## 6 Comparison  
The comparative analysis of various standards and protocols from existing research on identity management and authentication models focused on five major factors: scalability, reliability, security, adaptability, and cost. These factors provide essential insights for any  
Figure 8: Sequence diagram on working of ShoCard.  
organization, big or small, when planning to deploy, invest in, use, and choose between centralised (see Table 1) and decentralised (see Table 2) identity systems.  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Factor** & **LDAP** & **OAuth** & **RADIUS** & **SAML** \\ \hline \multirow{4}{*}{**Purpose**} & Directory access protocol for querying and modifying directory services [21; 22] & Authorization protocol to grant third-party access without exposing credentials [40; 41] & AAA for network access [30; 33] & SSO for secure authentication between identity providers and service providers [36] \\ \hline \multirow{4}{*}{**Authentication**} & Username- and password-based authentication [23; 25] & Access tokens for delegation [38] & Username and password, often paired with EAP for stronger authentication [33] & Based on user assertions exchanged between identity providers and service providers [37] \\ \hline \multirow{4}{*}{**Authorization**} & Uses role-based access control with permissions in the directory [23] & Access tokens for scope and permissions [40] & Coupled with authentication, includes service type and IP parameters [33] & Based on user assertions, used for authorization across different services [36] \\ \hline \multirow{4}{*}{**Encrypption and Security**} & LDAP communication can be secured with TLS/SSL, but credentials are often transmitted in encryption [40; 41] & Relies on HTTPS for transmission security credentials are credentials are encrypted [30] & Cans use TLS to secure communication; \\  & & & and token encryption [40; 41] & Crederdends are encrypted [30] & ITTPS ensuring secure message exchanges [16; 37] \\ \hline \multirow{4}{*}{**Scalability**} & Scales well for large organizations with complex directory structures [24] & Scalable for web apps and third-party services [40] & Suitable for large enterprise networks with distributed authentication needs [31] & Federated model supports scalability across multiple service providers [37] \\ \hline \multirow{4}{*}{**Vulnerabilities**} & Credentials can be exposed if not encrypted, risks of data leaks [23; 27] & Vulnerable to token misuse and scope overreach if not properly [46] & Susceptible to replay attacks and configuration & Prone to misconfigurations, possible XML-related vulnerabilities [16; 37] \\ \hline \multirow{4}{*}{**MFA**} & Can be integrated with other mechanisms such as OTP or biometric for added security [12] & Often integrated with two-factor authentication methods [40] & Supports integration with MFA systems such as EAP [33] & Supports MFA to strengthen SSO, integrating additional verification steps [16] \\ \hline \multirow{4}{*}{**Integration**} & Limited integration with modern web web-based applications [23] & Integrated with modern web applications using REST APIs [38; 40] & Supports integration with enterprise-grade network systems [30] & Integrated with web-based applications using SAML assertions [37] \\ \hline \multirow{4}{*}{**Protocol Base**} & TCP/IP protocol, uses specific directory protocols [21; 22] & HTTP-/HTTPS-based protocol, relies on REST APIs and JSON or XML for token transmission [38; 40] & Operates over User Datagram Protocol (UDP), supports EAP for authentication [33] & XML-based protocol, relies on SOAP, HTTP, and HTTPS for secure message exchanges [37] \\ \hline \multirow{4}{*}{**Use Cases**} & Used in enterprise environments for directory services [24] & Web and mobile applications, API access delegation [41] & Network access control in enterprise environments [31] & SSO for enterprise environments, academic institutions, and government services [16; 37] \\ \hline \hline \end{tabular}
\end{table}
Table 1: Comparison of centralised identity management protocols.