1.3.1. Compression, Encryption and Hashing: Exchanging Data: Computer Science A-Level OCR

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

Key Pair

Name the two categories of compression.

Lossy and lossless.

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

Lossless

What is the purpose of encryption?

To keep data secure during transmission.

Name one type of lossless compression.

One from:

● Run length encoding.

● Dictionary encoding.

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

Symmetric Encryption

How many keys are used in asymmetric encryption?

Two (one public and one private).

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

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.

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

A collision.

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

Run length encoding.

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

Hashing

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

Hash Table

What is meant by compression?

The process of reducing the space required to store a file.

Name two properties that a hashing algorithm should have.

Two from:

● Low chance of collision.

● Quick to calculate.

● Output smaller than input.