Quantum key distribution (QKD) is a method using some properties of quantum mechanics to create a secret shared cryptographic key even if an eavesdropper has access to unlimited computational power. All QKD protocols require that the parties have access to an authentic channel. Otherwise, QKD is vulnerable to man-in-themiddle attacks. This paper studies QKD from this point of view, emphasizing the necessity and sufficiency of using unconditionally secure authentication in QKD. In this work, a hybrid unconditionally secure authentication strategy is proposed for QKD protocols. It is based on a mixture of normal application of authentication codes and the so-called "counter-based" authentication method such that to achieve a better trade off between security and efficiency (in terms of the required size of initially shared secret data). Based on this strategy, a complete authenticated QKD protocol is described for a specific implementation of the well-known BB84 protocol. Some advantages of our protocol in comparison to other proposals are also highlighted.
Quantum key distribution (QKD) is a method using some properties of quantum mechanics to create a secret shared cryptographic key even if an eavesdropper has access to unlimited computational power. All QKD protocols require that the parties have access to an authentic channel. Otherwise, QKD is vulnerable to man-in-themiddle attacks. This paper studies QKD from this point of view, emphasizing the necessity and sufficiency of using unconditionally secure authentication in QKD. In this work, a hybrid unconditionally secure authentication strategy is proposed for QKD protocols. It is based on a mixture of normal application of authentication codes and the so-called "counter-based" authentication method such that to achieve a better trade off between security and efficiency (in terms of the required size of initially shared secret data). Based on this strategy, a complete authenticated QKD protocol is described for a specific implementation of the well-known BB84 protocol. Some advantages of our protocol in comparison to other proposals are also highlighted.
Quantum key distribution (QKD) is a method using some properties of quantum mechanics to create a secret shared cryptographic key even if an eavesdropper has access to unlimited computational power. All QKD protocols require that the parties have access to an authentic channel. Otherwise, QKD is vulnerable to man-in-the-middle attacks. This paper studies QKD from this point of view, emphasizing the necessity and sufficiency of using unconditionally secure authentication in QKD. In this work, a new technique of using unconditionally secure authentication is proposed for quantum cryptosystems. This technique is based on a hybrid of normal application of authentication codes and the so-called “counter-based” authentication method such that to achieve a better trade-off between security and efficiency (in terms of the required size of initially shared secret data). Based on this strategy, an authenticated version of a typical QKD protocol (the well-known BB84 protocol) is described. Some advantages of our protocol in comparison to other proposals are also highlighted.
Quantum Key Distribution (QKD) protocols, such as BB84, require secure authentication of their classical communication channel to ensure message integrity and authenticity, which is fundamental to successfully distribute unconditionally secure keys and prevent critical vulnerabilities. Traditionally, QKD relies on pre-shared secret keys for this authentication, posing significant scalability challenges. Employing asymmetric encryption methods is also not a viable alternative, as these methods are either vulnerable to quantum computing attacks or lack rigorous security proofs. To address these issues, we propose using the well-established Kerberos authentication protocol, which relies on symmetric cryptography inherently resistant to known quantum attacks, to securely distribute symmetric session keys that authenticate classical communication in QKD systems. We demonstrate the feasibility and practical security advantages of employing Kerberos-generated session keys, inherently resistant to quantum computing attacks, without modifying existing Kerberos workflows, providing a practical quantum-secure solution that leverages existing IT infrastructure.
The counter-intuitive features of quantum mechanics make it possible to solve problems and perform tasks that are beyond the abilities of non-quantum (classical) computers and communication devices. The field of quantum information processing studies how we can achieve such improvements by representing information as quantum states.One of the early achievements of quantum information processing is the development of quantum key distribution (QKD). QKD protocols allow two participants (Alice and Bob) to achieve the classically-impossible task of generating a secret shared key even if their adversary is computationally unlimited.Unfortunately, the security promises of QKD are true only in theory; practical implementations of QKD deviate from the theoretical protocols, and many of these deviations give rise to practical attacks. In this research thesis, we study the security properties of various QKD protocols in many practical settings:First, we study practical security of semiquantum key distribution (SQKD) protocols, where either Alice or Bob is non-quantum (classical). Following practical security problems in previous SQKD protocols, we suggest a new SQKD protocol (the "Mirror protocol") which can be securely implemented, and we prove it robust and secure against a wide range of attacks (the "uniform collective attacks").Then, we study "composable security" of the first QKD protocol created by Bennett and Brassard (BB84). BB84 has its unconditional security proved against adversaries performing the most general attacks in a theoretical (idealized) setting; however, some security approaches do not prove "composable security", which requires the secret key to remain secret even when Alice and Bob actually use it for cryptographic purposes. We generalize an algebraic security approach for BB84, making it prove composable security of BB84 (and many variants of BB84) against the most general attacks.Finally, we analyze an important practical attack (named "Bright Illumination"), showing how it can be modeled as a theoretical "Reversed-Space" attack.Overall, all results aim to enhance our understanding on how to bridge the gap between theory and practice in various sub-fields of QKD, and they may help solve a major open problem in the field of QKD: constructing a realistic QKD implementation that can be proved truly and unconditionally secure against any possible attack.
Quantum Key Distribution (QKD) is a secret key agreement technique that consists of two parts: quantum transmission and measurement on a quantum channel, and classical post-processing on a public communication channel. It enjoys provable unconditional security provided that the public communication channel is immutable. Otherwise, QKD is vulnerable to a man-in-the-middle attack. Immutable public communication channels, however, do not exist in practice. So we need to use authentication that implements the properties of an immutable channel as well as possible. One scheme that serves this purpose well is the Wegman-Carter authentication (WCA), which is built upon Almost Strongly Universal2 (ASU2) hashing. This scheme uses a new key in each authentication attempt to select a hash function from an ASU2 family, which is then used to generate the authentication tag for a message. The main focus of this dissertation is on authentication in the context of QKD. We study ASU2 hash functions, security of QKD that employs a computationally secure authentication, and also security of authentication with a partially known key. Specifically, we study the following. First, Universal hash functions and their constructions are reviewed, and as well as a new construction of ASU2 hash functions is presented. Second, security of QKD that employs a specific computationally secure authentication is studied. We present detailed attacks on various practical implementations of QKD that employs this authentication. We also provide countermeasures and prove necessary and sufficient conditions for upgrading the security of the authentication to the level of unconditional security. Third, Universal hash function based multiple authentication is studied. This uses a fixed ASU2 hash function followed by one-time pad encryption, to keep the hash function secret. We show that the one-time pad is necessary in every round for the authentication to be unconditionally secure. Lastly, we study security of the WCA scheme, in the case of a partially known authentication key. Here we prove tight information-theoretic security bounds and also analyse security using witness indistinguishability as used in the Universal Composability framework.
Classical cryptographic systems are increasingly challenged by advances in computing power and new algorithmic techniques, particularly with the rise of quantum computing, which threatens the security of current encryption methods. This has spurred interest in quantum-resistant cryptography, aimed at creating algorithms that can withstand attacks from quantum computers. Traditionally, secure key transport over alternate channels has been a significant challenge, but quantum mechanics offers a solution. Quantum Key Distribution (QKD) is a revolutionary method for secure communication that leverages quantum principles. Unlike traditional methods, QKD provides unconditional security, with key security ensured by the laws of physics rather than computational difficulty. The BB84 protocol, introduced in 1984 by Bennett and Brassard, is a leading QKD scheme known for its simplicity and effectiveness in generating eavesdropping-resistant cryptographic keys. It facilitates secure key transport over alternate channels. This documentation aims to advance QKD security by practically implementing and analyzing the BB84 protocol. Through detailed theoretical analysis, simulation studies, and experimental validation, the practical impacts, and limitations of BB84-based QKD systems are examined. Additionally, a practical implementation of quantum key distribution using a sudoku key demonstrates the process's simplicity and effectiveness. These findings are expected to pave new paths in the field of cryptanalysis in the emerging Quantum Age.
Quantum cryptography is basically based on a trusted channel in communication between two parties compared to classical channel. Recently, Quantum Key Distribution (QKD has become more secure transmission method used to transmit secret key between two legitimate parties. This paper discusses the implementation of QKD protocol (BB84 protocol), which is widely used today. The implementation simulates the communication of two parties who wish to share a secret key with the existing of eavesdropper. The existing of eavesdropper is simulated with two kinds of attacks, which is use as parameter to measure the length of final key agreed by both authenticated parties at the end of the communication. This paper also discuss about future works to fully implement the shared secret key.