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Wireless Security

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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Wireless Security

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  1. Wireless Security Presented by: Amit Kumar Singh Instructor : Dr. T. Andrew Yang

  2. 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.

  3. 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.

  4. 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.

  5. 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

  6. 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 <M,c(M)> with the key stream to get the cipher text. • Transmit ‘v’ and the cipher text over a radio link.

  7. Message CRC V Cipher Text How WEP Works Plain Text XOR Key Stream = RC4(v,k) Transmitted Data

  8. 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.

  9. 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.

  10. 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

  11. 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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