Codes and Ciphers Reading Comprehension.pdf

Detective quizzes

1. Mysterious Messages:
The Secret World of
Codes and Ciphers
For thousands of years, people have been
trading secrets, both personal and political.
And one of the best ways to ensure a secret
stays secret, is to put it into a code or cipher.
That way, only the recipient of the message
can unlock it – or at least, that’s the theory!
But what’s the difference between a code
and a cipher? In common parlance, not a lot.
Most of us use the terms interchangeably. But
if you’re a cryptologist (a person who studies
cryptography – the science of codes and
ciphers), then you might be a little more picky
about the terms you use. To cryptologists, a
code substitutes letters, numbers or symbols
for the meaning of the message. A cipher
uses a process, known as an algorithm, to
transform a message into something else.
Knowing the key to the cipher is important
when trying to solve it.
Substitution Ciphers
A substitution cipher is probably the simplest
type of cipher to create. Here, letters are
substituted for something else. One of the most
famous examples is the Caesar Shift Cipher,
named after Julius Caesar, who used it for
secret communications. It was said to involve
shifting each letter of the alphabet three places
to the right (so, A becomes D, B becomes E,
etc). Of course, this can be varied by changing
the number of places or the direction that the
letters shift so with this cipher, the key is the
number of spaces the alphabet is moved.
Caesar Shift Cipher
Give it a go:
can you solve this message,
where the key is four?
XLMW MW E GEIWEV WLMJX GMTLIV
1

2. Another example of a substitution cipher is the
Dancing Men, which was created by Arthur
Conan Doyle for his Sherlock Holmes story,
The Adventure of the Dancing Men, in 1903. He
drew a series of stick men in different poses,
with each pose representing a letter. If the stick
man was holding a flag, that meant the end of
the word was reached. Because Conan Doyle
didn’t use all the letters of the alphabet in his
message, some letters have no known symbols.
The key to this cipher is simply the sheet which
shows the equivalent letters for each stick man.
A popular cipher that’s easy to decode is the
Pigpen Cipher. Of course, because it’s popular
and easy, it’s not often entrusted with serious
communications! It’s thought to be many
centuries old, and was even used during the
Crusades. The cipher uses a series of grids and
dots to create representations for letters.
Here’s an example of a key – although you can
easily create your own:Dancing Men Cipher
Give it a go:
Pigpen Cipher
Give it a go:
ABC
DEF
GHI
JKL
MNO
PQR
S W
T XU Y
V Z
A B C D E G
H I L M N O
P R S T V Y
2

3. Transposition Ciphers
Unlike substitution ciphers, transposition ciphers use a key to scramble up the letters of a
message. There are many different ways of doing this, but a popular form of this cipher is the
Rail Fence Cipher. Here, the message is written diagonally up and down lines (or ‘rail fences’).
The message is then read back following the horizontal lines. So, for example:
THIS IS A RAIL FENCE CIPHER is written diagonally across the ‘rails’:
To create the new, ciphered message, we then read across the rail fence horizontally:
TACHRIEIIALCPSSFNHRIEE
To solve the cipher, you need to count the
letters in your encrypted message. However
many letters you have, that’s the number of
columns you’ll need to draw in your blank rail
fence. It helps if you know how many rows the
encryptor has used (which is the cipher key),
but if you don’t know, then it’s a case of trial
and error to solve the message.
e.g. TACHRIEIIALCPSSFNHRIEE has 22 letters, so
we need 22 columns. If we try a key of just two
rows, we can quickly see that this isn’t right:
And so we keep trying with three, then four, then
five rows, when we get to the correct solution.
T.......A.......C.....
.H.....R.I.....E.I....
..I...A...L...C...P...
...S.S.....F.N.....H.R
... I.......E.......E.
T.......A.......C.....
.H.....R.I.....E.I....
..I...A...L...C...P...
...S.S.....F.N.....H.R
... I.......E.......E.
T A C H R I E I I A L
C P S S F N H R I E E
Rail Fence Cipher
Give it a go:
can you solve this message,
where the key is three?
WDELOELN
3

4. Fan Codes
Nowadays, when we’re feeling hot we can switch
on an electric fan or open one of our double-
glazed windows. But in days gone by, ladies
would cool themselves down with hand-held
fans. Made out of bone, cloth or paper, fans
were exquisite and must-have accessories. But
they weren’t only used as a primitive form of air
con: fans were also a useful tool in the subtle art
of flirting. In fact, from the 18th century onwards
there was a whole coded language, centred on
how a lady used her fan. In an era where women
were expected to be demure and well-behaved,
and certainly not forward enough to proposition
a man, fans were a way of communicating their
desires. Fan codes included:
Military Codes
The military has always used codes and ciphers
to transmit messages, to avoid them being
understood should they fall into enemy hands.
During the Second World War, many different
ciphers were used, but code words were
also popular. Often military operations were
referred to by code names. So, for example,
D-Day on June 6th 1944 was known as
Operation Overlord, while the beaches involved
were given code-names such as Omaha, Juno
and Sword.
Touching the handle of the fan to your lips: kiss me
Drawing the fan across your cheek: I love you
Twirling the hand in the left hand: I want you to go
Carrying the fan in the right hand, in front of the face: follow me
Drawing the fan through the hand: I hate you
Fan Codes
Have a go:
what is this woman saying?
4

5. Floriography
For many centuries, people have assigned
figurative meanings to flowers and plants.
Think of the Christian symbol of the dove
carrying an olive branch, signifying peace.
Or, in Shakespeare’s Hamlet, Ophelia listing
flowers and plants with their meanings: ‘There’s
rosemary, that’s for remembrance… And there
is pansies, that’s for thoughts…’
But it was in the Victorian era that floriography
- the language of flowers - became particularly
popular; books were published on the subject,
and people would send floral arrangements
as coded messages when they were unable to
speak their feelings aloud.
The codes of flowers could be complex and
varied: colour played a big part, with red usually
signifying love, yellow suggesting friendship,
and white implying innocence and chastity. The
type of plant or flower was also important, and
meanings included:
A great example of this code in action can be
seen in the Enola Holmes film, starring Millie
Bobby Brown, where the young protagonist
solves a series of clues encoded in flowers.
Floriography
Have a go:
what might this bouquet signify?
Aster patience
Rose love
Acacia friendship
Bluebell humility
Calla lily great beauty
Daffodil unrequited love
Forget-me-not true love
Hawthorn hope
Juniper protection
Marigold grief
Parsley useful knowledge
Yellow hyacinth jealousy
5

6. Mysterious Messages: The Secret World of Codes and Ciphers
- Answers
Caesar Shift Cipher: This is a Caesar Shift Cipher
Dancing Men Cipher: Solve me
Pigpen Cipher: It’s easy
Transposition cipher: Well done
Fan codes: Follow me
Floriography: I feel grief for my unrequited love