Network Working Group                                       M. Behringer
Internet-Draft                                               M. Pritikin
Intended status: Informational                              S. Bjarnason
Expires: April 18, 2013                                            Cisco
                                                        October 15, 2012

                    Bootstrapping Trust on a Homenet


   A homenet must be aware of its borders, and the realms within those.
   This document proposes an approach to bootstrap trust in such an
   environment.  The idea is to select one device as the trust anchor
   and to enroll other devices into the domain.  The result is the
   creation of a domain of trust in the homenet, with a common trust
   anchor.  This trust model can subsequently be used to determine
   boundaries, and to autonomically bootstrap network services.

Status of this Memo

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   This Internet-Draft will expire on April 18, 2013.

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   include Simplified BSD License text as described in Section 4.e of
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1.  Problem Statement

   [I-D.ietf-homenet-arch] states that "It should be possible to
   automatically perform border discovery for the different borders."
   Simple approaches, such as terminating a homenet on a particular
   interface type do not easily allow for devices from different
   administrative realms to be locally connected.
   [I-D.ietf-homenet-arch] states further that "It is important that
   self-configuration with 'unintended' devices is avoided.  Methods are
   needed for devices to know whether they are intended to be part of
   the same homenet site or not."

   An approach is needed that allows to establish trust inside a homenet
   according to a policy set by the admin of the homenet.

2.  Approach

   An autonomic device can be a router, switch, PC, smartphone, or any
   other device, independent of its role in the network, which has the
   autonomic functionality mentioned below .  A homenet consists of
   autonomic devices and non-autonomic devices.  This approach requires
   at least one autonomic networking device, such as a router or switch.

   One autonomic device in the homenet takes on a registrar function.
   This could be manually enabled, for example on a smartphone autonomic
   app; in the absence of a registrar function, a device can also auto-
   select itself to take on this function, using some detection
   mechanism to resolve potential conflicts.

   The registrar creates a trust anchor for the homenet, and
   subsequently acts as a registration authority, granting domain
   certificates to other devices.

   Every autonomic device discovers neighbouring autonomic nodes through
   an autonomic neighbour discovery protocol.  This could be implemented
   for example through IPv6 neighbour discovery, using a to-be-assigned
   well-known multicast address indicating "all autonomic nodes on this

   An autonomic device signs its neighbour discovery packets.  If it has
   a domain certificate from the domain registrar, it uses that.  If
   not, it uses either a vendor certificate (e.g., an IEEE 802.1AR

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   [IDevID] credential) or a self-signed certificate.

   If two autonomic homenet devices use the same trust anchor they can
   verify each other's certificate thus establishing that the peer is a
   member of the same local domain.

   If one autonomic homenet device is member of a domain, and its
   neighbour is not, it invites the neighbour to join the domain.  The
   device without domain credentials requests to join the first domain
   it is presented with.  The device MUST only join a homenet domain
   when it is in the factory default configuration (e.g. it is not
   currently a member of a homenet).  The domain device proxies the
   request to the registrar, including the device credentials of the
   device without domain credentials.

   The registrar accepts or declines a request to join the domain, based
   on the credentials presented and other policy defined criteria such
   as proxy identity.  Any authorized device currently within the domain
   MAY provide supplemental criteria for help making this decision.  A
   smartphone autonomic application would be an ideal domain member to
   provide user interface functionality for the obtaining of
   supplemental criteria from end users.

   If a device is accepted into the domain, it is invited to request a
   domain certificate through a certificate enrollment process.

   The result is a common trust anchor and device certificates for all
   autonomic devices in a domain.  These certificates can subsequently
   be used to determine the boundaries of the homenet, to authenticate
   other domain nodes, and to autonomically enable services on the

3.  Security Considerations

   The approach as outlined in this document is open to a number of
   attacks at bootstrap time.  For example, a malicious device could
   pretend to be an expected device and assume its role.  This is
   however no different to current security models in home networks.

4.  Informative References

              Chown, T., Arkko, J., Brandt, A., Troan, O., and J. Weil,
              "Home Networking Architecture for IPv6",
              draft-ietf-homenet-arch-04 (work in progress), July 2012.

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   [IDevID]   IEEE Standard, "IEEE 802.1AR Secure Device Identifier",
              December 2009, <

Authors' Addresses

   Michael H. Behringer


   Max Pritikin


   Steinthor Bjarnason


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