Encryption (CIE IGCSE Computer Science)

Elsa writes a paragraph in an examination about encryption.

There are several terms missing from the paragraph.

Complete the paragraph using the list of given terms. Not all terms may need to be used.

Some terms may be used more than once.

• algorithm
• alphanumeric
• cookie
• cypher
• key
• padlock
• plain
• word processed

The data is encrypted using a .......................................... This is an ....................................... that is used to scramble the data. The data before encryption is known as ........................................ text. When the data has been encrypted it is known as ......................... text. To read the encrypted data it needs to be decrypted using a .................................... .

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In a simple symmetric encryption system, each letter of the alphabet is substituted with another.

The plain text message:

The quick brown fox jumps over the lazy dog.

becomes the cypher text message:

Zag towvs jumpy dmh coilr mngu zag bfke qmx.

a)

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