1.3.1 Compression, Encryption And Hashing

Question 1

Lossy compression

Answer 1

Removes non essential information. E.g reducing pixels in a image

Question 2

Lossless compression

Answer 2

Reduces file size but retains all data by recording patterns in data

Question 3

Length encoding

Answer 3

Looks for blocks of repeated data

Question 4

Dictionary coding

Answer 4

Using short code words to represent longer pieces of data

Question 5

Symmetric encryption

Answer 5

Uses a secret key to encrypt and decrypt data

Question 6

Asymmetric encryption

Answer 6

Uses two separate but related keys. A public and private key.

The public key is used to encrypt data sent to you and the private key, that only you know, is used to decrypt the data

Question 7

Hashing

Answer 7

A technique that allows you to ‘map’ data of variable length into a fixed length data value (a large number)