can be completely provided by the qubit string. Furthermore, the information-theoretic bound for the extraction of the key is obvious in composite coding.
Privacy amplification (PA) is the art of distilling a highly secret key from a partially secure string by public discussion. It is a vital procedure in quantum key distribution (QKD) to produce a theoretically unconditional secure key. The throughput of PA has become a bottleneck of the high-speed discrete variable QKD (DV-QKD) system. In this paper, a high-speed modular arithmetic hash PA scheme with GNU multiple precision (GMP) arithmetic library is presented. This scheme is implemented on two different central processing unit (CPU) platforms. The experimental results demon-strate that the throughput of this scheme achieves 260Mbps on the block size of 10^6 and 140Mbps on the block size of 10^8. This is the highest-speed recorded PA scheme on CPU platform to the authors knowledge.
Recently, a medical privacy protection scheme (MPPS) based on DNA coding and chaos was proposed in [IEEETrans. Nanobioscience, vol. 16, pp. 850--858, 2017], which uses two coupled chaotic system to generate cryptographic primitives to encrypt color DICOM image. Relying on several statistical experimental results and some theoretical analyses, the designers of MPPS claimed that it is secure against chosen-plaintext attack and the other classic attacks. However, the above conclusion is insufficient without cryptanalysis. In this paper, we first study some properties of MPPS and DNA coding and then propose a chosen-plaintext attack to reveal its equivalent secret-key. It is proved that the attack only needs $lceil log_{256}(3cdot Mcdot N)rceil+4$ chosen plain-images, where $M times N$ is the size of the RGB color image, and ``3 is the number of color channels. Also, the other claimed superiorities are questioned from the viewpoint of modern cryptography. Both theoretical and experimental results are provided to support the feasibility of the attack and the other reported security defects. The proposed cryptanalysis work will promote the proper application of DNA encoding in protecting multimedia data including the DICOM image.
We prove an achievability result for privacy amplification and decoupling in terms of the sandwiched Renyi entropy of order $alpha in (1,2]$; this extends previous results which worked for $alpha=2$. The fact that this proof works for $alpha$ close to 1 means that we can bypass the smooth min-entropy in the many applications where the bound comes from the fully quantum AEP or entropy accumulation, and carry out the whole proof using the Renyi entropy, thereby easily obtaining an error exponent for the final task. This effectively replaces smoothing, which is a difficult high-dimensional optimization problem, by an optimization problem over a single real parameter $alpha$.
Privacy amplification (PA) is an essential part in a quantum key distribution (QKD) system, distilling a highly secure key from a partially secure string by public negotiation between two parties. The optimization objectives of privacy amplification for QKD are large block size, high throughput and low cost. For the global optimization of these objectives, a novel privacy amplification algorithm is proposed in this paper by combining multilinear-modular-hashing and modular arithmetic hashing. This paper proves the security of this hybrid hashing PA algorithm within the framework of both information theory and composition security theory. A scheme based on this algorithm is implemented and evaluated on a CPU platform. The results on a typical CV-QKD system indicate that the throughput of this scheme (
[email protected]*10^8 input block size) is twice higher than the best existing scheme (140Mbps@1*10^8 input block size). Moreover, This scheme is implemented on a mobile CPU platform instead of a desktop CPU or a server CPU, which means that this algorithm has a better performance with a much lower cost and power consumption.
Isolated qubits are a special class of quantum devices, which can be used to implement tamper-resistant cryptographic hardware such as one-time memories (OTMs). Unfortunately, these OTM constructions leak some information, and standard methods for privacy amplification cannot be applied here, because the adversary has advance knowledge of the hash function that the honest parties will use. In this paper we show a stronger form of privacy amplification that solves this problem, using a fixed hash function that is secure against all possible adversaries in the isolated qubits model. This allows us to construct single-bit OTMs which only leak an exponentially small amount of information. We then study a natural generalization of the isolated qubits model, where the adversary is allowed to perform a polynomially-bounded number of entangling gates, in addition to unbounded local operations and classical communication (LOCC). We show that our technique for privacy amplification is also secure in this setting.