From the Riddles of Ancient Egypt to Cryptography in the Renaissance — 3500 Years in the Making - Codes: The Guide to Secrecy from Ancient to Modern Times - page 43

looking at the Renaissance influences. This is fitting since Trithemius is both a
man of the (end of) the Middle Ages, as well as a man of the (beginning of) the
Renaissance, given the fluid borders between these two time lines discussed at
the outset of this section. We will see that the above work pales in comparison
to what he contributed later. Stay tuned for more on this fascinating historical
figure in our cryptographic overview.
Figure 1.21: A modern-day steganographic device.
Courtesy of the CIA website. See
http://www.cia.gov/cia/information/artifacts/dollar.htm ,
where it is stated: “This hollow container, fashioned to look like an Eisen-
hower silver dollar, is still used today to hide and send messages or film
without being detected. Because it resembles ordinary pocket change, it is
virtually undetectable as a concealment device.”