Javadoc
Initialize the key pair generators, which in turn will create the
global SecureRandom, which may block waiting for entropy from
/dev/random on unix-like systems. So this should be called on startup
during the "may block for entropy" stage. Note that because this can
block, we still have to do lazy initialisation: We do NOT want to
have it blocking *at time of loading the classes*, as this will
likely appear as the node completely failing to load. Running this
after fproxy has started, with a warning timer, allows us to tell
the user what is going on if it takes a while.