In this paper, the elementary aspects of quantum cryptography are presented. First, we start with the introduction and history of quantum cryptography. Second, we give the definition of classical and quantum cryptography and emphasize the difference between the two. The idea of quantum cryptography will be explained further in the subsequent section, where the famous quantum key distribution example is presented. Lastly, we give the results of some computer simulations.
In this paper, the elementary aspects of quantum cryptography are presented. First, we start with the introduction and history of quantum cryptography. Second, we give the definition of classical and quantum cryptography and emphasize the difference between the two. The idea of quantum cryptography will be explained further in the subsequent section, where the famous quantum key distribution example is presented. Lastly, we give the results of some computer simulations.
The real-world systems of quantum cryptography represent an advancement in the field of communication, wherein the advantages offered by quantum mechanics are used to minimize security threats which are handled with classical computers. This chapter starts with introducing some concepts to the reader about Quantum Cryptography, starting with an overview of classical Cryptography and its limitations in this new era of quantum computing technologies. Certain aspects of quantum mechanics like superposition, quantum entanglement, no-cloning theorem, and their applications for Quantum Key Distribution are also studied. This followed a thorough analysis of key protocols BB84 and E91 to unmask their strengths in securing superior security. Security threats associated with quantum-cryptographic systems and their corresponding provable level of security are considered to strengthen the notion of quantum cryptography as opposed to methods of classical cryptography. The corresponding characteristics of such quantum-cryptographic methods are also discussed for their application in proper targets. By the end of this chapter, we will attempt to explain the conception of some complications regarding quantum mechanics, and how they are now of use in modern practices of quantum cryptography and why such techniques are needed at all.
Quantum cryptography is the art and science of exploiting quantum mechanical effects in order to perform cryptographic tasks. While the most well-known example of this discipline is quantum key distribution (QKD), there exist many other applications such as quantum money, randomness generation, secure two- and multi-party computation and delegated quantum computation. Quantum cryptography also studies the limitations and challenges resulting from quantum adversaries-including the impossibility of quantum bit commitment, the difficulty of quantum rewinding and the definition of quantum security models for classical primitives. In this review article, aimed primarily at cryptographers unfamiliar with the quantum world, we survey the area of theoretical quantum cryptography, with an emphasis on the constructions and limitations beyond the realm of QKD.
This paper first gives a brief introduction of quantum cryptography and several principal quantum effects involved by quantum key; then it describes in detail the development history of quantum cryptography at home, gives some topics in the research of quantum cryptography, including quantum key distribution, quantum signature, quantum identity authentication, quantum encryption, quantum secret-sharing, and their brief descriptions, and analyzes in depth some hindering factors in practical quantum cryptography; finally, the development of quantum cryptography is forecasted.
The word cryptography originates from two Greek words: kryptos (secret) and graphein (writing). Thus cryptography is the art of communicating a message in secret manner or in other words, it is the art of rendering a message unintelligible to any unauthorized party. Its history is very old and exciting. From the beginning of human civilization there was a need to hide information from unauthorized people. This need gave birth to cryptography. Initial cryptographic protocols were very simple. With time they have become much more sophisticated and secure. However, all the classical cryptographic protocols developed so far are secure under some assumptions. In contrast, the protocols of quantum cryptography are unconditionally secure. This particular aspect of quantum cryptography makes it very interesting. This chapter aims to provide a flavor of the intrinsic beauty of various aspects of secure quantum communication. Before we start a journey into the fascinating world of secure quantum communication, it would be apt to become familiar with the jargon used in this field and also with some interesting protocols of classical cryptography. Let us first do that.
The practical implementation of quantum information technologies requires, for the most part, highly advanced and currently experimental procedures. One exception is quantum cryptography, or quantum key distribution, which has been successfully demonstrated in many laboratories and has reached an advanced level of development. It will probably become the first commercial application of quantum information. In quantum key distribution, Alice and Bob exploit a quantum channel to create a secret shared key comprising a random string of binary digits. This key can then be used to protect a subsequent communication between them. The principal idea is that the secrecy of the key distribution is ensured by the laws of quantum physics. Proving security for practical communication systems is a challenging problem and requires techniques that are beyond the scope of this book. At a fundamental level, however, the ideas are simple and may readily be understood with the knowledge we have already acquired. Quantum cryptography is the latest idea in the long history of secure (and not so secure) communications and, if it is to develop, it will have to compete with existing technologies. For this reason we begin with a brief survey of the history and current state of the art in secure communications before turning to the possibilities offered by quantum communications. The history of cryptography is a long and fascinating one. As a consequence of the success or, more spectacularly, the failure of ciphers, wars have been fought, battles decided, kingdoms won, and heads lost. In the information age, ciphers and cryptosystems have become part of everyday life; we use them to protect our computers, to shop over the Internet, and to access our money via an ATM (automated teller machine). One of the oldest and simplest of all ciphers is the transposition or Caesarean cipher (attributed to Julius Caesar), in which the letters are shifted by a known (and secret) number of places in the alphabet. If the shift is 1, for example, then A is enciphered as B, B→C, · · ·, Y→Z, Z→A. A shift of five places leads us to make the replacements A→F, B→G, · · ·, Y→D, Z→E.
Quantum cryptography (QC) as an important technology to protect the security of the future network communication, has gained extensive attention from both academia and industry in recent years. This paper provides a concise up-to-date review of QC, including Quantum key distribution (QKD), Quantum authentication, Quantum public-key cryptography (QPKC), and so on. Our aim is to pave a comprehensive and solid starting ground for interested readers. We firstly clarify the definition of QC. Secondly, we present the current understanding of QC from different levels, including the basic knowledge of quantum information processing, QC protocols and the attacks in QC. Finally, we discuss the challenges and opportunities in this hopeful field.