SqORAM: Read-Optimized Sequential Write-Only Oblivious RAM

Oblivious RAM protocols (ORAMs) allow a client to access data from an untrusted storage device without revealing the access patterns. Typically, the ORAM adversary can observe both read and write accesses. Write-only ORAMs target a more practical, {\em multi-snapshot adversary} only monitoring client writes -- typical for plausible deniability and censorship-resilient systems. This allows write-only ORAMs to achieve significantly-better asymptotic performance. However, these apparent gains do not materialize in real deployments primarily due to the random data placement strategies used to break correlations between logical and physical namespaces, a required property for write access privacy. Random access performs poorly on both rotational disks and SSDs (often increasing wear significantly, and interfering with wear-leveling mechanisms). In this work, we introduce SqORAM, a new locality-preserving write-only ORAM that preserves write access privacy without requiring random data access. Data blocks close to each other in the logical domain land in close proximity on the physical media. Importantly, SqORAM maintains this data locality property over time, significantly increasing read throughput. A full Linux kernel-level implementation of SqORAM is 100x faster than non locality-preserving solutions for standard workloads and is 60-100% faster than the state-of-the-art for typical file system workloads

Wink: Deniable Secure Messaging

End-to-end encrypted (E2EE) messaging is an essential first step towards combating increasingly privacy-intrusive laws. Unfortunately, it is vulnerable to compelled key disclosure -- law-mandated, coerced, or simply by device compromise. This work introduces Wink, the first plausibly-deniable messaging system protecting message confidentiality even when users are coerced to hand over keys/passwords. Wink can surreptitiously inject hidden messages in the standard random coins (e.g., salt, IVs) used by existing E2EE protocols. It does so as part of legitimate secure cryptographic functionality deployed inside widely-available trusted execution environments (TEEs) such as TrustZone. This provides a powerful mechanism for hidden untraceable communication using virtually unchanged unsuspecting existing E2EE messaging apps, as well as strong plausible deniability. Wink has been demonstrated with multiple existing E2EE applications (including Telegram and Signal) with minimal (external) instrumentation, negligible overheads, and crucially without changing on-wire message formats

INFUSE: Invisible plausibly-deniable file system for NAND flash

Protecting sensitive data stored on local storage devices e.g., laptops, tablets etc. is essential for privacy. When adversaries are powerful enough to coerce users to reveal encryption keys/passwords, encryption alone becomes insufficient for data protection. Additional mechanisms are required to hide the very presence of sensitive data

Efficient Range ORAM with O(log⁡2N)\mathbb{O}(\log^{2}{N}) Locality

Oblivious RAM protocols (ORAMs) allow a client to access data from an untrusted storage device without revealing to that device any information about their access pattern. Typically this is accomplished through random shuffling of the data such that the storage device cannot determine where individual blocks are located, resulting in a highly randomized access pattern. Storage devices however, are typically optimized for \emph{sequential} access. A large number of random disk seeks during standard ORAM operation induce a substantial overhead. In this paper, we introduce rORAM, an ORAM specifically suited for accessing ranges of \emph{sequentially logical blocks} while \emph{minimizing the number of random physical disk seeks}. rORAM obtains significantly better asymptotic efficiency than prior designs (Asharov et al., ePrint 2017, Demertzis et al., CRYPTO 2018) reducing {\em both} the number of seeks and communication complexity by a multiplicative factor of $\mathbb{O}(\log N)$. An rORAM prototype is 30-50x times faster than Path ORAM for similar range-query workloads on local HDDs, 30x faster for local SSDs, and 10x faster for network block devices. rORAM\u27s novel disk layout can also speed up standard ORAM constructions, e.g., resulting in a 2x faster Path ORAM variant. Importantly, experiments demonstrate suitability for real world applications -- rORAM is up to 5x faster running a file server and up to 11x faster running a range-query intensive video server workloads compared to standard Path ORAM