Online Security
Caesar Ciphers
Substitution Ciphers
100

What is the purpose of the public key?

Turns the customer's data (plain text) into encrypted data (cipher text)

100

What does the key mean in a Caesar Cipher?

How many spaces the alphabet has shifted.

100

How are Substitution Ciphers different from Caesar Ciphers?

Substitution Ciphers use a keyword as the beginning of the cipher alphabet, with the rest of the alphabet following either forwards or backwards. For example:

ABCDEFGHIJKLMNOPQRSTUVWXYZ

ZEBRACDFGHIJKLMNOPQSTUVWXY


200

What is the purpose of the Private Key

Turns the encrypted data (cipher text) into plain text.

200

What does a shift of K mean in a Caesar Cipher?

The Caesar Cipher starts with A becoming K

200

What would be the first letter in the cipher alphabet after the keyword "Alphabet"?

C

300

Name both ways a customer can tell they are on a secure website

HTTPS in the address, and a padlock symbol in the corner.

300

Using a shift of 2 to the right, decrypt this code:

Fq pqv hqtigv rgpeknu pgzv yggm

Do not forget pencils next week

300

Why are substitution Ciphers harder to crack than Caesar Ciphers?

The alphabet is not always in order, so unlike Caesar Ciphers, if you know one letter, you won't always know the rest.

400

What is the name of the set of protocols that allows the customer's browser to talk to the shop?

Secure Socket Layer (SSL)

400

Using a shift of K, decrypt this message:

Wb Qkexd myevn lokd Tkcyx kd Dklvo Doxxsc

Mr Gaunt could beat Jason at Table Tennis

400

What is Frequency Analysis? What is the most common and least common letters in the english Alphabet?

Frequency analysis is the study of the distribution of the letters in a text.

Most Common letter: E

Least Common Letter: Z

500
Should we be worried about hackers when we shop online? Why or why not?

We should be worried in general, but our data is so secure when shopping online that we shouldn't be worried about our data being stolen.

500

Using Frequency Analysis, Decode this message:

P dpzo dl jvbsk kv aopz lclyf slzzvu

I wish we could do this every lesson

500

With the keyword Zebra, and the alphabet carrying on forwards, decode this text:

Sfa qtl pgqaq gl sfa azqs

The sun rises in the east