Amorphous slicing of extended finite state machines

Slicing is useful for many Software Engineering applications and has been widely studied for three decades, but there has been comparatively little work on slicing Extended Finite State Machines (EFSMs). This paper introduces a set of dependency based EFSM slicing algorithms and an accompanying tool. We demonstrate that our algorithms are suitable for dependence based slicing. We use our tool to conduct experiments on ten EFSMs, including benchmarks and industrial EFSMs. Ours is the first empirical study of dependence based program slicing for EFSMs. Compared to the only previously published dependence based algorithm, our average slice is smaller 40% of the time and larger only 10% of the time, with an average slice size of 35% for termination insensitive slicing

The Almost Equivalence by Asymptotic Probabilities for Regular Languages and Its Computational Complexities

We introduce p-equivalence by asymptotic probabilities, which is a weak almost-equivalence based on zero-one laws in finite model theory. In this paper, we consider the computational complexities of p-equivalence problems for regular languages and provide the following details. First, we give an robustness of p-equivalence and a logical characterization for p-equivalence. The characterization is useful to generate some algorithms for p-equivalence problems by coupling with standard results from descriptive complexity. Second, we give the computational complexities for the p-equivalence problems by the logical characterization. The computational complexities are the same as for the (fully) equivalence problems. Finally, we apply the proofs for p-equivalence to some generalized equivalences.Comment: In Proceedings GandALF 2016, arXiv:1609.0364

Emmett Scott School Yearbook - The Rattler 1965

The Rattler was the official yearbook for Emmett Scott High School in Rock Hill, SC and had a print run from 1951 through 1970. Emmett Scott opened in 1920 as the first public school for blacks in Rock Hill, SC and was a segregated educational institution from 1920 until South Carolina Schools were desegregated in 1970. Emmett Scott School included all grades until 1956 when Emmett Scott High School began serving just junior high and high school grades.https://digitalcommons.winthrop.edu/emmettscottschool/1014/thumbnail.jp

Automated Grading and Feedback of Regular Expressions

To keep up with the current spread of education, there has arisen the need to have automated tools to evaluate assignments. As a part of this thesis, we have developed a technique to evaluate assignments on regular expressions (regexes). Every student is different and so is their solution, thus making it hard to have a single approach to grade it all. Hence, in addition to the existing techniques, we offer a new way of evaluating regexes. We call this the regex edit distance. The idea behind this is to find the minimal changes that we could make in a wrong answer to make its language equivalent to that of a correct answer. This approach is along the lines of the one used by Automata Tutor to grade DFAs. We also spoke to different graders and observed that they were in some sense computing the regex edit distance to assign partial credit. Computing the regex edit distance is a PSPACE-hard problem and seems computationally intractable even for college level submissions. To deal with this intractability, we look at a simpler version of regex edit distance that can be computed for many college level submissions. We hypothesize that our version of regex edit distance is a good metric for evaluating and awarding partial credit for regexes. We ran an initial study and we observed a strong relation between the partial credit awarded and our version of regex edit distance

High performance stride-based network payload inspection

There are two main drivers for network payload inspection: malicious data, attacks, virus detection in Network Intrusion Detection System (NIDS) and content detection in Data Leakage Prevention System (DLPS) or Copyright Infringement Detection System (CIDS). Network attacks are getting more and more prevalent. Traditional network firewalls can only check the packet header, but fail to detect attacks hidden in the packet payload. Therefore, the NIDS with Deep Packet Inspection (DPI) function has been developed and widely deployed. By checking each byte of a packet against the pattern set, which is called pattern matching, NIDS is able to detect the attack codes hidden in the payload. The pattern set is usually organized as a Deterministic Finite Automata (DFA). The processing time of DFA is proportional to the length of the input string, but the memory cost of a DFA is quite large. Meanwhile, the link bandwidth and the traffic of the Internet are rapidly increasing, the size of the attack signature database is also growing larger and larger due to the diversification of the attacks. Consequently, there is a strong demand for high performance and low storage cost NIDS. Traditional softwarebased and hardware-based pattern matching algorithms are have difficulty satisfying the processing speed requirement, thus high performance network payload inspection methods are needed to enable deep packet inspection at line rate. In this thesis, Stride Finite Automata (StriFA), a novel finite automata family to accelerate both string matching and regular expression matching, is presented. Compared with the conventional finite automata, which scan the entire traffic stream to locate malicious information, the StriFA only needs to scan samples of the traffic stream to find the suspicious information, thus increasing the matching speed and reducing memory requirements. Technologies such as instant messaging software (Skype, MSN) or BitTorrent file sharing methods, allow convenient sharing of information between managers, employees, customers, and partners. This, however, leads to two kinds of major security risks when exchanging data between different people: firstly, leakage of sensitive data from a company and, secondly, distribution of copyright infringing products in Peer to Peer (P2P) networks. Traditional DFA-based DPI solutions cannot be used for inspection of file distribution in P2P networks due to the potential out-of-order manner of the data delivery. To address this problem, a hybrid finite automaton called Skip-Stride-Neighbor Finite Automaton (S2NFA) is proposed to solve this problem. It combines benefits of the following three structures: 1) Skip-FA, which is used to solve the out-of-order data scanning problem; 2) Stride-DFA, which is introduced to reduce the memory usage of Skip-FA; 3) Neighbor-DFA which is based on the characteristics of Stride-DFA to get a low false positive rate at the additional cost of a small increase in memory consumption

Accelerating Regular-Expression Matching on FPGAs with High-Level Synthesis

The importance of security infrastructures for high-throughput networks has rapidly grown as a result of expanding internet traffic and increasingly high-bandwidth connections. Intrusion-detection systems (IDSs), such as SNORT, rely upon rule sets designed to alert system administrators of malicious packets. Methods for deep-packet inspection, which often depend upon regular-expression searches, can be accelerated on programmable-logic (PL) architectures using non-deterministic finite automata (NFAs). Prior designs have relied upon register-transfer level (RTL) design descriptions and have achieved efficient resource utilization through fine-grained optimizations. New advances made by field-programmable gate array (FPGA) vendors have led to powerful compiler toolchains for OpenCL and SYCL that allow for rapid development on PL architectures while generating competitive designs in terms of performance. The goal of this research is to evaluate performance differences between a custom, SYCL- and OpenCL-based, acceleration architecture for regular expressions and comparable RTL-based designs. The simplicity of the application, which requires only basic hardware building blocks, adds to the novelty of the comparison. In contrast to prior RTL-based solutions, which show frequency degradation with bandwidth scaling, this approach is able to maintain stable and high operating frequencies at the cost of resource usage. By scaling input bandwidth with multi-character transformations, high-throughput designs can be realized.Using Intel's OpenCL compiler, throughputs in excess of 17 Gbps can be achieved on Intel’s Arria 10 Programmable Acceleration Card and 19.4 Gbps with Intel's Stratix 10 Programmable Acceleration Card, outperforming similar designs with RTL, as reported in the literature. SYCL-based designs, synthesized with Intel's oneAPI compiler show performance degradation but still achieve higher throughput, up to 15.6 Gbps, than past RTL-based implementations. Overall, OpenCL and SYCL development yields both competitive results, when compared to the fine-grained RTL development process, and many ease-of-use improvements and design abstractions

FPgrep and FPsed: Packet Payload Processors for Managing the Flow of Digital Content on Local Area Networks and the Internet

As computer networks increase in speed, it becomes difficult to monitor and manage the transmitted digital content. To alleviate these problems, hardware-based search (FPgrep) and search-and-replace (FPsed) modules have been developed. FP-grep has the ability to scan packet payloads for a given set of regular expressions and pass or drop packets based on the payload contents. FPsed also scans packet payloads for a set of regular expressions and adds the ability to modify the payload if desired. The hardware circuits that implement the FPgrep and FPsed modules can be generated, compiled, and synthesized using a simple web interface. Once a module is created it is programmed into logic on a Field Programmable Gate Array (FPGA). The FPgrep and FPsed modules use FPGAs to process packets at the full rate of Gigabit-speed networks. Both modules, along with several supporting applications were developed and tested using the Field Programmable Port Extender (FPX) platform. Applications developed for the modules currently include a spam filter, virus protection, an information security filter, as well as a copyright enforcement function