Two Centuries On, a Cryptologist Cracks a Presidential Code - WSJ.com (http://online.wsj.com/article/SB124648494429082661.html)

Nice find, thanks for posting.

Most folks tend to think of cryptography, if at all, as something that has manifested itself only in our electronic age, when in reality it has been used in various forms for hundreds of years. It is truly a fascinating topic....especially when you get into secrets embedded in pictures for the purpose of secure "hidden in plain sight" transmission....

Some of the math and technical detail gets pretty hairy, but there's a seminal work on this topic written by Bruce Schneirer (sp), entitled "Applied Cryptography." Its an amazing read, even if you don't get all or even most of the math.