Privacy And Authentication for Wireless Local Area Networks

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Privacy And Authentication for Wireless Local
Area Networks

• Ashar Aziz
• Whitfield Diffie
• Sun Microsystems, Inc

Presented by Naveen Srinivasan.
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OUTLINE

• Loopholes in wireless
• Design Goals
• Design Overview
• Message Exchange in Protocol
• Other Issues

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• Loopholes in Wireless medium
• Wireless receivers
• No physical constraints
• Design Goals
• Privacy of wireless data communication and
  authenticity of the communicating parties
• Seamless integration into existing wired network
• Mutual authentication
• To take advantage of shared key cryptography

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• Two ways to achieve security
• Secure wireless link
• Obviates the need for upgrading existing network
• secured(wired)secured(wireless)
• End-to-End Approach
• application layer
• transport layer
• upgrading existing network

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Design Overview

• Public key and shared key cryptographic
  techniques
• Public Key session key and authentication
• Shared Key privacy

CA
Pub Key
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Content of the Certificate
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Message 1

• CH1 128 bit random number
• List of SK algorithm include algo and key size
• Base station on receiving could indentify that it
  received from mobile but it doesnt know if the
  certificate belongs to Mobile
• Certificate
• Invalid rejects the connection
• Valid Reply to message as mentioned in Message
  2

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Message 2

• Issues in choosing the SKCS
• Why list of SKCSs and CH1 is sent in Msg 2 ?

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Message 3
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(No Transcript)
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Data Packet Issues

• Problems
• Packet losses
• Playback attack
• Solutions
• Message ID
• Count of no. of 64-bits blocks that have been
  sent
• Last 64-bits of the cipher-text of the last
  packet
• Assumes taken care by higher layer protocol

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Operation with Multiple CAs

• Previous protocol description single network wide
  CA not feasible
• Hierarchy of CA s is employed
• Base Station
• Not only include the certificate but also the
  certificate path
• Mobile
• Just its own certificate