Cryptography is a method of secure communication between two or more parties. The crucial step is exchanging a key in a secure manner. There are, however, two problems with conventional cryptography. First the sender and the receiver should exchange the key through highly reliable and secure channels. The second problem is that a clever eavesdropper can, by a careful analysis of the sent information, reconstruct the key. In this chapter, schemes to overcome these problems are presented. First a scheme for exchanging a key over public channels, the so-called RSA algorithm, is discussed. Then the protocols for the quantum key distribution (QKD), the Bennett–Brassard-84 (BB-84) and Bennett-92(B-92) protocols, are then presented. The QKD protocols are exclusively derived using Bohr’s principle of complementarity. An application of these ideas to the design of secure quantum money is discussed.
Cryptography is a method of secure communication between two or more parties. The crucial step is exchanging a key in a secure manner. There are, however, two problems with conventional cryptography. First the sender and the receiver should exchange the key through highly reliable and secure channels. The second problem is that a clever eavesdropper can, by a careful analysis of the sent information, reconstruct the key. In this chapter, schemes to overcome these problems are presented. First a scheme for exchanging a key over public channels, the so-called RSA algorithm, is discussed. Then the protocols for the quantum key distribution (QKD), the Bennett–Brassard-84 (BB-84) and Bennett-92(B-92) protocols, are then presented. The QKD protocols are exclusively derived using Bohr’s principle of complementarity. An application of these ideas to the design of secure quantum money is discussed.
Quantum cryptography provides secret communication, which offers various security factors like confidentiality, integrity, and authentication assurance based on the law of physics. The law of physics states that quantum computing can also be applied into the communication sector, which is particularly in the field of cryptography. Then quantum can significantly distribute the data securely by applying quantum key distribution (QKD), quantum key sharing, etc. In the classical cryptography, it is difficult to compute secret keys using security concepts like key exchange and authentication, etc., and it fails to provide adequate protection during data communication as it needs some effective computation in terms of security. The lack of security in the data communication can be overcome by using the concept of quantum computing. Generally, in quantum computing, elementary quantum systems like polarized photons are used to transmit digital information based on the principle of uncertainty as it gives rise to a significant phenomenon of effective security in terms of communication compared to existing concepts related to cryptography. In quantum computing, the detection ratio for identifying the data which are sent through a communication channel is more difficult as it uses qubits and photons to represent the data that are sent. Quantum channels are used to distribute the information between two users as it passes through the unprotected classical channels as it is unknown to anyone else. Assuming that Alice and Bob use a latent noise channel to send a key, reconciliation is the process of correcting errors between Alice and Bob’s version of the key. This is done by public discussion, which leaks some information about the secret key to an undercover. This chapter gives a discussion on QKD concepts as it helps to provide a secure communication, where the information is broadcasting through a quantum channel. Finally, the various existing quantum protocols are described in relation to some security measures based on QKD, and the standard QKD protocol of BB84 is discussed.
Quantum cryptography lies at the intersection of information theory and quantum mechanics. Cryptosystems come in two major classes depending on whether the key is shared in public or in secret. Public key cryptosystems are special in that they allow two people, who have not yet met, to communicate securely by looking-up encryption methods in a public directory. In quantum cryptography, the sender and receiver have two types of communication channels: a classical public channel and a quantum channel. The best application of cryptography is to allow a secure communication. In the near future, quantum cryptography may be used in top-secret applications in the military, for example, as the basis of communication links. The first protocol for quantum cryptography was proposed in 1984 by C. H. Bennett and G. Brassard. Some of the basic quantum cryptographic systems are: four-states protocol, two-states protocol, 4+2 protocol and multi-photon and multi-stage protocol.
Secure data exchange over the network is ensured by the requirements of confidentiality, integrity and availability of information. To meet these requirements, sent data is encrypted on the sending side, and the received information is decrypted on the receiving side. Transmitted message is encrypted according to rules determined by the algorithm and key. Crypto security of encrypted information depends on the key length. Among the encryption algorithms, there are algorithms with a symmetric (private) key and with an asymmetric (public) key. Despite all the advantages of a private key, asymmetric keys are used to deliver it from one user to another (key distribution). However, high-performance quantum computers are capable to decrypt intercepted data. Therefore, modern cryptographic systems use quantum key distribution method. The idea of using quantum bits was proposed in 1970 by S. Wiesner. In 1984, Ch. Bennett and G. Brassard proposed the BB84 protocol. The use of «entangled » quanta for systems with quantum key distribution was offerred in 1991 by A. Eckert. All modern quantum cryptography systems are based on these above-mentioned protocols.
Security awareness is one of the most pressing topics in today's globe. The idea of cryptography is introduced when the subject is information security. Conventional cryptography-based security techniques rely on the presumption that keys are shared before secure connections. The most crucial factor to consider when integrating cryptographic operations into account when integrating cryptographic operations in with any system is the safe key management strategy required for sending and transferring a secret key between two entities The systems will be vulnerable to bugs and possibly fatal external assaults if the fundamental management methods are poor A method for securely encrypting data sent between parties is quantum cryptography. and spotting eavesdroppers trying to overhear the conversation. Quantum cryptography may be the solution to these issues a quantum cryptography application, Quantum Key Distribution (QKD), refers to the production of a cryptographic key with unconditional security assured by physical rules. Quantum cryptography is a kind of encryption. We examine the quantum key exchange protocol (BB84 protocol) in this study and the way that it significantly improves data transfer security when compared to standard encryption techniques. The main objective of quantum cryptography is to offer a trustworthy way to provide a secure method of communication between the intended peers only and to detect the Eavesdropper presence.
Irrespective of the duration for which the classical system based on bits remains secure, the imminent advent of quantum systems demands a robust cryptographic mechanism to safeguard both manifest data and the existing system’s structure and infrastructure against various threats. Quantum mechanics may provide a solution in the form of quantum key distribution (QKD), a set of processes designed to generate and exchange cryptographic keys between two parties. Each unique method and algorithm within QKD can be characterized as a protocol. In 1984, Charles Bennett and Gilles Brassard introduced the first QKD protocol, BB84. Subsequent QKD protocols have been developed based on different principles, including Heisenberg’s uncertainty principle, polarization, entanglement, and the non-cloning theory. Other scientists have enhanced some QKD protocols, leading to variations with different names. However, not all these protocols can be implemented in classical systems, as they specifically require a quantum system. The current challenge revolves around the complex and pressing need to develop a QKD protocol that can function effectively on classical systems, quantum systems, or both. In the chapter, QKD protocols are comprehensively examined, with each protocol being meticulously reviewed through technical steps elucidating how the protocol facilitates the exchange of secret keys. Each QKD protocol is dissected to unveil its underlying mechanisms, providing a detailed exploration of the cryptographic procedures involved in generating and exchanging secure cryptographic keys.
One promising way to use quantum information to secure everyday communication is through the distribution of quantum keys. By exchanging a secret key, the Quantum Key Distribution (QKD) approach allows two parties to communicate securely.BB84 protocol is among the most well-known QKD protocols. In this protocol, qubits are exchanged via a quantum channel between the sender and the receiver. This enables them to produce a shared key that is impenetrable to eavesdroppers and illustrate the fundamental ideas of QKD using current simulations and implementations. The results of this study demonstrate that the BB84 protocol is a highly secure QKD technique that has been investigated in great detail and used in a variety of contexts. Additionally, over the enhancements made to the BB84 protocol such as the use of advanced error correction techniques and decoy states to increase its security and usability is discussed. With an emphasis on the BB84 protocol in secure communication technologies, this study offers an extensive analysis of QKD systems overall.