Chap 5

Question 1

Four components of PKI are

Answer 1

Public Key infrastructure has four components:

1. Certification authority
2. Registration authority responsible for verifying cert contents for the CA
3. Repository : system that accepts certs and CRLs certificate revocation lists and distributed them
4. Archive : long term storage of info from CA

Question 2

Asymmetric algorithms are: five are…

Answer 2

RSA
Diffie -Hellman
El gamal 
Merkle-Hellman (trapdoor) knapsack 
Elliptic curve

RSA: key transport based on factoring prime numbers

Diffie Hellman : vulnerable to MITM attacks. Both encrypt wth each other’s public keysand Their own private keys to make symmetric key known only to them. Based on discrete logarithms

El gamal: unpatented.also based on discrete algorithms, but includes encryption and digital signatures

Merle-Hellman : based on fixed weights and is broken

Elliptic curve: more efficient can use smaller key

Question 3

Describe the three different types of asymmetric cryptography

Answer 3

1. Secure message: ensures confidentiality sender encrypts with recipients public key
2. Open message format: you know it’s from me but everyone can see the message. Sender encrypts with senders private key and message can be decrypted with senders public key which everyone has. Auth but no confidentiality
3. Secure and signed: both 1&2 =C &A. Encrypts with recipients public key first then with senders private key.

Question 4

What are two ways you have message authentication?

What does message authentication guarantee?

Answer 4

What are two ways you have message authentication?

Message digests:

Digital signatures: RSA, DSA & elliptic curve digital signature algorithm

What does message authentication guaranttee?
Authenticity and integrity

Question 5

Name three types of fire detection and two types of fire suppression systems?

These are essentially to protecting lives and facilities.

Answer 5

1. Heat sensing: a) fixed temp b) rate of rise detection
2. Flame sensing a) flame flicker/pulse b) infrared (expensive)
3. Smoke sensing a) photoelectric (sense variations in light intensity) b) beam (sense disruption to beams of light by smoke) c) ionization -detect disturbances in radioactive current d) aspirating - draws air into chamber to detect smoke

Fire suppression:
1. Water sprinkler 
A. Wet pipe most reliable and most used.
B. Dry pipe
C. Deluge not used for computer systems 
D. Proactive - heat sensor triggers water and alarm. If fusible link melts then water discharged 

2. Gas discharge systems

Question 6

What are the types of classes of fires and what are the ways to extinguish those fires?

Answer 6

Class a: common combustibles
Water soda acid

Class b: burnable fuels
Soda acid co2 halon

Class c: electrical
Co2 halon
Remember to turn off electricity

Question 7

Examples of symmetric key algorithms are:

Answer 7

Symmetric algorithms include:

DES: 1970 NSA data encryption standard. 64 bit block cipher with 56-bit key
Has four modes: Electronic code book ecb block ; CBC Cipher block chain block; Cipher feedback CFB stream; Output Feedback OFB stream.

3DES : expensive, slow - 4 variations of triple Des: EEE-2, EdE-2, EEE-3, EDE-3; encrypt with first key, encrypt with second key, encrypt with first key... (3 56 bit keys equals 168 bit key length)
blowfish / Twofish
IDEA: block, patented; in PGP email
RC 4, RC5, TC6 Rivest ciphers 
AES/ Rijndael block:

Question 8

What are the different encryption available at different levels of the OSI model?

Answer 8

Layer 2: link encryption (every node has separate key pairs; slower than end to end; PPTP point to point tunnel protocol (standard VPN); L2TP Layer 2 tunneling protocol

Layer 3: IPSec

Layer 4: SSL