Telecom CH7

Question 1

What is the primary technology behind modern WLANs, and what standard does it rely on?

Answer 1

primary technology: radio freqeuncy and relies on IEEE 802.11 standard

Question 2

different modes of operation in WLAN

Answer 2

1. Infrastructure
2. Ad-Hoc
3. Wi-Fi direct

Question 3

Describe the difference between infrastructure mode and ad-hoc mode in WLANs.

Answer 3

1. Infrastructure: wireless devices connect to an AP (router) which manages communication for multiple STA’s
2. Ad-Hoc: devices communicate directly with each other without AP

Question 4

Explain the process of joining a Wi-Fi network from the perspective of a wireless station (STA).

Answer 4

The STA scans for available networks
Sends an association request to the AP
AP runs an authentication process
if successful, it sends an association response and establishes a secure connection

Question 5

Outline the evolution of WLAN security.

Answer 5

1. WEP : first security protocol, basic encryption and vulnerable to attacks
2. WPA: introduced TKIP for improved encryption
3. WPA2: enhanced security implementing AES.
4. WPA3: Introduced SAE, enhanced protection.

Question 6

Why is WEP considered insecure, and what specific vulnerabilities does it have?

Answer 6

Weak encryption
same secret key for authentication and encryption
IV reuse
Weak key

Question 7

What were the goals of WEP?

Answer 7

confidentiality
access control
data integrity

Question 8

What are the two types of keys supported by WEP?

Answer 8

1. Default key (40 or 104 bits)
   uses same encryption process
2. Key mapping key (individual key)

Question 9

What is the problem with IV reuse in WEP?

Answer 9

The 24-bit IV has a limited number of unique values, so it is reused and vulnerable to attacks

Question 10

How IV reuse in WEP can lead to security vulnerabilities.

Answer 10

IV reuse allows attackers to capture packets with the same IV, analyze patterns and recover the encryption key.

Question 11

What’s the problem with a weak key in WEP?

Answer 11

If a weak key is used, the first few bytes of the output reveals a lot of information about the
key, so breaking the key is made easier

Question 12

Possible improvements for WEP

Answer 12

use longer IV space
Filter out weak IV’s
Discard first 256 outputs of RC4 algorithm
Additional protection: Firewall, VPN

Question 13

What are the two IEEE 802.11i security protocols?

Answer 13

WPA

WPA2

Question 14

Describe how the Temporal Key Integrity Protocol (TKIP) works and its purpose in WPA.

Answer 14

TKIP generates a unique encryption key for each packet, addressing key reuse issues in WEP

Question 15

What encryption method is used in WPA2 for data confidentiality?

Answer 15

WPA2 uses AES-CCMP a secure encryption method