Pedagogy
Everyone should have an Activities Handout
keyed to the presentation. We use it for
understanding codes and exchanging “secret”
messages. Staff walk around to help students
one-on-one, as needed.
From “What Works”
1. Children learn science best when they can
do experiments, so that they can witness
science in action.
2. The mere inclusion of a portrait of an
historical figure is mere window-dressing. It
may even be distracting, especially for
students who lack basic reading skills.
3. When teachers explain exactly what
students are expected to learn and illustrated
the steps needed to accomplish a particular
task, students learn more (clear goals and
assignments, ask questions, give chance to
practice).
4. Constructive feedback, including deserved
praise and specific suggestions, helps
students learn, as well as develop positive
self-esteem.
Background: remove before presentation*
5. Memorizing helps students absorb and
retain the factual information on which
understanding and critical thought are based.
6. Student achievement rises when teachers
ask questions that require students to apply,
analyze, synthesize, and evaluate information
in addition to simply recalling facts.
~~~~~~~~~~~~~~~~~~~~~~~
You learn … by iteration—that is, by going
over the same material many times. Each
time you do that, the material makes a little
more sense.
Richard A. Muller
(physicist)
~~~~~~~~~~~~~~~~~~~~~~~~~
Tell me: I may not get it, and I'm sure to forget
it.
Show me: I may get it, I'll remember it for a
little while.
Have me do it: I may understand it, and it
may stick for a while.
* There are lots of these to remove.
Preview
What?
Preview (continued)
2
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00001
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Complete Activity 1a to decode the title.
CC II HH D R N E E A G b x C b C y K T O x
Cracking The Code
Keeping Information Safe
Copyright Notice:
This presentation may only be used free of charge and only for educational purposes, and may not be
sold or otherwise used for commercial purposes
Decoding The Title
C I H D R N E E A G b x C b C x K T O x x
C
R
A
C
K
I
N
G
T
Cracking The Code
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The previous code is properly called a letters-based transposition cipher,
in which the letters in the plain text are systematically rearranged through
the use of a table of a set number of rows and columns. Transposition
codes, which rearrange words instead of ciphers, also include
Keynumbers. The Keynumber indicates the order in which he columns are
rearranged to form the codetext, that is, the routing of the transposition.
See reference 5 on the Reading List at the end of this presentation.
During the 1800s and into the 1900s people printed secret messages in
the private message columns (called “agony columns”) of newspapers.
Private codes/ciphers were used to maintain privacy and to reduce
message length, which reduced the cost.
Cards with a square cipher were printed and sold so as to provide a way to
write private messages on postcards and, later, in telegrams that would be
“secret.”
Objectives
1. Learn what codes are.
2. See how they work.
3. Make and use some wellknown ones.
Codes are USEFUL!
Radio/TV/Movies
Phones
Military
Product Barcodes
Banking
QR Code
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Good codes are ones that are: EASY for the SENDER to encode a
message, and for the RECEIVER to decode the message, but very difficult
for ANYBODY ELSE to decode.
Mathematicians, computer scientists, and engineers have figured out
clever codes for sending secrets that, for now at least, are very very
difficult to break.
We make use of data codes whenever we use a password to check email, withdraw money from an automated bank teller machine, make a
cellular phone call, or charge a purchase over the Internet.
We rely on encryption to ensure the validity of our financial transactions,
prove our identity, and safeguard our privacy. Although some people
hesitate to conduct business over the Internet, most of us engage in online
transactions with confidence that encryption protects our activities.
Error control codes are used to detect and correct errors that occur when
data are transferred or stored.
Background: remove before presentation
Encryption has long been used by militaries and governments for secret
communication. Encryption is now commonly used in protecting information
within many kinds of civilian systems. Businesses and institutions use
encryption for of their data in transit, and for their data in storage.
Encryption can be used to protect data "at rest", such as files on computers
and storage devices (e.g. USB flash drives). Encrypting such files at rest
helps protect them should physical security measures fail.
Digital rights management systems which prevent unauthorized use or
reproduction of copyrighted material and protect software against reverse
engineering are another example of using encryption on data at rest.
Encryption protects data in transit, for example data being transferred via
networks (e.g. the Internet, e-commerce), mobile telephones, wireless
microphones, wireless intercom systems, Bluetooth devices and bank
automatic teller machines. There have been numerous reports of data in
transit being intercepted in recent years. Encrypting data in transit also helps
to secure it as it is often difficult to physically secure all access to networks.
Activity 1b: QR Code
Use a cell phone to decode
this Quick Read Code.
Cracking The Code
At [School Name]
Presented on [Date]
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Custom QR codes can be created at the website experis.us/ieee.
A QR (“Quick Response”) code is a cell phone readable 2D bar code that can store
website URL's, plain text, phone numbers, email addresses and pretty much any
other alphanumeric data.. It holds data both horizontally and vertically, unlike a bar
code, which holds information only horizontally.
The square shape stores approximately 90 alphanumeric characters for a standard
33x33 square, while a UPC code holds only 12 numerals.
The codes are used to share:
—A simple URL or contact information
—Nutrition stats for fast food
—A company's brand, like Louis Vuitton's colorful illustrated code
—Interactive profiles and story pages on tombstones
—A greeting for fellow digiphiles on T-shirts
It stores up to 4296 characters they are internationally standardized, so a QR code is
a QR code all over the world - they've been big in Japan forever, broke into Europe
and the UK a few years back, and are now getting real traction in USA.
To make things a bit more robust, the QR Code also contains its own error correction
data, internal orientation calibration and self-alignment markers. In this way it doesn't
matter whether the QR code is upside down or wrapped around a curved surface, the
message will still get through.
Background: remove before presentation
Morse Code (Student have been asking about this code.)
Morse code is a method for transmitting information, using short and long
marks or pulses - "dots" and "dashes" - for the letters, numerals, punctuation
and special characters of a message. It was created for Samuel F. B. Morse's
electric telegraph in the mid-1830s, and was used early radio communication.
When using Morse code, a dash is equal to three dots. A space between
parts of the same letter is equal to one dot. A space between two letters is
equal to three dots and a space between two words is equal to five dots.
The pauses between two transmitted characters should be three times as
long as the pause between two symbols (dot or dash). The pause between
two words should be approximately twice as long as the pause between two
characters.
SCYTALE
(Pronounced skit’ il lee)
Spartan messengers carried
coded messages on their belts
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A scytale is strip of parchment paper which is wrapped around a cylinder of a
specific diameter. The plaintext message is written on the paper while the
paper is wound around the cylinder. Once the paper is unwound, the
message becomes difficult to read. To decipher the message, you simply wind
the paper around another cylinder of the same diameter.
The earliest recorded instance of encryption dates to about 400 BCE, when
the Spartans used the scytale to send coded messages between military
commanders. Often the strip was a leather belt that looked as if it had been
decorated with random letters. A message on a belt-sized strip could consist
of 8 to 10 vertical rows.
For a message written in three rows, extracting every third letter will decipher
the message. This code is one of the easiest to crack and therefore is not
very secure. However, they say the Greeks used it, off and on, for hundreds
of years.
A simple, easy to create, scytale device can be made from an ordinary
wooden lead pencil, which usually has six sides. Use a ½ cm strip of paper.
SCYTALE Example
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Long Scytale Message
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oreband
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Four score and seven
years ago our forefathers
brought forth…
Background: remove before presentation
The Gettysburg Address, Gettysburg, Pennsylvania, 11 / 19 / 1863:
Four score and seven years ago our fathers brought forth on this continent, a new
nation, conceived in Liberty, and dedicated to the proposition that all men are created
equal.
Now we are engaged in a great civil war, testing whether that nation, or any nation so
conceived and so dedicated, can long endure. We are met on a great battle-field of
that war. We have come to dedicate a portion of that field, as a final resting place for
those who here gave their lives that that nation might live. It is altogether fitting and
proper that we should do this.
But, in a larger sense, we can not dedicate -- we can not consecrate -- we can not
hallow -- this ground. The brave men, living and dead, who struggled here, have
consecrated it, far above our poor power to add or detract. The world will little note, nor
long remember what we say here, but it can never forget what they did here. It is for us
the living, rather, to be dedicated here to the unfinished work which they who fought
here have thus far so nobly advanced. It is rather for us to be here dedicated to the
great task remaining before us -- that from these honored dead we take increased
devotion to that cause for which they gave the last full measure of devotion -- that we
here highly resolve that these dead shall not have died in vain -- that this nation, under
God, shall have a new birth of freedom -- and that government of the people, by the
people, for the people, shall not perish from the earth.
ACTIVITY 2: Scytale Message Exchange
Step 1. Get a riddle statement and its answer, or make
your own, and write the statement on a strip.
Step 2. Wind the strip on the rod (blank side up), keeping
it attached at all times. .
Step 3. Write the riddle answer on the mounted scytale
strip.
Step 4. Without detaching it, unwind one end of the
scytale strip and exchange with a partner.
Step 6. Wind the partner’s attached scytale strip on the
rod, read the message, and write it in space
provided!
Codes: Substitute and Swap Letters, Numbers, Symbols
Word
Substitute
Four
score
and
seven
4
scor
n
7
Codes: Substitute and Swap Letters, Numbers, Symbols
PLAIN TEXT:
I don’t like my new haircut!
CODED:
@:-(
@ :-(
@ :-(
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@:-(
Emoticon: a representation of a facial
expression (as a smile or frown) created by
typing a sequence of characters.
Some combinations used in texting are below.
(Ask the students for more?)
CUL8R
):
WAN2TLK?
ATB
ASA
Codes: Substitute and Swap Letters, Numbers, Symbols
What did the baby porcupine ask the cactus?
( Coded) Answer:
SI THAT UOY ?OMMYM
SI THAT UOY
?OMMYM
baby porcupine
cactus
Decoded Answer:
IS THAT YOU MOMMY?
Activity 3
Activity 3a: Student Rearrangements
Make up your own rearrangement of
ISxTHATxYOUxMOMMY?xx
and write it in the space on the Activity
Sheet for Activity 3a.
(cont.)
Activity 3a: Solution Using Rectangular Coding
/ISxTH/ATxYO/UxMOM/MY?xx/
I
S
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IAUM STxY xxM? TYOx HOMx
Activity 3
Activity 3b: Other Rearrangements
ISxTHATxYOUxMOMMY?xx
Some possibilities:
xx?YMMOMxUOYxTAHTxSI (backwards)
xxMOMMY?xYOUxTHATxIS (reversed
words)
(cont.)
Activity 3
Activity 3c: Random Order
ISxTHATxYOUxMOMMY?xx
Randomly selecting the letters:
Y M x x x x A? T T O I H S U O Y M M
(cont.)
Factorial
How many ways can the 12 characters
I S T H A T Y O U M A ?
be arranged?
12 x 11 x 10 x 9 x 8 x 7 x 5 x 4 x 3 x 2 x 1
= 12! (“12 factorial”)
= 479,001,600 ways
Do we have the time to write all the arrangements?
Hardly! (479 years)
Is that you
Mommy?
Background: remove before presentation
This uses the factorial operation (which is not used subsequently) and
the concept that decrypting by “trying all possible combinations” is
frequently not a good idea.
We are assuming that, by hand, we can write about one million
combinations per year, so it will take about 479 years to write all of
them—and a lot of paper! (Don’t try this at home!)
Caesar’s Code
Caesar used a “shift code” with a “Key”
for messages to his Generals.
Key = 3
a is
b is
c is
y
z
replaced by D
replaced by E
replaced by F
...
is replaced by B
is replaced by C
meet me at seven
at mcdonalds
(Continued on the next chart.)
Caesar’s Code (continued)
meet me at seven at mcdonalds
PHHW PH W H H
W P
PHHW PH DW VHYHQ DW PFGRQDOGV
key = 3
m
e
t
becomes
becomes
becomes
P
H
W
(Continued on the next chart)
Background: remove before presentation
A Caesar cipher is one of the simplest (and easiest cracked)
encryption methods. It is a Substitution Cipher that involves replacing
each letter of the secret message with a different letter of the alphabet,
which is three positions further in the alphabet. The pattern wraps
around to the beginning: X becomes A, Y becomes B, and Z becomes
C.
The Caesar cipher replaces the characters of the plaintext-alphabet
with other characters. This is called monoalphabetic substitution.
Unfortunately, simplicity of use is a double-edged sword:
The ciphertext thus encoded is highly susceptible to being decoded.
Caesar’s cipher is easy to “crack:” simply move each letter in the
encoded message back three spaces in the alphabet.
32
Other Values Of The Key
Key = 3 is the value that Caesar used:
D E F G H I J K L M N O P Q R S T U V W X Y Z A B C
a b c d e f g h i j k l m n o p q r s t u v w x y z
If Key = 10, what does “j” code to?
K L M N O P Q R S T U V W X Y Z A B C D E F G H I J
a b c d e f g h i j k l m n o p q r s t u v w x y z
How many values can Key have?
26: 0, 1, 2, 3, … ,25
Caesar Slide
Key = 3 (Caesar):
a b c d e f g h i j k l m n o p q r s t u v w x y z
D E F G H I J K L M N O P Q R S T U V W X Y Z A B C
a
defghijklmnopqrstuvwxyzabc
hijklmnopqrstuvwxyz
ABCDEFGHIJKLMNOPQRSTUVWXYZ
Caesar Slide With Key = 3
Activity 4: Construct A Caesar Slide
defghijklmnopqrstuvwxyzabc
ABCDEFGHIJKLMNOPQRSTUVWXYZ
1. Cut out the upper-case strip on the Activity Handout.
2. In line with the two cuts in your card, insert and center the
upper-case strip. Optional: tape it securely.
3. Cut the two lower-case alphabet strips, tape them end-toend, and insert it above the other strip.
4. For coding and decoding, slide the lower-case strip to
match up the two alphabets with the value of the Key.
Activity 4 (continued)
Try out your Caesar Slide on the coded text:
HPHTWWXPPELEXTOYTRSE
(The Key is NOT 3. It is between 8 and 12.)
The Key is 11.
The decoded message is:
WE WILL MEET AT MIDNIGHT
Website for coding/decoding software:
http://www.braingle.com/brainteasers/codes/caesar.php
Activity 5: Caesar-Slide Message Exchange
For a (short!) secret message of your choosing,
1. Code the message with a Key of your choosing.
2.Exchange the coded message with a partner.
(Please tell each other the range in which your Key
falls. For example, “It’s between 19 and 23.”)
3.Decode your partner’s message.”
37
Activity 6: Secret Message, Sliding Panel
I’m out of here!
Worthie Sir John: Hope, that is the beste
comfort of the afflicted, cannot much, I
fear me, help you now. That I would say to
you, is this only; if ever I may be able to
Complete Activity 6 to find
requite that I owe you, stand not upon
message.
asking me. the
‘Tishidden
not much
I can do: but what
I can do, bee very sure I will. I knowe
that, pa
if deathe comes, if ordinary men fear
it, it frights not you, accounting it for a
high honour, to have such a rewarde of your
panelateastendofchapelslides
loyalty.
Pray yet that you may be spared
this soe bitter, cup. I fear not that you
will grudge any sufferings; onlie if bie
submission you can turn them away, ‘tis the
part of a wise man. Tell me, an if you can,
to do for you anything that you wolde have
done. The general goes back on Wednesday.
Restinge your servant to command.
[Signed]
R.T.
panel at east end of chapel slides
Chapel
Background: remove before presentation
In 1642 Sir John Trevanion, who fought for King Charles I, was
captured and imprisoned in Colchester Castle. More than likely, Sir
John was beginning to sweat because he knew that two of this
comrades had already made the long walk to the gallows. Things
looked grim for Sir John, when he received a message from a fiend,
R.T.
The seemingly harmless note actually contained coded instructions
on how to escape. RT’s code is called a null cipher, which conceals
the letters of the plaintext within a string other letters. To unmask the
message within the message, select the third letter after each
punctuation mark. (“Panel at east end of chapel slides.”)
John’s jailers didn’t know who R.T. was, but they found nothing
suspicious in the letter and delivered it to the prisoner. Just as no
one questioned the letter, no one questioned Sir John’s request to
spend time in quiet prayer in the chapel. After an hour, his jailer
finally entered the chapel to check on the prisoner. Sir John was
long gone through the secret escape panel.
Story 1
Mary Queen of Scots
sent messages in a barrel
Story 1: Mary Queen of Scots
Sent Messages in a Barrel
Background: remove before presentation
Mary Stuart, 1542-1587, Queen of Scotland and disputed heir to the English
throne was kept a prisoner for nineteen years by Queen Elizabeth, fearing
that Mary would lead a rebellion against her.
Mary communicated with her supporters using a combination cipher and
nomenclator. (A nomemclator is a system of coding that relies on a cipher
alphabet, which is used to code the majority of a message, and a limited list
of codewords.)
She sealed her notes in a watertight packet and inserted it in a keg bung of
a beer barrel.
After discovery, Mary was tried, found guilty largely on the basis of
deciphered treasonous messages, and beheaded. (She believed her cipher
was secure, and so discussed her treasonous plans more openly than she
would have if she’d suspected her messages might be read.) Reminder: tell
the interesting way Mary was tricked into revealing the identity of her coconspirators.
More Secure Code: Keyword Alphabet
Keyword = DIAMONDBACKS
DIAMONDBACKS
DIAMONBCKS
ABCDEFGHIJKLMNOPQRSTUVWXYZ
DIAMONBCKSABCDEFGHIJKLMNOPQRSTUVWXYZ
DIAMONBCKSABCDEFGHIJKLMNOPQRSTUVWXYZ
DIAMONBCKSEFGHJLPQRTUVWXYZ
Plaintext Alphabet:
Keyword Alphabet:
abcdefghijklmnopqrstuvwxyz
DIAMONBCKSEFGHJLPQRTUVWXYZ
Background: remove before presentation
Kerckhoff’s Principle:
Coding algorithms should be made public; all of the security of a cipher
system needs to lie in the Key.
A “good” Keyword is easy to remember, is long enough to change the
sequence of the code alphabet, and includes one or more of the letters V
W X Y Z (which are near the end of the alphabet).
Frequent changing of the Keyword makes the cipher harder to “break.”
Activity 7: Example (Keyword = DIAMONDBACKS)
Complete Activity 7 to decode the message
GOOT GO DT GAMJHDFMR
keyword alphabet:
plaintext alphabet:
DIAMONBCKSEFGHJLPQRTUVWXYZ
abcdefghijklmnopqrstuvwxyz
coded message: GOOT GO DT GAMJHDFMR
decoded message: meet ?? ?? ?????????
meet me at mcdonalds
Recall that with the Caesar Code (Key = 3):
phhw ph dw pfgrqdogv
Background: remove before presentation
Note that if we had the time, we could ask the students to use their
Caesar Slides to do the decoding.
The alphabets are:
abcdefghijklmnopqrstuvwxyz
DIAMONBCKSEFGHJLPQRTUVWXYZ
Activity 8:
Exchange A Keyword-Alphabet Message
For a (short) secret message of your choice.
1. Code it using a Keyword Alphabet.
2. Exchange it with that of a partner.
3. Decode each other’s message. (Please tell
each other the Keywords you used.)
Vigenère/Beaufort Code Vigenère/Beaufort Array
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C D E F G H I J K L M N O P Q
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F G H I J K L M N O P Q R S T
G H I J K L M N O P Q R S T U
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T U V W X Y“JOE”
Z A B C D E
R S T U V W X Y Z A B C D E F
S T U V W X Y Z A B C D E F G
T U V W X Y Z A B C D E F G H
U V W X Y Z A B C D E F G H I
V W X Y Z A B C D E F G H I J
W X Y Z A B C D E F G H I J K
X Y Z A B C D E F G H I J K L
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Background: remove before presentation
In the 1500s, Blaise de Vigenère, a French diplomat, invented the first
polyalphabetic cipher, a method for encrypting different letters in a message with
different ciphers in which letters may be encoded differently depending on their
position in the document. This cipher system is polyalphabetic, which means more
than one cipher alphabet is used. This is the reason for the repeating keyword. The
result is coded text in which the same letter, such as the two L’s, represents different
plaintext letters.
For many years Vigenère’s cipher was considered unbreakable, but Charles
Babbage, showed in the 1850s that it was not so. Babbage hacked the system by
looking for repeated strings of letters. In any message that is much longer than the
key, some repeats are bound to occur. How would an eavesdropper exploit this fact?
If, say, the ciphertext “UPK” appeared twice, 21 letters apart, then he could deduce
that 21 was probably a multiple of the keyword’s length. Or to put it another way, the
number of letters in the keyword was a divisor of 21. (1, 3, 7, and 21.) Given enough
clues of this sort, an eavesdropper could pin down the exact length of the keyword.
Once he knew the length, he could do ordinary frequency analysis to decode the
message. Notice that the math comes first: The eavesdropper figures out the length
of the keyword before even attempting to figure out what its letters are. Babbage’s
ingenious technique broke new ground in cryptography, by introducing mathematical
tools to a subject that previously had seemed to be about words. Even if an
encryption system does not use mathematics explicitly, its hidden patterns can often
be teased out that way--mathematics is, after all, the science of patterns.
How To Use The V/B Array
1. Find the known
letter in the leftmost column or
the top-most
row.
2. Move in to the
Keyword letter.
3. Move back out
perpendicularly
to the unknown
letter.
------------- coded letters ------------
--- plain letters (decoded letters) --A
B
C
D
E
F
G
H
I
J
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M
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a
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A
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g
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keyword
letters are
always in
the array
Vigenére/Beaufort Array
z
Z
A
B
C
D
E
F
G
H
I
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K
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M
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Vigenére/Beaufort Code Example
Hi, gang!
Bob
Riddle:
What did Bob buy a roll of tape for?
?
For the Keyword JOE the
coded answer is:
VBAGATYON
Keyword: JOEJOE JOE
Coded Answer: VBAGATYON
Decoded Answer: ?????????
Continued on Next Chart…
ACTIVITY 9: Decode V/B Riddle
Coded:
What did Bob buy
a roll of tape for?
To decode:
1. Find the
coded
letter in
left-most
column.
2. Move over
to the
Keyword
letter.
3. Move up
to the
plain
letter.
Keyword:
A
B
C
D
E
F
G
H
I
J
K
L
M
N
O
P
Q
R
S
T
U
V
W
X
Y
Z
a
A
B
C
D
E
F
G
H
I
J
K
L
M
N
O
P
Q
R
S
T
U
V
W
X
Y
Z
b
B
C
D
E
F
G
H
I
J
K
L
M
N
O
P
Q
R
S
T
U
V
W
X
Y
Z
A
Decoded
c
C
D
E
F
G
H
I
J
K
L
M
N
O
P
Q
R
S
T
U
V
W
X
Y
Z
A
B
d
D
E
F
G
H
I
J
K
L
M
N
O
P
Q
R
S
T
U
V
W
X
Y
Z
A
B
C
e
E
F
G
H
I
J
K
L
M
N
O
P
Q
R
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T
U
V
W
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Y
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A
B
C
D
f
F
G
H
I
J
K
L
M
N
O
P
Q
R
S
T
U
V
W
X
Y
Z
A
B
C
D
E
g h
G: H
H I
I J
J K
K L
L M
M N
N O
O P
P Q
Q R
R S
S T
T U
U V
V W
W X
X Y
Y Z
Z A
A B
B C
C D
D E
E F
F G
V B A G A T Y O N
J O E J O E J O E
o n e d o l l a r
i
I
J
K
L
M
N
O
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Q
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j
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k
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l
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M
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O
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Q
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m
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o
O
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p
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Activity 10: Another V/B Riddle
What did Bob want the roll of tape for?
?
For Keyword BOB the coded answer is:
WGWIQZKOIW
Coded:
Keyword:
Decoded:
WGWIQZKOIW
BOBBOBBOBB
??????????
ACTIVITY 10 (continued)
Riddle: What did Bob want the roll of tape for?
To decode:
1. Find the coded
letter in left-most
column.
2. Move over to the
Keyword letter.
3. Move up to the
plain letter.
WGWIQZXBIJ
Keyword: BOBBOBBOBB
Decoded: fiftycents
f
Coded:
A
B
C
D
E
F
G
H
y
J
K
L
M
N
O
P
Q
R
S
T
U
V
W
X
Y
Z
a
A
B
C
D
E
F
G
H
I
J
K
L
M
N
O
P
Q
R
S
T
U
V
W
X
Y
Z
b
B
C
D
E
F
G
H
I
J
K
L
M
N
O
P
Q
R
S
T
U
V
W
X
Y
Z
A
c
C
D
E
F
G
H
I
J
K
L
M
N
O
P
Q
R
S
T
U
V
W
X
Y
Z
A
B
d
D
E
F
G
H
I
J
K
L
M
N
O
P
Q
R
S
T
U
V
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Y
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A
B
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E
F
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g
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O
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h
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ACTIVITY 11 V/B Code Message Exchange
For a (short) secret message of your choice:
1. Code the with a Vigenère/Beaufort Code.
2. Exchange the message with that of a partner.
3. Decode your partner’s message. (Please tell
each other the Keyword used)
Background: remove before presentation
See also:
http://ruffnekk.stormloader.com/beaufort_tool.html
http://www.simonsingh.net/The_Black_Chamber/vigenere_cipher.html
http://www.simonsingh.net/The_Black_Chamber/vigenere_tool.html
http://www.math.tamu.edu/~dallen/hollywood/breaking/v.htm
STORY 2:
Germany promised Mexico the states
Arizona, Texas, and New Mexico
Coded Telegram From
Germany to Mexico
Cartoon in U.S. Newspaper
56
Background: remove before presentation
The most sensational solution of a single coded message in recent history
(according to Martin Gardiner) occurred during World War I. In 1917 the
German Foreign Minister, Arthur Zimmerman, the German foreign minister,
sent a cable to Mexico, using a diplomatic code called 0075. It announced
Germany’s plan to begin unrestricted submarine warfare. If America entered
the war, the cable continued, Germany promised to give Mexico the states of
Arizona, Texas, and New Mexico--if Mexico would only join fighting against
the United States.
The Germans intended to begin unrestricted submarine (U boat) warfare and
thereby cut off the flow of goods so badly needed by the British and French
forces.
The cable was intercepted and the code broken by British intelligence, then
passed on to President Woodrow Wilson. America had been reluctant to
enter the war. But news about the Zimmermann telegram so enraged the
U.S. Congress and the public that the Congress declared war on Germany
30 days after the telegram appeared in U.S. newspapers. Had we no done
so, it is probable that Germany would have won the war. “Never before or
since,” writes David Kahn, “has so much turned upon the solution of a secret
message.”
Background: remove before presentation
STORY 2: Germany would give Arizona,
Texas, and New Mexico to Mexico
The telegram (January 16, 1917) :
"We intend to begin on the first of February unrestricted submarine warfare. We shall
endeavor in spite of this to keep the United States of America neutral. In the event of
this not succeeding, we make Mexico a proposal of alliance on the following basis:
make war together, make peace together, generous financial support and an
understanding on our part that Mexico is to reconquer the lost territory in Texas, New
Mexico, and Arizona. The settlement in detail is left to you. You will inform
the[Mexican] President of the above most secretly as soon as the outbreak of war
with the United States of America is certain and add the suggestion that he should,
on his own initiative, invite Japan to immediate adherence and at the same time
mediate between Japan and ourselves. Please call the President's attention to the
fact that the ruthless employment of our submarines now offers the prospect of
compelling England in a few months to make peace." Signed, ZIMMERMANN
(Mexico formally declined Zimmermann's proposals on April 14, by which time the
U.S. had declared war on Germany.)
STORY 3: Why did the British let them
shoot down the airplane?
During WWII, enemy spies learned that the actor Leslie Howard
would fly from Spain to England.
They believed his travel companion was Winston Churchill!
So, the enemy made plans to shoot down the plane.
The British allowed the enemy to shoot down the plane.
Background: remove before presentation
STORY 3: Why did the British let them
shoot down the airplane?
Leslie Howard (3 April 1893 – 1 June 1943) was an English actor (“Gone
With the Wind), director, and producer of Hungarian origin. He was active
in anti-Nazi propaganda, and worked with British or Allied Intelligence,
which may have led to his untimely death in 1943 when his airliner was
shot down, sparking modern conspiracy theories regarding his death.
The Allies had broken an important German code just days before Howard
was to take a flight from Lisbon, Spain. His travel companion happened to
look like Winston Churchill. Fascists spotted Howard’s companion and
planned to shoot down the plane. The Allies learned of this plan, but
allowed the flight to occur to keep the German code system from being
changed by the Germans, and the plane was indeed shot down by
German planes over the Bay of Biscay, between Spain and England.
Story 4 Enigma Coding Machine
This German
coding system,
used by its
Navy, was the
best one before
computers were
invented.
The code was
broken by the
British and the
Americans even
before the U.S.
entered the war.
Background: remove before presentation
London (CNN) – An Enigma machine which was featured in a Hollywood movie
about the codebreakers of World War II has smashed auction estimates and sold for
a world record price.
The encoding device sparked a three-way bidding war when it went under the
hammer at Christie's in London Thursday, selling for £133,250 ($208,137) -- more
than double the upper estimate of £50,000.
Christie's said the previous record for an Enigma machine was £67,250, at the same
auction house, in November 2010.
Vitally important to the Nazi war machine, the Enigma machine was used by the
German military to encrypt messages into a form they believed was unbreakable.
However, the code was cracked by a team of cryptologists at Bletchley Park in
southern England -- a breakthrough widely credited with having shortened the war
by at least two years. Thousands of the machines are thought to have been
produced from the 1920s, through to the end of the Second World War, but it is rare
for one to come up for sale.
The story of the codebreakers has inspired several books, and a movie starring
Oscar-winning actress Kate Winslet. The Enigma machine sold Thursday was one of
several used in the 2001 film.
Background: remove before presentation
http://edition.cnn.com/2011/WORLD/europe/09/16/enigma.machine.auction/index.html
Although the number of the ciphering machines still in existence is thought to remain in the thousands, "it is rare for one to come up
for sale," says Christie's specialist, James Hyslop. "Many are believed to have been produced but it's not a particularly high
survival," he adds.
During the wartime period, the Enigma machine was the most advanced device of its kind, a forerunner of the first modern
computer systems.
Originally produced by a Dutch company for commercial use in the aftermath of the First World War, the technology was snapped
up for sole use by the German military in 1929.
Employing a complex series of interchangeable rotors, the machine would encode messages before sending them via Morse code
to an identical device in another location.
If the receiving Enigma was attuned to the same settings -- one of a possible 158 million million million combinations -- the
encrypted message would then be automatically decoded.
Historians have recognized that Bletchley played a very significant part in the war, shortening it by at least two years
--Simon Greenish
The mindboggling numbers involved led the Germans to believe that it was "impossible to crack" the Enigma, Hyslop explains,
hence its importance to the Nazi war machine.
Unbeknown to Hitler's charges however, a group of code breakers based at Bletchley Park in the English countryside had devised
a way to do just that.
Led by the English mathematician Alan Turing, this small army of cryptologists, linguists, scientists and data analysts managed to
create a system that at its peak was breaking as many as 6,000 encrypted German Enigma messages every day.
"The importance of the Enigma machine and the efforts of those at Bletchley to decode it cannot be underestimated," says Simon
Greenish, Director of the Bletchley Park Museum.
"Historians have, until comparatively recently, recognized that Bletchley played a very significant part in the war, shortening it by at
least two years," he says. "But some are now beginning to say that perhaps it made the difference in terms of winning (the war)."
The extraordinary efforts of those involved, Greenish adds, played a vital role in gathering the intelligence that helped shape pivotal
battles such as D-Day, the Russian campaign, the North African campaign and the battle for the Atlantic.
Greenish claims the role played by the Enigma in determining the outcome of WWII alone is enough to guarantee its status as a
relic of great historical importance.
Enigma Coding Machine
Background: remove before presentation
The Enigma (Greek for ”riddle“) is a ciphering-machine developed in Germany by
Arthur Scherbius in 1926 for use by businesses. Originally Enigma was used only for
civilian purposes and was sold by a company founded by Scherbius. However, near
the end of the twenties, the German Wehrmacht started using the Enigma for military
purposes, and thus it vanished from the market. It is estimated that between 30,000
and 200,0002 Enigma machines were manufactured during World War II.
The Enigma has six main components:
• A keyboard, similar to a typewriter
• A light field with small lights for each letter
• A set of rollers, each one representing a monoalphabetic device
• A reflector
• A plug-board
• A battery
The plug-board contains 26 sockets, each one labeled with a letter. When a button on
the keyboard is pressed, voltage is applied to the conducting path of the pressed
button. This conducting path usually leads directly to the rollers, unless the previously
pressed letter is connected to another letter on the plug board. In this case, the electric
current would first pass this connection and then the conducting path to the rollers.
The conducting paths of each single roller are wired in an arbitrary way. The rollers can
be turned and, depending on the position of the rollers, a different conducting path is
created, which leads to the reflector. From there, the electric current flows back over all
rollers. When voltage is applied at the end of the conducting path of Y, a small light for
a letter glows, unless the letter is connected to another letter on the plug-board, in
which case the small light of this letter would glow.
64
Background: remove before presentation
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After multiple rotations, the rotor positions yield the proper
shifted alphabet for determining the coded (or decoded) letter.
Story 4 Enigma Coding Machine
Background: remove before presentation
It took three German soldiers to operate the Enigma machine. One would key
in the message text. One called out the letters as they lighted, and the third
wrote down the letters as they were called out.
During WWII both the Germans and the Japanese thought they had a cipher
system that couldn't be broken. Both systems were broken however, even
before the U.S. officially entered he war. Both used “state of the art” cipher
machines. Germany never realized that Great Briton and the U.S. were
“reading” much of their Enigma message traffic throughout the war.
The Japanese cipher machine was code-named “PURPLE” and was used
initially for diplomatic message traffic. It was quite different from the German
ENGMA machine and used electrical relays in a typewriter-like device.
American cryptanalysts worked almost two years to develop a solution to the
Japanese machine. The final step in the solution was to construct a machine
that functioned identically to the PURPLE machine . The American machine
was surprisingly similar in appearance to the actual Japanese machine—even
though the Americans had never seen the Japanese machine.
66
Enigma Coding Machine
Background: remove before presentation
It has to be known which roller belongs to which position in order to decode a message
with the Enigma. The ring position, which determines the offset of the inner wiring to the
carry-over to the next roller, has to be known as well. Also, the connections on the plug
board have to be known. Since the rollers are turning around with different speed,
depending on their position, the starting positions of the rollers also have to be known.
Setting up a communications net involved selecting the rotors for the day and placing
them in the machine in the proper left-to-right order.
During the war, the Enigma was improved continuously, which resulted in more than 50
different versions. Nevertheless, English and Polish code-analysts managed to crack
German radio messages several times, which had a great impact on the war. The Polish
secret service had access to an Enigma-machine from the time when it was still
commercially available. And thus, Polish mathematicians managed to reverse engineer
the wiring of the Enigma, which enabled them to crack the key a few months later.
The Enigma had been cracked – until the Germans started to use an Enigma-variant
with a new wiring. The Polish and also the British secret service later on developed
machines to ease the cracking of German radio messages. Until the end of World War
II, the British employed up to 7,000 people in a decoding-center. The German military
issued extra rotors with each machine--two for Army and Air Force machines and four
for Navy.
Enigma Coding Machine
Background: remove before presentation
Part electrical, part mechanical, the Enigma was like a combination lock with more than
10^23 possible combinations--this is roughly the number of tablespoons of water in all
the world’s oceans. Moreover, the Germans changed the combination every day—
sometimes several times a day. Recipients of the transmissions needed to possess not
only a duplicate Enigma machine, but also to know the correct combination.
If the Allies had had to rely solely on frequency analysis or trial and error, they would still
be hunting for that one-tablespoon of water in an ocean of possibilities. However, thanks
in large part to crucial earlier work by Polish cryptographers and mathematicians, a team
of British codebreakers
These achievements greatly shortened the war, hereby saving countless lives. Alan
Turing found a shortcut that eliminated almost all of the trial and error for finding the
current combination. Now it was more like hunting for one particular tablespoon of water
in a small wading pool. Turing’s solution exploited both the mathematical structure of the
Enigma machine and certain regularities in the German transmissions, such as (1) their
punctual release each morning of a weather bulletin containing the word “Wetter” (the
German word for “weather”), and (2) the fact that the Enigma could not encipher any
letter as itself, and (3) many German messages were similar.
Bletchley Park built 16 machines (“bombes,” based on machines and designs that were
given as a jump start to the British by Polish intelligence—devised by Marian Rajewski, a
23-year-old mathematician) The machines were used day and night to decipher Enigma.
By early 1942 they were able to decipher all that day’s messages within an hour.
68
Bletchley Park
Bletchley Park built 16 machines to crack the Enigma code,
based on the machines and designs of a 23-year-old Polish
mathematician.
The “bombes” were used day and night to decipher Enigma
messages sent by the German Navy.
By early 1942 the British were able to decipher all that day’s
messages within an hour.
Story 5 Bletchley Park
Background: remove before presentation
Bletchley Park is located in England, midway between Oxford and
Cambridge Universities (http://www.frobenius.com/bletchley.htm).
On this site during Word War II, 22,000 men and women, with prewar help from Poland, broke the German Lorenz and Enigma ciphers,
as well as Japanese and Italian codes and ciphers.
They used innovative mathematical analyses and were assisted by
two computing machines developed there by teams led by the
famous mathematician/computer scientist Alan Turing.
Bletchley Park and the American counterpart at Mt. Vernon Seminary
in Washington, D.C. also played a central role in helping Montgomery
win at Alamein, and in the D-Day landings. During the Normandy
invasion Bletchley Park was receiving over 4,800 German military
messages a day to decode.
See also: Secret Code Breaker II by Robert Reynard (1977)
Background: remove before presentation
http://www.bletchleypark.org/
STORY 6: Recruiting For Bletchley Park
“He’s always
puttering around
with that heap.”
PILOT
O T
AFTER
KINDLY
FILLET
T
K
F I
N
R
Y
E T
T I N K E R
T I N K E R
T O Y
What he turned
his car into.
T O Y
Story 6 Recruiting For Bletchley Park
Background: remove before presentation
To recruit code breakers for Bletchley Park, the British asked readers
of the London Daily Telegraph (the highest-selling British newspaper)
to complete the crossword puzzle in under 12 minutes.
Those who replied were invited to complete another special
crossword test, and 6 of the 25 people who took that test were hired
for work at Bletchley Park.
After the war the people at Bletchley Park were told to go home and
never speak about their role, much of which remains classified.
Note:
A new Jumble appears daily in the Arizona Star. Also, google
“Jumble” for more.
Number Worms
Nowadays information to be coded is
usually first represented by either
1. decimal numbers, or
2. binary numbers.
1. Using decimal numbers:
A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
| | | | | | | | | | | | | | | | | | | | | | | | | |
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25
A is 00, B is 01, C is 02, … , Z is 25
Example
Riddle: How much dirt is in a
cylindrical hole 1m deep and
2m in diameter?
2
How much
1 dirt?
Coding the Riddle (not the Answer) as a number worm:
H O W
M U C H
D I R T etc.
A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
| | | | | | | | | | | | | | | | | | | | | | | | | |
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25
Coded Riddle:
07 14 22 12 20 02 07
Number Worms - 1
03 08 17 19 etc.
75
Activity 12: Number Worm Decoding
Coded Answer (for Key = 20):
Y = 33 34 33 24 34 33 31 44 20 28 27
= +20
= -20
2
1
How
much dirt?
33 34 33 24
- 20 20 20 20
34 33 31 44
20 20 20 20
20 28 37
20 20 20
13 14 13 04
14 13 11 24
00 08 17
N
O
N
E
O
N
L
Y
A
I
R
A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
| | | | | | | | | | | | | | | | | | | | | | | | | |
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25
Number Worms Using 0’s and 1’s
Information to be coded is first represented by either
decimal numbers, or
binary numbers (0’s and 1’s)
A
B
C
D
E
F
G
00001
00010
00011
00100
00101
00110
00111
H
I
J
K
L
M
N
01000
01001
01010
01011
01100
01101
0110
O
P
Q
R
S
T
U
01111
10000
10001
10010
10011
10100
10101
V
W
X
Y
Z
10110
10111
11000
11001
11010
SPACE 00000
PERIOD 01100
ASCII Code
128 letters, numbers, and
other characters can be
represented.
For example, A is 1000001
It’s time-consuming
and easy to make
errors in working
with so many
bits/character.
So we are using a
modified ASCII
code with only 5
bits/character.
A
B
C
D
E
F
G
00001
00010
00011
00100
00101
00110
00111
78
Riddle: What did Paul Revere
say after his ride?
Coded Answer:
10111 01000 01111 00001
A
B
C
D
E
F
G
00001
00010
00011
00100
00101
00110
00111
H
I
J
K
L
M
N
01000
01001
01010
01011
01100
01101
0110
O
P
Q
R
S
T
U
01111
10000
10001
10010
10011
10100
10101
V
W
X
Y
Z
10110
10111
11000
11001
11010
SPACE 00000
PERIOD 01100
10111
01000
01111
00001
W
H
O
A
79
Riddle: What flower tells what the teacher
did after sitting on a tack?
Answer: 10010 01111 10011 00101
R
Decoded:
A
B
C
D
E
F
G
00001
00010
00011
00100
00101
00110
00111
H
I
J
K
L
M
N
01000
01001
01010
01011
01100
01101
0110
O
P
Q
R
S
T
U
01111
10000
10001
10010
10011
10100
10101
O
S
V
W
X
Y
Z
10110
10111
11000
11001
11010
SPACE 00000
PERIOD 01100
E
Concealing The Answer
Coded Answer:
10010 01111 10011 00101
Decoded Answer: R
O
S
E
No Key was used.
So, ROSE is coded using standard
ASCII, which everyone knows.
Let’s put in a Key, to conceal the answer.
Code ROSE With The Key “JOE”
A
B
C
D
E
F
G

00001
00010
00011
00100
00101
00110
00111
H
I
J
K
L
M
N
01000
01001
01010
01011
01100
01101
01110
O
P
Q
R
S
T
U
01111
10000
10001
10010
10011
10100
10101
V 10110
W 10111
X 11000
Y 11001
Z 11010
SP 00000
10010 01111 10011 00101
ROSE
01010 01111 00101 01010
JOEJ (Key= JOE)
????? ????? ????? ?????
ROSE  JOEJ
Combine the plaintext and the key
by using “”
(to be continued)
Coding ROSE With  JOEJ

10010 01111 10011 00101 ROSE
01010 01111 00101 01010 JOEJ (KEY)
????? ????? ?????
? ?????
? ?? ROSE  JOEJ
1
0
0
1
 1
 0
 1
 0
?
?
?
?
(to be continued)
Or:

1
0
0
1
 1
 0
 1
 0
0
0
1
1
 1
 0
 1
 0
1
0
0
1
84
Background: remove before presentation
Note that is the Exclusive-Or operation of Boolean algebra (but
those terms may be too scary, so we label it as the “OR” operation).
Analogies:
We are combining operands bit-by-bit using a logic operation that is
easy to implement in digital hardware.
1.The is “like” addition, except for 1 1 = 0,
which is like [1 + 1 = 0 carry 1].
2.The is “like” subtraction, except for 0 1 = 0,
which is like [0 − 1 = − 0 borrow 1].
3.The is “like” the way the word “or” is used, except that this is
the Boolean OR operation, with 1 OR 1 = 0.
By using , we get a symmetrical key—one whose value is exactly
the same for both coding and decoding.
85
Activity 13:  JOEJ
0
0
1
1
 0
 1
 0
 1
0
1
1
0
10010
01111
10011
00101
ROSE
 01010
01111
00101
01010
JOEJ (Key=JOE)
11000
00000
10110
01111
ROSEJOEJ
 01010
01111
00101
01010
JOEJ (Key=JOE)
10010
01111
10011
00101
ROSE
ROSE JOEJ JOEJ
JOEJ works both ways!
The key is “symmetric under .”
86
Background: remove before presentation
A
B
C
D
E
F
G
00001
00010
00011
00100
00101
00110
00111
H
I
J
K
L
M
N
01000
01001
01010
01011
01100
01101
01110
O
P
Q
R
S
T
U
01111
10000
10001
10010
10011
10100
10101
V
W
X
Y
Z
10110
10111
11000
11001
11100
SPACE 00000
FYI: ROSEJOEJ decodes to “XV O”
11000 00000 10110 01111
O
space
V
X
Activity 14: Ghost Riddle
What do ghosts chew?
A
B
C
D
E
F
G
00001
00010
00011
00100
00101
00110
00111
H
I
J
K
L
M
N
01000
01001
01010
01011
01100
01101
01110
O
P
Q
R
S
T
U
01111
10000
10001
10010
10011
10100
10101
V
W
X
Y
Z
10110
10111
11000
11001
11010
SP 00000
Coded answer for the Key “GHOSTS”:
0010100111000001001110110111000100001000010000011011001
Decoded answer:
???????????????????????????????????????????????????????
Activity 14: Ghost Riddle (continued)
A
B
C
D
E
F
G
00001
00010
00011
00100
00101
00110
00111
H
I
J
K
L
M
N
01000
01001
01010
01011
01100
01101
01110
O
P
Q
R
S
T
U
01111
10000
10001
10010
10011
10100
10101
V 10110
W 10111
X 11000
Y 11001
Z 11010
SP 00000
Coded Answer 0010100111000001001110110111000100001000010000011011001
GHOSTSGHOST 0011101000011111001110100100110011101000011111001110100
0010100111000001001110110111000100001000010000011011001
 0011101000011111001110100100110011101000011111001110100
_________________________________________________________________________
_
0001001111011110000000010011110111100000001111010101101
00010|01111|01111|00000|00010|01111|01111|00000|00111|10101|01101
|
|
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|
|
|
|
|
|
|
G
U
B | O | O |
| B | O | O |
|
|
| M
Background: remove before presentation
Chewing this or any other (preferably sugar-free) gum
immediately after eating can be a significant aid to
digestion.
Caution: Don’t try this at school!
90
Kids DES (Data Encryption Standard)
Congratulations!
You have just done Kids DES.
The practical version uses “rounds,” “shifting,” and “swapping.”
The current version of DES, called AES, is being used worldwide.
Background: remove before presentation
In 1977 the U.S. introduced the Data Encryption Standard, DES. It became the most widely
used cryptosystem in the world. DES was initially developed by IBM, as a modification of an
earlier system known as Lucifer. In DES, the plaintext is written in the form of binary numbers
and divided into blocks of 64 bits. Each block undergoes a complicated procedure.
Sender and receiver receive a key—a block of 56 bits. From this the DES procedure produces
16 partial keys of length 48 bits each. The method method combines a block of 32 bits with one
of the partial keys (above), so that a new block of 32 bits is created. This is the preparatory
stage. Next, 16 consecutive steps follow of exchanging right and left blocks and linking with on
the partial keys of 48 bits, and finally the two halves (now shuffled and combined with partial
keys) are reunited into a block of 64 bits. Only with a knowledge of the key can the decoder
retrace the individual steps and thus arrive at the original block Etc. There are more
sophisticated modes of encryption that provide additional security.
In 2002 DES was replaced by Advanced Encryption Standard (AES) as the National Security
Agency's official "secure encryption" algorithm. The AES ciphers have been analyzed
extensively and are now used worldwide. The AES cipher is specified as a number of repetitions
of transformation “rounds” that convert the input plaintext into the final output of ciphertext. Each
round consists of several processing steps, including one that depends on the encryption key. A
set of reverse rounds are applied to transform ciphertext back into the original plaintext using
the same encryption key. AES has 10 rounds of processing for 128-bit keys, 12 for 192-bit keys,
and 14 for 256-bit keys. By 2006, the best known attacks were on 7 rounds for 128-bit keys, 8
92
for 192-bit keys, and 9 for 256-bit keys.
Background: remove before presentation
The first major symmetric algorithm developed for computers in the United States was the Data
Encryption Standard (DES), approved for use in the 1970s. The DES uses a 56-bit key. Even
though the description of DES is quite lengthy, it has been implemented very efficiently, both in
hardware or in software. The only arithmetic operations to be performed are exclusive-ors of
bitstrings. The other operations can all be done by table look-up (in software) or by hard-wiring
them into a circuit.
DES (AES) is used in banking transactions using standards developed by the American
Bankers Association.
DES (AES) is used to encrypt personal identification numbers (PINs) and account transactions
carried out by automatic teller machines (ATMs).
DES (AES) is used by the Clearing House Interbank Payments System (CHIPS to authenticate
transactions involving trillions of $ per week.
DES (AES) is also used in DOE, DOJ, and the Federal Reserve System.
Because computers have become increasingly faster since the '70s, security experts no longer
consider DES secure -- although a 56-bit key offers more than 70 quadrillion possible
combinations (70,000,000,000,000,000), an attack of brute force (simply trying every possible
combination in order to find the right key) could easily decipher encrypted data in a short while.
DES has since been replaced by the Advanced Encryption Standard (AES), which uses 128-,
192- or 256-bit keys. Most people believe that AES will be a sufficient encryption standard for a
long time coming: A 128-bit key, for instance, can have more than
300,000,000,000,000,000,000,000,000,000,000,000 key combinations [source: CES
Communications].
93
Summary: Coding Techniques We Used
AEWxOEYTRxGDNxE?
Decoded Riddle:
ARExWExDONExYET?
Coded Answer (DIAMONBCKS):
DPGJRT
Coded Answer (Shift Code):
GRSUYZ
Coded Riddle (rectangular):
1.
2.
3.
4.
5.
6.
7.
8.
Rectangular
ARExWExDONExYET?
Scytale
Answer (in Invisible Ink)
Caesar Shift
Keyword
Punctuation
Vigenère/Beaufort
Decimal Worms
Binary Worms
Background: remove before presentation
Invisible Ink
Text written on paper with a pen with lemon juice as its ink (or a
variety of other commonly available substances) “disappears.” The
text can be made to reappear by heating the paper.
General George Washington and others used invisible ink and codes
to communicate vital information in hand-written letters. Instead of
using lemon ink and heat, they would do the writing with a chemical
that would disappear, which they called the agent. And then when
they were ready to read it, they’d use a completely different chemical,
which they called the reagent.
Simple, right? Agent and reagent. As long as the they kept the
second chemical away from the enemy, the enemy can never figure
out what was written.
They would also put their messages the first few pages of common
books, sometimes between the lines of text. That’s where we get the
phrase “Read between the lines.” They use books because they
believed that no one would search for messages there, and because
they needed good-quality paper for the chemicals of the invisible ink
to work best.
Background: remove before presentation
Invisible Ink
Product Description
Read and write secret messages, anywhere…in light or
darkness. Includes invisible ink and a hidden UV light
that you can position at any angle…all built inside.
Ages 8+.
Spy Net
Invisible Ink Pen
$8.94 @
Amazon.com
This Spy Net invisible ink pen is what you need to read
and write secret messages. It has a LED light to read
in the dark!
Read and write secret messages
Create secret messages no one else can read
Built-in LED light allows you to read in the dark
Requires 3 AG13 batteries
Background: remove before presentation
The Culper Ring
The “Culper” Ring was a civilian spy ring set up by General George Washington at
the height of the American Revolutionary War, to send messages to General
Washington about the activities of the British in New York. The general public was
not aware of the Ring's existence until the 1930s. It was the pre-cursor of
intelligence services such as the CIA.
Secrecy was so strict that Washington did not know the identity of all the operatives.
Members were given code names. For example, Washington's code was 711. (No
one used their real name. To relay messages they used coded messages published
in newspapers, and invisible ink to write between the lines of what appeared to be a
typical letter. The invisible ink methods are still in use by the CIA today.
General Benedict Arnold, who became disgruntled with the American cause after he
had not been paid for 7 years, devised a plot to sell West Point to the British for
20,000 pounds. His plot was discovered by the Culper Ring and relayed
Washington, but Arnold also caught word that his plot had been discovered and he
fled down the Hudson River to the British. He attempted to round up the members of
the Culper Ring but only succeeded in being captured by some of them.
Women were also an integral part of the Culper Ring. At this time in history, women
were expected to share their husbands beliefs and not to be directly and openly
involved in politics. For this reason, they would not be suspected of being spies.
Bad Use Of Coding—Why?
RIDDLE: How did the plumber feel after
working all day to fix the sink?
Coded Answer:
EIRADDN
Decoded Answer:
DRAINED
Background: remove before presentation
Useful Websites:
www.wolframalpha.com (calculations such as 8979mod 3337 = 858)
www.navajocodetalkers.org (Navajo Code Talkers)
www.braingle.com/brainteasers/codes/caesar.php (Caesar Cipher)
web.mit.edu/network/pgp.html (Pretty Good Privacy)
www.tropsoft.com/strongenc/des.htm (DES information)
www.bletchleypark.org.uk (British WWII codebreakers and Enigma)
www.topsecretrosies.com/Top_Secret_Rosies/Home.html (USA
women codebreakers)
8. www.softschools.com/testresults.do?id=392
9. www.simonsingh.net/Navajo_Code.html (Navajo Code Talkers AND
code-making/code-breaking software for our codes)
10. www.braingle.com/brainteasers/codes/caesar.php (coding/decoding
software)
1.
2.
3.
4.
5.
6.
7.
Background: remove before presentation
Reading List
1. Code Breakers: From Hieroglyphs to Hackers; Simon Adams, DK Publishing,
2002.
2. Code Breaking: A History And Exploration; Rudolf Kippenhahn, Overlook Press,
1999.
3. Mysterious Messages: A History of Codes and Ciphers; Gary L. Blackwood,
Dutton Children’s Books, 2009.
4. The Code Book by Simon Singh; Doubleday, 1999.
5. Secret Code Breaker: A Cryptanalyst’s Handbook by Robert Reynard; Smith
and Daniel Marketing, 1996. Also: Secret Code Breaker II, and Secret Code
Breaker III.
6. Cryptography: Theory And Practice by Douglas R. Stinson; CRC Press, 1995.
7. Crypto: How The Code Rebels Beat The Government—Saving Privacy In The
Digital Age; Steven Levy, Viking Penguin, 2001.
8. Codes, Ciphers, And Secret Writing; Martin Gardner; Dover, 1984.
9. The Codebreakers: The Story of Secret Writing; David Kahn, Scribner, 1996.