CAESAR CIPHER Lesson 1 Caesar Cipher Named after

CAESAR CIPHER

Lesson 1 Caesar Cipher • Named after Julius Caesar who used this method to send messages to his military • It involves shifting the letters of the alphabet along by a certain number of places. • The Key tells us how many places it has been shifted, if the key is 3 then we move all the letters 3 places to the right • So the letter A becomes D and so on

Lesson 1 So if we receive a message of PDWKV LV WKH EHVW and the key is 3 It translates to ‘maths is the best’ (which is true)

Lesson 1 The Caesar Cipher wheel This can be used to decode a message easily Optional, if you cannot print don’t worry. You are going to make your own. You will need: • The template • Scissors • Some twine or split pin

Lesson 2 Decipher these codes…. . • BMT ITJX FQJC FHHNIJSYFQQD XMTTY? (key 5) • UHTL AOL IHUR AOHA HSLEZ BUJSL DVYRLK MVY (key 7) • HSLE HLD XC RCTYD ACPGTZFD UZM? (key 11) If you finish write your own Stormbreaker themed secret message!

Lesson 2 Answers…. . • BMT ITJX FQJC FHHNIJSYFQQD XMTTY? (key 5) Who does Alex accidentally shoot? (the prime minister) • UHTL AOL IHUR AOHA HSLEZ BUJSL DVYRLK MVY (key 7) Name the bank that Alexs uncle worked for (The Royal and General) • HSLE HLD XC RCTYD ACPGTZFD UZM? (key 11) What was Mr Grins previous job? (worked as a knife catcher in the circus)

Lesson 3 Transposition Ciphers • These ciphers are much harder to crack than Caesar ciphers • A transposition means that the letters of the code are rearranged into a different order

Lesson 3 Transposition Ciphers • For example, ICBKAOREMDERAEAA, can be rearranged into rows of length 4 to give: • The message is then read from down the columns – I am a codebreaker.

Lesson 3 Lets do this one together • TIOICCBKTHSRFUORIEIAEFLDENSSMDITEAGT ( make 4 rows of length 9)

Lesson 3 Lets do this one together • TIOICCBKTHSRFUORIEIAEFLDENSSMDITEAGT ( make 4 rows of length 9) T I O I C C B K T H S R F U O R I E I A E F L D E N S S M D I T E A G T

Lesson 3 Your turn! • Weaggxhthrsoiaekaesrvsditaeoetolisnvsoelsogiawshtnrclhnihyeheyom (make 8 rows of 8) • WSETUDDEHYHTRHLHSWEOOHSALEAHWUWEOTIRYEANAPNBEOLNSG (make 10 rows of 5)

Lesson 3 Answers • Weaggxhthrsoiaekaesrvsditaeoetolisnvsoelsogiawshtnrclhnihyeheyom (make 8 rows of 8) W H A T I S T H • E R E A S O N Y A S S E N G R E G O R O V I C H G I V E S A L E X A S T O W H Y H E D O E S N O T K I L L H I M What is the reason Yassen Gregorovich gives Alex as to why he does not kill him?

Lesson 3 Answers • WSETUDDEHYHTRHLHSWEOOHSALEAHWUWEOTIRYEANAPNBEOLNSG (make 10 rows of 5) W H O W A S T H E P E R S O N T H A T B U L L I E D H E R O D S A Y L E W H E N H E W A S Who was the person that bullied Herod Sayle when he was young? Y O U N G

Lesson 4 Tips on how to write your own • Think of a sentence and take out all of the spaces and punctuation • Count how many letters you have • You need to fit your message into a rectangular grid • What if the number of letters is a prime number? • What would be a good number of letters? Have a go!