Weikeng Chen (UC Berkeley), Raluca Ada Popa (UC Berkeley)

File-sharing systems like Dropbox offer insufficient privacy because a compromised server can see the file contents in the clear. Although encryption can hide such contents from the servers, metadata leakage remains significant. The goal of our work is to develop a file-sharing system that hides metadata---including user identities and file access patterns.

Metal is the first file-sharing system that hides such metadata from malicious users and that has a latency of only a few seconds. The core of Metal consists of a new two-server multi-user oblivious RAM (ORAM) scheme, which is secure against malicious users, a metadata hiding access control protocol, and a capability sharing protocol.

Compared with the state-of-the-art malicious-user file-sharing scheme PIR-MCORAM (Maffei et al.'17), which does not hide user identities, Metal hides the user identities and is 500x faster (in terms of amortized latency) or 10^5x faster (in terms of worst-case latency).

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Secure Sublinear Time Differentially Private Median Computation

Jonas Böhler (SAP Security Research), Florian Kerschbaum (University of Waterloo)

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Snappy: Fast On-chain Payments with Practical Collaterals

Vasilios Mavroudis (University College London), Karl Wüst (ETH Zurich), Aritra Dhar (ETH Zurich), Kari Kostiainen (ETH Zurich), Srdjan Capkun (ETH Zurich)

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Cross-Origin State Inference (COSI) Attacks: Leaking Web Site States...

Avinash Sudhodanan (IMDEA Software Institute), Soheil Khodayari (CISPA Helmholtz Center for Information Security), Juan Caballero (IMDEA Software Institute)

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Post-Quantum Authentication in TLS 1.3: A Performance Study

Dimitrios Sikeridis (The University of New Mexico), Panos Kampanakis (Cisco Systems), Michael Devetsikiotis (The University of New Mexico)

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