  We consider a wireless communication system with a passive eavesdropper, in
which a transmitter and legitimate receiver generate and use key bits to secure
the transmission of their data. These bits are added to and used from a pool of
available key bits. In this work, we analyze the reliability of the system in
terms of the probability that the budget of available key bits will be
exhausted. In addition, we investigate the latency before a transmission can
take place. Since security, reliability, and latency are three important
metrics for modern communication systems, it is of great interest to jointly
analyze them in relation to the system parameters. In particular, we show under
what conditions the system may remain in an active state indefinitely, i.e.,
never run out of available secret-key bits. The results presented in this work
will allow system designers to adjust the system parameters in such a way that
the requirements of the application in terms of both reliability and latency
are met.
