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Versions: 00 01                                                         
anima Working Group                                        M. Richardson
Internet-Draft                                  Sandelman Software Works
Intended status: Standards Track                            12 July 2021
Expires: 13 January 2022

    Involuntary Onwership Transfer of IoT devices: problem statement


   This document details a problem statement relating to ownership of
   IoT devices.

   The problem details is that of changing ownership or possession of a
   device when against the consent or knowledge of the device and/or

   Examples relating to outer door control are used to illustrate the
   problem statement in an intuitive scope.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
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   This Internet-Draft will expire on 13 January 2022.

Copyright Notice

   Copyright (c) 2021 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents (https://trustee.ietf.org/
   license-info) in effect on the date of publication of this document.
   Please review these documents carefully, as they describe your rights
   and restrictions with respect to this document.  Code Components

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   extracted from this document must include Simplified BSD License text
   as described in Section 4.e of the Trust Legal Provisions and are
   provided without warranty as described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Door Locks  . . . . . . . . . . . . . . . . . . . . . . . . .   3
     2.1.  Human Relationships to Doors and Door locks . . . . . . .   3
       2.1.1.  Single owner  . . . . . . . . . . . . . . . . . . . .   4
       2.1.2.  Family home . . . . . . . . . . . . . . . . . . . . .   4
       2.1.3.  Roomates  . . . . . . . . . . . . . . . . . . . . . .   4
       2.1.4.  Apartment building  . . . . . . . . . . . . . . . . .   5
       2.1.5.  Rented or Leased Dwellings  . . . . . . . . . . . . .   5
       2.1.6.  Hotels  . . . . . . . . . . . . . . . . . . . . . . .   6
     2.2.  Rented Automobiles  . . . . . . . . . . . . . . . . . . .   6
     2.3.  Additional Third Parties who need access  . . . . . . . .   8
   3.  Death of a Home Owner . . . . . . . . . . . . . . . . . . . .   8
   4.  Multi-person Dwelling: how to kick that that deadbeat roomate
           out?  . . . . . . . . . . . . . . . . . . . . . . . . . .   9
   5.  Getting rid of the abusive Spouse . . . . . . . . . . . . . .   9
   6.  What is ownership . . . . . . . . . . . . . . . . . . . . . .  10
   7.  Questions and Opportunities . . . . . . . . . . . . . . . . .  10
   8.  Privacy Considerations  . . . . . . . . . . . . . . . . . . .  11
   9.  Security Considerations . . . . . . . . . . . . . . . . . . .  12
   10. IANA Considerations . . . . . . . . . . . . . . . . . . . . .  12
   11. Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .  12
   12. Changelog . . . . . . . . . . . . . . . . . . . . . . . . . .  12
   13. Informative References  . . . . . . . . . . . . . . . . . . .  12
   Appendix A.  Personal Devices . . . . . . . . . . . . . . . . . .  14
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .  15

1.  Introduction

   Much has been written about how to secure IoT devices against both
   physical attacks and those that are done through network protocols.
   (Insert survey articles)

   In most cases, the goal of the security mechanisms is to make sure
   that the device remains under control its lawful or intended owner.
   One example of such a definition of this control could be to mean
   that the device accepts commands only from that owner and that the
   device provides information only to destinations that the owner

   This document explores the problem of what happens when the physical
   or legal ownership of the device does not correspond to the logical
   ownership of the device.

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   There are many ways to explain, scope, and illustrate the general
   problem.  It is much easier to understand with concrete examples, and
   in this example the front-door lock scenarios are used an easy to
   understand way to connect to real life intuition.  It is believed
   that most other IoT authorization and ownership problems are probably
   subsets of the situations outlined here.

2.  Door Locks

   Most people live in some kind of dwelling with at least one door.
   When there is more one door, one of them is usually the front-door.
   This is the primary method of entry and exit, and it usually connects
   to the street and thus to the rest of the world.  It is where both
   strangers and friends arrive and depart, while other doors (side,
   garage, balcony, basement and back doors) may lead only areas from
   which further egress may be impossible, difficult, or deadly.

   The door lock is among the simplest of IoT actuator: after
   potentially many layers of system, there is a single output pin from
   the lock microcontroller which operates some kind of solenoid.  When
   the solenoid is operated, the door unlocks.

   Of course, some doors may be much more complicated with automatic
   opening or closing motors, sensors to make sure there is clearance
   before opening, and that the door is clear before closing.  Some
   doors may slide, lift, rotate or perhaps in the future, modulate to
   alternate dimensions in order to create an opening.  None of those
   details matter to this document.

   Also irrelevant to this document are the mechanical details of the
   door lock itself.  While the physical characteristics of the lock are
   terribly important to actual lock design, it is assumed in this
   document that the mechanical aspects of the lock is of sufficient
   quality to resist the expected amount of brute force that is
   anticipated to be applied to it.

   The history of physical door locks is frequent tussle between lock
   makers who attempt to make locks more resistant to attack, vs thieves
   who use ever more sophisticated methods to attack the locks.  There
   is an obvious relationship to cryptography and cryptoanalysts, and it
   is hardly surprising that many cryptographers and cryptoanalysists
   are also competent lock pickers. [blazepicking]

2.1.  Human Relationships to Doors and Door locks

   Homes and apartments come with a complex set of ownership conditions,
   often via laws established over many centuries.  Many places have
   very ancient laws about when and how a Hotel may evict people.

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2.1.1.  Single owner

   The simplest situation is that of a freestanding dwelling, owned by a
   single individual.

2.1.2.  Family home

   To the single individual one adds a spouse, some children of a
   variety of ages, grandparents, sisters, brothers, neighbours, cat-
   sitters, etc.

   Some members of the household may be trusted to open or close the
   door from the inside only.  For instance a younger child might be
   allowed to open the door when inside, and only when there is someone
   else in the house.

   The child would not be allowed to leave the house and lock the door,
   and preventing such an young child from locking themselves out might
   a useful feature.

   Many homes choose to have deadbolts which require a key to lock the
   door when leaving.  Pulling the door shut is insufficient to lock the

   Other owners prefer that the door lock itself when pulled closed, and
   so might use a spring-bolt lock.

   Still others have double deadbolts which require a key in the inside
   in order to lock or unlock the door.  People prefer these if they are
   concerned that a thief will enter their home through a window, and
   then will go out the front door with their stuff.  The double
   deadbolt requires a key to unlock from the inside.  The downside of
   the double deadbolt is that in the event of a emergency, it is not
   possible to use the door without the key.  As a result, many homes
   with a double deadbolt will have a key hanging nearby, but not within
   reach of a window.

2.1.3.  Roomates

   One scenario where there are multiple unrelated individuals in a
   dwelling is when it is shared by roomates.  Each roomate will have
   co-signed the lease and will have an equal right to be in the
   apartment.  It would be inappropriate for any roomate to have the
   power to lock out the other roomates.

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   This is constrasted with a owner (or renter) who sublets one or two
   rooms to other people.  In that case, this primary owner should have
   more power over who can enter and exit, subject to some legal
   restrictions.  The degree to which subletter have legal rights varies
   by jurisdiction.

   Can any of these individuals give a "key" to girlfriend/boyfriend?
   This is definitely a complexity of the situation which is usually not
   seen in the family home.

2.1.4.  Apartment building

   An apartment building consists of many dwellings with some common
   space.  (This is distinguished from a multi-tenant building where
   each tenant has their own front-door.)

   Residents of an apartment buildings must pass through a common front
   door.  Historically access to such buildings was via a kind of guard,
   the door-man.  This has now been replaced with some kind of master-
   key on the front-door, which a telephone mediated system that allows
   visitors to "buzz" up to the appropriate apartment.  The resident of
   that apartment then activates a circuit to unlock the front door.

   Historically, these telephone systems were hardwired private handsets
   present in each apartment.  This meant that anyone who was in the
   apartment could let anyone else in.

   More modern system are tied into the public telephone system, and a
   DTMF tone is used to unlock the front door.  With such a system, if
   the phone number attached to the apartment is a mobile phone, then a
   resident can buzz themselves while outside the apartment, and then
   buzz themselves in.

   The modern apartment system does not usually provide for multiple
   numbers to be attached to the system, and a guest in such an
   apartment would be unable to, for instance, let medical people in, if
   the primary resident took ill.

2.1.5.  Rented or Leased Dwellings

   Many dwellings are owned by one person, but occupied by another
   person based upon a rental agreement.

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   Historically such agreements were based upon leases of many months to
   years, but intermediation of the relationship by a number of dotcom
   companies have reduced the lease time to days, and the same rental
   systems are expected to accomodate what is more like a Hotel
   relationship.  That situation is handled in the Section 2.1.6

   In many cases the owner (or property manager) of the home has a legal
   right to enter, under certain circumstances.  For instance to effect
   repairs, to show the dwelling to a new potential tenant, and in
   emergencies, to do things like shut off water or gas to avoid damage.

   Notice is often required for most activities, most laws allow a
   landlord to enter without notice during emergencies to do things like
   shut off water when there is a leak.  A landlord can also be
   compelled to open the door for a police warrant, and in cases where
   the police suspect harm, they often will enter without a warrant.

   This situation is even more complex in apartment buildings, even
   where the apartments are owned (and occupied by the owners).  There
   is still a building manager, and there are still water leaks.

   There is additionally, many common areas to which many people should
   get access.  Some areas like common rooms are multi-access, but
   during a reserved time, are exclusive to the person who made the

   Additionally, there are secondary areas that are private to each
   residents, such lockers for bicycles and parking spaces.

2.1.6.  Hotels


2.2.  Rented Automobiles

   Automobiles have doors, locks, and ignition locks.  There are
   sometimes different keys for the different locks.  The valet key for
   instance, allows the driver door to be opened and the car to be
   started, but does not provide access to the glove compartment or the

   Automobiles are rented in a variety of ways: from hourly rentals by
   car-sharing companies (e.g., [communauto], [zipcar], [tribecar]..),
   to traditional daily rentals by well-known companies, to yearly car

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   During the valid period of rental, the motorist probably needs to
   have complete control of the vehicle.  If any other party had any
   control of the vehicle, it might significantly change the legal
   liability for activity done with the vehicle.

   This is usually done by giving them a key which they must insert into
   the ignition.

   Some car sharing companies have schemes involving lockboxes (with
   master physical keys!) to share the car-specific key.  (This is
   rather akin to Kerberos tickets: one key is used to unlock another

   Increasingly automobiles are going "keyless", and it is sometimes
   sufficient for the "fob" to be just near the vehicle, but the fob is
   essentially still a key.

   Many manufacturers are now using the individual's smartphone to
   unlock the car via Bluetooth or NFC, and once inside the vehicle, the
   phone serves as the "fob", authorizing the vehicle to run.

   Integration with the smartphone has a transaction cost to it: the
   phone/car connection must be onboarded in some way, and is therefore
   only suitable for car owners, or longer-term leases.

   Shorter term leases may transition to use of a smartphone, but today,
   they are mostly based upon passive RFID FOBs or physical keys.
   Today, when used via smartphone, there is a satellite or LTE based
   care security system that the drive interacts with via the Internet.
   There are reports of people being stranded in the woods for days,
   because the were too far away from the LTE tower, and the vehicle
   would not unlock or start without authorization.

   At the end of the rental period, the access for the motorist must be
   revoked.  This is akin to getting rid of roomate (Section 4).  But
   there are some caveats: there has to be some kind of grace period or
   interlock with the renting agency, as the vehicle might not yet have
   been returned properly.  They could just be late.  The vehicle could
   stall meters from the proper location and need to be restarted.  Once
   at the proper location, the motorist might still need to access the
   trunk or other compartments to retrieve their belongings.

   But, once properly returned, the vehicle should no longer be
   accessible to the original renter.

   The next renter may be standing waiting, particularly if the vehicle
   is late.  The transition from one renter to another needs to have a
   standardized ceremony.

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   For long-term leases the process may be more complex at the end.
   While some significant grace period (compared to rental period) is
   appropriate for short-term, for longer term leases, the owner likely
   needs to be able to disable the vehicle some few number of days after
   the end of the lease.  But, never before.

2.3.  Additional Third Parties who need access

   In addition to this obvious arms race, there are specific third
   parties that bring their own interests to the locks in the front-door
   lock scenario, e.g. law enforcement or fire departments.

   In some places there are locks which accept keys carried by fire,
   police or postal personnel.  For instance, the service key in a
   building allows the fire department to override the elevator
   controls.  The electrical panels and gas systems in the buildings may
   also be accessible by the fire department in order to cut off
   electricity or gas during a fire.

   The mailboxes of an apartment (and the outer door to get to the
   mailbox) can be opened by the postal carrier in order to deliver the
   residents mail.  The French PTT T-10 key is an example of such a key,
   and there is a law and regulation around it as well.

   This is an example of a master key necessary in most multi-tenant

   It is hardly surprising that there was significant concern when the
   fire/police "master key" for the city of New York was being openly
   sold on ebay. (see [huffpostkey] and [fdnymaster])

   A digital door (and elevator control) key that could be safely
   deployed as a replacement for this physical key would be a
   significant improvement over the physical keys.  It would be easier
   to add new users and revoke old users, and an audit log of who used
   what key in which building could be easily generated.

3.  Death of a Home Owner

   Start from a single freestanding dwelling, owned by a single
   individual, and ask what happens when the individual dies.  How do
   the inheritors (or the executors of the estate) take possession of
   the property?  Prior to electronic door locks, a physical key can be
   used, and if one is not available, then a locksmith can be engaged.
   This may require a legal statement from an appropriate authority, at
   which point the locksmith may make use of a drill, or maybe even some
   other implements such as saws or battering rams.

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   The same techniques can probably be used against electronic door
   locks that do not use keys, but can this technique be used against,
   for instance, smart toasters, furnaces or automobiles?

   Repairing a hole in a front door is a nuisance.  Replacing a furnace
   or other large appliances due to a death is unacceptable.

   In particular, automobile locks are usually designed to resist
   significant amounts of force as they are often the target for
   thieves.  The vehicles are left unattended in public parking lots
   among many other automobiles for many hours at a time, and it is even
   a common occurance that a person legitimately walks up to the wrong
   automobile (having forgotten exactly where they parked) an attempts
   to unlock it.

   Any tool or protocol that the locksmith can employ against the
   automobile could also be employed by a malicious attacker.  Any
   mechanism that the automobile maker includes in the system to allow a
   locksmith (or legal court) to open the vehicle would be the target of
   attackers.  This is fundamentally why security protocols do not
   include back doors ([RFC1984]).

4.  Multi-person Dwelling: how to kick that that deadbeat roomate out?

   The situation above was for a single dwelling.  Many dwellings are
   occupied by multiple people, often jointly.

   Should any of the occupants be allowed to change the locks, that is,
   change the entry authorization for other occupants?  Under normal
   circumstances, the answer should probably be no.  Under the situation
   of a legal injunction, the answer may be yes.  How can the door lock
   system know?  How can the party which is asking for the injunction
   know that the door lock has no other secret authorizations?

   If the legal system must be a party to this activity, how does the
   home owner, not involved in such a process know that the legal
   system's computers haven't itself been compromised?  This is one of
   the major arguments against official escrow: the escrow system is now
   a very high value target.

5.  Getting rid of the abusive Spouse

   The situation where a couple separate under duress requires that
   access to the original home be restricted.  That is, the door locks
   must be rekeyed.  Digitally, this means removing the access to the
   abusive spouse.

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   Is this different than the case of roomates?  Not really: multiple
   people had access to the door lock before, and one must be removed.
   For the case of roomates, each had a legal right to access, and no
   roomate should be allowed to revoke access for the other roomate.

   Now, in the case of separation, the remaining "roomate" must now be
   permitted to revoke access for the other "roomate"

6.  What is ownership

   One technical definition of ownership might be that the device has an
   identity certificate from the owner.  This is a good definition, and
   it is currently what is used in [RFC8995], [MATTER], and many other
   similar systems.

   In the security space, the vernacular term, "p0wned" is often used to
   refer to a device that is no longer under the control of the
   legitimate owner.  That is, an attacker has taken control of the
   device, usually through some security vulnerability, and now the
   attacker controls what code the device will run.

   So a deeper notion of what it means to own a device is that it could
   involve control of what software a device runs.  Whomever controls
   the software in a device controls what the device does, and whose
   commands it obeys.  This can generally be expressed in the form of an
   authorization from a Trust Provisioning Authority (Section 7 of

   Control and access decisions are not usually changed by changes to
   the firmware of the device.  (Not withstanding the dispute between
   the FBI and Apple: [applefbi]) For good or bad, all devices of a
   particular type run the same firmware that the manufacturer has
   provided.  The decision as to who is in control of the device is
   determined by the firmware based upon the identities of the parties.

   All of the challenges in the previous section boil down to finding a
   way to express the question as to whether an identity is allowed

7.  Questions and Opportunities

   While the example of the front door lock was used as an exemplar,
   essentially the same question applies to pretty much all forms of
   actuator.  Access to some sensors may be significantly simpler, but
   other sensors will be as complex as any actuator.

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   A primary question is whether the front door problem is a superset of
   all other problems.  If so, then a solution to the front door
   ownership can provide for all other actuators.

   Or, if there some other physical world interaction which is more
   complex, then the front door may be a subnet of it.  Alternatively
   there may be some other master pattern which does not overlap with
   the front door and it would provide a different model.  Some
   actuators might be a subset of these two models.

   The various modes of front door interaction need to be named.  Based
   upon the above description, these would include: roomates, spouses,
   ex-spouses, renter/owners, tenant/superintendant, fire-department,
   police officer, young-children/parent, adult-children/seniors...

   The automobile, personal or medical device interactions are mostly
   variations on the front door.  Instead of superintendant, substitude
   mechanic, leasor or ER doctor.  Instead of child, substitute
   neighbour-who-borrows your tools.

   The IETF has created a number of authorization systems.  This starts
   with SPKI [RFC2393], OAUTH2 [RFC6749], Authorization in Constrained
   Environment [RFC7744], SAML ([oasissaml] and [RFC7522]).  There are
   many others: most are based on the providing virtual access to a
   virtual resource (computer, web resource,etc.) rather than
   authorizing physical access to a physical resource.

   Can the required policies be representing in the existing frameworks?
   If so, are the frameworks we have sufficiently small as to live
   within a front door lock?  Perhaps a better question is: what is the
   price point that society is willing to pay for a front-door system
   which satisfies the various needs of the multitude of stakeholders

8.  Privacy Considerations

   There is a significant tussle between having policies which are
   clearly asserted (and auditable) and having privacy for the
   individuals or groups named.

   For instance, it may be entirely appropriate for a front door to make
   it clear who is allowed access in the event of emergency, such that
   those people can easily be found.  On the other hand, it may be
   inappropriate for the front door to list one's current romantic
   interests as having access.  (Such access might even be

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   A significant mix of abstract identities ("The Superintendant of the
   Building"), along with pseudonymous identities will be required.

9.  Security Considerations

   This entire document is about a proposed set of authorization

10.  IANA Considerations

   This documents makes no IANA Requests.

11.  Acknowledgements


12.  Changelog

13.  Informative References

   [applefbi] "Apple, Americans, and Security vs. FBI", n.d.,

              Blaze, M., "Notes on Picking Pin Tumbler Locks", 7
              November 2003,

              "Communauto Car Sharing", n.d.,

              Schneier, B., "Schneier on Security: Master Key", 10
              January 2012,

              Huffington Post, "Daniel Ferraris, Retired Locksmith,
              Sells NYC Master Keys On eBay", 10 January 2012,

   [MATTER]   Alliance, C.S., "Connected Home over IP Specification", 1
              July 2021, <https://buildwithmatter.com/>.

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              "OASIS Security Services (SAML) TC", n.d.,

   [RFC1984]  IAB and IESG, "IAB and IESG Statement on Cryptographic
              Technology and the Internet", BCP 200, RFC 1984,
              DOI 10.17487/RFC1984, August 1996,

   [RFC2393]  Shacham, A., Monsour, R., Pereira, R., and M. Thomas, "IP
              Payload Compression Protocol (IPComp)", RFC 2393,
              DOI 10.17487/RFC2393, December 1998,

   [RFC6749]  Hardt, D., Ed., "The OAuth 2.0 Authorization Framework",
              RFC 6749, DOI 10.17487/RFC6749, October 2012,

   [RFC7522]  Campbell, B., Mortimore, C., and M. Jones, "Security
              Assertion Markup Language (SAML) 2.0 Profile for OAuth 2.0
              Client Authentication and Authorization Grants", RFC 7522,
              DOI 10.17487/RFC7522, May 2015,

   [RFC7744]  Seitz, L., Ed., Gerdes, S., Ed., Selander, G., Mani, M.,
              and S. Kumar, "Use Cases for Authentication and
              Authorization in Constrained Environments", RFC 7744,
              DOI 10.17487/RFC7744, January 2016,

   [RFC8995]  Pritikin, M., Richardson, M., Eckert, T., Behringer, M.,
              and K. Watsen, "Bootstrapping Remote Secure Key
              Infrastructure (BRSKI)", RFC 8995, DOI 10.17487/RFC8995,
              May 2021, <https://www.rfc-editor.org/info/rfc8995>.

   [RFC9019]  Moran, B., Tschofenig, H., Brown, D., and M. Meriac, "A
              Firmware Update Architecture for Internet of Things",
              RFC 9019, DOI 10.17487/RFC9019, April 2021,

   [tribecar] "Tribe Car", n.d., <https://www.tribecar.com/>.

   [zipcar]   "ZIP Car", n.d., <https://zipcar.com/>.

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Appendix A.  Personal Devices

   There is an increasing number of devices that a person might have on
   their person or around them.  The list is endless, and goes from step
   trackers, to watches, to recreational (exercize) heart monitors,
   shoes, shirts with displays (for fun or for the disco), to intimate
   devices that might be worn at unusual times.

   Some devices may belong only temporarily to a person.  For instance,
   a tread-mill or weight-lifting machine, or even a kitchen appliance.
   After the user is finished with the device it may need to reset to be
   ready for the next user.

   A kitchen appliance (a blender or microwave) might have only a small
   number of legitimate users (the members of the household), but when
   one person is using it, it might remain exclusive.

   The same appliance, however, might also be purchased for use in a
   workplace kitchen, and so the number of legitimate users might range
   in the hundreds.  The users will want the appliance to remember their
   personalized settings.

   The names of the previous users should not be easily divulged, but at
   the same time, the name of the person who used it should be available
   to a privileged user (owner), for the case the finding out who broke
   the device.  In this case, it might seem obvious that the device has
   a privileged owner, and may also have just users.  But this
   interaction may be quite complex, and is subject to a wide variety of
   locally significant social compacts.

   In addition, devices get lent.  This could be akin to thinking about
   there being users vs owners, with the owner always being the one
   responsible for the device.  However, passing on a coffee maker to
   one's child who is moving to another city is not always a loan, and
   not always a gift.  Which one it is may not be obvious to the people
   involved until later on.  The parent may forget about it, thinking
   they have given it away, while the (adult) child might pass it on to
   a friend.  Only when the friend tries to "own" the device, do they
   find out that the parent is still the owner.  Now what?  Does the
   device have to be returned to the parent to physically give away

   If the answer to the above question is no, then does this in essence
   enable theft?  Is this a kind of theft that we need to care about?
   Does it matter if this is a $50 coffee maker, vs a $600 espresso
   machine?  Or can we even set a meaningful threshold?  Theft of a $600
   espresso machine might not be a problem for some people, while the
   loss of a $50 coffee machine might be a rather big problem.

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Internet-Draft                   iot-iot                       July 2021

Author's Address

   Michael Richardson
   Sandelman Software Works

   Email: mcr+ietf@sandelman.ca

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