# Blockchain-Based Model for Incentivized Cyber Threat Intelligence Sharing
## 4 Experimental Evaluation and Discussion
### Experimental Evaluation
\begin{table}
\begin{tabular}{l l} \hline \hline
**Parameter Definition** & **Value** \\ \hline Reward of CTI data producer & 100 \\ Reward of CTI data consumer & 10 \\ Reward of CTI data reviewer & 10 \\ Subscription fee & EUR 500 \\ Number of produced CTI data & 2 \\ Weight coefficients of quality factors (all are equal) & 0.5 \\ All CTI data consumers download and read provided CTI data & - \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Initial values of simulation parameters. Figure 8: The user interface for the reviewer. monetary reward of participants in the network. However, we cannot set the subscription fee too high, as it must be an attractive and affordable investment for the participants. For simulation purposes, the absolute value of the subscription fee is not very important, as the relationship between the subscription fee and the reward score in euros is straightforward. For example, if we double the value of the subscription fee, the value of the reward score in euros will also be doubled. The most interesting relationship is between the number of participants in the network and the value of the reward score in euros. This relationship is depicted in Figure 9.  
Figure 9 shows that an increase in the number of participants in the network invokes an increase in the value of the reward score in euros. This increase slows down with the increasing number of participants. This tendency is in accordance with economic logic, where a bigger profit is usually related to a larger number of CTI data consumers. Thus, \begin{table}
\begin{tabular}{c c c c} \hline \hline \multicolumn{4}{c}{**Subscription Fee is EUR 500, CTI Data Producer Reward Score is 130**} \\ \hline \hline \multirow{2}{*}{**Number of Participants**} & \multirow{2}{*}{**Reviewer Reward Score**} & **Ordinary CTI Data** & \multirow{2}{*}{**Value of Score in Euros**} \\  & & **Consumer Reward Score** & \\ \hline
10 & 30 \(\times\) 3 = 90 & 6 \(\times\) 10 = 60 & EUR 8.92 \\ \hline
20 & 30 \(\times\) 3 = 90 & 16 \(\times\) 10 = 160 & EUR 13.15 \\ \hline
30 & 30 \(\times\) 3 = 90 & 26 \(\times\) 10 = 260 & EUR 15.62 \\ \hline
40 & 30 \(\times\) 3 = 90 & 36 \(\times\) 10 = 360 & EUR 17.24 \\ \hline
50 & 30 \(\times\) 3 = 90 & 46 \(\times\) 10 = 460 & EUR 18.38 \\ \hline
60 & 30 \(\times\) 3 = 90 & 56 \(\times\) 10 = 560 & EUR 19.23 \\ \hline
70 & 30 \(\times\) 3 = 90 & 66 \(\times\) 10 = 660 & EUR 19.88 \\ \hline
80 & 30 \(\times\) 3 = 90 & 76 \(\times\) 10 = 760 & EUR 20.40 \\ \hline
90 & 30 \(\times\) 3 = 90 & 86 \(\times\) 10 = 860 & EUR 20.83 \\ \hline
100 & 30 \(\times\) 3 = 90 & 96 \(\times\) 10 = 960 & EUR 21.18 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Simulation of reward scores. Figure 9: Value of reward score based on the number of participants. The parameter value of the amount of provided CTI data was held constant during the simulation. However, when the number of participants in the network increases, the amount of provided CTI data can also increase. In such a case, the value of the reward score in euros will be smaller in comparison with the current situation, as the number of collected rating scores will increase. For example, let us consider a situation whereby 50 participants are available in the network and three cases of different CTI data are provided. In this case, the value of the reward score in euros is 12.25 in comparison with the value for two CTI data, which is 18.38. The obtained value for three pieces of CTI data is much smaller than for two, but is higher than for 10 participants. Hence, the effect of a larger number of participants still holds, and there is no need to regulate the reward score of the CTI data producers and consumers when the amount of produced CTI data increases.