The disk showed which letter
is to be substituted for another
letter. (In the image at right, the
N is A, the O is Z, etc.) A new
code is generated each time
the disks are adjusted. For the
system to work, the recipient
required an identical cipher
disk—as well as instructions
on how to set it. Rotation rules
could be determined verbally
in advance or announced by
the fi rst encrypted characters
of the message. For centuries
the code disk was considered
uncrackable—and it gave the
Vatican a decisive strategic
advantage. The protection of
this new encryption technique
enabled popes to seek secular
power, infl uence politics
in Europe, claim land
and cities, put kings
under pressure, and
get rid of powerful
enemies, thereby
changing Europe
in lasting ways.Did the VA T I C A N
control Europe with
a SECRET DISK?
IN WITH
THE NEW
With the code
disk, the Vatican
had established
a new era of
communication.
Before this time,
sealed letters
could easily be
opened and
even falsifi ed.W
hen those first
Crusaders came
back to Europe
after leaving the
Holy Land at the end of the
11th century, they brought
something dangerous back
with them: not diseases nor
weapons, but a mathematical
formula—which induced wars,
toppled rulers, and shook the
power structure of the entire
continent. Frequency analysis
is a technique that could be
used to decode almost all of
the ciphers known at the time.
And that had consequences:
Encoded letters—which during
the Middle Ages would pass
through the hands of dozens
of messengers, coachmen,
and sailors—were suddenly
no longer safe. No one could
tell who had read his or her
letter before it was delivered.
It was a disaster for Europe’s
power players, because even
though their codes and thus
their messages were no longer
safe, there was no alternative
for the kings and popes but to
continue sending letters.
Consequently, scholar and
cryptographer Leon Battista
Alberti was commissioned to
develop a secure encryption
method for the pope in 1467.
Soon after he invented a code
disk, which consisted of two
rotatable rings—he had made
a polyalphabetic cipher disk
that was far ahead of its time.
THE BATTISTA CODE: (^) YZYJ= POPE