Quantum computers could break currently used asymmetric cryptographic schemes in a few years using Shor's algorithm. They are used in numerous protocols and applications to secure authenticity as well as key agreement, and quantum-safe alternatives are urgently needed. NIST therefore initiated a standardization process. This requires intensive evaluation, also with regard to performance and integrability. Here, the integration into TLS 1.3 plays an important role, since it is used for 90% of all Internet connections. In the present work, algorithms for quantum-safe key exchange during TLS 1.3 handshake were reviewed. The focus is on the influence of dedicated network parameters such as transmission rate or packet loss in order to gain insights regarding the suitability of the algorithms under corresponding network conditions. For the implementation, a framework by Paquin et al. was extended to emulate network scenarios and capture the handshake duration for selected algorithms. It is shown that the evaluated candidates Kyber, Saber and NTRU as well as the alternative NTRU Prime have a very good overall performance and partly undercut the handshake duration of the classical ECDH. The choice of a higher security level or hybrid variants does not make a significant difference here. This is not the case with alternatives such as FrodoKEM, SIKE, HQC or BIKE, which have individual disadvantages and whose respective performance varies greatly depending on the security level and hybrid implementation. This is especially true for the data-intensive algorithm FrodoKEM. In general, the prevailing network characteristics should be taken into account when choosing scheme and variant. Further it becomes clear that the performance of the handshake is influenced by external factors such as TCP mechanisms or MTU, which could compensate for possible disadvantages due to PQC if configured appropriately.
Quantum computers could break currently used asymmetric cryptographic schemes in a few years using Shor's algorithm. They are used in numerous protocols and applications to secure authenticity as well as key agreement, and quantum-safe alternatives are urgently needed. NIST therefore initiated a standardization process. This requires intensive evaluation, also with regard to performance and integrability. Here, the integration into TLS 1.3 plays an important role, since it is used for 90% of all Internet connections. In the present work, algorithms for quantum-safe key exchange during TLS 1.3 handshake were reviewed. The focus is on the influence of dedicated network parameters such as transmission rate or packet loss in order to gain insights regarding the suitability of the algorithms under corresponding network conditions. For the implementation, a framework by Paquin et al. was extended to emulate network scenarios and capture the handshake duration for selected algorithms. It is shown that the evaluated candidates Kyber, Saber and NTRU as well as the alternative NTRU Prime have a very good overall performance and partly undercut the handshake duration of the classical ECDH. The choice of a higher security level or hybrid variants does not make a significant difference here. This is not the case with alternatives such as FrodoKEM, SIKE, HQC or BIKE, which have individual disadvantages and whose respective performance varies greatly depending on the security level and hybrid implementation. This is especially true for the data-intensive algorithm FrodoKEM. In general, the prevailing network characteristics should be taken into account when choosing scheme and variant. Further it becomes clear that the performance of the handshake is influenced by external factors such as TCP mechanisms or MTU, which could compensate for possible disadvantages due to PQC if configured appropriately.
The emergence of quantum computing presents a significant threat to classical cryptographic primitives, particularly those employed in securing internet communications via widely used protocols such as Transport Layer Security (TLS). As conventional key exchange mechanisms will become increasingly vulnerable in the post-quantum era, the integration of post-quantum cryptographic (PQC) algorithms into existing security protocols is of utmost importance. This study investigates the impact of incorporating PQC key encapsulation mechanisms—specifically, the recent standards CRYSTALS-Kyber and HQC, in conjunction with the candidate standard BIKE—into the TLS 1.3 handshake. A comprehensive experimental evaluation was conducted to measure handshake latency under emulated network conditions with varying packet loss probabilities. The findings offer useful insights into the performance trade-offs introduced by PQC integration and further highlight the necessity of a timely transition to post-quantum cryptographic standards.
The anticipated emergence of a cryptographically-relevant quantum computer (CRQC) would fundamentally compromise much of the security used in public key cryptography today. Traditional cryptographic systems, commonly used for key exchanges and digital signatures, are therefore vulnerable. Efforts to standardize and migrate to post-quantum cryptographic (PQC) alternatives require rigorous empirical evaluation to ensure that these new methods in which we place our security are not vulnerable to quantum computers or less secure than the traditional systems that they aim to replace. This thesis explores one method of combining the security of today’s key exchanges with that of the newly standardized post-quantum alternatives using a hybrid approach within the Transport Layer Security (TLS) 1.3 protocol. This was implemented into MbedTLS, and tests were conducted to evaluate the impact of different hybrid key combinations in a simulated network environment with restrictive Maximum Transmission Unit (MTU) sizes and higher levels of packet loss. The results indicated that the TCP segmentation introduced by the limiting MTU was the greatest factor affecting the TLS 1.3 handshake latency when performed over lossy networks.
Quantum Computers (QCs) differ radically from traditional computers and can efficiently solve mathematical problems fundamental to our current cryptographic algorithms. Although existing QCs need to accommodate more qubits to break cryptographic algorithms, the concern of ''Store-Now-Decrypt-Later'' (i.e., adversaries store encrypted data today and decrypt them once powerful QCs become available) highlights the necessity to adopt quantum-safe approaches as soon as possible. In this work, we investigate the performance impact of Post-Quantum Cryptography (PQC) on TLS 1.3. Different signature algorithms and key agreements (as proposed by the National Institute of Standards and Technology (NIST)) are examined through black- and white-box measurements to get precise handshake latencies and computational costs per participating library. We emulated loss, bandwidth, and delay to analyze constrained environments. Our results reveal that HQC and Kyber are on par with our current state-of-the-art, while Dilithium and Falcon are even faster. We observed no performance drawback from using hybrid algorithms; moreover, on higher NIST security levels, PQC outperformed any algorithm in use today. Hence, we conclude that post-quantum TLS is suitable for adoption in today's systems.
Aim: The imminent advent of large-scale quantum computers within the next years is expected to highly affect the security of several cryptosystems that are now considered secure; this mainly holds for classical, long-established, public key cryptographic algorithms such as RSA and elliptic curve cryptography. Apparently, any security protocol that relies on such ciphers, including the transport layer security (TLS) protocol which constitutes a somewhat de facto standard for the security on the web, will not be considered secure in the post-quantum era. To alleviate the security risks stemming from quantum computing, several proposals have been submitted to the relevant procedure initiated by NIST towards evaluating and standardizing one or more quantum-resistant public-key cryptographic algorithms. This paper focuses on embedding post-quantum secure cryptographic algorithms into the TLS protocol to analyze its performance. More precisely, the paper aims to analyze whether this transition to post-quantum secure algorithms will have a significant impact on the user experience due to the possible increase of client--server communication times. Methods: Having as the starting point several important works in the field, several experiments were carried out, using combinations of cloud and local virtual machines per case and considering all the post-quantum cryptographic algorithm finalists for key exchange from the third round of the ongoing NIST process, for various cryptographic as well as network parameters. Results: Our results exhibit that, for key exchange in TLS, the best performance among the post-quantum secure ciphers is achieved by the Saber and CRYSTAL-Kyber variants for all security levels, regardless of the underlying computing power. The performance is comparable to that of the corresponding one achieved by a classical elliptic curve algorithm for key exchange for both RTT and packet loss ratio — i.e., the network parameters seem to have the same effect on post-quantum secure algorithms as in the case of a conventional elliptic curve algorithm. However, the effect of the network parameters on the performance is more crucial than the effect of the underlying chosen ciphers. Conclusion: According to the experiments, we conclude that there exist very promising algorithms that could be utilized in TLS in the near future, which may behave even better than the conventional elliptic curve algorithms for key exchange. It should also be pointed out that NIST announced on 5 July 2022 (i.e., after the completion of our research experiments) that, for general encryption used when we access secure websites, the CRYSTALS-Kyber algorithm has been selected, having as one of its advantages the speed of operation. Hence, the results of our paper are fully in line with the progress of the NIST process. Taking into account that the NIST process is still ongoing (now in its fourth round) with the aim to select more algorithms, as well as that some algorithms may be standardized outside NIST, it becomes evident that our results provide very useful insights on performance aspects of the post-quantum secure algorithms.
Due to the increasing attainability of quantum computers, the threat to traditional cryptographic algorithms is more relevant than ever before. However, the field of Post-Quantum Cryptography (PQC) to address this is still young and may potentially exhibit security vulnerabilities. In this paper, the role of Pre-Shared Keys (PSK) is analyzed in an attack scenario with both traditional and post-quantum algorithms potentially broken. We present a scheme for improved integration of external PSKs into a PQC-secured TLS 1.3 handshake, with a focus on no security compromises and broad deployment options. In that context, the protection of long-term secrets on dedicated security tokens and the integration of Quantum Key Distribution (QKD) are elaborated. For QKD integration, our scheme enables a deployment without QKD-specific changes to TLS. In addition to the scheme itself, a reference implementation is presented and evaluated to demonstrate its technical viability. Our results indicate that the general integration of PSKs into the TLS handshake adds negligible overhead while substantially increasing the achieved security level. Although deployments using dedicated security tokens or QKD systems have a significant influence on handshake times, specific applications could benefit greatly from the added security guarantees.
The emergence of large-scale quantum computers poses a significant threat to current cryptographic protocols, particularly Transport Layer Security (TLS), which relies on RSA and elliptic curve cryptography vulnerable to Shor's algorithm. This paper presents a hybrid framework for quantum-resistant TLS handshakes that integrates post-quantum cryptography (PQC), quantum key distribution (QKD) and classical cryptography to provide comprehensive protection against both classical and quantum attacks. The approach employs three QKD protocols; BB84, E91, and Measurement-Device-Independent QKD (MDI-QKD) alongside NIST-standardized PQC algorithms as well as alternative candidates such as HQC and BIKE. A key innovation is the QKD key management module, which addresses performance bottlenecks through periodic key generation and secure reuse within predefined retention periods, significantly reducing QKD overhead in TLS handshakes. The experimental implementation using the quantum network simulator evaluated 144 distinct cryptographic protocol combinations. Results demonstrate that ML-KEM combined with ML-DSA provides optimal PQC performance, while QKD protocol selection is distance-dependent: BB84 for short-range and MDI-QKD for long-distance communication. The framework includes various attack mitigation mechanisms and ensure security as long as at least one cryptographic method remains uncompromised. Consistent with current global quantum network usage, the proposed TLS approach is designed primarily for MAN and WAN environments rather than the Internet, providing a balanced solution that combines theoretical security guarantees with computational efficiency.