1.3.1

Question 1

What is compression?

Answer 1

Reducing the size of a file, usually to speed up transmission

Question 2

What is lossy compression?

Answer 2

Some data is lost when compressing the file

Question 3

What is lossless compression?

Answer 3

No data is lost when compressing the file

Question 4

What are the two types of lossless compression?

Answer 4

• run length encoding
• dictionary encoding

Question 5

What is encryption?

Answer 5

When data is scrambled to keep it secure during transmission

Question 6

What is symmetric encryption?

Answer 6

This is where the same key is used for encrypting and decrypting the file

Question 7

What is asymmetric encryption?

Answer 7

This is where a public key is used to encrypt files and a private key is used to decrypt

Question 8

What is hashing?

Answer 8

The act of turning an input (key) into a fixed size output (hash)

Question 9

What is a collision?

Answer 9

When two inputs are hashed to the same value

Question 10

What are the characteristics of a good hash function?

Answer 10

• low chance of collisions
• hash smaller than key
• quick to calculate