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Privacy And Authentication for Wireless Local Area Networks

Privacy And Authentication for Wireless Local Area Networks. Ashar Aziz Whitfield Diffie Sun Microsystems, Inc. Presented by: Naveen Srinivasan. OUTLINE. Loopholes in wireless Design Goals Design Overview Message Exchange in Protocol Other Issues. Loopholes in Wireless medium

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Privacy And Authentication for Wireless Local Area Networks

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  1. Privacy And Authentication for Wireless Local Area Networks Ashar Aziz Whitfield Diffie Sun Microsystems, Inc Presented by: Naveen Srinivasan. Privacy and Authentication for Wireless LAN

  2. OUTLINE • Loopholes in wireless • Design Goals • Design Overview • Message Exchange in Protocol • Other Issues Privacy and Authentication for Wireless LAN

  3. 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 Privacy and Authentication for Wireless LAN

  4. 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 Privacy and Authentication for Wireless LAN

  5. Pub Key Challenge/Response Protocol Mobile Base Design Overview Public key and shared key cryptographic techniques • Public Key : session key and authentication • Shared Key: privacy CA Pub Key Privacy and Authentication for Wireless LAN

  6. Contents: • Serial Number • Validity Period • Machine Name • Machine Public Key • CA Name CA Content of the Certificate Privacy and Authentication for Wireless LAN

  7. Message #1 Cert_Mobile, CH1, Lists of SKCSs Mobile Base • 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 doesn’t know if the certificate belongs to Mobile • Certificate • Invalid – rejects the connection • Valid – Reply to message as mentioned in Message #2 Privacy and Authentication for Wireless LAN

  8. Message #2 Cert_Base, E(Pub_mobile, RN1), Chosen SKCS, Sig(Priv_Base, { E(pub_Mobile, RN1), Chosen SKCS, CH1, List of SKCSs}) Mobile Base • Issues in choosing the SKCS • Why list of SKCSs and CH1 is sent in Msg #2 ? Privacy and Authentication for Wireless LAN

  9. Message #3 E(Pub_Base, RN2), Sig{ Priv_Mobile, { E(Pub_Base, RN2), E(Pub_Mobile, RN1) } } Mobile Base Privacy and Authentication for Wireless LAN

  10. Privacy and Authentication for Wireless LAN

  11. 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 Privacy and Authentication for Wireless LAN

  12. 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 Privacy and Authentication for Wireless LAN

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