Εκπαίδευση - Σπουδές

Ερευνητικά Ενδιαφέροντα

Διδασκαλία

Δημοσιεύσεις σε Διεθνή Περιοδικά (Journals)


Copyright Notice: This material is presented to ensure timely dissemination of scholarly and technical work. Copyright and all rights therein are retained by authors or by other copyright holders. All persons copying this information are expected to adhere to the terms and constraints invoked by each author's copyright. In most cases, these works may not be reposted or mass reproduced without the explicit permission of the copyright holder.


K. Pexaras, I. G. Karybali, E. Kalligeros, "Optimization and Hardware Implementation of Image and Video Watermarking for Low Cost Applications", IEEE Transactions on Circuits and Systems I: Regular Papers, Vol. 66, No. 6, pp. 2088-2101, 2019, https://ieeexplore.ieee.org/stamp/s..., IF = 3.934
 

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.

Επιστημονικά Συνέδρια (Conferences)


Copyright Notice: This material is presented to ensure timely dissemination of scholarly and technical work. Copyright and all rights therein are retained by authors or by other copyright holders. All persons copying this information are expected to adhere to the terms and constraints invoked by each author's copyright. In most cases, these works may not be reposted or mass reproduced without the explicit permission of the copyright holder.


K. Pexaras, C. Tsiourakis, I. G. Karybali, E. Kalligeros, "Optimization and Hardware Implementation of Image Watermarking for Low Cost Applications", IEEE International Conference on Electronics, Circuits and Systems (ICECS), pp. 347-350, Dec, 2017, http://ieeexplore.ieee.org/stamp/st...
 

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.

N. Karousos, K. Pexaras, I. G. Karybali, E. Kalligeros, "Weighted Logic Locking: A New Approach for IC Piracy Protection", IEEE International Symposium on On-Line Testing and Robust System Design (IOLTS), pp. 221-226, Jul, 2017, http://ieeexplore.ieee.org/stamp/st...
 

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).

Βιβλία


Copyright Notice: This material is presented to ensure timely dissemination of scholarly and technical work. Copyright and all rights therein are retained by authors or by other copyright holders. All persons copying this information are expected to adhere to the terms and constraints invoked by each author's copyright. In most cases, these works may not be reposted or mass reproduced without the explicit permission of the copyright holder.


Κεφάλαια σε Βιβλία


Copyright Notice: This material is presented to ensure timely dissemination of scholarly and technical work. Copyright and all rights therein are retained by authors or by other copyright holders. All persons copying this information are expected to adhere to the terms and constraints invoked by each author's copyright. In most cases, these works may not be reposted or mass reproduced without the explicit permission of the copyright holder.


Επιμέλεια Πρακτικών Διεθνών Συνεδρίων


Copyright Notice: This material is presented to ensure timely dissemination of scholarly and technical work. Copyright and all rights therein are retained by authors or by other copyright holders. All persons copying this information are expected to adhere to the terms and constraints invoked by each author's copyright. In most cases, these works may not be reposted or mass reproduced without the explicit permission of the copyright holder.