Faculty Publications
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Item Cryptanalysis and Improvement of Remote User Authentication Scheme Using Smart Card(Institute of Electrical and Electronics Engineers Inc., 2016) Madhusudhan, R.; Hegde, M.In a distributed environment, one of the major concerns is authentication of remote users. In this sector, legitimate users are more powerful attackers. The remote systems working with password and smart card ensures authorised access. Smart card based remote user authentication schemes have been adopted due to their low computation cost and portability. In 2012, Wen and Li proposed an improved dynamic ID based remote user authentication with key agreement scheme. They stated that their scheme provides protection against impersonation attack and preserves secret information. In this paper, we unveil the drawbacks of Wen and Li's scheme. Also we show that their scheme does not detect wrong password quickly, making it vulnerable to insider and smart card stolen attack. Further the scheme provides no protection for forward secrecy. To solve these security weaknesses, we propose a robust authentication scheme which overcomes all the pointed flaws, by keeping eminence of Wen and Li's scheme. © 2016 IEEE.Item Smart Card Based Remote User Authentication Scheme for Cloud Computing(Institute of Electrical and Electronics Engineers Inc., 2019) Madhusudhan, R.; Hegde, M.Cloud computing is an emerging technology in modern society. In recent years mobile users and cloud service providers are increased rapidly. In the cloud or any other distributed environment, if the users increased then security risks also increase parallelly. Many security problems are still unclear even after the advanced security measures have been taken. Security of stored data in the server is one of the most challenging issues in the cloud-based environment. Only authorized users should access the stored data of the server. Authentication plays a significant role in providing authorization. Therefore, in cloud computing, authentication is the primary measure to protect the data and the server from an unauthorized user. In this paper, an efficient authentication scheme using the smart card in the cloud environment is proposed. In the proposed scheme, with the help of a single private key, the user can access many cloud services. Also, the proposed scheme resists all security attacks. Through the simulation using the AVISPA tool, it is proved that the proposed scheme is robust and suitable for practical implementation. © 2019 IEEE.Item Security bound enhancement of remote user authentication using smart card(Elsevier Ltd, 2017) Madhusudhan, R.; Hegde, M.Distribution of resources and services via open network has becoming latest trend in information technology. This is provided by many service provider servers. In open network, hackers can easily obtain the communication data. Therefore, open networks and servers demand the security to protect data and information. Hence, network security is most important requirement in distributed system. In this security system, authentication is considered as the fundamental and essential method. Recently many remote user authentication schemes are proposed. In 2012, WANG Ding et al. proposed a remote user authentication scheme, in which the author stated that the scheme provides protection against offline password guessing, impersonation and other known key attacks. By cryptanalysis we have identified that, WANG Ding et al.'s scheme does not provide user anonymity, once the smart card is stolen. This scheme is also susceptible to offline password guessing attack, server masquerading attack, stolen smart card attack and insider attack. Further, this scheme still has problem with proper perfect forward secrecy and user revocation. In order to fix these security weaknesses, an enhanced authentication scheme is proposed and analysed using the formal verification tool for measuring the robustness. From the observation of computational efficiency of the proposed scheme, we conclude that the scheme is more robust and easy to implement practically. © 2017Item A secure and enhanced elliptic curve cryptography-based dynamic authentication scheme using smart card(John Wiley and Sons Ltd vgorayska@wiley.com Southern Gate Chichester, West Sussex PO19 8SQ, 2018) Madhusudhan, R.; Hegde, M.; Memon, I.In remote system security, 2-factor authentication is one of the security approaches and provides fundamental protection to the system. Recently, numerous 2-factor authentication schemes are proposed. In 2014, Troung et al proposed an enhanced dynamic authentication scheme using smart card mainly to provide anonymity, secure mutual authentication, and session key security. By the analysis of Troung et al's scheme, we observed that Troung et al' s scheme does not provide user anonymity, perfect forward secrecy, server's secret key security and does not allow the user to choose his/her password. We also identified that Troung et al's scheme is vulnerable to replay attack. To fix these security weaknesses, a robust authentication scheme is proposed and analyzed using the formal verification tool for measuring the robustness. From the observation of computational efficiency of the proposed scheme, we conclude that the scheme is more secure and easy to implement practically. © © 2018 John Wiley & Sons, Ltd.Item Green covalent surface functionalization of carbon nanofillers and hybridization to improve the thermal and electrical properties of RTV SR nanocomposites(Elsevier Ltd, 2025) Chandrashekar, A.; Hegde, M.; Siya; Karthik Reddy, B.; Jineesh, J.A.; Ravichandran, V.; Eswaraiah, E.; Prabhu, T.N.In this work, graphene (GP) and multiwalled carbon nanotubes (MWCNT) are covalently surface functionalized via a green method using clove extract. The clove–modified carbon hybrid silicone rubber (SR) nanocomposites are fabricated by incorporating clove –modified GP (CGP) and MWCNT (CMWCNT) in various weight ratios with a total filler loading of 10 wt%. Our study investigated the effect of green covalent surface modification and the use of hybrid filler on the thermal and electrical properties of the silicone rubber. The nanocomposite with 9:1 hybrid ratio showed the highest thermal conductivity of about 0.406 W m?1 K?1, 103 % enhancement and thermal effusivity of about 766.2 Ws1/2 m?2 K?1, 29.64 % enhancement with respect to pure SR. Thermal management performance was evaluated by applying thermal compounds as thermal interface material on a 1 W light emitting diode (LED) bulb for testing. It was found that during heating, the hybrid composite with 9:1 ratio showed 2.3 °C reduction in the surface temperature of the LED bulb (under ON condition) and reduced the surface temperature by 1.8 ? within 20 s and reached almost room temperature in 100 s (under OFF condition). In addition, nanocomposite with 9:1 hybrid ratio showed excellent thermal stability, enhanced electrical resistivity which presents a promising strategy for designing thermally conductive polymer nanocomposites based thermal interface materials in managing excess heat for thermal management applications. © 2025Item Enhancement of thermal conductivity in silicone rubber nanocomposites via low loading of polydopamine-coated copper nanowires(Elsevier Ltd, 2025) Hegde, M.; Chandrashekar, A.; Reddy B, K.; Jineesh, J.A.; Ajeya, K.P.; Prabhu, T.N.In recent years, thermally conductive polymer nanocomposites have garnered significant interest due to their wide application in the electronic industry. In the present work, we report thermally conductive silicone rubber-based nanocomposites at lower filler loading of polydopamine-coated copper nanowires (PDA@CuNW). First, copper nanowires (CuNW) are synthesized by the liquid phase reduction method and modified with polydopamine (PDA) by in-situ polymerization. The synthesized CuNW and PDA@CuNW are incorporated into Silicone rubber (SR) varying from 1 to 5 wt% via solution casting. The incorporation of 5 wt% PDA@CuNW resulted in a 62 % improvement in the thermal conductivity of SR. In addition, the nanocomposite showed the highest thermal effusivity of 735 Ws1/2m?2 K?1 even at 5 wt% loading. These results can be attributed to the better adhesion of PDA to the SR matrix confirmed by Field Emission-Scanning Electron Microscopy (FE-SEM). Thermogravimetric analysis showed that the modification of copper nanowires improved the thermal stability of SR. The electrical resistivity of SR increased with the addition of PDA@CuNW. The tensile stress-strain studies reveal that the strength of the SR/PDA@CuNW was improved compared to neat SR and SR/CuNW composites. Moreover, the elongation at break reached up to 972 % which is a 395 % improvement with respect to plain SR. In this work, simultaneous improvement in thermal conductivity and electrical resistivity is achieved while preserving the mechanical properties of the SR nanocomposites. Flexible nanocomposites with improved thermal and electrical properties and minimal filler loading have great significance in high-performance thermal management materials. © 2025 Elsevier LtdItem Synergistic enhancement in thermal conductivity of RTV silicone rubber via non-covalently surface-modified graphene and MWCNT hybrid fillers(Springer, 2025) Chandrashekar, A.; Hegde, M.; Siya Shetty; Reddy, B.K.; Jineesh, J.A.; Varrla, E.; Prabhu, T.N.Effective thermal management is critical for advanced electronic devices, yet conventional polymer-based thermal interface materials (TIMs) often exhibit low thermal conductivity, poor filler dispersion, and high interfacial resistance. This study addresses these limitations by enhancing filler–matrix interactions and exploiting synergistic effects between dual-dimensional carbon nanofillers. Graphene (GPs) and multiwalled carbon nanotubes (MWCNTs) were non-covalently surface modified using phenyl glycidyl ether (PGE) via ultrasonication in THF, improving dispersion and compatibility with room temperature vulcanizing silicone rubber (RTV SR). The surface-functionalized fillers (PGE@GP, PGE@MWCNT) were characterized using FTIR, Raman spectroscopy, FESEM, and TGA to confirm successful modification. Composite films were fabricated by incorporating PGE-modified fillers into RTV SR at three different hybrid ratios (PGE@GP:PGE@MWCNT = 9:1, 8:2, and 7:3) with a total filler content of 10 wt%. The composite with a 9:1 ratio achieved the highest thermal conductivity of 0.459 ± 0.001 Wm?1 K?1, representing a 129.5% enhancement over pure RTV SR. The observed 48.06% synergistic improvement highlights the effectiveness of combining dual-dimensional fillers. Additionally, the composite retained electrical insulation, a critical property for TIM applications. Application tests using a 1 W LED bulb demonstrated the composite’s ability to dissipate heat efficiently, confirming its potential as a high performance, electrically insulating thermal interface material for modern electronic systems. © The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature 2025.