Real-Life Communication
You work for the National Security Agency. You've been asked to
decipher the coded message below. The NSA suspects this is a list of cities
in Canada and the United States where members of an arms smuggling ring have
made deliveries. One of the ringleaders is nicknamed "Teach" because he used
to be a geography teacher. The intercepted message was found in a 1981 Rand
McNally Road Atlas.
The List
- Ixjg Oimc, Ixjg
- Heqyw, Xwqli Aeuwle
- Ozkvvwo, Thwwlgzdowfo
- Yrkj Eqkuxrvju, Wupfusrv
- Att Akpqk, Vnhunfat
- Ypthjzius, Tpddpynbdsccd
- Qllcf Who, Chcvhizfohm
- Bg-Qkewb fe-Xy! Xy!, Deuius
- Zjbqg jz Sozzimj, Rvbxvkvi
- Kteeteetsrws, Djosgtd
You determine this is a simple substitution cipher according to a
system in which each letter gets replaced with its own cipher equivalent.
Punctuation is truly represented. You also suspect each line is encoded with
its own different substitution code.
To crack the code, you'll need
an atlas, some imagination and persistence. Give it a try. There's a pattern
to the way the codes are constructed. If you figure out some of them, you
should be able to figure out the rest.
When you're done, summarize
the method of encryption used by the arms dealers in a report to your supervisor.
Hint
The
easiest way to figure this out is by looking for word length and repetition
patterns that might be equivalent to state or province names. All the substitutions
are based on the plaintext sequence ABCDEFGHIJKLMNOPQRSTUVWXYZ and successive
slides of the ciphertext sequence GEORAPHYISFUNZXWVTQMLKJDCB. This is your
key to solving the puzzle.
Breaking the Code
ABCDEFGHIJKLMNOPQRSTUVWXYZ
-- Plain
GEORAPHYISFUNZXWVTQMLKJDCB -- Cipher
Ixjg
Oimc, Ixjg
Iowa City, Iowa
Successive slides means the
second city key becomes:
ABCDEFGHIJKLMNOPQRSTUVWXYZ -- Plain
EORAPHYISFUNZXWVTQMLKJDCBG
-- Cipher
For city three the key becomes:
ABCDEFGHIJKLMNOPQRSTUVWXYZ
-- Plain
ORAPHYISFUNZXWVTQMLKJDCBGE -- Cipher
Armed with that
information, you can now solve the rest of the cryptographic list and make
a report to your supervisor.