# A P2P Scheme for Debating and Voting with Unconditional Flexibility
## 5 Experiments and Discussion  
The following experiments are oriented towards measuring the suitability of this method to carry out boardroom debates and voting. The debate tool has been selected on the basis of its features which include flexibility and the lack of a moderator [45]. In this debate tool, participants can send proposals, opinions, and votes. In this approach, only proposals and votes must be protected by the system. Figure 5 shows these kinds of contributions in relation to two different experiences. The first, case A, (charts (a) and (b) in Figure 5) corresponds to a group of 18 students who debated for 20 min. The second, case B, (charts (c) and (d) in Figure 5) was another debate carried out by 23 students in a period of 44 min. Charts (a) and (c) in Figure 5 show the activity in each interval related to sending proposals (black line) or sending votes (columns). Box plots (b) and (d) in Figure 5 show the average interval and its distribution between deliveries (votes and proposals) measured in each experience. These two experiences offer an estimation of the activity in a debate group. Specifically, the average number of proposals from each user which could be voted on was 2.47. The boardroom voting system has to deal with this level of activity, so the process time will be analyzed in these scenarios. The first phase is to obtain the signing of the aliases, which implies generating the alias keys, blinding, signature, removing the blind factor, and checking. All of these steps were measured for only two users using different key sizes (from 768 bits to 2048 bits), and the result presented in chart (a) in Figure 6. These times were measured in computers with Intel Core i-3 processors, 3.1 GHz, and 4 GB of RAM. The chart shows that the heaviest processes were key generation and signature. Nevertheless, the slowest case takes only 1.71 s.  
Additionally, all the traffic crosses a TLS channel between each pair of users. Chart (b) in Figure 6 presents the time needed to establish a TLS channel for two RSA key sizes. The dispersion of time intervals is caused by the different keys and the operating system (Windows 10) which had to manage many threads. The highlight of this chart is the obtention of a reference for two magnitudes: the actual duration of setting a TLS channel and the expected delay added by other common processes. Chart (c) reveals the time in seconds that each user took to initialize when there were more than two users (case of chart (a)). This increased following a curve (it is non-linear) as the key size increases, and following a straight line when group size increased. For instance, the group of 18 users (case A) generated a starting time from 10.38 s (key size of 768 bits) to 13.94 s (key size of 2048 bits). Case B varied from 13.4 s to 17.57 s. This increased with the number of users to frustratingly lengthy times (73.45 s for 100 users and 2048 bits). Figure 5: Debate experiences. Case A: 18 students. Case B: 23 students. Chart (c) shows only the minimum time required in the protocol for initialization, without considering anonymous channels. These channels can add time or not (Section 2), and are selected according to the system features (delay, security, mobility, etc.). However, as an example, chart (d) shows the complete initialization time including the anonymous channels when they are based on the TOR network. Assuming three hops per circuit, the average establishing time is 1.9 s. This raises the initialization to a value of 261.6 s. in the worst case scenario (100 users and 2048 bits for RSA keys). Nevertheless, this happens only at the beginning of the process. Once the debate is initialized, the messages are encrypted by symmetric keys (TLS channels), which means a negligible computing cost compared with usual network delays. The question now is how much traffic can be managed by common users. On the one hand the experimental results produced an average number of proposals per user (2.49), which provided the number of votes cast in a limited time (1920s).