The enigma project
The Secret World of Codes and Codebreaking
Code: whole words or phases are replaced by
a letter or number
Cipher: individual letters are replaced with
other letters or symbols
Plaintext: normal English Ciphertext: coded English
ACTIVITY 1 Decipher the ciphertext on the strip of paper.
CLUE: You will have to use a pencil. But you don’t use the pencil in the usual way!
Scytale: Used by the Spartans in Ancient Greece 2500 years ago
Scytales must be the same size to be able to decipher a message
Scytales must be the same size to be able to decipher a message
Cipher =
Algorithm
+
Key
Caesar Shift Cipher
a b c d e f
b c d e f
g h
g h i
MISS ELLIS NJTT FMMJT
Caesar Shift Cipher
MXOLXV FDHVDU WKH
URPDQ JHHCHU
VTXDVKHG KLV ZLIH LQ
D OHPRQ VTXHHCHU
ACTIVITY 2 Decipher this message. Each plaintext letter has been moved three places forward in the alphabet…
7K
MXOLXV FDHVDU WKH
URPDQ JHHCHU
H
P J
VTXDVKHG KLV ZLIH LQ
D OHPRQ VTXHHCHU
Caesar Shift Cipher Julius Caesar the Roman Geezer Squashed his wife in
A Lemon Squeezer!
Caesar Shift Cipher How many possible keys are there with the Caesar Shift Cipher? 25
ACTIVITY 3
How many possible keys are there when you swap each letter of the alphabet with another letter?
400 million billion billion
400 000 000 000 000 000 000 000 000
400 million billion billion keys
6.5 billion people in the world 31 million seconds in a year
If everyone in the world checked one key per second, it would still take 2 billion years to check them all
Mary Queen of Scots and the Babington Plot
One of the messages Mary Queen of Scots sent to Babington
ACTIVITY 4
How would you go about trying to crack this type of cipher when there are a possible 400 million billion billion keys?
An unusual message
Today, by radio, and also on giant hoardings, a rabbi, an admiral notorious for his links to masonry, a trio of cardinals and a trio, too, of politicians inform us all of how our country now risks dying of starvation.
ACTIVITY 5
Have a conversation with the person sitting next to you WITHOUT using any words that contain the letter E
START NOW
STOP!
Al Kindi’s book written in 800 AD
Code Breaking Tips
Common letters
One letter words
Common words
Double letters
Clues
WW2 Enigma Machine
General Guderian’s Command-post vehicle
Bletchley Park – Government Code and Cipher School