# A Secure IoT-Based Authentication System in Cloud Computing Environment
## 5 Performance Evaluation  
In this section, we will present the schemes of [PERSON] et al. [45], [PERSON] et al. [36], [PERSON] et al. [42], and the performance evaluation of our schemes. Four authentication schemes only use a one-way hash operation, exclusive or operation, and concatenate operation. By comparing the execution time of an exclusive or operation to that of a one-way hash function or a symmetric algorithm, we ignored the execution time of an exclusive or operation., We chose SHA-2(256 bits) and AES as one-way hash functions and symmetric encryption/decryption algorithms, two of which are the most commonly used encryption methods in secure communications. Tables 1-3 show a comparison of the security properties, computation cost, and communication cost among four respective authentication schemes. In Table 1, \"O\" means that the scheme can achieve a security requirement or resist the attack; \"X\" means that the scheme cannot achieve a security requirement or resist the attack. In Table 2, \"\(T_{h}\)\" is one computation time of one-way hash function operation, and \"\(T_{s}\)\" is one computation time of symmetric encryption/decryption. The \"\(T_{h}\)\" and \"\(T_{s}\)\" s' values are 0.00517 ms and 0.02148 ms, respectively according to [PERSON] et al. [42]. \begin{table}
\begin{tabular}{c c c c c c c c c c} \hline \hline
**Property** & **R1** & **R2** & **R3** & **R4** & **R5** & **R6** & **R7** & **R8** & **R9** \\ \hline [PERSON] et al.’s scheme [36] & O & O & O & X & O & O & O & O & X \\ \hline [PERSON] et al.’s scheme [45] & O & X & O & X & O & O & O & O & X \\ \hline [PERSON] et al.’s [42] & X & O & X & O & O & O & O & O & O \\ \hline Ours & O & O & O & O & O & O & O & O & O \\ \hline \hline \end{tabular}  
* R1: Mutual authentication. R2: Session key for all entities. R3: User anonymity. R4: Resistance to off-line guessing attack. R5: Resistance to insider attack. R6: Resistance to stolen smart card attack. R7: Resistance to de-synchronization attack. R8: Resistance to forgery attack. R9: Resistance to user tracking attack.  
\end{table} 
Table 1: Comparison of Security Properties among Four Authentication Schemes. Table 2 shows that our proposed scheme is in the middle regarding calculating costs. However, it is important to consider the trade-off between security and efficiency when we were designing a secure communication scheme. As can be seen from Table 1, the scheme proposed by us has better security than other schemes. We also assessed the communication costs of our scheme and other schemes, as shown in Table 3. The communication costs are the bits of parameters which passed during authentication. The Figure 5 shows the bar chart of the comparison of total calculation cost. Our scheme gets more cost than [PERSON] et al. 's [42] because we add an additional step at the last of the authentication phase to achieve mutual authentication. We only calculate the communication cost in the login and authentication phases due to the use of fewer number of times in the registration phase and password change phase. Therefore, in terms of security and efficiency, we can argue that our proposed scheme is more suitable for the Internet of Things environment than other related schemes. \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline  & **Entities** & \begin{tabular}{c} **Registration** \\ **Phase** \\ \end{tabular}  & **Login Phase** & \ \begin{tabular}{c} **Authentication** \\ **Phase** \\ \end{tabular}  & **Password Change** & \begin{tabular}{c} **Total Operations of Login** \\ **and Authentication** \\ \end{tabular}