Encryption and Compression Flashcards Preview

1 Computing AS Level (JoshH) > Encryption and Compression > Flashcards

Flashcards in Encryption and Compression Deck (11)
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1

What is compression?

The act of making file size smaller

2

How many types of compression are there?

2

3

Define the two types of compression

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

4

What is Run Length Encoding (RLE)

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

5

Define encryption

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

6

Define decryption

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

7

Define cipher

CIPHER - The algorithm for encryption

8

Define key

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

9

Define plaintext

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

10

What is the Vernam cipher

Uses Baudot Code and the XOR bitwise operator
Uses a one-time pad key (randomly generated and changes after 1 use)

11

What is computational security?

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