4.1 Compression and Encryption Flashcards

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1
Q

Benefits of reducing the amount of data (compression):

A
  • Data is sent more quickly
  • Less bandwidth
  • Less buffering on audio and video streams
  • Less storage is required
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2
Q

Types of compression

A

Lossy, lossless

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3
Q

Lossy

A

Non-essential data is permanently removed

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4
Q

Lossless

A

Patterns in the data are spotted and summaries in a shorter format without permanently removing any information

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5
Q

RLE (Run length encoding)

A
  • A basic method of compression that summaries consecutive patterns of the same data
  • Works well with image and sound data where data could be repeated many times
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6
Q

Dictionary compression

A

Spots regularly occurring data and stores it separately in a dictionary

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7
Q

Encryption

A

Hashing or encrypting data so that it cannot be understood and doesn’t possess the means to decrypt it

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8
Q

Caesar cipher

A

Shifts the alphabet

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9
Q

Ways to break caesar cipher

A

Brute force, frequency analysis

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10
Q

Vernam cipher

A

The encryption key is also known as the one-time pad, is the only cipher proven to be unbreakable

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11
Q

Vernam cipher key

A
  • A truly random sequence or equal in length than the plaintext and only ever used once
  • Shared with the recipient by hand, independently of the message and destroyed immediately after use
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12
Q

Algorithmic security

A
  • Keys are determined using a computer algorithm
  • A key derived from an algorithm can be unpicked
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13
Q

Symmetric encryption (private key encryption)

A

Same key is used to encrypt and decrypt data

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14
Q

Security problems with symmetric encryption

A

The key must also be transferred to the recipient

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15
Q

Asymmetric encryption

A
  • Only uses two separate but related keys
  • Public key is made public so that others wishing to send data can use this key to encrypt it
  • Encrypted messages can only be decrypted with the private key
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16
Q

Hashing functions

A

One way functions that provide mapping between an arbitrary length input and a usually fixed length or smaller output