Today’s smartphone operating systems frequently fail to provide users with visibility into how third-party applications collect and share their private data. We address these shortcomings with TaintDroid, an efficient, system-wide dynamic taint tracking and analysis system capable of simultaneously tracking multiple sources of sensitive data. TaintDroid enables realtime analysis by leveraging Android’s virtualized execution environment. TaintDroid incurs only 32p performance overhead on a CPU-bound microbenchmark and imposes negligible overhead on interactive third-party applications. Using TaintDroid to monitor the behavior of 30 popular third-party Android applications, in our 2010 study we found 20 applications potentially misused users’ private information; so did a similar fraction of the tested applications in our 2012 study. Monitoring the flow of privacy-sensitive data with TaintDroid provides valuable input for smartphone users and security service firms seeking to identify misbehaving applications.

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TaintDroid: An Information-Flow Tracking System for Realtime Privacy Monitoring on Smartphones

Today's smartphone operating systems frequently fail to provide users with adequate control over and visibility into how third-party applications use their private data. We address these shortcomings with TaintDroid, an efficient, system-wide dynamic taint tracking and analysis system capable of simultaneously tracking multiple sources of sensitive data. TaintDroid provides realtime analysis by leveraging Android's virtualized execution environment. TaintDroid incurs only 14% performance overhead on a CPU-bound micro-benchmark and imposes negligible overhead on interactive third-party applications. Using TaintDroid to monitor the behavior of 30 popular third-party Android applications, we found 68 instances of potential misuse of users' private information across 20 applications. Monitoring sensitive data with TaintDroid provides informed use of third-party applications for phone users and valuable input for smartphone security service firms seeking to identify misbehaving applications.

/pdf/taintdroid-an-information-flow-tracking-system-for-realtime-3fnz9lwdso.pdf

TaintDroid: an information-flow tracking system for realtime privacy monitoring on smartphones

Ordered Binary-Decision Diagrams (OBDDs) represent Boolean functions as directed acyclic graphs. They form a canonical representation, making testing of functional properties such as satisfiability and equivalence straightforward. A number of operations on Boolean functions can be implemented as graph algorithms on OBDD data structures. Using OBDDs, a wide variety of problems can be solved through symbolic analysis. First, the possible variations in system parameters and operating conditions are encoded with Boolean variables. Then the system is evaluated for all variations by a sequence of OBDD operations. Researchers have thus solved a number of problems in digital-system design, finite-state system analysis, artificial intelligence, and mathematical logic. This paper describes the OBDD data structure and surveys a number of applications that have been solved by OBDD-based symbolic analysis.

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Symbolic Boolean manipulation with ordered binary-decision diagrams

Physical Unclonable Functions (PUFs) are innovative circuit primitives that extract secrets from physical characteristics of integrated circuits (ICs). We present PUF designs that exploit inherent delay characteristics of wires and transistors that differ from chip to chip, and describe how PUFs can enable low-cost authentication of individual ICs and generate volatile secret keys for cryptographic operations.

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Physical unclonable functions for device authentication and secret key generation

Physical Unclonable Functions for Device Authentication and Secret Key Generation

Accurate comparative analysis tools for low-homology proteins remains a difficult challenge in computational biology, especially sequence alignment and consensus folding problems. We present partiFold-Align, the first algorithm for simultaneous alignment and consensus folding of unaligned protein sequences; the algorithm's complexity is polynomial in time and space. Algorithmically, partiFold-Align exploits sparsity in the set of super-secondary structure pairings and alignment candidates to achieve an effectively cubic running time for simultaneous pairwise alignment and folding. We demonstrate the efficacy of these techniques on transmembrane β-barrel proteins, an important yet difficult class of proteins with few known three-dimensional structures. Testing against structurally derived sequence alignments, partiFold-Align significantly outperforms state-of-the-art pairwise and multiple sequence alignment tools in the most difficult low-sequence homology case. It also improves secondary structur...

Simultaneous Alignment and Folding of Protein Sequences

—Trellis is a mix-net based anonymous broadcast system with cryptographic security guarantees. Trellis can be used to anonymously publish documents or communicate with other users, all while assuming full network surveillance. In Trellis, users send messages through a set of servers in successive rounds. The servers mix and post the messages to a public bulletin board, hiding which users sent which messages. Trellis hides all network-level metadata, remains robust to changing network conditions, guarantees availability to honest users, and scales with the number of mix servers. Trellis pro- vides three to five orders of magnitude faster performance and better network robustness compared to Atom, the state-of-the-art anonymous broadcast system with a similar threat model. In achieving these guarantees, Trellis contributes: (1) a simpler theoretical mixing analysis for a routing mix network constructed with a fraction of malicious servers, (2) anonymous routing tokens for verifiable random paths, and (3) lightweight blame protocols built on top of onion routing to identify and eliminate malicious parties. We implement and evaluate Trellis in a networked deploy- ment. With 64 servers located across four geographic regions, Trellis achieves a throughput of 220 bits per second with 100,000 users. With 128 servers, Trellis achieves a throughput of 320 bits per second. Trellis’s throughput is only 100 to 1000 × slower compared to Tor (which has 6,000 servers and 2M daily users) and is therefore potentially deployable at a smaller “enterprise” scale. Our implementation is open-source.

Trellis: Robust and Scalable Metadata-private Anonymous Broadcast

Sequential testability aspects in the decomposition of finite state machines (FSMs) are addressed. It is shown that the sequential testability of an FSM can be enhanced more easily when the machine is recognized to be, or is synthesized as, an interconnection of smaller machines. An exhaustive classification of redundant faults that can occur in a single FSM embedded in an interacting sequential circuit is presented. Associating each class of these redundant faults with a don't care set, a synthesis procedure is described that exploits the don't cares optimally to obtain an irredundant interacting sequential circuit with no area overhead. The synthesis procedure operates on a distributed-style representation of interacting state transition graphs (STGs), carrying out a series of local analyses. Insights into sequential logic synthesis improving on current optimization techniques for interacting sequential circuits are presented. >

Testability driven synthesis of interacting finite state machines

Oblivious RAM (ORAM) is a cryptographic primitive that hides memory access patterns as seen by untrusted storage. This paper proposes Ring ORAM, the most bandwidth-efficient ORAM scheme for the small client storage setting in both theory and practice. Ring ORAM is the first tree-based ORAM whose bandwidth is independent of the ORAM bucket size, a property that unlocks multiple performance improvements. First, Ring ORAM's overall bandwidth is 2.3× to 4× better than Path ORAM, the prior-art scheme for small client storage. Second, if memory can perform simple untrusted computation, Ring ORAM achieves constant online bandwidth (∼ 60× improvement over Path ORAM for practical parameters). As a case study, we show Ring ORAM speeds up program completion time in a secure processor by 1.5× relative to Path ORAM. On the theory side, Ring ORAM features a tighter and significantly simpler analysis than Path ORAM.

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Constants Count: Practical Improvements to Oblivious RAM

Now that we have developed tools which can efficiently estimate the average power dissipation of combinational and sequential logic circuits, we have a means of comparing different implementations of the same system, and therefore a way to direct logic synthesis tools for low power optimization.

Srinivas Devadas

Papers

Simultaneous Alignment and Folding of Protein Sequences

Trellis: Robust and Scalable Metadata-private Anonymous Broadcast

Testability driven synthesis of interacting finite state machines

Constants Count: Practical Improvements to Oblivious RAM

Optimization Techniques for Low Power Circuits