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1. Secure Distributed Applications the Decent Way

   https://doi.org/10.1145/3457340.3458304  

   Zheng, Haofan; Arden, Owen (May 2021, ASSS '21: Proceedings of the 2021 International Symposium on Advanced Security on Software and Systems)

   null (Ed.)

   Remote attestation (RA) authenticates code running in trusted execution environments (TEEs), allowing trusted code to be deployed even on untrusted hosts. However, trust relationships established by one component in a distributed application may impact the security of other components, making it difficult to reason about the security of the application as a whole. Furthermore, traditional RA approaches interact badly with modern web service design, which tends to employ small interacting microservices, short session lifetimes, and little or no state. This paper presents the Decent Application Platform, a framework for building secure decentralized applications. Decent applications authenticate and authorize distributed enclave components using a protocol based on self-attestation certificates, a reusable credential based on RA and verifiable by a third party. Components mutually authenticate each other not only based on their code, but also based on the other components they trust, ensuring that no transitively-connected components receive unauthorized information. While some other TEE frameworks support mutual authentication in some form, Decent is the only system that supports mutual authentication without requiring an additional trusted third party besides the trusted hardware's manufacturer. We have verified the secrecy and authenticity of Decent application data in ProVerif, and implemented two applications to evaluate Decent's expressiveness and performance: DecentRide, a ride-sharing service, and DecentHT, a distributed hash table. On the YCSB benchmark, we show that DecentHT achieves 7.5x higher throughput and 3.67x lower latency compared to a non-Decent implementation. 

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2. Profile Based Privacy for Locally Private Computations

   Geumlek, J and (July 2019, Abstracts of papers - IEEE International Symposium on Information Theory)

   Differential privacy has emerged as a gold standard in privacy-preserving data analysis. A popular variant is local differential privacy, where the data holder is the trusted curator. A major barrier, however, towards a wider adoption of this model is that it offers a poor privacy-utility tradeoff. In this work, we address this problem by introducing a new variant of local privacy called profile-based privacy. The central idea is that the problem setting comes with a graph G of data generating distributions, whose edges encode sensitive pairs of distributions that should be made indistinguishable. This provides higher utility because unlike local differential privacy, we no longer need to make every pair of private values in the domain indistinguishable, and instead only protect the identity of the underlying distribution. We establish privacy properties of the profile-based privacy definition, such as post-processing invariance and graceful composition. Finally, we provide mechanisms that are private in this framework, and show via simulations that they achieve higher utility than the corresponding local differential privacy mechanisms. 

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3. Duet: an expressive higher-order language and linear type system for statically enforcing differential privacy

   https://doi.org/10.1145/3360598  

   Near, Joseph P.; Darais, David; Abuah, Chike; Stevens, Tim; Gaddamadugu, Pranav; Wang, Lun; Somani, Neel; Zhang, Mu; Sharma, Nikhil; Shan, Alex; et al (October 2019, Proceedings of the ACM on Programming Languages)

   null (Ed.)

   During the past decade, differential privacy has become the gold standard for protecting the privacy of individuals. However, verifying that a particular program provides differential privacy often remains a manual task to be completed by an expert in the field. Language-based techniques have been proposed for fully automating proofs of differential privacy via type system design, however these results have lagged behind advances in differentially-private algorithms, leaving a noticeable gap in programs which can be automatically verified while also providing state-of-the-art bounds on privacy. We propose Duet, an expressive higher-order language, linear type system and tool for automatically verifying differential privacy of general-purpose higher-order programs. In addition to general purpose programming, Duet supports encoding machine learning algorithms such as stochastic gradient descent, as well as common auxiliary data analysis tasks such as clipping, normalization and hyperparameter tuning - each of which are particularly challenging to encode in a statically verified differential privacy framework. We present a core design of the Duet language and linear type system, and complete key proofs about privacy for well-typed programs. We then show how to extend Duet to support realistic machine learning applications and recent variants of differential privacy which result in improved accuracy for many practical differentially private algorithms. Finally, we implement several differentially private machine learning algorithms in Duet which have never before been automatically verified by a language-based tool, and we present experimental results which demonstrate the benefits of Duet's language design in terms of accuracy of trained machine learning models. 

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4. BLENDER: Enabling Local Search with a Hybrid Differential Privacy Model

   https://doi.org/10.29012/jpc.680  

   Avent, Brendan; Korolova, Aleksandra; Zeber, David; Hovden, Torgeir; Livshits, Benjamin (October 2019, Journal of Privacy and Confidentiality)

   We propose a hybrid model of differential privacy that considers a combination of regular and opt-in users who desire the differential privacy guarantees of the local privacy model and the trusted curator model, respectively. We demonstrate that within this model, it is possible to design a new type of blended algorithm that improves the utility of obtained data, while providing users with their desired privacy guarantees. We apply this algorithm to the task of privately computing the head of the search log and show that the blended approach provides significant improvements in the utility of the data compared to related work. Specifically, on two large search click data sets, comprising 1.75 and 16 GB, respectively, our approach attains NDCG values exceeding 95% across a range of privacy budget values. 

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5. Trusted IP Solution in Multi-tenant Cloud FPGA Platform

   https://doi.org/10.1109/WF-IoT54382.2022.10152167  

   Ahmed, Muhammed Kawser; Saha, Sujan Kumar; Bobda, Christophe (October 2022, 2022 IEEE 8th World Forum on Internet of Things (WF-IoT))

   Because FPGAs outperform traditional processing cores like CPUs and GPUs in terms of performance per watt and flexibility, they are being used more and more in cloud and data center applications. There are growing worries about the security risks posed by multi-tenant sharing as the demand for hardware acceleration increases and gradually gives way to FPGA multi-tenancy in the cloud. The confidentiality, integrity, and availability of FPGA-accelerated applications may be compromised if space-shared FPGAs are made available to many cloud tenants. We propose a root of trust-based trusted execution mechanism called TrustToken to prevent harmful software-level attackers from getting unauthorized access and jeopardizing security. With safe key creation and truly random sources, TrustToken creates a security block that serves as the foundation of trust-based IP security. By offering crucial security characteristics, such as secure, isolated execution and trusted user interaction, TrustToken only permits trustworthy connection between the non-trusted third-party IP and the rest of the SoC environment. The suggested approach does this by connecting the third-party IP interface to the TrustToken Controller and running run-time checks on the correctness of the IP authorization(Token) signals. With an emphasis on software-based assaults targeting unauthorized access and information leakage, we offer a noble hardware/software architecture for trusted execution in FPGA-accelerated clouds and data centers. 

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