In today s world, the traditional way of password based authentication is having limitations in addressing the security concerns of the digital users. There is a strong movement in favour of passwordless authentication to secure our cyber identities and digital assets. In the recent years, a lot of research outputs have been published in the field of authentication with techniques like multifactor authentication, passwordless authentication, adaptive authentication and continuous authentication. Not only the user, but also the device, the application etc. must be authenticated to access the resources, facilities and services. Even though the passwords face some serious security issues, they enjoy considerable user acceptance and hence some schemes termed as semi-passwordless authentication are also prevalent. This paper goes through existing authentication schemes, their security issues, attacks and the next step ahead.

Cyber-physical Systems can be defined as a complex networked control system, which normally develop by combining several physical components with the cyber space. Cyber Physical System are already a part of our daily life. As its already being a part of everyone life, CPS also have great potential security threats and can be vulnerable to various cyber-attacks without showing any sign directly to component failure. To protect user security and privacy is a fundamental concern of any kind of system; either it’s a simple web application or supplicated professional system. Digital Multifactor authentication is one of the best ways to make secure authentication. It covers many different areas of a Cyberconnected world, including online payments, communications, access right management, etc. Most of the time, Multifactor authentication is little complex as it requires extra step from users. This paper will discuss the evolution from single authentication to Multi-Factor Authentication (MFA) starting from Single-Factor Authentication (SFA) and through Two-Factor Authentication (2FA). This paper seeks to analyze and evaluate the most prominent authentication techniques based on accuracy, cost, and feasibility of implementation. We also suggest several authentication schemes which incorporate with Multifactor authentication for CPS.

Multifactor Authentication - Internet connected Children s toys are a type of IoT devices that the security community should pay particular attention. A cyber-predator may interact with or gather confidential data about children without being physically present if IoT toys are hacked. Authentication to verify user identity is essential for all internetconnected applications, where relying on single authentication is not considered safe, especially in children s applications. Children often use easy-to-guess passwords in smart applications associated with the Internet of Things (IoT) for children s toys. In this paper, we propose to activate multi-factor authentication on the IoTs for children s toys connected to the internet using companion applications. When changing the user s behaviour (by IP address, GPS, OS version, and browser), the child s identity must be verified by two-factor authentication to prevent unauthorized access to preserve the child s safety and privacy. This paper introduces multi-authentication mechanisms: a password and another authentication type, either mobile phone SMS, security token, digital certificate, or biometric authentication.

Multifactor Authentication - The article describes the development and integrated implementation of software modules of photo and video identification system, the system of user voice recognition by 12 parameters, neural network weights, Euclidean distance comparison of real numbers of arrays. The user s biometric data is encrypted and stored in the target folder. Based on the generated data set was developed and proposed a method for synthesizing the parameters of the mathematical model of convolutional neural network represented in the form of an array of real numbers, which are unique identifiers of the user of a personal computer. The training of the training model of multifactor authentication is implemented using categorical cross-entropy. The training sample is generated by adding distorted images by changing the receptive fields of the convolutional neural network. The authors have studied and applied features of simulation modeling of user authorization systems. The main goal of the study is to provide the necessary level of security of user accounts of personal devices. The task of this study is the software implementation of the synthesis of the mathematical model and the training neural network, necessary to provide the maximum level of protection of the user operating system of the device. The result of the research is the developed mathematical model of the software complex of multifactor authentication using biometric technologies, available for users of personal computers and automated workplaces of enterprises.

Multifactor Authentication - Cyber-physical Systems can be defined as a complex networked control system, which normally develop by combining several physical components with the cyber space. Cyber Physical System are already a part of our daily life. As its already being a part of everyone life, CPS also have great potential security threats and can be vulnerable to various cyber-attacks without showing any sign directly to component failure. To protect user security and privacy is a fundamental concern of any kind of system; either it’s a simple web application or supplicated professional system. Digital Multifactor authentication is one of the best ways to make secure authentication. It covers many different areas of a Cyberconnected world, including online payments, communications, access right management, etc. Most of the time, Multifactor authentication is little complex as it requires extra step from users. This paper will discuss the evolution from single authentication to Multi-Factor Authentication (MFA) starting from Single-Factor Authentication (SFA) and through Two-Factor Authentication (2FA). This paper seeks to analyze and evaluate the most prominent authentication techniques based on accuracy, cost, and feasibility of implementation. We also suggest several authentication schemes which incorporate with Multifactor authentication for CPS.

Multifactor Authentication - Authentication is one of the primary problems with system security. The key component of the access control process to prevent unauthorised users from accessing data and resources is authentication, which may be described as the act of verifying a user s identity. The validity of the user cannot be guaranteed by a static technique of authentication. This led to the development of more cutting-edge authentication techniques. To increase the system s security, two factor authentication was initially deployed, followed by multi factor authentication. Later, adaptive authentication was added and it also had some problems. When authenticating a user in this study, an unique collection of user features was taken into account. A performance optimization technique was included since this research takes many user factors into account, and it improved performance by 25\%.

Multifactor Authentication - Authentication is a mandatory factor in network security since decades. Conventional authentication schemes failed to improve system’s security, performance and scalability thus, two-factor, three factor and multifactor authentication schemes are developed. As technology grows, from single server authentication to multiserver authentication schemes and protocols are emerged. Single to multifactor authentication can be used as per the aspect and field of study. Different aspects may use different cryptographic schemes, key agreement to improve security, performance and scalability.

Multifactor Authentication - Cloud computing is a breakthrough advancement that provides ubiquitous services over the internet in an easy way to distribute information offering various advantages to both society and individuals. Recently, cloud technology has eased everyone’s life more favorable. However, privacy-preservation is an important issue to be tackled effectively in cloud environment while retrieving data services. Numerous techniques have been developed so far to verify user identity by exploiting authentication factor, whereas such techniques are inefficient and they are easily susceptible to unknown users and attacks. In order to address such problems, a multifactor authentication scheme is proposed using Hashing, Chebyshev polynomial, Key and OneTime Token (HCK-OTT) based multifactor authentication scheme for privacy-preserved data security in cloud. The entities involved in this proposed approach for effective authentication are user, cloud server, and data owner. The model is developed by considering various functionalities, such as encryption, Elliptic Curve Cryptography (ECC), XOR, and hashing function. The proposed HCK-OTT-based multifactor authentication scheme has achieved a minimum value of 22.654s for computational time, 70.5MB for memory usage, and 21.543s for communication cost with 64 bit key length.

Multifactor Authentication - Dhillon and Kalra proposed a multi-factor user authentication scheme for IoT. The authors claim their scheme to have practical utility for the IoT environment. However, we find that their scheme has numerous flaws such as insider attack and inefficient authentication. An adversary can work as a middle-man between the sensor node and the user, and the user can set-up a session key with the sensor node. Besides, the scheme does not establish the mutual authentication between every pair of entities. Thus, the scheme is inconvenient for practical use. We conclude this article by providing some suggestions for the improvement of the analysed scheme to remove the weaknesses identified in it.

Multifactor Authentication - With the growth of the number in smart devices based on IoT, keeping a secure data processing among them has become even more significant in cloud computing. However, a high security is needed to protect the huge amount of data privacy. In this regard, many authentication approaches are presented in IoT-Cloud-based Architecture. However, computation, latency, and security strength are major issues to provide authentication for users. We propose the Multifactor Scalable Lightweight Cryptography for IoTCloud to enhance security to protect the user or organization s information. The non-sensitive and sensitive data are generated from IoT devices and stored in our proposed hybrid public and private cloud after the encryptions. Hence, encryptions for public cloud and private cloud data are done by Digital Signature Algorithm and Policy based Attribute encryption algorithm with Moth fly optimization. This optimization is chosen as the key parameter efficiently. The three multifactors are then used to perform the three levels of authentication by Trust based Authentication Scheme. Following this, the proposed multifactor authentication is simulated and compared with existing approaches to analyze the performance in terms of computational and execution time and security strength. As a result, the proposed method is shown 97\% of security strength and minimum computation and execution time than other conventional approaches.

Multifactor Authentication - Internet of Things (IoT) has become an information bridge between societies. Wireless sensor networks (WSNs) are one of the emergent technologies that work as the main force in IoT. Applications based on WSN include environment monitoring, smart healthcare, user legitimacy authentication, and data security. Recently, many multifactor user authentication schemes for WSNs have been proposed using smart cards, passwords, as well as biometric features. Unfortunately, these schemes are shown to be susceptible towards several attacks and these includes password guessing attack, impersonation attack, and Man-in-the-middle (MITM) attack due to non-uniform security evaluation criteria. In this paper, we propose a lightweight multifactor authentication scheme using only hash function of the timestamp (TS) and One Time Password (OTP). Furthermore, public key and private key is incorporated to secure the communication channel. The security analysis shows that the proposed scheme satisfies all the security requirement and insusceptible towards some wellknown attack (password guessing attack, impersonation attack and MITM).

Multifactor Authentication - Today, with the rapid development of the information society and the increasingly complex computer network environment, multi-factor authentication, as one of the security protection technologies, plays an important role in both IT science and business. How to safely complete multi-factor authentication without affecting user experience has attracted extensive attention from researchers in the field of business security protection and network security. The purpose of this paper is to apply multi-factor authentication technology to enterprise security protection systems, develop and design a security protection technology based on multi-factor authentication dynamic authorization, and provide enterprises with unified identity management and authority management methods. The cornerstone of trust and security to ensure uninterrupted and stable operation of users. The original master key k is subjected to secondary multi-factor processing, which enhances the user s authentication ability and effectively avoids the risk of easy password theft and disguised identity. In order to meet the given VoIP security requirements, a SIP multi-factor authentication protocol is proposed for the VoIP environment by using the multi-factor authentication technology to solve the security problem. The performance test results show that due to the influence of data encryption and decryption, the response time of the encrypted database is 100s longer than that of the unencrypted one, but the growth rate is 10\% smaller than that of the unencrypted one. Therefore, the performance of this scheme is better when the amount of data is larger.

Internet-scale Computing Security - Cloud computing provides customers with enormous compute power and storage capacity, allowing them to deploy their computation and data-intensive applications without having to invest in infrastructure. Many firms use cloud computing as a means of relocating and maintaining resources outside of their enterprise, regardless of the cloud server s location. However, preserving the data in cloud leads to a number of issues related to data loss, accountability, security etc. Such fears become a great barrier to the adoption of the cloud services by users. Cloud computing offers a high scale storage facility for internet users with reference to the cost based on the usage of facilities provided. Privacy protection of a user s data is considered as a challenge as the internal operations offered by the service providers cannot be accessed by the users. Hence, it becomes necessary for monitoring the usage of the client s data in cloud. In this research, we suggest an effective cloud storage solution for accessing patient medical records across hospitals in different countries while maintaining data security and integrity. In the suggested system, multifactor authentication for user login to the cloud, homomorphic encryption for data storage with integrity verification, and integrity verification have all been implemented effectively. To illustrate the efficacy of the proposed strategy, an experimental investigation was conducted.

Cloud computing provides customers with enormous compute power and storage capacity, allowing them to deploy their computation and data-intensive applications without having to invest in infrastructure. Many firms use cloud computing as a means of relocating and maintaining resources outside of their enterprise, regardless of the cloud server's location. However, preserving the data in cloud leads to a number of issues related to data loss, accountability, security etc. Such fears become a great barrier to the adoption of the cloud services by users. Cloud computing offers a high scale storage facility for internet users with reference to the cost based on the usage of facilities provided. Privacy protection of a user's data is considered as a challenge as the internal operations offered by the service providers cannot be accessed by the users. Hence, it becomes necessary for monitoring the usage of the client's data in cloud. In this research, we suggest an effective cloud storage solution for accessing patient medical records across hospitals in different countries while maintaining data security and integrity. In the suggested system, multifactor authentication for user login to the cloud, homomorphic encryption for data storage with integrity verification, and integrity verification have all been implemented effectively. To illustrate the efficacy of the proposed strategy, an experimental investigation was conducted.

Cyber-physical Systems can be defined as a complex networked control system, which normally develop by combining several physical components with the cyber space. Cyber Physical System are already a part of our daily life. As its already being a part of everyone life, CPS also have great potential security threats and can be vulnerable to various cyber-attacks without showing any sign directly to component failure. To protect user security and privacy is a fundamental concern of any kind of system; either it’s a simple web application or supplicated professional system. Digital Multifactor authentication is one of the best ways to make secure authentication. It covers many different areas of a Cyber-connected world, including online payments, communications, access right management, etc. Most of the time, Multifactor authentication is little complex as it requires extra step from users. This paper will discuss the evolution from single authentication to Multi-Factor Authentication (MFA) starting from Single-Factor Authentication (SFA) and through Two-Factor Authentication (2FA). This paper seeks to analyze and evaluate the most prominent authentication techniques based on accuracy, cost, and feasibility of implementation. We also suggest several authentication schemes which incorporate with Multifactor authentication for CPS.