Encryption and Compression

Question 1

What is compression?

Answer 1

The act of making file size smaller

Question 2

How many types of compression are there?

Answer 2

2

Question 3

Define the two types of compression

Answer 3

LOSSLESS
No data is lost in compression and original can be recreated exactly
LOSSY
Data deemed non-essential is deleted. An exact replica can not be recovered
Lossy can be compressed to much smaller than lossless compression

Question 4

What is Run Length Encoding (RLE)

Answer 4

Search for patterns in code that can shortened.
1111122255311111 - 16 bits of data
1, 3 2, 2 5, 1 3, 5 1 - 10 bits of data

Question 5

Define encryption

Answer 5

ENCRYPTION is the conversion of data into a form that is difficult to read by an unauthorised third party.

Question 6

Define decryption

Answer 6

DECRYPTION is the process of turning scrambled data into data that can be understood.

Question 7

Define cipher

Answer 7

CIPHER - The algorithm for encryption

Question 8

Define key

Answer 8

KEY - The secret information used to encrypt/decrypt the data

Question 9

Define plaintext

Answer 9

PLAINTEXT - The original form of the data CIPHERTEXT - The encrypted data

Question 10

What is the Vernam cipher

Answer 10

Uses Baudot Code and the XOR bitwise operator

Uses a one-time pad key (randomly generated and changes after 1 use)

Question 11

What is computational security?

Answer 11

A cipher that is computationally secure is theoretically breakable but not when using current technology in a timeframe that would be useful.