1.3.1 Encryption and shi

Question 1

Lossy

Answer 1

PERNAMENTLY removes data

Question 2

Lossless

Answer 2

REWRITES in more efficient format

Question 3

Compression

Answer 3

Reducing storage space required by file (helps transfer over internet)

Question 4

Run Length Encoding

Answer 4

() Repeated values are replaced with ONE OCCURENCE followed by NUMBER OF TIMEs it should be repeated

• Relies on consecutive data being the same, otherwise doesnt reduce much

Question 5

Dictionary Encoding

Answer 5

() Frequently occuring data replaced with INDEX
() Compressed data is stored alongside DICTIONARY which matches frequently occuring data to an index

Question 6

Symmetric Encryption

Answer 6

() Sender and receiver share PRIVATE KEY
() KEY EXCHANGE: Private key distributed
() Both for encrypting and decrypting
() If key intercepted, all data intercepted

Question 7

Asymmetric

Answer 7

KEY PAIR: PUBLIC KEY, PRIVATE KEY (Mathmatically related)
Public key: ENCRYPTION
Private key: DECRYPTION

Private Key Encryption: Verifies message was sent by you (signed)

Question 8

Symmetric and assymetric eval:

Answer 8

+ Symmetric: Large databases, messages in bulk

Question 9

Hashing

Answer 9

() KEY: Input, HASH: Fixed size value
() Uses a hash function
() Hashes cant be reversed
() Collision methods: Store items in a list under hash value, use a second hash to generate a new hash

Uses:
() Lookup data in constant time
() Constant time activities such as caches and databases

Good Hashes:
() Low chance of collision
() Quick to calculate
() Smaller than the input