Week 13 UAS

Question 1

Security rests on?

Answer 1

1. confidentiality
2. authenticity
3. integrity
4. availability.

Question 2

Attacks Classification?

Answer 2

1.  Passive Attacks
–  System unaltered, hard to detect.
–  Eavesdropping on, or monitoring of, transmissions to:
     •  obtain message contents, or 
     •  monitor traffic flows.

2. Active Attacks .
   – System altered, easier to detect. – ModificaAon of data stream to:
   • masquerade of one enAty as some other.
   • replay previous messages.
   • modify messages in transit.
   • denial of service.

Question 3

Impact of attacks?

Answer 3

•  Theft of confidential information.
•  Unauthorized use of 
   –  Network bandwidth.
   –  Computing resource.
•  Spread of false information.
•  Disruption of legitimate services.

Question 4

Methods of Defence from Attacks?

Answer 4

•  Information Protection 
     –  Encryption.
•  Software Controls
     –  Access limitations in a data base.
     –  In operating system protect each user from other users.
•  Hardware Controls 
     –  Smartcard, biometric.
•  Policies
     –  Frequent changes of passwords.
•  Physical Controls

Question 5

Study of encryption principles/methods

characterized by

Answer 5

•  Number of keys used.
     – Single-key or secret key.
     – Two-key or public key.
•  Type of encryption operations used
     – Substitution. 
     – Transposition. 
     – Product .
•  Way in which plaintext is processed 
     – Block.
     – Stream.

Question 6

An encryption scheme has five ingredients:

Answer 6

1. Plaintext.
2. Encryption algorithm.
3. Secret Key.
4. Ciphertext.
5. Decryption algorithm.

Question 7

Key in cryptography?

Answer 7

1. Public-key, which may be known by anybody.

2. Private-key, known only to the recipient.