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Wireless Security. Presented by: Amit Kumar Singh Instructor : Dr. T. Andrew Yang. Going Wireless. Recent technologies include 802.11b,802.11g etc. Most commonly and widely present are 802.11b (11 mbps) 802.11b uses security techniques like WEP to make the network secure.

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Presentation Transcript
wireless security

Wireless Security

Presented by: Amit Kumar Singh

Instructor : Dr. T. Andrew Yang

going wireless
Going Wireless
  • Recent technologies include 802.11b,802.11g etc.
  • Most commonly and widely present are 802.11b (11 mbps)
  • 802.11b uses security techniques like WEP to make the network secure.
  • IEEE came up with 802.11x standards for wireless ethernet.
what is wep
What is WEP ?
  • Wireless connections need to be secured since the intruders should not be allowed to access, read and modify the network traffic.
  • Mobile systems should be connected at the same time.
  • Algorithm is required which provides a high level of security as provided by the physical wired networks.
  • Protect wireless communication from eavesdropping, prevent unauthorized access.
security goals of wep
Security Goals of WEP:
  • Access Control
    • Ensure that your wireless infrastructure is not used.
  • Data Integrity
    • Ensure that your data packets are not modified in transit.
  • Confidentiality
    • Ensure that contents of your wireless traffic is not leaked.
understanding wep
Understanding WEP
  • WEP relies on a secret key which is shared between the sender (mobile station) and the receiver (access point).
  • Secret Key : packets are encrypted using the secret key before they are transmitted.
  • Integrity Check : it is used to ensure that packets are not modified in transit
understanding wep contd
Understanding WEP contd…
  • To send a message to M:
    • Compute the checksum c(M). Checksum does not depend on the secret key ‘k’.
    • Pick a IV ‘v’ and generate a key stream RC4(v,k).
    • XOR with the key stream to get the cipher text.
    • Transmit ‘v’ and the cipher text over a radio link.
how wep works
Message

CRC

V

Cipher Text

How WEP Works

Plain Text

XOR

Key Stream = RC4(v,k)

Transmitted Data

how wep works1
How WEP works ?
  • WEP uses RC4 encryption algorithm known as “stream cipher” to protect the confidentiality of its data.
  • Stream cipher operates by expanding a short key into an infinite pseudo-random key stream.
  • Sender XOR’s the key stream with plaintext to produce cipher text.
  • Receiver has the copy of the same key, and uses it to generate an identical key stream.
  • XORing the key stream with the cipher text yields the original message.
attack types
Attack types
  • Passive Attacks
    • To decrypt the traffic based on statistical analysis (Statistical Attack)
  • Active Attacks
    • To inject new traffic from authorized mobile stations, based on known plaintext.
  • Active Attacks
    • To decrypt the traffic based on tricking the access point
  • Dictionary Attacks
    • Allow real time automated decryption of all traffic.
defenses of wep
Defenses of WEP
  • Integrity Check (IC) field
    • Used to ensure that packet has not been modified in transit
  • Initialization Vector (IV)
    • Used to avoid encrypting two cipher texts with the same key stream
    • Used to argument the shared key and produce a different RC4 key for each packet
references
References
  • http://www.cs.fsu.edu/~yasinsac/group/slides/cubukcu.pdf
  • http://www.isaac.cs.berkeley.edu/isaac/wep-faq.html
  • www.itserv.com/wireless
  • http://www.bluefiresecurity.com/bluefire_downloads.php?download=main
  • http://www.isaac.cs.berkeley.edu/isaac/mobicom.pdf
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