Abstract
Non-Intrusive Load Monitoring (NILM) aims to determine individual-appliance energy consumption with minimum cost, by decomposing aggregated electricity measurements. Although important for achieving energy conservation and cost minimization, NILM requires high-frequency sampling rates to provide accurate results. This requirement significantly increases the need for storage and computational resources in the electric utility’s fog/ cloud infrastructure, and for bandwidth on the customer’s side. To resolve these issues, on-site disaggregation, i.e., on the monitoring device, can be employed. However, to keep device-cost low, lightweight NILM algorithms are needed. To this end, a lightweight event-detection algorithm designed to ease on-site implementation, on either software or hardware, is proposed. Event detection is the first, critical half of the well-established event-based NILM approach; it identifies appliance state changes (events). Although a few lightweight event-detection techniques, utilizing high-frequency data, have been presented in the literature, their performance is relatively low in complex-load cases. The proposed algorithm utilizes simple-to-compute features and employs multiple simple criteria to declare an event as detected, and slope-coefficient inspection to identify steady states. Moreover, it can detect events with very small time difference between them. Comparisons show that its performance is superior even against more complex event-detection approaches, while its low computational cost is also verified.

Abstract
While logic locking is a promising defense to protect hardware designs, many attacks have been shown to undermine its security by retrieving the secret key. All the powerful attacks rely on a working chip, i.e., an oracle, and in particular, heavily use the test access. The proposed technique DisORC turns the oracle into a dishonest one whenever a potential attack is detected. DisORC works on the premise that structural testing of chips need not be performed with the correct functionality. We implement this capability by adding circuitry around a logic-locked design that reconfigures its functionality upon detecting access to scan chains. Any attempt to access scan chains disconnects the secret key from the circuit, and clears all of its traces, isolating and securing it. We also pair this defense with a truly random logic locking (TRLL) scheme that makes random decisions in inserting key gates and retaining signal polarities without relying on any logic synthesis technique to perform bubble pushing. Any netlist analysis-based attack, known or anticipated, will then learn nothing useful to infer the key values. The combined defense DisORC + TRLL thwarts oracle-based and netlist analysis-based attacks while delivering sufficient corruption levels at the outputs. We also show that the proposed defense is cost effective and can be integrated into the design flow easily. The proposed logic locking defense provides protection against untrusted foundry, testing facility, end users, and any combination of them colluding together.

Abstract
The prevalence of wireless networks has made the long-term need for communications security more imperative. In various wireless applications, images and/or video constitute critical data for transmission. For their copyright protection and authentication, watermarking can be used. In many cases, the cost of wireless nodes must be kept low, which means that their processing and/or power capabilities are very limited. In such cases, low-cost hardware implementations of digital image/video watermarking techniques are necessary. However, to end up with such implementations, proper selection of watermarking techniques is not enough. For this reason, in this paper, we introduce computation optimizations of the implemented algorithm to keep the integer part of arithmetic operations at optimal size, and, hence, arithmetic units as small as possible. In addition, further analysis is performed to reduce quantization error. Three different hardware-architecture variants, two for image watermarking and one for video (pipelined), are proposed, which reutilize the already small arithmetic units in different computation steps, to further reduce implementation cost. The proposed designs compare favorably to already existing implementations in terms of area, power, and performance. Moreover, the watermarked images'/frames' errors, compared to their floating point counterparts, are very small, while robustness to various attacks is high.

Abstract
In this paper a new technique for performing image registration with subpixel accuracy is presented. The proposed technique, which is based on the maximization of the correlation coefficient function, does not require the reconstruction of the intensity values and provides a closed-form solution to the subpixel translation estimation problem. Moreover, an efficient iterative scheme is proposed, which reduces considerably the overall computational cost of the image registration problem. This scheme properly combined with the proposed similarity measure results in a fast spatial domain technique for subpixel image registration.

Abstract
The aim of this paper is to improve the performance of spatial domain watermarking. To this end, a new perceptual mask and a new detection scheme are proposed. The proposed spatial perceptual mask is based on the cover image prediction error sequence and matches very well with the properties of the human visual system. It exhibits superior performance compared to existing spatial masking schemes. Moreover, it allows for a significantly increased strength of the watermark while, at the same time, the watermark visibility is decreased. The new blind detection scheme comprises an efficient prewhitening process and a correlation-based detector. The prewhitening process is based on the least-squares prediction error filter and substantially improves the detector’s performance. The correlation-based detector that was selected is shown to be the most suitable for the problem at hand. The improved performance of the proposed detection scheme has been justified theoretically for the case of linear filtering plus noise attack and through extensive simulations. The theoretical analysis is independent of the proposed mask and the derived expressions can be used for any watermarking technique based on spatial masking. It is shown though that in most cases the detector performs better if the proposed mask is employed.

Abstract
Logic locking has received a lot of attention in the literature due to its very attractive hardware-security characteristics: it can protect against IP piracy and overproduction throughout the whole IC supply chain. However, a large class of logic-locking attacks, the oracle-based ones, take advantage of a functional copy of the chip, the oracle, to extract the key that protects the chip. So far, the techniques dealing with oracle-based attacks focus on the netlist that the attacker possesses, assuming that the oracle is always available. For this reason, they are usually overcome by new attacks. In this paper, we propose a hardware security scheme that targets the protection of the oracle circuit, by locking the circuit when the, necessary for setting the inputs and observing the outputs, scan in/out process begins. Hence, no correct input/output pairs can be acquired to perform the attacks. The proposed scheme is not based on controlling global signals like test_enable or scan_enable, whose values can be easily suppressed by the attacker. Security threats are identified, discussed and addressed. The developed scheme is combined with a traditional logic locking technique with high output corruptibility, to achieve increased levels of protection.

Abstract
In many resource/ power constrained applications (e.g., in wireless-network nodes) there is a need for low cost hardware implementations of digital image watermarking techniques. However, to end up with such an implementation, a proper selection of a watermarking technique, based on performance and cost criteria, is not enough. For that reason, in this paper we introduce computation optimizations of the implemented algorithm to keep the integer portion of arithmetic operations at optimal size, and, hence, arithmetic units as small as possible. Additionally, the proposed architecture reutilizes those units in different computation steps, to further reduce implementation cost. The proposed design compares favorably with the already existing implementations, in terms of area, power and performance.

Abstract
Logic locking has been successfully used for protecting digital circuits against IC piracy. Modern logic locking techniques offer significant security advantages, like high corruptibility of the locked circuit's outputs when applying random keys (= 50% Hamming Distance -HD- compared to the correct outputs), or resilience to the key-sensitization attack. However, there are no techniques to combine both advantages. To solve this problem, weighted logic locking is proposed in this paper. Instead of the conventional single key-input control, the proposed technique uses multiple key-inputs to control every key-gate. This new, weighted key-gate control is by construction immune to the key-sensitization attack, while by employing a new key-gate insertion metric, 50% HD is obtained even for circuits with many outputs. Additionally, weighted key-gate control increases dramatically the probability of any key-gate to corrupt the circuit’s values, which means that fewer key-gates are needed to achieve 50% HD. This way, execution time for locking the circuits is drastically reduced. Apart from these advantages, weighted logic locking is fairly "generic" and can be combined with other techniques to improve security (e.g., to thwart the SAT attack).

Abstract
The contribution of this paper is twofold. First, a new spatial domain image registration technique with subpixel accuracy is presented. This technique is based on a double maximization of the correlation coefficient and provides a closed-form solution to the subpixel translation estimation problem. Second, an efficient iterative scheme for integer registration is proposed, which reduces significantly the number of searches, as compared to the exhaustive search. This scheme can be used as a pre-processing step in the sub-pixel accuracy technique, leading to lower computational complexity. Extensive simulation results have shown that the performance of the proposed technique compares very favorably with respect to existing ones.

Abstract
In this paper, a new scheme for image watermarking in spatial domain based on space-time block coding is proposed. Specifically, a 4x4 real orthogonal design is employed for embedding a multiplicative watermark in the image. The image is divided into four blocks, which, after some simple operations, can be viewed as four different flat fading channels. At the receiver’s end, a low cost maximum likelihood decoding is performed based only on linear processing. This scheme turns out to perform much better than repetitive watermarking, taking advantage of the well-known merits of space-time block coding, i.e., it achieves full diversity offering at the same time the maximum possible transmission rate for real constellations.

Abstract
In this paper a new blind image-adaptive watermarking scheme is proposed. The scheme employs a new spatial mask whose construction is based on the HVS’s (Human Visual System) properties. Specifically, the mask is a function of the local variance of the cover image prediction error sequence. An improved blind detection scheme has also been developed, based on a proper pre-whitening process. Due to the above modifications the proposed technique exhibits superior performance as compared to conventional HVS-based blind adaptive watermarking. The proposed detector’s performance improvement has been justified theoretically for the cases of no attack, noise attack and linear filtering attack, and is also verified through extensive simulations. The theoretical analysis is independent of the proposed mask and the derived expressions can be used for any watermarking technique based on spatial masking. Moreover, proper expressions have been derived that enable the computation of detection thresholds adaptable to the attacking conditions.

Abstract
In this paper a new blind image-adaptive watermarking technique is proposed. The main contributions in this work are the following. First, a new spatial mask taking into account the Human Visual System (HVS) properties, is proposed. The mask is constructed based on the local variance of the cover image prediction ermr sequence. Second, an improved detection scheme has heen developed, which is blind, in the sense that no knowledge concerning the cover image is required. The similarity measure used in the detector is the normalized correlation between the reproduced watermark and the prediction error of the watermarked and possibly attacked image (instead of the image itself). Due to the above modifications the proposed technique exhibits superior performance as compared to the conventional HVS-based blind adaptive watermarking. This performance improvement has been justified theoretically and verified through extensive simulations. In particular, the proposed technique is robust to additive white noise, JPEG and Wavelet compression, filtering etc.

Abstract
In many applications the image registration task turns out to be a fundamental prerequisite for any further processing and analysis. In the proposed paper a new eÆcient technique is presented, appropriate for registering images which are translated and rotated versions of a reference image. The technique consists of two main parts: an efficiently implemented prewhitening part, and an iterative part which yields the unknown displacements after a few iterations. The cross-correlation operations involved in the iterative part are performed efficiently via a new scheme based on a proper partitioning of the images and the use of the FFT. Note that this efficient scheme is also applicable to the conventional spatial cross-correlation method. The new registration technique exhibits a superior performance as compared to the conventional cross-correlation method.

Abstract
In many applications the image registration task is a fundamental prerequisite for any further processing and analysis. In the proposed paper a new efficient technique is presented, appropriate for registering images, which are translated and rotated versions of a reference image. The technique consists of two main parts: an efficiently implemented prewhitening part and an iterative part, which yields the unknown displacements after a few iterations. The most costly part of the algorithm (i.e. cross-correlation computations) is performed efficiently via a new scheme based on a proper partitioning of the images and the use of the FFT. The new registration technique exhibits a superior performance compared to the conventional cross-correlation method. The new technique has been successfully applied in a visual diagnostic method for detecting, in vivo, epithelial dysplasias and malignancies.