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Raw Input

Our system is based on a X-windows capturing program which gives us the delays between key events with a 10 millisecond resolution. This data is then passed to a Java program which performs the statistical analysis.

The xlisten output from the string ``I love AI'' is shown in figure 1. The meaning of the output fields is as follows:

• p = press event, r = release event
• Symbol of pressed key
• Key mask, where bit 0 = Shift, bit 1 = Caps Lock, bit 2 = Control, bit 3 = Alt
• Key-code
• Delay in milliseconds since last event

It is interesting to note that the order of the characters is interleaved. Unfortunately the X-server processes the keystrokes in batches, yielding 0 as latency between the individual events.

 
Figure 1: Raw xlisten output 

 
Figure 2:  Keystroke Latencies in a Bigram