Short Message Service (sms) security solution for mobile devices

d. User 
Interface 
The main screen captures for the application is shown in the figures 
below. 
Figure 15. Performance Measurement Application Main Screen 
The 
Mode
field indicates the current encryption mode setting, which 
can be RSA, AES or Baseline. The 
Key
field displays the current key length 
setting. The 
Input Size
field is selectable from 160 bytes, 10 kb and 100 kb. 
However the measurements are conducted using inputs of 100kb only. The 
Iterations
field allows users to key in the number of iterations for the encryption. 
The 
Duration
field shows the time that has elapsed since the start of the first 
encryption. The 
Power
fields, from left to right, show the starting battery power 
level, the current battery power level and the power consumption, respectively. 
The scrolling text box below is used to display status and other debugging 
information.

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Figure 16. Performance Measurement Application Menu 
The left menu has the option to Generate Files. This function 
generates input text files, which are exactly of the sizes of 160 bytes, 10kb and 
100 kb, and filled with random ASCII characters. The same function is also used 
to create and refresh log files after the measurements. The right menu shows the 
current mode of encryption selected and allows users to change the mode as 
desired. 
2. 
Assumptions and Limitations 
a. Battery 
Properties 
The data collection requires multiple charging and recharging of the 
battery. It is assumed that the chemical properties of the battery remain constant 
throughout the measurement process. A Lithium Ion battery like the one used in 
the experiment typically lasts 300-500 discharge/charge cycles [36]. 

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b. Linearity 
It is assumed that the discharge of the battery is linear and that the 
battery strength provided by the API is accurate. In actual fact, battery discharge 
is almost never linear. Typically, the discharge characteristics are more linear in 
the mid range. Therefore, in this experiment, only the middle bands between 
40% and 80% are used as measurement data.