Cryptography 101

The vocabulary of codes

Anagram – letters of a word rearranged to say something else

bilateral – a code containing just 2 symbols

Cipher – a code in which each letter or number is represented by another letter or number

Code – the general term for any system that changes a message to make it harder or easier to understand

Cryptography – the art of writing coded messages

encryption – the act of concealing something by turning it into code

hieroglyphics – coded picture writing

key – the solution that allows you to decipher a coded message

Plaintext – the original message

3 simple codes to warm you up!

1: Reverse Codes

Full reverse

DEHCTAW GNIEB SI ESUOH EHT EDISNI YATS

Individual words

YATS EDISNI EHT ESUOH SI GNIEB DEHCTAW

Letter pairs

TSYA NIISED HTH EUOES SI EBNIW GTAHCDE

WEOL RDKD FIR MOEMHTT HO ET OEUDTIS

WORK FROM THE OUTSIDE TO THE MIDDLE

2: Number Codes

A – 1, B – 2 , C – 3 etc

JOT = 10 / 15 / 20

20 8 5 / 19 5 3 18 5 20 / 6 9 12 5 19 /

1 18 5 / 9 14 / 20 8 5 / 19 1 6 5

THE SECRET FILES ARE IN THE SAFE

3: Vowel Codes

A E I O U

YUAR SICRIT PERCIL WOLL ERROVI UN MUNDEY MURNONG

YOUR SECRET PARCEL WILL ARRIVE ON MONDAY MORNING

Simple COMBINATION Codes

Reverse codesNumber codesVowel codes

UNWRCOSHHCUUL

UNWRCOSHHCUUL

Hint – 2 stage process using pair reversal and vowels

ON WR CI SH HC OO L

NO RW IC HS CH OO L

UN WR CO SH HC UU L

The code breaker’s challenge

There are 9 parts to the code maker’s challenge – each step will give you part of a master key which you will need to crack the

final code...and win a prize!

The code breaker’s challengePart 1

A mysterious letter has arrived on your doormat. It has an Egyptian postmark, and very neat, old-fashioned handwriting on the

envelope. Inside is a single thin piece of paper, and written on it is a coded message:

W R O T I U A T T H I E L P H E B I T

Greek Codes

The Spartan Scytale

Aeneas’ light hole code

Polybius grid code

1 2 3 4 51 A B C D E2 F G H I / J K3 L M N O P4 Q R S T U5 V W X Y Z

A = 11, B = 12, S = 43, Y = 54

54 34 45 42 / 13 34 51 15 42 / 24 43 / 12 31 34 52 33 / 42 15 44 45 42 33 / 44 34 /

12 11 43 15 / 11 44 / 34 33 13 15

Y O U R / C O V E R / I S / B L O W N / R E T U R N / T O /B A S E / A T / O N C E

The code breaker’s challengePart 2

After playing with your computer for several hours, you feel it’s time to take a break. You go

to get a drink – but when you return, you realise instantly that someone has used the

machine while you were away. A strange sequence of numbers has been typed out

across the screen, and written beneath is the following message – ‘you’ve been flamed’

1424512414154423151131352311121544

243344343511244243113314

213124351511132335112442

114234453314

Caesar’s code

Letter shift version (3)

KHOOR IHOORZ FRGH EUHDNHUV

A B C D E F G

A B C D E F G

Keyword version

A B C D E F G H I J

F I S H E R A B C D

K L M N O P Q R S T

G J K L M N O P Q T

U V W X Y Z

U V W X Y Z

C FK F TEFSBEP WCTB F QBCLY BEFH !

Keyword protection

The Freemasons’ code

The code breaker’s challengePart 3

Your computer lets you know that someone has sent you an email. The address f the

sender seems to be somewhere in Egypt. The message reads as follows:

YPLQQ / LAA / SDO / HOSSOPQ / CJ / SDO / JOWS / SDPOO / YLBOEPOKGOPQ /

YDKHHOJRO / KJQVOPQ

Written below this are what appear to be six random words:

ComputerSoftwareTerminalKeyboard

HackerMouse

Renaissance Codes

Bacon’s Bilateral codea AAAAA g AABBA n ABBAA t BAABAb AAAAB h AABBB o ABBAB u-v BAABBc AAABA I-j ABAAA p ABBBA w BABAAd AAABB k ABAAB q ABBBB x BABABe AABAA l ABABA r BAAAA y BABBAf AABAB m ABABB s BAAAB z BABBB

Every ‘marked letter’ represents ‘B’Every ‘unmarked’ letter represents ‘A’

Marking can include – underlining, italics, size differences, capitalisation, pin pricking, invisible ink

How wonderful it was to see you last weekend. I hope you enjoyed our day in London as much as I did.

How wonderful it was to see you last weekend. I hope you enjoyed our day in London as much as I did.

How wonderful it was to see you last weekend. I hope you enjoyed our day in London as much as I did.

Babba abbab baabb aaaaa baaaa aabaa abaaa

Abbaa aaabb aaaaa abbaa aabba aabaa baaa aaaaa

You are in danger

The Vigenere tableau

1) Choose a keyword : MANCHESTER

2) Above your message write out the keyword repeatedly

m a n c h e s t e r m a

s e n d s u p p l i e s

3) Using the plaintext on the ‘x’ axis of the tableau and the keyword letters on the ‘y’ axis, compose the coded message

(without the keyword, this is almost unbreakable)

SEND

MANCHESTER

m a n c h e s t e r m a

s e n d s u p p l i e s

E E A

EEAF WLBPYKLW

To decipher, you simply reverse the rules by writing the keyword repeatedly above the coded message

Then take the first letter of the keyword on the ‘x’ axis and follow the tableau down until it meets the code letter

Read across to the ‘y’ axis to identify the original plaintext

m a n c h e s t e r m a

e e a f w l b p y k l w

S E

Keyword = SOAP

TFODCSKANGOKH

KHRTWHFSIVZPOJJG

UCRDFOTXGBSBD

KWDTZCLAQZCMT

Use the Vigenere tableau to crack these 10 words – when considered together you will be able to identify 5 popular TV soap operas

Modern Cryptology

Frequency tables

E T A O N R I S H D L G C M U F Y P W B V K X J Q Z

Single letter words - I or A in English

Double letters tend to be – B D E F G L M N O P R S T

Look out for short words from which you can make educated guesses

Combine deduction, common sense, patience and guess work!

Above all else – keep your key up to date

The code breaker’s challengePart 4

Someone has tucked 4 coded messages inside your bag when you were not looking. The first

3 are written using different codes. The 4th uses the same code as one of the first 3 and

contains the answer you need for this part of the challenge.

CODE 1:

P OMUPNQMU GPK AN SATTUH AHNATU OSU JPD

OMUU HUPM OSU WUNOUMH WPFF JR OSU RAUFT

Clues: O = T, A = I, G = M, N = S

- -------- --- -- ------ ------ --- --- ----

---- --- ------- ---- -- --- -----

CODE 2:

TDMRM FS C SMNRMT PCSSCBM IMTWMML TDM SKUBBJMRS NCVM CLE

TDM OJE DOUSM

Clues: The letters from P-Z have not changed

----- -- - ------ ------- -------

--- --------- ---- --- --- --- -----

CODE 3:

JSST JS DK TCS QNNJ ISCDKM TCS RSLQST MNNQ DK TCS INNGLFRS FKM JFGS RUQS

KNINMY RSSR YNU

Clues: F = A, Q = R

---- -- -- --- ---- ------ --- ------ ---- -- ---

-------- --- ---- ---- ------ ---- ---

CODE 4:

TDM WORE YOU LMME TO WRFTM EOWLCS TDM CLSWMR DMRM FS DOT

Clues: E = D

--- ---- --- ---- -- ----- ---- -- --- ------

---- -- ---

The code breaker’s challengePart 5

You receive a message at school, telling you to go to the OMR. When you get there you find the following message scrawled on the wall…

Sir ArthUR ConAn doyLe WaS the CreatOr of The wOrlD’s GreaTesT deTeCtiVe shErlOck holMEs. ConAn DOylE was BORn iN edInBurgH, AnD Although HE studied medIcINe, hE SOoN turned To WriTInG. Sherlock hoLMEs fiRST ApPEaRed In thE Novel a sTudy In sCarlet, WhiCH wAs NArrateD By HiS friEnd Dr jOhN h. wAtsoN. thE detecTIvE soon BEcaMe famous fOr hIs BrilLIaNT skills oF DeDUCtIon, AS WeLL AS fOR HiS fIery Character. His arch-ENEmy Was tHE EviL professor MORiArty. Holmes waS So PoPulaR that eVeN afTer hE seemed to FAlL to HiS DeaTh during a FigHt AbovE A wATerfall, cONan dOylE was fORCed tO BRInG hiM back AfTeR A hUgE PuBlIC oUTcRy.

Crossword Codes

1) Both sender and receiver must have the same blank crossword.

2) The message is written from left to right in the blank squares.

3) The code is then achieved by copying out the text again, but this time working vertically.

4) To decipher the message it must be written into the blank grid vertically but read off horizontally.

T H I S M E T

H O D O F

C R E A T I N G A C

O D E I S

S I M P L

E B U T V E R

Y E F F E

C T I V E

This method of creating a code is simple but very effective

HCOEY TRSC HOEDBET AI IDTUFV SIEME MNT EOGIPVF TAE FCSLRE

The code breaker’s challengePart 6

A strange looking card arrived in the post this morning – addressed to you, with an Egyptian

stamp on it. On one side, it has the code: 20 / 9 / 13 / 5 / 19

On the other side it says:

LNTSWTES CSNE OAFTFHGAR NIIEI GTONCS RGHENF ATAAL TIRHTLTSY UGHX OEIRHLIW

Examining the postcard more closely you find a clue written underneath the stamp: the word

‘newspaper’.

The following grids appeared in national newspapers on the day the card was posted. Fill the correct grid vertically to read off a horizontal

message – the answer is a kind of insect.

Daily Telegraph

The Times

Daily Mirror

Daily Express

Typewriter codes & the history of QWERTY

One to the leftOne to the right

One aboveOne below

Alternate between one or more of these variations with key

QGLR AIYBS SIWA L NIBJWT VINV NLJW QGWB UR WZOKISWA?

HWHMMMMK !

The code breaker’s challengePart 7

You are taking your laptop out of the cupboard to work on some homework for school, when you notice a sheet of paper taped to the underside.

The printed message reads:

DVLWW LRR BYC OQWB WCFCH OCBBCVW

Sherlock Holmes & the dancing men

The code breaker’s challengePart 8

You are visiting a museum at 221B Baker street on a school trip, when you stumble across an old piece of paper. It looks like a coded letter made

up of odd looking stick men.

Clues: How do letters usually start?Who is the letter to and from?

At school the next day, you are browsing through the library when you come across a folded piece of paper with your name on it, sticking out of an

anthology of detective fiction.

Upon opening it, you discover another set of dancing men – could this bring you one step

closer to cracking the master code?

Shopping list codes

The code breaker’s challengePart 9

This morning you found a list scrawled on the back of one of your exercise books. None of your

friends or family has owned up – is this list of purchases as innocent as it looks>

Clues: The code is hiding a 7 letter word.

Newspaper’s bill £5Dry cleaning £8Take away pizza £7Light bulbs £3Fridge magnet £2Car-park token £2Cinema ticket £5

The final code breaker’s challenge!

QR codes

Augmented reality

The Vaudeville telepathy act

The GReY code

Pick a card...any card