1.3.1 Compression, Encryption & Hashing

Question 1

What name is given to the public and private keys used in asymmetric encryption?

Answer 1

Key Pair

Question 2

Name the two categories of compression:

Answer 2

Lossy and Lossless

Question 3

In which type of compression is the quality of a file not degraded?

Answer 3

Lossless

Question 4

What is the purpose of encryption?

Answer 4

To keep data secure during transmission

Question 5

Name one type of lossless compression:

Answer 5

Either:

Run length encoding
Dictionary encoding

Question 6

In which form of encryption do the sender and receiver share the same private key?

Answer 6

Symmetric encryption

Question 7

How many keys are used in asymmetric encryption?

Answer 7

Two (one public and one private key)

Question 8

If person A wants to send a message to person B using asymmetric encryption, which key should they use to encrypt the message?

A: A’s public key
B: A’s private key
C: B’s public key
D: B’s private key

Answer 8

C: B’s public key

A message encrypted with B’s public key can only be decrypted with B’s private key, which only B has access to

Question 9

What is said to have occurred when two keys map to the same hash?

Answer 9

A collision

Question 10

In which kind of lossless compression are repeated characters replaced by one occurs fr and the number of times to repeat the character?

Answer 10

Run length encoding

Question 11

What name is given to the process of turning an input into a fixed size value?

Answer 11

Hashing

Question 12

Which data structure uses hashing to store information with constant lookup time?

Answer 12

Hash Table

Question 13

What is meant by compression?

Answer 13

The process of reducing the space required to store a file

Question 14

Name two properties that a hashing algorithm should have:

Answer 14

Two from:

• Low chance of collision
• Quick to calculate
• Output smaller than input