## 4 Multiple Authentication Methods Using DID in the Blockchain
### Discussion  
Research on authentication using blockchain technology is just beginning, and this research is still in the early stages. The study \"Biometric Information and OTP based on Authentication Mechanisms using Blockchain\" is a study that records biometric information on a blockchain and authenticates users in that way. This study's results are compared and analyzed in Table 1 below. \begin{table}
\begin{tabular}{c c c} \hline \hline  & **Related Research** & **The Model Proposed in This Study** \\  & **(Blockchain-Based Authentication)** & \\ \hline \multirow{2}{*}{Multiple authentication} & \multirow{2}{*}{Normal} & Good (multi-factor authentication and random authentication methods are mixed, so multi-factor authentication is created in various situations) \\ \hline Integrity & Good & Good \\ \hline \multirow{2}{*}{Security} & Normal (authenticates sequentially, so it is relatively normal) & Good (multi-factor authentication and random authentication methods are mixed, so multi-factor authentication is created in various situations) \\ \hline \multirow{2}{*}{Convenience} & DID not applied & DID applied \\ \hline \multirow{2}{*}{Energy consumption} & \multirow{2}{*}{Since the execution step is simple, energy consumption is low.} & Relatively higher energy consumption as it performs multiple steps, but not significantly higher. \\ \cline{1-1}  & & \\ \end{tabular}
\end{table} 
Table 1: Comparison of related research and this study. The existing method of user authentication is two-factor authentication using an ID or OTP, but in the proposed method, various authentication methods are performed by applying a random sequence of multi-factor authentication methods. In both techniques, the stored authentication information is recorded on the blockchain, so there is no possibility of tampering or forgery. In the existing technique, security is a method of two-step authentication based on the blockchain after ID or OTP authentication. The proposed model is applied to various authentication methods at random, and finally, stability is improved by performing authentication based on biometric face ID. The big difference from previous studies is whether DID technology is applied. Applying DID technology, which is a technique that can authenticate users with a single ID when logging into multiple organizations, has the advantage of increasing user convenience. In addition, by applying DID technology when logging in to multiple organizations, a single ID can be authenticated, which has the advantage of increasing user convenience. In addition, the recent smartphone replacement cycle in Korea is only around 33 months, which is not long. In other words, since the proportion of usage of the latest smartphones in Korea is high, the fingerprint recognition and face recognition required in this study can be utilized effectively, the proportion of use in mobile applications can be increased, and even general users will be able to use various biometrics authentication technologies. Due to the limited amount of power in smartphones, an analysis of energy consumption utilizing this method is required. Since the proposed method performs authentication in several steps, there may be relatively more energy consumption, but it is not large. There is a trade-off relationship between security and energy consumption. In addition, taking Korea as an example, when applying a solution using a mobile device, authentication methods such as fingerprint recognition and face recognition have been routinely used without any problems. One more use of the mobile application by the user does not drain the battery to the point of being inconvenient in their daily lives. Therefore, it cannot be said that the system proposed in this study consumes too much more of the battery of the mobile device. Blockchain has mainly two well-known challenges, which are scalability and high cost. Blockchain technology involves several complex algorithms to process a single transaction.