With the other books we've had similar discussions about secrets and their place, so I thought it was interesting that Cryptonomicon treats these encrypted messages as secrets that have a set lifespan. On page 55, Randy asks "How long do you want these messages to remain secret?" ... "Five years? Ten years? Twenty-Five years?" It's interesting to see a character who recognize the difficulty of keeping secrets and the inevitability of secrets emerging into the open i.e. it's just a matter of time.