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URP Usage Scenarios for Mobility. James Kempf Sun Microsystems, Inc. Problem Statement:Service Authorization.
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URP Usage Scenarios for Mobility James Kempf Sun Microsystems, Inc.
Problem Statement:Service Authorization • Protocol exchange involved in authorizing a Mobile Node for particular network services after handover is often more extensive than actually setting up the service itself (ex. COPS flows in draft-thomas-seamoby-rsvp-analysis-00.txt). • Could seriously delay Mobile Node obtaining authorized service. • Possible to solve efficiently at edge with context transfer. • Difficult to solve back in network, alternatives unappealing: • Context transfer flooding. • Selective context transfer based on tracking of mobile node’s routes. • Initial URP registration provides Mobile Node with something like a lightweight encrypted capabilities token, the possession of which is sufficient to identify the Mobile Node as authorized for a collection of network level services. • Each router examines token, grants Mobile Node’s packets the requested service if allowed. • Router acts as both PDP and PEP since Mobile Node’s initial packets contain authorization token.
Problem Statement: Authentication Challenge • The network requires some means to issue a lightweight challenge the Mobile Node to authenticate, for example, after handover • The Mobile Node requires some means to challenge the network. • Especially true for 802.11, where anybody can set up an access point (e.g. fake bank teller problem). • Initial URP exchange sets up. • URP RA provides the Mobile Node with a cryptographically protected response token to present when challenged. • Mobile Node provides URP RA with a cryptographically protected response token with which to reply when challenged.
Motivation: Privacy • Network operator or user may want to hide the fact that a particular mobile is in a particular subnet. • Can’t use IPv6 <subnet id,interface id> for IP address. • Draft talks about using an identity token. • Possible but better ways to do this (e.g. SUCV, BAKE, etc.). • Somewhat half baked. • BUT...URP can provide the vehicle for setting up initial conditions (keying, etc.).
Requirements • Provide a means whereby a Mobile Node’s packets can securely prove authorization for a particular network level service after handover without requiring an extensive protocol exchange. • Provide a secure authentication tokens whereby a Mobile Node can challenge the network after handover, and the network can challenge the Mobile Node. • Set up initial conditions for masking Mobile Node’s location and origin.