arXiv subjects

Thomas Loruenser

Publications and source records attributed to Thomas Loruenser.

6 recordsLinked to original sources

arXiv2026

A Pragmatic Comparison of Cryptographic Computation Technologies for Machine Learning

As security demands increase, the importance of secure computation technologies grows, yet these technologies can often seem overwhelming to practitioners. Furthermore, many approaches focus only on a single technology, potentially overlooking superior alternatives. This work aims to address the issue of selecting the right technology for secure computation by presenting a comparative analysis of two highly relevant cryptographic methods and their software implementations, with a particular focus on machine learning. Firstly, we provide a theoretical summary and comparison of the secure computation paradigms of secure multi-party computation (SMPC) and fully homomorphic encryption (FHE). We outline the advantages and limitations of the protocols, as well as the relevant open-source software implementations. Secondly, we present the results of extensive benchmarking of the main software frameworks identified for machine learning operations and models. Regarding the current state of the art in FHE, we observe that it outperforms SMPC for regressions. Additionally it may be faster for simple dense networks using GPUs or Hybrid Models. Conversely, SMPC showed superior performance for complex models such as CNNs. Our results should pave the way for more technology-agnostic benchmarking of secure computation technologies for machine learning, providing guidance for practitioners looking to adopt these technologies.

cs.CR↗

arXiv2024

Secure Computation and Trustless Data Intermediaries in Data Spaces

This paper explores the integration of advanced cryptographic techniques for secure computation in data spaces to enable secure and trusted data sharing, which is essential for the evolving data economy. In addition, the paper examines the role of data intermediaries, as outlined in the EU Data Governance Act, in data spaces and specifically introduces the idea of trustless intermediaries that do not have access to their users' data. Therefore, we exploit the introduced secure computation methods, i.e. Secure Multi-Party Computation (MPC) and Fully Homomorphic Encryption (FHE), and discuss the security benefits. Overall, we identify and address key challenges for integration, focusing on areas such as identity management, policy enforcement, node selection, and access control, and present solutions through real-world use cases, including air traffic management, manufacturing, and secondary data use. Furthermore, through the analysis of practical applications, this work proposes a comprehensive framework for the implementation and standardization of secure computing technologies in dynamic, trustless data environments, paving the way for future research and development of a secure and interoperable data ecosystem.

cs.CR↗

arXiv2022

On the Security of Offloading Post-Processing for Quantum Key Distribution

Quantum key distribution (QKD) has been researched for almost four decades and is currently making its way to commercial applications. However, deployment of the technology at scale is challenging, because of the very particular nature of QKD and its physical limitations. Among others, QKD is computationally intensive in the post-processing phase and devices are therefore complex and power hungry, which leads to problems in certain application scenarios. In this work we study the possibility to offload computationally intensive parts in the QKD post-processing stack in a secure way to untrusted hardware. We show how error correction can be securely offloaded for discrete-variable QKD to a single untrusted server and that the same method cannot be used for long distance continuous-variable QKD. Furthermore, we analyze possibilities for multi-server protocols to be used for error correction and privacy amplification. Even in cases where it is not possible to offload to an external server, being able to delegate computation to untrusted hardware components on the device could improve the cost and certification effort for device manufacturers.

quant-ph↗

arXiv2022

A Verifiable Multiparty Computation Solver for the Assignment Problem and Applications to Air Traffic Management

The assignment problem is an essential problem in many application fields and frequently used to optimize resource usage. The problem is well understood and various efficient algorithms exist to solve the problem. However, it was unclear what practical performance could be achieved for privacy preserving implementations based on multiparty computation (MPC) by leveraging more efficient solution strategies than MPC based simplex solvers for linear programs. We solve this question by implementing and comparing different optimized MPC algorithms to solve the assignment problem for reasonable problem sizes. Our empirical approach revealed various insights to MPC based optimization and we measured a significant (50x) speedup compared to the known simplex based approach. Furthermore, we also study the overhead introduced by making the results publicly verifiable by means of non-interactive zero-knowledge proofs. By leveraging modern proof systems we also achieve significant speedup for proof and verification times compared to the previously proposed approaches as well as compact proof sizes.

cs.CR↗

arXiv2021

Towards a Performance Model for Byzantine Fault Tolerant (Storage) Services

Byzantine fault-tolerant systems have been researched for more than four decades, and although shown possible early, the solutions were impractical for a long time. With PBFT the first practical solution was proposed in 1999 and spawned new research which culminated in novel applications using it today. Although the safety and liveness properties of PBFT-type protocols have been rigorously analyzed, when it comes to practical performance only empirical results - often in artificial settings - are known and imperfections on the communication channels are not specifically considered. In this work we present the first performance model for PBFT specifically considering the impact of unreliable channels and the use of different transport protocols over them. We also did extensive simulations to verify the model and to gain more insight on the impact of deployment parameters on the overall transaction time. We show that the usage of UDP can lead to significant speedup for PBFT protocols compared to TCP when tuned accordingly even over lossy channels. Finally, we compared the simulation to a real implementation and measure the benefits of a developed improvement directly. We found that the impact on the design of the network layer has been overlooked in the past but offers some additional room for improvement when it comes to practical performance. In this work we are focusing on the optimistic case with no node failures, as this is hopefully the most relevant situation.

cs.DC↗

arXiv2015

Towards a New Paradigm for Privacy and Security in Cloud Services

The market for cloud computing can be considered as the major growth area in ICT. However, big companies and public authorities are reluctant to entrust their most sensitive data to external parties for storage and processing. The reason for their hesitation is clear: There exist no satisfactory approaches to adequately protect the data during its lifetime in the cloud. The EU Project Prismacloud (Horizon 2020 programme; duration 2/2015-7/2018) addresses these challenges and yields a portfolio of novel technologies to build security enabled cloud services, guaranteeing the required security with the strongest notion possible, namely by means of cryptography. We present a new approach towards a next generation of security and privacy enabled services to be deployed in only partially trusted cloud infrastructures.

cs.CR↗