Droplet: Decentralized Authorization and Access Control for Encrypted Data Streams


Hossein Shafagh and Lukas Burkhalter, ETH Zurich; Sylvia Ratnasamy, UC Berkeley; Anwar Hithnawi, ETH Zurich & UC Berkeley


This paper presents Droplet, a decentralized data access control service. Droplet enables data owners to securely and selectively share their encrypted data while guaranteeing data confidentiality in the presence of unauthorized parties and compromised data servers. Droplet’s contribution lies in coupling two key ideas: (i) a cryptographically-enforced access control construction for encrypted data streams which enables users to define fine-grained stream-specific access policies, and (ii) a decentralized authorization service that serves user-defined access policies. In this paper, we present Droplet’s design, the reference implementation of Droplet, and the experimental results of three case-study applications deployed with Droplet: Fitbit activity tracker, Ava health tracker, and ECOviz smart meter dashboard, demonstrating Droplet’s applicability for secure sharing of IoT streams.

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@inproceedings {255352,
author = {Hossein Shafagh and Lukas Burkhalter and Sylvia Ratnasamy and Anwar Hithnawi},
title = {Droplet: Decentralized Authorization and Access Control for Encrypted Data Streams},
booktitle = {29th {USENIX} Security Symposium ({USENIX} Security 20)},
year = {2020},
isbn = {978-1-939133-17-5},
pages = {2469--2486},
url = {https://www.usenix.org/conference/usenixsecurity20/presentation/shafagh},
publisher = {{USENIX} Association},
month = aug,

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