Figure 2 - uploaded by Aleksander Mallasvik
Content may be subject to copyright.
Source publication
his thesis investigates the use of hand gestures as an additional modality in authentication schemes, to thwart the risk of observation (shoulder surfing) attacks. We used the accelerometer already embedded in the iPod Touch to gather accelerometer signals, which were used to conduct experiments on how accurately we could recognize and differentiat...
Contexts in source publication
Context 1
... this thesis though, where we will mostly use tilting motions, recording linear motions will be satisfactory. Figure 2 shows the orientation of the accelerometer in the device, as well as explaining the basic details about the relationship between the device orientation, and the x, y and z coordinates. It is important for us to understand these aspects, as they directly affect the outcome of the gesture recognition module. ...
Context 2
... Left flip (LF): a controlled wrist flip where the participant holds the device in the start position illustrated in Figure 6, and from there tilts the device to the left so the device is in a vertical position with the screen facing left. Due to the accelerometers orientation in the device (shown in Figure 2), a left flip should only be concerned with the x and z directions. The y-direction is theoretically not included in this movement, and the data produced in this direction, for both the right and left flip, will mostly be noise caused by shivering. ...
Context 3
... this case, it is the x direction that is the uninteresting axis, as this in theory should only consist of noise. Figure 12 supports this hypothesis, as we can see that the general templates for a front and back flips x axis is situated around 0 in acceleration. Similar to what we saw in Figure 10, we do experience some variances in the noise direction, for the same reasons as expressed earlier. ...
Context 4
... y axis is, as shown in Figure 12, the axis where a front and back flip differs the most. We clearly see that the signals are pretty much identical, but inverted. ...
Context 5
... capability of our wrists restrict our front flips more than our back flips. This is clearly seen in Figure 12(c), where the front flip produce significantly less acceleration in the z direction. This may of course vary from person to person, which is shown in the more elaborate graphs in Appendix A, but for the average participant, our wrist are easier to bend backwards than forwards. ...
Context 6
... basic flow of the protocol is shown in Appendix B.1, Figure 29. The principal idea behind the protocol is to use the gestures as a challenge to the user, by forcing him to not only enter the correct PIN digits, but also by having him place them in the correct order, by using different gestures. ...
