249 research outputs found

    Relationship between problem-based learning experience and self-directed learning readiness

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    Tun Hussein Onn University of Malaysia (UTHM) has been implementing Problem-Based Learning (PBL) to some degree in various subjects. However, to this day no empirical data has been gathered on the effectiveness of PBL as a methodology to develop self-directed learning (SDL) skills. The purpose of this \ud study is to investigate self-directed learning readiness (SDLR) among UTHM students exposed to vaiying PBL exposure intensity. SDLR was measured using the modified version of Self-Directed Learning Readiness (SDLRS). Participants in this study were first-year undergraduate students at UTHM. The instrument was administrated to students in Electrical and Electronics Engineering, Civil and Environmental Engineering, and Technical Education (N=260). Data were analyzed using descriptive and inferential statistical techniques with analysis of variance (ANOVA) and the independent /'-test for equal variance for hypotheses testing. The results of this study indicate that overall SDLR level increase with PBL exposure up to exposure intensity twice, beyond which no increase in SDLR was observed with increase in PBL exposure. Within the same academic programme, results did not show a statistically significant difference of SDLR level between groups exposed to varying PBL exposure intensity. However, significant difference was found in some dimensions of the SDLR for the Technical Education students. Within the same education background, results did not show a statistically significant difference of SDLR level between groups exposed to varying PBL intensity. However, significant difference was found in some dimensions of the SDLR for students with both Matriculations and STPM background. A statistically significant difference of SDLR level was found between Electrical Engineering and Technical Education students for exposure once and in some SDLR dimensions. No statistically significant difference was found between students from different academic programme for exposure twice or thrice. The data supports the conclusion that SDLR level increases with increase in PBL exposure intensity up to a certain extent only, beyond which no increase of SDLR can be observed. The data also suggest that only certain dimensions of the SDLR improve with increased exposure to PBL

    Reliable and High-Performance Hardware Architectures for the Advanced Encryption Standard/Galois Counter Mode

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    The high level of security and the fast hardware and software implementations of the Advanced Encryption Standard (AES) have made it the first choice for many critical applications. Since its acceptance as the adopted symmetric-key algorithm, the AES has been utilized in various security-constrained applications, many of which are power and resource constrained and require reliable and efficient hardware implementations. In this thesis, first, we investigate the AES algorithm from the concurrent fault detection point of view. We note that in addition to the efficiency requirements of the AES, it must be reliable against transient and permanent internal faults or malicious faults aiming at revealing the secret key. This reliability analysis and proposing efficient and effective fault detection schemes are essential because fault attacks have become a serious concern in cryptographic applications. Therefore, we propose, design, and implement various novel concurrent fault detection schemes for different AES hardware architectures. These include different structure-dependent and independent approaches for detecting single and multiple stuck-at faults using single and multi-bit signatures. The recently standardized authentication mode of the AES, i.e., Galois/Counter Mode (GCM), is also considered in this thesis. We propose efficient architectures for the AES-GCM algorithm. In this regard, we investigate the AES algorithm and we propose low-complexity and low-power hardware implementations for it, emphasizing on its nonlinear transformation, i.e., SubByes (S-boxes). We present new formulations for this transformation and through exhaustive hardware implementations, we show that the proposed architectures outperform their counterparts in terms of efficiency. Moreover, we present parallel, high-performance new schemes for the hardware implementations of the GCM to improve its throughput and reduce its latency. The performance of the proposed efficient architectures for the AES-GCM and their fault detection approaches are benchmarked using application-specific integrated circuit (ASIC) and field-programmable gate array (FPGA) hardware platforms. Our comparison results show that the proposed hardware architectures outperform their existing counterparts in terms of efficiency and fault detection capability

    VLSI implementation of AES algorithm

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    In the present era of information processing through computers and access of private information over the internet like bank account information even the transaction of money, business deal through video conferencing, encryption of the messages in various forms has become inevitable. There are mainly two types of encryption algorithms, private key (also called symmetric key having single key for encryption and decryption) and public key (separate key for encryption and decryption). In the present work, hardware optimization for AES architecture has been done in different stages. The hardware comparison results show that as AES architecture has critical path delay of 9.78 ns when conventional s-box is used, whereas it has critical path delay of 8.17 ns using proposed s-box architecture. The total clock cycles required to encrypt 128 bits of data using proposed AES architecture are 86 and therefore, throughput of the AES design in Spartan-6 of Xilinx FPGA is approximately 182.2 Mbits/s. To achieve the very high speed, full custom design of s-box in composite field has been done for the proposed s-box architecture in Cadence Virtuoso. The novel XOR gate is proposed for use in s-box design which is efficient in terms of delay and power along with high noise margin. The implementation has been done in 180 nm UMC technology. Total dynamic power in the proposed XOR gate is 0.63 µW as compared to 5.27 µW in the existing design of XOR. The designed s-box using proposed XOR occupies a total area of 27348 µm2. The s-box chip consumes 22.6 µW dynamic power and has 8.2 ns delay after post layout simulation has been performed

    Fault Detection in Crypto-Devices

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    Soft Error Resistant Design of the AES Cipher Using SRAM-based FPGA

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    This thesis presents a new architecture for the reliable implementation of the symmetric-key algorithm Advanced Encryption Standard (AES) in Field Programmable Gate Arrays (FPGAs). Since FPGAs are prone to soft errors caused by radiation, and AES is highly sensitive to errors, reliable architectures are of significant concern. Energetic particles hitting a device can flip bits in FPGA SRAM cells controlling all aspects of the implementation. Unlike previous research, heterogeneous error detection techniques based on properties of the circuit and functionality are used to provide adequate reliability at the lowest possible cost. The use of dual ported block memory for SubBytes, duplication for the control circuitry, and a new enhanced parity technique for MixColumns is proposed. Previous parity techniques cover single errors in datapath registers, however, soft errors can occur in the control circuitry as well as in SRAM cells forming the combinational logic and routing. In this research, propagation of single errors is investigated in the routed netlist. Weaknesses of the previous parity techniques are identified. Architectural redesign at the register-transfer level is introduced to resolve undetected single errors in both the routing and the combinational logic. Reliability of the AES implementation is not only a critical issue in large scale FPGA-based systems but also at both higher altitudes and in space applications where there are a larger number of energetic particles. Thus, this research is important for providing efficient soft error resistant design in many current and future secure applications

    A Multiple Bit Parity Fault Detection Scheme for The Advanced Encryption Standard Galois/Counter Mode

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    The Advanced Encryption Standard (AES) is a symmetric-key block cipher for electronic data announced by the U.S. National Institute of Standards and Technology (NIST) in 2001. The encryption process is based on symmetric key (using the same key for both encryption and decryption) for block encryption of 128, 192, and 256 bits in size. AES and its standardized authentication Galois/Counter Mode (GCM) have been adopted in numerous security-based applications. GCM is a mode of operation for AES symmetric key cryptographic block ciphers, which has been selected for its high throughput rates in high speed communication channels. The GCM is an algorithm for authenticated encryption to provide both data authenticity and confidentiality that can be achieved with reasonable hardware resources. The hardware implementation of the AES-GCM demands tremendous amount of logic blocks and gates. Due to natural faults or intrusion attacks, faulty outputs in different logic blocks of the AES-GCM module results in erroneous output. There exist plenty of specific literature on methods of fault detection in the AES section of the AES-GCM. In this thesis, we consider a novel fault detection of the GCM section using parity prediction. For the purpose of fault detection in GCM, two independent methods are proposed. First, a new technique of fault detection using parity prediction for the entire GCM loop is presented. Then, matrix based CRC multiple-bit parity prediction schemes are developed and implemented. As a result, we achieve the fault coverage of about 99% with the longest path delay and area overhead of 23% and 10.9% respectively. The false alarm is 0.12% which can be ignored based on the number of injected faults

    Tamper-Resistant Arithmetic for Public-Key Cryptography

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    Cryptographic hardware has found many uses in many ubiquitous and pervasive security devices with a small form factor, e.g. SIM cards, smart cards, electronic security tokens, and soon even RFIDs. With applications in banking, telecommunication, healthcare, e-commerce and entertainment, these devices use cryptography to provide security services like authentication, identification and confidentiality to the user. However, the widespread adoption of these devices into the mass market, and the lack of a physical security perimeter have increased the risk of theft, reverse engineering, and cloning. Despite the use of strong cryptographic algorithms, these devices often succumb to powerful side-channel attacks. These attacks provide a motivated third party with access to the inner workings of the device and therefore the opportunity to circumvent the protection of the cryptographic envelope. Apart from passive side-channel analysis, which has been the subject of intense research for over a decade, active tampering attacks like fault analysis have recently gained increased attention from the academic and industrial research community. In this dissertation we address the question of how to protect cryptographic devices against this kind of attacks. More specifically, we focus our attention on public key algorithms like elliptic curve cryptography and their underlying arithmetic structure. In our research we address challenges such as the cost of implementation, the level of protection, and the error model in an adversarial situation. The approaches that we investigated all apply concepts from coding theory, in particular the theory of cyclic codes. This seems intuitive, since both public key cryptography and cyclic codes share finite field arithmetic as a common foundation. The major contributions of our research are (a) a generalization of cyclic codes that allow embedding of finite fields into redundant rings under a ring homomorphism, (b) a new family of non-linear arithmetic residue codes with very high error detection probability, (c) a set of new low-cost arithmetic primitives for optimal extension field arithmetic based on robust codes, and (d) design techniques for tamper resilient finite state machines
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