URP Usage Scenarios for Mobility

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.