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- 1. Open Ended
Julius Caesar used a extremely simple substitution cipher to send messages to his troops. He substituted each letter by the letter that was 3 places further along in the alphabet, so that “a” was replaced with “D”, “b” with “E” and so on. This is a substitution cipher with a key of 3.
Using a key of 4, tell me what the encrypted letters are for these plain text letters (print out the Caesar Cipher tables attached to this lesson to help you decode and encode the messages.)
A, D, L , P, X and Z
- 2. Open Ended
In a Caesar Cipher each letter in the plain text is shifted from 1 (Plain text A = Cipher B) to 25 (Plain text A = Cipher Z) places in the Cipher text.
To encrypt, shift each letter up the alphabet according to the key.
To decrypt, just shift each letter down the alphabet according to the key.
a. With a key of 10, plain text A would be encrypted to what encrypted letter?
b. With a key of 7, encrypted letter x becomes what plain text letter?
- 3. Open Ended
Computer scientists would call 3 the “key” for this cipher. How many different keys are possible in the English alphabet?
- 4. Multiple Choice
Convert "GJGB" cipher-text back into plain text using the key: 1
FIFA
DUKE
YALE
BAMA
- 5. Multiple Choice
Convert "VOOVXF" cipher-text back into plain text using the key: 20
ATTACK
ANIMAL
CHARGE
GIVEUP
- 6. Open Ended
Encrypt the plain text word 'COVID" with a key of 7.
- 7. Multiple Choice
Convert "OQQC" cipher-text back into plain text using the key: 10
DATE
MILK
EGGS
HAMS
- 8. Multiple Choice
Bletchley Park is a 19th-century mansion and estate in Buckinghamshire, England that became the principal centre of Allied code-breaking during the Second World War.
During World War II, the estate housed the British Government Code and Cypher School (GC&CS), which regularly penetrated the secret communications of the Axis Powers--most importantly the German Enigma and Lorenz ciphers.
According to the official historian of British Intelligence, the "Ultra" intelligence produced at Bletchley shortened the war by two to four years, and without it the outcome of the war would have been uncertain.
Which of the four answers below is the corrcetly encrypted text for Bletchly Park?
Rbujsxbuo Fqhb
Rhujsxbuo Fqha
Rbujsxbuo Fqha
Rrujsxbuo Fqha
- 9. Multiple Choice
"Manchester City FC" is plain text and the cipher text is: "Bpcrwthitg Rxin UR" - What would the encryption key be?
15
10
12
4
- 10. Open Ended
Using the Caesar Cipher, encode the name of your school with a Key = 3
- 11. Open Ended
Decode this message, which was encoded using the Caesar cipher from the table above:
- 12. Open Ended
Encrypt "keep this secret"with a shift of 3.
- 13. Open Ended
Encrypt your teacher's name with a shift of 5.
- 14. Open Ended
Decrypt the answers to the following riddle. They were encrypted using a Caesar cipher with a shift of 3.
- 15. Open Ended
What's the difference between a teacher and a train? decipher the message.
- 16. Open Ended
Decrypt the following note Evie wrote to Abby. She used a Caesar Cipher with a shift of 4, 6 or 8.
- 17. Open Ended
Encrypt your school’s name using a Caesar Cipher with a shift of 8.
- 18. Open Ended
Encrypt “private information” using a Caesar Cipher with a
shift of 5.
- 19. Open Ended
Decipher this message from Gravity Falls using a Caesar Cipher. You need to figure out the key.
You may need the Cryptography Reference Sheet to complete this assignment. The Royal Order video will also help. This coded message is also printed out in the reference sheet and you may want to work on it there and then write your answer in Quizizz.
- Answer choicesTagsAnswer choicesTags