mahdi sajadieh

This paper introduces a non-isolated step-up converter featuring coupling inductors and a voltage multiplier circuit with soft switching. By connecting the secondary coupling inductors in series, the current ripple at the input is minimized, while the multiplier circuit reduces voltage stress on the main power circuit switches. This reduction in voltage on the power MOSFETs and diodes leads to decreased conduction losses and lower circuit costs. Additionally, the large capacitor absorbs the energy from the leakage inductor and transfers it to the output, mitigating the reverse recovery issues of the diodes caused by zero-current switching and ensuring zero-voltage switching for all switches. To validate the converter's performance, a practical 200W prototype was constructed, demonstrating an efficiency of 94.2% under nominal load conditions.

The diffusion layer plays an important role in a block cipher. Some block ciphers, such as ARIA, Camellia, and Skinny use binary matrices as diffusion layers which can be efficiently implemented in hardware and software. In this paper, the goal is to propose some new binary matrices with suitable values for the active S-boxes for R rounds. Firstly, some new $16 \times 16$ matrices are proposed whose software implementations are better than the corresponding one for the ARIA block cipher. Also, the values for the minimum active S-boxes for these matrices are greater than the corresponding values for the ARIA block cipher for $R>5$.To design $32 \times 32$ matrices, a structure with a special form is proposed. Using this structure, a $32\times 32$ binary matrix is proposed which guarantees at least 48 active S-boxes for 8 rounds of an SPN structure with this matrix as its diffusion layer. By extending this structure, a $32\times 32$ non-binary matrix is presented which results in at least 60 active S-boxes after 8 rounds.

In this paper, a zero-voltage switching step-down converter is presented, which uses the technique of coupled inductor and series capacitor to reduce the voltage gain. Therefore, the voltage stress on the switches is reduced. The auxiliary circuit has the minimum number of elements, on the other hand, the auxiliary switch is also switched under ZV, and the reverse recovery problem of the freewheeling diode is also solved. The energy of the leakage inductor is discharged to the capacitor C and is properly transferred to the output. As a result, the capacitor C not only absorbs the energy of the leakage inductance, but also causes a further decrease in the voltage gain. Since the switches are operated complementary, it is easy to implement the control circuit. The simulation results show an increase in efficiency by 4% compared to the hard switching counterpart. Also, to confirm the correctness of the theoretical analyzes of the proposed high step-down converter, a 50 W practical prototype has been made.

In recent years, the Internet of Things (IoT) networks have extensively been used in various practical field, one of the most important of which is medical Internet of Things (MIoT). In these networks, radio frequency identification (RFID) is one of the main technologies in creating an authentication system that is able to efficiently identify and identify medical equipment and patients. Therefore, researchers in this field have proposed different authentication protocols for RFID-based MIOT systems and claimed that they are resistant to active and passive attacks. Contrary to their claims, most of these protocols are not resistant to conventional attacks. Fan et al. have recently proposed a lightweight RFID authentication scheme for cloud-based RFID health-care systems and claimed that it is sufficiently efficient and secure. In this paper , we analyzed the Fan et al protocole and demonstrated that their protocol is vulnerable to replay, reader impersonation, tag tracking, and de-synchronization attacks. Moreover, we show how the similarity of some of their protocol messages causes attack. Then, we propose an improved protocol (LRAMP) that is resistant to these and other known attacks in RFID authentication protocol. According to security analysis, we can see that the LRAPM protocol has a high level of security. This high security can only be achieved by adding a new message and changing other messages. A comparison of the performance of the LRAPM protocol shows that this protocol is comparable to similar protocols in terms of computational costs, storage costs and communication costs.

In terms of security, MDS matrices are one of the best choices for diffusion layer of block ciphers. However, as these matrices grow in size, their software implementation becomes a challenge. In this paper, to benefit from the properties of MDS matrices and avoid the mentioned challenge, we use 4*4 MDS matrices to build some 16*16 matrices with low number of zero elements. We show that if these matrices are used as diffusion layer of software-based SPN structures, the resulting block ciphers have similar properties as AES in software implementation complexity (i.e. the number of required CPU instructions) and resistance against linear and differential attacks. Moreover, the best impossible differential and square distinguishers for the proposed 16*16 structures have similar length as SPN structures with 16*16 MDS matrices. Thus, the new structures outperform AES with respect to the impossible differential and square attacks. Additionally, we show that if the proposed SPN structure uses the AES key schedule, its results for the differential related-key attacks are better than those for AES. We also extend the idea and use 4*4 MDS matrices to design 24*24 and 32*32 matrices with acceptable properties for SPN structure design. Finally, we extend the idea to propose some matrices for Feistel structures with SP-type F-functions. We show that the resulting structures are more secure than the improved type-II GFS.

Counting the minimum number of differential active S-boxes is a common way to evaluate the security of block ciphers against differential and linear cryptanalysis. In this paper, we use mixed-integer linear programming (MILP) to calculate minimum number of active S-boxes of the some Feistel structures. We focus on Type-II of Feistel structures with four and six partitions and explain how to analyze them by MILP when they have more than one MDS2 matrices (like Clefia) in their structure. Moreover, we propose a new four partitions Feistel structure with three multiple MDS matrices which have more active S-boxes rather than Clefia structure. We also generalize Clefia structure in to six partitions Feistel structure by three multiple MDS matrices for 192 bits block size.