To safeguard user data privacy, on-device inference has emerged as a prominent paradigm on mobile and Internet of Things (IoT) devices. This paradigm involves deploying a model provided by a third party on local devices to perform inference tasks. However, it exposes the private model to two primary security threats: model stealing (MS) and membership inference attacks (MIA). To mitigate these risks, existing wisdom deploys models within Trusted Execution Environments (TEEs), which is a secure isolated execution space. Nonetheless, the constrained secure memory capacity in TEEs makes it challenging to achieve full model security with low inference latency.

Mobile application updates occur frequently, and they continue to add considerable traffic over the Internet. Differencing algorithms, which compute a small delta between the new version and the old version, are often employed to reduce the update overhead. Transforming the old and new files into the decoded similarity spaces can drastically reduce the delta size. However, this transformation is often hindered by two practical reasons: (1) insufficient decoding (2) long recompression time. To address this challenge, we have proposed two general approaches to transforming the compressed files (more specifically, deflate stream) into the full decoded similarity space and partial decoded similarity space, with low recompression time. The first approach uses recompression-aware searching mechanism, based on a general full decoding tool to transform deflate stream to the full decoded similarity space with a configurable searching complexity, even when it cannot be recompressed identically. The second approach uses a novel solution to transform a deflate stream into the partial decoded similarity space with differencing-friendly LZ77 token reencoding. We have also proposed an algorithm called MDiffPatch to exploit the full and partial decoded similarity spaces. The algorithm can well balance compression ratio and recompression time by exposing a tunable parameter. Extensive evaluation results show that MDiffPatch achieves lower compression ratio than state-of-the-art algorithms and its tunable parameter allows us to achieve a good tradeoff between compression ratio and recompression time.

Internet of Things (IoT) applications have recently been widely used in safety-critical scenarios. To prevent sensitive information leaks, IoT device vendors provide hardware-assisted protections, called Trusted Execution Environments (TEEs), like ARM Trust-Zone. Programming a TEE-based application requires separate code for two components, significantly slowing down the development process. Existing solutions tackle this issue by automatic code partition while not successfully applying it in two complicated scenarios: adding trusted logic and interactions with secure peripherals.We propose dTEE, a declarative approach to secure IoT applications based on TrustZone. dTEE proposes a rapid approach that enables developers to declare tiered-sensitive variables and functions of existing applications. Besides, dTEE automatically transforms device drivers into trusted ones. We evaluate dTEE on four real-world IoT applications and seven micro-benchmarks. Results show that dTEE achieves high expressiveness for supporting 50% more applications than existing approaches and reduces 90% of the lines of code against handcrafted development.

Mobile application updates occur frequently, and they continue to add considerable traffic over the Internet. Differencing algorithms, which compute a small delta between the new version and the old version, are often employed to reduce the update overhead. Researchers have proposed many differencing algorithms over the years. Unfortunately, it is currently unknown how these algorithms quantitatively perform for different categories of applications. It is also challenging to know the impacts of different techniques and whether a technique in one algorithm can be integrated into another algorithm for further performance improvement. This paper conducts the first systematic study to understand the performance of four widely used differencing algorithms for mobile application updates, including xdelta3, bsdiff, archive-patcher, and HDiffPatch with respect to five key metrics, including compression ratio, differencing time/memory overhead, and reconstruction time/memory overhead. We perform measurements for 200 mobile applications, and analyze key techniques (such as decompressing-before-differencing, sliding window, and copy instructions merging) that influence the performance of these algorithms. We have provided four important findings which give insights to further optimize for performance improvement. Guided by these insights, we have also proposed a novel algorithm,sdiff, which achieves the smallest compression ratio to state-of-the-art algorithms by combining an appropriately chosen set of key techniques.