Today, hybrid cryptosystems are important part in structure of information telecommunication systems. That's why information security measures are extremely crucial at each stage of cryptosystem development life cycle. One of the most important specific of modern cryptosystems is the fact, that they often deployed in unprotected environment and outside the physically secured perimeter. That introduces new attack vectors, e.g. kleptographic attacks which include implementation forgery at endpoints. Such attack types are extremely dangerous because of the victim, who is a participant of some restricted area (electronic document flow, payment system, secure communication etc.), may induce threats for non-compromised participants (e.g., sensitive information leakage). One of the ways to solve mitigate this risks is development subliminal channel free cryptosystems which are resistant against different types of kleptographic attacks. In the article we show results belong to development of SETUP free cryptographic protocol development. Firstly, we suggest formal model for basic ''challenge-response'' protocol with subliminal channel. Using this formal model, we introduce sufficient conditions which lead to impossibility of existence of subliminal channels. Also the theorem about sufficient conditions has been formulated and proved. Further, we suggest improvements of basic protocols -- nonce generation and 1-round Diffie-Hellman key agreement protocol with design that is based of sufficient conditions. Using formalization of suggested enhanced protocols we formulated and proved the theorem about SETUP resistance property for these protocols. Our results may be useful for other SETUP free protocols development, this will be helpful for increasing security of hybrid cryptosystem.
Today, hybrid cryptosystems are important part in structure of information telecommunication systems. That's why information security measures are extremely crucial at each stage of cryptosystem development life cycle. One of the most important specific of modern cryptosystems is the fact, that they often deployed in unprotected environment and outside the physically secured perimeter. That introduces new attack vectors, e.g. kleptographic attacks which include implementation forgery at endpoints. Such attack types are extremely dangerous because of the victim, who is a participant of some restricted area (electronic document flow, payment system, secure communication etc.), may induce threats for non-compromised participants (e.g., sensitive information leakage). One of the ways to solve mitigate this risks is development subliminal channel free cryptosystems which are resistant against different types of kleptographic attacks. In the article we show results belong to development of SETUP free cryptographic protocol development. Firstly, we suggest formal model for basic ''challenge-response'' protocol with subliminal channel. Using this formal model, we introduce sufficient conditions which lead to impossibility of existence of subliminal channels. Also the theorem about sufficient conditions has been formulated and proved. Further, we suggest improvements of basic protocols -- nonce generation and 1-round Diffie-Hellman key agreement protocol with design that is based of sufficient conditions. Using formalization of suggested enhanced protocols we formulated and proved the theorem about SETUP resistance property for these protocols. Our results may be useful for other SETUP free protocols development, this will be helpful for increasing security of hybrid cryptosystem.
Introduction/purpose: The problem of efficient distribution of cryptographic keys in communication systems has existed since its first days and is especially emphasized by the emergence of mass communication systems. Defining and implementing efficient protocols for symmetric cryptographic keys establishment in such circumstances is of great importance in raising information security in cyberspace. Methods: Using the methods of Information Theory and Secure Multiparty Computation, protocols for direct establishment of cryptographic keys between communication parties have been defined. Results: The paper defines two new approaches to the problem of establishing cryptographic keys. The novelty in the protocol defined in the security model based on information theory is based on the source of common randomness, which in this case is the EEG signal of each subject participating in the communication system. Experimental results show that the amount of information leaking to the attacker is close to zero. A novelty in the second case, which provides security with keys at the level of computer security by applying Secure Multiparty Computation, is in the new application field, namely generation and distribution of symmetric cryptographic keys. It is characteristic of both approaches that within the framework of formal theories, it is possible to draw conclusions about their security characteristics in a formal way. Conclusions: The paper describes two new approaches for establishing cryptographic keys in symmetric cryptographic systems with experimental results. The significance of the proposed solutions lies in the fact that they enable the establishment of secure communication between communication parties from end to end, avoiding the influence of a trusted third party. In that way, the achieved communication level security significantly increases in relation to classical cryptographic systems.
Key exchange protocols, first introduced by Diffie and Hellman in 1976, are one of the most widely-deployed cryptographic protocols. They allow two parties, that have never interacted before, to establish shared secrets. These shared cryptographic keys may subsequently be used to establish a secure communication channel. Use cases include the classic client-server setting that is for example at play when browsing the internet, but also chats via end-to-end-encrypted instant messaging applications. Security-wise, we generally demand of key exchange protocols to achieve key secrecy and authentication. While, informally, authentication ensures that the communicating parties have confidence in the identity of their peers, key secrecy ensures that any shared cryptographic key that is established via the key exchange protocol is only known to the participants in the protocol and can be used securely in cryptographic protocols, i.e., is sufficiently random. In 1993, Bellare and Rogaway gave a first formalization of key exchange protocol security that captures these properties with respect to powerful adversaries with full control over the network. Their model constitutes the basis of the many subsequent treatments of authenticated key exchange security, including the models presented in this thesis. The common methodological approach underlying all of these formalizations is the provable security paradigm, which has become a standard tool in assessing the security of cryptographic protocols and primitives. So-called security models specify the expected security guarantees of the scheme in question with regards to a well-defined class of adversaries. Proofs that validate these security claims do so by reducing the security of the overall scheme to the security of the underlying cryptographic primitives and hardness assumptions. However, advances in computational power and more sophisticated cryptanalytic capabilities often render exactly these components insecure. Especially the advent of quantum computers will have a devastating effect on much of today's public key cryptography. This is especially true for key exchange protocols since they rely crucially on public-key algorithms. In this thesis, our focus in future-proofing key exchange protocols is two-fold. First, we focus on extending security models for key exchange protocols to capture the (un)expected break of cryptographic primitives and hardness assumptions. The aim is to gain assurances with respect to future adversaries and to investigate the effects of primitive failures on key exchange protocols. More specifically, we explore how key exchange protocols can be safely transitioned to new, post-quantum secure algorithms with hybrid techniques. Hybrids combine classical and post-quantum algorithms such that the overall key agreement scheme remains secure as long as one of the two base schemes remains secure. For this, we introduce security notions for key encapsulation mechanisms that account for adversaries with varying levels of quantum capabilities and present three new constructions for hybrid key encapsulation mechanisms. Our hybrid designs are practice-inspired and for example capture draft proposals for hybrid modes in the Transport Layer Security (TLS) protocol, which is one of the most widely-deployed cryptographic protocols that enables key agreement. Furthermore, our notion of breakdown resilience for key exchange protocols allows to gauge the security of past session keys in the event of a failure of a cryptographic component in the key exchange. We exercise our model on variants of the post-quantum secure key exchange protocol NewHope by Alkim et al. Thereby, we confirm the intuition that, in order to guard against adversaries that only have access to quantum computing power in the (more distant) future, it is sufficient to use classically-secure authentication mechanisms alongside post-quantum key agreement to achieve authenticated key exchange. As with any mathematical statement, theorems in the provable security paradigm are only as valid as the underlying assumptions. A careful consideration of any newly made assumption is thus essential to ensure the meaningfulness of the statement itself and make the assumption a viable tool for future analyses. Thus, secondly, we systematically classify the PRF-ODH assumption, a complexity-theoretic hardness assumption that has been used in key exchange security analyses of such prominent protocols as TLS, Signal, and Wireguard. In particular, we give a unified, parametrized definition of the assumption encompassing different variants that are present in the literature. We relate the resulting parametrized notions in terms of their strength and show where these assumptions fit in the collection of well-understood related hardness assumptions. We finally sketch our result on the impossibility of instantiating this assumption in the standard model, thereby disposing of the uncertainty in the community whether PRF-ODH is in fact a standard model assumption, i.e., removes the usage of some idealized assumptions in key exchange protocol proofs.
Recent advances in quantum technology and the potential that practical quantum computers may become a reality in the future have led to renewed interest in developing cryptographic technologies that are secure against conventional and quantum attacks. Currently, virtually all asymmetric cryptographic schemes in use are threatened by the potential development of powerful quantum computers. Post-quantum cryptography is one of main the ways to combat this threat. Its security is based on the complexity of mathematical problems that are currently considered unsolvable efficiently, even with the help of quantum computers. The security of information systems is ensured through protection against various threats that use system vulnerabilities. Security protocols are the building blocks of secure communication. They implement security mechanisms to provide security services. Security protocols are considered abstract when analyzed, but may have additional vulnerabilities in implementation. This work contains a holistic study of security protocols. Basics of security protocols, taxonomy of attacks on security protocols and their implementation are considered, as well as various methods and models of protocol security analysis. In particular, the differences between information-theoretic and computational security, computational and symbolic models are specified. In addition, an overview of the computational security models for Authenticated Key Exchange (AKE) and Password Authentication Key Exchange (PAKE) protocols is provided. The most important security models for the AKE and PAKE protocols were also described. With the emergence of new technologies that may have different security requirements, as well as with increased opportunities for competition, there is always a need to develop new protocols. Thus, the purpose of this article is to review, classify, analyze, and research the vulnerabilities of information systems from classical, quantum, and special attacks, performed taking into account the forecast regarding the possibilities of attacks on post-quantum cryptographic transformations; studying security assessment models for existing cryptographic protocols, as well as reviewing and benchmarking security models and providing suggestions for protection against existing potential attacks.
Quantum computing, which uses quantum physics’ superposition and entanglement, has the potential to revolutionize a number of disciplines, including material science, cryptography, and optimization. But the emergence of quantum computing also brings serious security risks, putting cryptography measures to the test and opening up new vulnerabilities. This work offers a thorough examination of these security risks in information processing using quantum computing. We investigate quantum-specific attacks that take advantage of quantum systems’ unique properties, going beyond cryptographic flaws. Quantum side-channel attacks on quantum hardware and quantum spying attempts on quantum key distribution (QKD) protocols highlight the practical issues in protecting quantum communication networks. Long-term dangers to data privacy and integrity also arise from the possibility of data gathering for future decryption, in which attackers gather and store encrypted data now in anticipation of being able to decrypt it later with more potent quantum computers. We first investigate the threats that quantum algorithms bring to the security of the cryptographic protocols in use today. Shor’s method jeopardizes the security of popular public-key cryptosystems such as RSA, ECC, and Diffie-Hellman because it can solve discrete logarithms and factor large integers quickly. Grover’s approach, similarly, weakens the security of symmetric-key cryptography systems by essentially halving their key strength while providing a quadratic speedup for brute-force searches. In order to mitigate these risks, we address the creation and application of post-quantum cryptography algorithms that are resistant to quantum assaults. For quantum communication networks, better QKD methods and infrastructure that is resistant to quantum emulation are crucial security considerations. Proactively developing responses and staying ahead of emerging dangers require constant research and observation. In summary, while quantum computing holds immense potential, it also introduces new security challenges that require resolution to protect information processing systems. This analysis emphasizes how critical it is to switch to cryptography techniques that are resistant to quantum computing and to put in place comprehensive security measures in order to protect against the constantly changing danger landscape that this technology poses. This chapter provides a concise overview of the key concepts that a comprehensive study would encompass.
This chapter is concerned with cryptographic protocols. We begin with an explanation of what components a cryptographic protocol consists of. We then illustrate the complexity of designing a secure cryptographic protocol by considering an artificially simple scenario, for which we propose and analyse seven candidate protocols. For each of these protocols, we comment on whether, or under which conditions, they meet the required specification. We go on to look at the important class of authentication and key establishment protocols. We identify typical goals and examine some important protocols in this class, including the Diffie–Hellman protocol.
The article develops a comprehensive threat model for hybrid quantum-secured communication channels of corporate networks operating under conditions of multi-vector cyberattacks and highly dynamic threat scenarios.An analysis of the vulnerabilities of the electronic communication infrastructure is conducted, taking into account the synergistic interaction of classical cryptographic protocols, post-quantum cryptographic protection algorithms, and quantum key distribution technologies.Special attention is paid to the investigation of attack vectors aimed at compromising the processes of key information management, authentication, and the establishment of secure connections in hybrid network environments.A multi-level classification of threats is proposed, covering the physical, data link, network, transport, and application layers of the OSI model, as well as a separate category of threats caused by the use of quantum computing resources by a potential attacker.Specific attack scenarios are considered, including quantum-enhanced cryptanalytic methods, attacks on the hardware implementation of quantum protocols, the compromise of trusted nodes, and the impact on key distribution channels.The paper analyzes software and hardware mechanisms for ensuring the cryptographic strength and fault tolerance of hybrid communication channels, in particular, mechanisms for dynamic key information management, the integration of quantum key distribution protocols into corporate telecommunication environments, and the application of post-quantum cryptographic primitives to protect control and user data.Architectural solutions are proposed for the orchestration of cryptographic services, security status monitoring, and adaptive reconfiguration of security mechanisms in real time.Based on the obtained results, a generalized protection model for hybrid quantum-secured communication channels is formed, aimed at increasing the level of information security, cyber resilience, and the continuity of corporate networks functioning under the conditions of complex combined attacks and the transition to the quantum computing era.