then placed in a corked tube in the stoppers of beer barrels for Mary Stuart,
Queen of Scots. Anthony Babington plotted to kill Queen Elizabeth I. He
used beer barrels to conceal his message, telling Mary Stuart of the plot
and his intent to place her, Mary, on the throne. He demanded a personal
reply. In doing so, Mary implicated herself when the barrels were confiscated
long enough to copy the message. They decrypted the message using letter
frequency techniques (see Table 4.1 of §4.1). Mary Stuart was subsequently
charged with treason and beheaded.
Double agents began to be widespread, especially during the American
Revolution. Indeed, the infamous Benedict Arnold used a particular code
called a book code. Because he was trusted, his correspondence was never
checked and thus never tested. Not knowing whether that would continue
to be true, he often used invisible ink to further hide his code.
Aaron Burr, who had at one time worked for Arnold, got caught up in
his own scandal after Thomas Jefferson was elected president. Burr had
been elected vice president, and he was ambitious and wanted to advance to
the presidency. Alexander Hamilton learned of a plot to have New England
and New York secede and publicly linked Burr to the plot. This led to
the famous Hamilton–Burr duel, where Hamilton was killed. People turned
against Burr as a result, and he, in turn, developed an elaborate scheme to
get rid of Jefferson. The scheme included ciphers to link all of the many
parts and people, some from Spain and England. Despite eventual evidence
of deciphered messages, Burr was not convicted of treason.
Telegraphy and various ciphers played key roles during the Civil War.
The Stager cipher was particularly amenable to telegraphy because it
was a simple word transposition. The message was written in lines and
transcribed using the columns that the lines formed. Secrecy was further
secured by throwing in extraneous symbols and creating mazes through the
columns. Consider the following simple example:
j o e i s
a n t t o
s o r o n
o n a r t
Most likely this would be read as “Joe is ant [antithetical] to soron
[General Soron] on art”. But the intent is to read it as “Jason traitor”.
Women have always been directly involved in cryptography. An interest-
ing example occurred during the Battle of Bull Run. A woman called Rebel
Rose Greenhow sent messages to the Confederate defenders about Union
troop movements and numbers. She used everything from pockets hidden
in her clothing to coded designs embroidered into her dresses. She was so
effective that the Federal authorities began counterespionage missions and
tracked leaks to party and parlor gossip. Greenhow’s chief nemesis turned
out to be Allan Pinkerton, the famous detective. He eventually trapped her
and had her imprisoned; however, even from her cell she managed to create
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