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Cryptography from quantum uncertainty in the presence of quantum side information

Niek J. Bouman

Published Oct 1, 2008• 0 citations
OpenAlex

Abstract

The thesis starts with a high-level introduction into cryptography and quantum mechanics. Chapter 2 gives a theoretical foundation by introducing probability theory, information theory, functional analysis, quantum mechanics and quantum information theory. Chapter 3, 4 and 5 are editions of work published earlier.\n\nIn Chapter 3, we present a quantum-information-theoretic tool to analyze random sampling in a quantum setting. In particular, we present two new rigorous security proofs that make use of our new sampling tool: one for BB84 quantum key distribution, and one for a quantum reduction from oblivious transfer (OT) to bit commitment.\n\nChapter 4 studies the problem of message authentication from a weak key (which is a key that is not uniformly random, e.g., a password) in a new scenario. In this scenario, the weak key is a one-time session key that is derived from a public source of randomness with the help of a long-term key (e.g., a password). We propose a new four-round protocol for message authentication from a weak (session) key. \n\nIn Chapter 5 we present a new entropic uncertainty relation and furthermore we consider the task of password-based identification. We devise a new quantum identification protocol that is secure in two security models simultaneously.

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The thesis starts with a high-level introduction into cryptography and quantum mechanics. Chapter 2 gives a theoretical foundation by introducing probability theory, information theory, functional analysis, quantum mechanics and quantum information theory. Chapter 3, 4 and 5 are editions of work published earlier.\n\nIn Chapter 3, we present a quantum-information-theoretic tool to analyze random sampling in a quantum setting. In particular, we present two new rigorous security proofs that make use of our new sampling tool: one for BB84 quantum key distribution, and one for a quantum reduction from oblivious transfer (OT) to bit commitment.\n\nChapter 4 studies the problem of message authentication from a weak key (which is a key that is not uniformly random, e.g., a password) in a new scenario. In this scenario, the weak key is a one-time session key that is derived from a public source of randomness with the help of a long-term key (e.g., a password). We propose a new four-round protocol for message authentication from a weak (session) key. \n\nIn Chapter 5 we present a new entropic uncertainty relation and furthermore we consider the task of password-based identification. We devise a new quantum identification protocol that is secure in two security models simultaneously.
It has been shown recently that the framework of quantum sampling, as introduced by Bouman and Fehr, can lead to new entropic uncertainty relations highly applicable to finite-key cryptographic analyses. Here we revisit these so-called sampling-based entropic uncertainty relations, deriving newer, more powerful, relations and applying them to source-independent quantum random number generators and high-dimensional quantum key distribution protocols. Along the way, we prove several interesting results in the asymptotic case for our entropic uncertainty relations. These sampling-based approaches to entropic uncertainty, and their application to quantum cryptography, hold great potential for deriving proofs of security for quantum cryptographic systems, and the approaches we use here may be applicable to an even wider range of scenarios.
It has been shown recently that the framework of quantum sampling, as introduced by Bouman and Fehr, can lead to new entropic uncertainty relations highly applicable to finite-key cryptographic analyses. Here we revisit these so-called sampling-based entropic uncertainty relations, deriving newer, more powerful, relations and applying them to source-independent quantum random number generators and high-dimensional quantum key distribution protocols. Along the way, we prove several interesting results in the asymptotic case for our entropic uncertainty relations. These sampling-based approaches to entropic uncertainty, and their application to quantum cryptography, hold great potential for deriving proofs of security for quantum cryptographic systems, and the approaches we use here may be applicable to an even wider range of scenarios.
The main goals of cryptography are the encryption of messages to render them unintelligible to third parties and the authentication of messages to certify that they have not been modified. These goals can be accomplished if the sender ("Alice") and recipient ("Bob") both possess a secret random binary digit (bit) known as "key". It is essential that Alice and Bob acquire the key material with a high level of confidence that any third party ("Eve") does not have even partial information about the random bit sequence. If Alice and Bob communicate solely through classical messages (as opposed to Quantum cryptography), it is impossible for them to generate a certifiably secret key. QKD are the new generation of cryptographic systems which allow two remote parties (Alice and Bob) to generate a secret key with privacy guaranteed by quantum mechanics. They generate a random key securely over an optical fiber connection (also known as Quantum channel). This random key is then used for encryption and decryption of confidential messages, which then can be sent in encrypted form over any non-secure communication channel. In this thesis, we study two fiber-based QKD systems namely "oneway" and "two-way". Both systems have their unique advantage which distinguish them to one another. In one-way, the complexity of the electronic system may reduce. However more attention has to be made on the optical setup due to the requirement of active compensation. In the two-way, the requirement of optical setup may reduce but the attention moves to the electronic system which requires precise and short pulse especially for high speed in Alice system configuration. Our developed prototype is capable to support either one-way and two-way QKD system. We also solved some of the issues from the previous prototype Kumar [2008] which limited the system to be used in high speed. For instance: the synchronization system now uses a single synchronization signal per frame; the frame initialization time delay is reduced to 140ms per frame; pulse shaping distortion due to current consumption. We also introduced the security perspective for B92 protocol with uninformative states. This is done by utilizing the security analysis for BB84 such as entanglement distillation protocol (EDP) [...], smooth Ra'©nyi entropy [...] and composable security [...]. Numerous proposal on smooth Ra'©nyi entropy as general case [...] either for finite security analysis [...] or in asymptotic limit [...] assist us to deduce finite security perspective for B92 with uninformative states. [...] This thesis is organized as follow, initially starts with a general introduction to the cryptography and its relation with quantum cryptography. This is elaborated in Chapter One. In the Second Chapter we will go through the background of quantum mechanics and quantum information and introduce some parameters and theory mostly used in Quantum Key Distribution. These include quantum measurement, state behavior and the security analysis parameters. The second chapter will give the background concepts for the QKD in perspective of quantum information. The Third Chapter will explore more detailed information towards QKD. It starts with the basic architecture algorithm of the quantum cryptography system and details each components of the architecture. Later we focus on the security analysis specifically for the B92 protocol. Finally in the chapter, we will make some finite element analysis for the B92 protocol with uninformative states. In Chapter Four and onwards, we are discussing the experimental implementation and analysis. We begin with the heart of our system which is the field programmable gate array (FPGA) system. We explain the detailed architecture of our FPGA system and how the system works. The module that we develop in our FPGA system in order to work inside the QKD system is also explained in detail. We reserve the modification and advanced work of this system for the future by giving the original codes in the Appendix A. Chapter Five is one of the shortest chapters in this thesis. This chapter explains our electronic development and the opto-electronic device which are used in the QKD system. The main device that we develop for the QKD system is our Mezzanine board for FPGA. This mezzanine board supports some functions that are not available from the FPGA in order to make the system functional. Other developments include opto-electronic board and proportional-integral-derivative (PID) controller with the current driver. Chapter Six is the main experimental part. In this Chapter we start to give the introduction to our optical setup. We detail out our configuration of the setup and finally show our results taken from experimental work. Finally in Chapter Seven we conclude our work and purposed future work which actually need to done for the system.
Cryptography plays an integral role in secure communication and is usually the strongest link in the chain of security. Yet security problems abound in electronic communication: spyware, phishing, denial of service, and side-channel attacks are still major concerns. The main goal in this thesis is to consider how cryptographic techniques can be extended to offer greater defence against these non-traditional security threats. \n \nIn the first part of this thesis, we consider problems in classical cryptography. We introduce multi-factor password-authenticated key exchange which allows secure authentication and key agreement based on multiple short secrets, such as a long-term password and a one-time response; it can provide an enhanced level of assurance in higher security scenarios because a multi-factor protocol is designed to remain secure even if all but one of the factors has been compromised due to attacks such as phishing or spyware. Next, we consider the integration of denial of service countermeasures with key exchange protocols: by introducing a formal model for denial of service resilience that complements the extended Canetti-Krawczyk model for secure key agreement, we cover a wide range of existing denial of service attacks and prevent them by carefully using client puzzles. Additionally, we look at how side-channel attacks affect certain types of formulae used in elliptic curve cryptography, and demonstrate that information leaked during field operations such as addition, subtraction, and multiplication can be exploited by an attacker. \n \nIn the second part of this thesis, we examine cryptography in the quantum setting. We argue that quantum key distribution will have an important role to play in future information security infrastructures and will operate best when integrated with the powerful public key infrastructures that are used today. Finally, we present a new look at quantum money and describe a quantum coin scheme where the coins are not easily counterfeited, are locally verifiable, and can be transferred to another party.
Quantum information science has completely changed the way we think about and process information. From the simple realization that information is physical, we have been able to use the peculiar features of quantum mechanical phenomena to our advantage. Designing algorithms whose performance exceeds those running on classical computers, and performing secret communication whose security can actually be proven from sound assumptions are two main catalysts for the establishment of the field. This thesis discusses some progress in quantum key distribution and quantum randomness generation. Quantum key distribution, which is motivated by the increasing need to communicate securely, is on the verge of becoming an established technology. With the goal of extending the reach of quantum key distribution to more realistic scenarios, we present a study on reference-frame-independent protocols whose knowledge can help design more efficient protocols, and a framework to the security analysis of distributed-phase-reference protocols, which have been missing for many years. This allows these protocols to be used in practice against the most general adversary, although the key rate is rather pessimistic. In quantum randomness generation, the amount of extractable randomness from a quantum system depends on the level of trust or characterization of the devices; we present a study into such interaction. In the extreme situation of distrust, i.e. device-independent scenarios, we study the effect of the input randomness on the certifying power of such scenarios, and realize that one cannot amplify an arbitrary min-entropy source device-independently. Finally we discuss the amount of randomness in post-selected data, which has consequences on practical randomness generation protocols. The in depth study of randomness generation from quantum processes is well justified by the important role of randomness in modern computer science and other fields.