Having all clocks synchronized throughout a system is often an assumption that doesn't hold for embedded devices. Specialized devices may not need to know the time to perform their function. However, in security protocols, accurate time keeping is often important. For example, in TLS, the X.509 certificates that are used to prove the identity of web servers contain a validity range. There is a not before and not after time that specifies when that certificate is valid. Without an accurate time keeping system, a device can't enforce this date range allowing it to possibly accept expired or not yet valid certificates.
If you use your BBB in an offline environment, but still need accurate time, then you can insert a coin cell battery into the battery compartment of the CryptoCape. When the BBB is disconnected from power, the RTC will receive enough power from the battery to maintain accurate time.
The BBB already contains an RTC; however, it lacks a dedicated...
