Performance Evaluation, Comparison and Improvement of the Hardware Implementations of the Advanced Encryption Standard S-box

The Advanced Encryption Standard (AES) is the most popular algorithm used in symmetric key cryptography. The efficient computation of AES is essential for many computing platforms. The S-box is the only nonlinear transformation step of the AES algorithm. Efficient implementation of the AES S-box is very crucial for AES hardware. The AES S-box could be implemented by using look-up table method or by using finite field arithmetic. The finite field arithmetic design approach to implement the AES S-box is superior in saving the hardware resources. The main objective of this thesis is to evaluate, compare and improve the hardware implementations of the forward, inverse and combined AES S-box in terms of area and/or delay. Both the composite field GF((2^4)^2) and the tower field GF(((2^2)^2)^2) are considered. Our first improvement is the optimization of the input and output linear mappings of the S- box in order to design a more compact circuit. Our second improvement aims at modifying the architecture of the S-box to achieve a higher speed. We used multiplication of the S-box input by an 8-bit binary field element to optimize the input and output transformation matrices of the S-box. A Matlab® search is then conducted to find more compact linear mappings for the S-box. We also modified the fast S-box architecture, in addition to optimizing and searching the extended linear input mappings to improve the speed of Reyhani et al. fast S-box. The improved fast S-box, Fast 3, is the fastest and most efficient (measured by area × delay) AES S-box available in the literature, up to our knowledge. We also improved the area and delay of the inversion circuit of the lightweight and fast S-boxes in [69], by slightly modifying the exponentiation block and designing a new subfield inverter block. The improved inversion circuit leads to a more compact and a faster lightweight S-box and it yields a lower area fast S-box. Moreover, we show that the “tech. XORs” concept proposed by Maximov et al. [54] to estimate the delay of the S-box is not accurate. We show how to use the logical effort method [74] instead to estimate and compare the delay of previous and improved S-boxes, regardless of the CMOS technology library used for the implementation. We verified all the codes at the RTL level using Mentor Graphics Modelsim®, by comparing against the legitimate S-box outputs. We synthesized the designs using STM 65nm CMOS standard cell library and we used VHDL coding as the design entry method to Synopsys Design Compiler®. The synthesis results confirm the lower area and / or delay of the improved S-box designs and match our space and timing analyses

Efficacy and Safety of Topical Tranexamic Acid Alone or in Combination with Either Fractional Carbon Dioxide Laser or Microneedling for the Treatment of Melasma

Introduction: Tranexamic acid (TXA) is a promising treatment modality for melasma. Microneedling (MN) and fractional carbon dioxide (CO2) laser were reported to enhance TXA transepidermal delivery. Objectives: To compare efficacy and safety of topical TXA alone or in combination with either fractional CO2 laser or MN for treatment of melasma. Methods: Thirty females with facial melasma were divided randomly into 3 equal groups after excluding pregnant and lactating women and those using oral contraceptives or other hormonal therapy. Patients of group A were treated with fractional CO2 laser and those of group B were treated with MN (4 sessions, 3 weeks apart for both) with immediate topical application of TXA 5% solution after sessions and daily application of 5% TXA cream for both groups. Patients of group C were treated by topical daily application of TXA 5% cream. Evaluation was done by modified melasma area and severity index scores (mMASI), patient satisfaction and dermoscopy. Results: Statistically significant improvement of mMASI was reported in all studied groups with a significantly better improvement in patients of groups A and B than those of group C, meanwhile the difference between groups A and B was statistically insignificant. Conclusions: Topical TXA is a safe and fairly effective treatment modality for facial melasma. Combining TXA with either fractional CO2 laser or MN yielded significantly better improvement than when used alone. Fractional CO2 laser carries the risk of post-inflammatory hyperpigmentation in patients with skin types III and IV and requires meticulous patient selection

Smashing the Implementation Records of AES S-box

Canright S-box has been known as the most compact S-box design since its introduction back in CHES’05. Boyar-Peralta proposed logic-minimization heuristics that could reduce the gate count of Canright S-box from 120 gates to 113 gates, however synthesis results did not reflect much improvement. In CHES’15, Ueno et al. proposed an S-box that has a slightly higher area, but significantly faster than the previous designs, hence it was the most efficient (measured by area×delay) S-box implementation to date. In this paper, we propose two new designs for the AES S-box. One design has a smaller implementation area than both Canright and the 113-gate S-boxes. Hence, our first design is the smallest AES S-box to date, breaking the 13 years implementation record of Canright. The second design is faster and smaller than the Ueno S-box. Hence, our second design is both the fastest and the most efficient S-box design to date. While doing so, we also propose new logicminimization heuristics that outperform the previous algorithms of Boyar-Peralta. Finally, we conduct an exhaustive evaluation of each and every block in the S-box circuit, using both structural and behavioral HDL modeling, to reach the optimum synergy between theoretical algorithms and technology-supported optimization tools. We show that involving the technology-supported CAD tools in the analysis results in several counter-intuitive results

New Low-Area Designs for the AES Forward, Inverse and Combined S-boxes

The implementation of AES S-boxes is one of the most extensively studied areas of cryptography. In this paper, we propose three new hardware designs for the AES S-box that can serve in the forward, inverse and combined data paths. Each of these designs represents the smallest AES S-box ever proposed in its respective category. We achieve this goal by using new tower field representation over normal bases and optimizing each and every block inside the three proposed architectures. Our complexity analysis and ASIC synthesis results in the CMOS STM 65nm, as well as the NanGate 15nm technologies, show that our designs outperform their counterparts in terms of area and power

Clinical Outcomes and Survival Analysis of Remdesivir as a Treatment Option for Moderate to Severe COVID-19 Patients

Background: Remdesivir is a broad-spectrum antiviral that has been approved as promising medicine worldwide for the fatal pandemic COVID-19 disease. There is a debate over its efficacy, with different studies taking into account a variety of factors. Therefore, we conducted this study to evaluate the primary composite outcome of mortality rate, need for mechanical ventilation (MV), and escalation of care among Remdesivir (RDV) and non-Remdesivir (NoRDV) groups. Methods: Patients with moderate and severe PCR-confirmed COVID-19 infection were observed retrospectively, before and after including RDV in the treatment protocol during the period from August 2020 to February 2021. Result: From the 509 hospitalized patients, 35% received Remdesivir, with 64% being severe patients. The median age in both groups was 59 years old, and there was no significant difference between the two groups regarding gender, baseline characteristics, and comorbidities. In contrast, the median hospital length of stay in the RDV group was lower (8 days) than the NoRDV (9 days), p = 0.004. The composite outcome was 17.7% in the RDV group and 22.2% in the NoRDV group, but the difference was statistically insignificant (p-value 0.289). Adjusted logistic regression demonstrated a non-significant lower association of the composite outcome with RDV use (OR 0.623, 95CI% 0.37–1.02), and a significant reduction occurred in patients <60 years old (OR 0.39, 95%CI 0.17–0.83). However, survival analysis for mortality, MV, and transfer to a higher level revealed insignificant differences in the median time between groups. Subgroup analyses showed that RDV utilization had a non-significant effect on the risk of all three outcomes across different groups. Conclusion: Despite controlling all patient characteristics, treatment with RDV did not improve patient outcomes over other antivirals and standard care. There is an urgent need for further studies to investigate and evaluate new therapeutic approaches or combinations

Clinico-Pathological Features and Immunohistochemical Comparison of p16, p53, and Ki-67 Expression in Muscle-Invasive and Non-Muscle-Invasive Conventional Urothelial Bladder Carcinoma

Introduction: The identification of bladder detrusor muscle invasion in urothelial cancer is essential for prognosis and management. We studied the clinical, histological, and immunohistochemical expression of p16, p53, and Ki-67 in urothelial detrusor muscle-invasive bladder cancer (MIBC) and urothelial non-detrusor muscle-invasive bladder cancer (NMIBC) in Egyptian patients. Methods: Sixty-two bladder urothelial cancer cases obtained through TURBT were included and divided into two groups: (MIBC, stage T2) and NMIBC (T1). Tissue blocks were recut and re-examined microscopically; then, the immunostaining of p16, p53, and Ki-67 was performed to compare both groups and evaluate the 13% cut-off for Ki-67, 20% for p53, and p16 intensity in various conditions aided by telepathology technology. Results and conclusion: Hematuria was the main clinical first presentation, with no significant difference between either group. The mean age was 61.6 years, with male predominance (52 males and 10 females). The absence of papillary histological pattern was associated with a higher stage, including detrusor muscle invasion (p = 0.000). The overall average percent of p53 immunostaining was 12.9%, revealing no significant difference between MIBC and NMIBC when a cut-off of 20% was implicated. The Ki-67 expression was correlated with higher grade and muscle invasion; however, no association was found with the other two markers’ expression. The negative immunostaining of p16 was associated with low grade and NMIBC in the case of the preservation of the papillary pattern. We recommend further studies on the cut-off of widely used markers and more immunohistochemical and genetic studies on the p16(INK4A), taking into consideration the histological pattern of conventional carcinomas