BRSKI enrollment of with disconnected Registrars -- smarkaklink
draft-richardson-anima-smarkaklink-00
The information below is for an old version of the document.
| Document | Type |
This is an older version of an Internet-Draft whose latest revision state is "Expired".
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|---|---|---|---|
| Authors | Michael Richardson , Jacques Latour , Faud Khan , Abhishek Joshi | ||
| Last updated | 2019-03-11 | ||
| Replaces | draft-richardson-anima-smartpledge | ||
| RFC stream | (None) | ||
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| Stream | Stream state | (No stream defined) | |
| Consensus boilerplate | Unknown | ||
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draft-richardson-anima-smarkaklink-00
6tisch Working Group M. Richardson
Internet-Draft Sandelman Software Works
Intended status: Informational J. Latour
Expires: September 12, 2019 CIRA Labs
F. Khan
A. Joshi
Twelve Dot Systems
March 11, 2019
BRSKI enrollment of with disconnected Registrars -- smarkaklink
draft-richardson-anima-smarkaklink-00
Abstract
This document details the mechanism used for initial enrollment using
a smartphone of a BRSKI Registrar system.
There are two key differences in assumption from
[I-D.ietf-anima-bootstrapping-keyinfra]: that the intended registrar
has Internet, and that the Pledge has no user-interface.
This variation on BRSKI is intended to be used in the situation where
the registrar device is new out of the box and is the intended
gateway to the Internet (such as a home gateway), but has not yet
been configured. This work is also intended as a transition to the
Wi-Fi Alliance work on the Device Provisioning Protocol (DPP).
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
working documents as Internet-Drafts. The list of current Internet-
Drafts is at https://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on September 12, 2019.
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Copyright Notice
Copyright (c) 2019 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
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to this document. Code Components extracted from this document must
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the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Intermittent Device connectivity . . . . . . . . . . . . 4
1.2. Additional Motivation . . . . . . . . . . . . . . . . . . 4
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 5
2.1. History and Origin of the name . . . . . . . . . . . . . 6
3. Requirements Language . . . . . . . . . . . . . . . . . . . . 6
4. Assumptions and Required Setup . . . . . . . . . . . . . . . 6
5. Protocol Overview . . . . . . . . . . . . . . . . . . . . . . 7
5.1. Scan the QR code . . . . . . . . . . . . . . . . . . . . 7
5.2. Enroll with the manufacturer . . . . . . . . . . . . . . 7
5.3. Connect to BRSKI join network . . . . . . . . . . . . . . 7
5.4. Connect to Adolescent Registrar (AR) . . . . . . . . . . 8
5.5. Pledge Requests Voucher-Request from the Adolescent
Registrar . . . . . . . . . . . . . . . . . . . . . . . . 8
5.6. AR processing of voucher-request, request. . . . . . . . 9
5.6.1. Additions to Voucher-Request . . . . . . . . . . . . 9
5.7. Smartphone validates connection . . . . . . . . . . . . . 9
5.8. Smart-Phone connects to MASA . . . . . . . . . . . . . . 10
5.9. MASA processing . . . . . . . . . . . . . . . . . . . . . 10
5.10. Smartpledge processing of voucher . . . . . . . . . . . . 10
5.11. Adolescent Registrar (AR) receives voucher . . . . . . . 11
5.12. Adolescent Registrar (AR) grows up . . . . . . . . . . . 11
5.13. Smartphone enrolls . . . . . . . . . . . . . . . . . . . 11
5.14. Validation of connection . . . . . . . . . . . . . . . . 12
6. Protocol Details . . . . . . . . . . . . . . . . . . . . . . 12
6.1. Quick Response Code (QR code) . . . . . . . . . . . . . . 12
6.1.1. The Smarkaklink Attribute . . . . . . . . . . . . . . 13
6.1.2. Link-Layer Address Attribute . . . . . . . . . . . . 13
6.1.3. ESSID Name Attribute . . . . . . . . . . . . . . . . 14
6.2. Enrollment using EST . . . . . . . . . . . . . . . . . . 14
7. Smart Pledge enrollment with manufacturer . . . . . . . . . . 14
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7.1. minimal Smart Pledge enrollment . . . . . . . . . . . . . 16
8. Threat Analysis . . . . . . . . . . . . . . . . . . . . . . . 16
8.1. Wrong Administrator . . . . . . . . . . . . . . . . . . . 16
8.2. Rogue Administrator . . . . . . . . . . . . . . . . . . . 16
8.3. Attack from Internal device . . . . . . . . . . . . . . . 16
8.4. Attack from camera enabled robot . . . . . . . . . . . . 16
8.5. Attack from manipulator enabled robot . . . . . . . . . . 17
9. Security Considerations . . . . . . . . . . . . . . . . . . . 17
10. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 17
11. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 17
12. References . . . . . . . . . . . . . . . . . . . . . . . . . 17
12.1. Normative References . . . . . . . . . . . . . . . . . . 17
12.2. Informative References . . . . . . . . . . . . . . . . . 18
Appendix A. Resulting DPP QR code specification . . . . . . . . 18
Appendix B. Swagger.IO definition of API . . . . . . . . . . . . 19
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 22
1. Introduction
The problem of bootstrapping a new device is described at length in
[I-D.ietf-anima-bootstrapping-keyinfra] (aka BRSKI). The problem
that BRSKI solves is the case of a smart, properly configured network
with a minimum of network connectivity (or previously pre-previoned
with nonceless vouchers), and a relatively stupid new device (the
Pledge), which lacks a user interface.
The BRSKI problem is one of trust: how does the new device trust that
it has found the correct network to join, and how does the new
network become convinced that the new device is a device that is
intended to join. BRSKI solves the problem well for the case where
the network is well connected and can easily talk to the device's
Manufacturer Authorized Signing Authority (MASA), while providing
appropriate proxy mechanisms to enable the new pledge to communicate
it's proximity assertion to the MASA as well.
This document is about a variation of the problem: when the new
device being introduce has no network connectivity, but a new device
is intended to serve as the Registrar for the network. This new
device is likely a home (or small office) gateway, and until it is
properly configured there will be no direct network connectivity.
There are a number of protocols that permit an ISP to consider a new
router brought into a home to be a new pledge to the ISPs' network,
and for that new device to integrated into the ISP's (autonomic)
network. BRSKI can be used itself, and there are ways to use the
Broadband Form's TR-069 to bootstrap the device in this way. This
document is not about the situation where the router device is
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intended to belong to the ISP, but about the situation where the home
user intends to own and control the device.
1.1. Intermittent Device connectivity
There is an additional variation which this variation solves: the
case where there is one or more devices in a place with no immediate
connectivity to a Registrar. An example of this could be a new home
construction where a furnace, thermostat or other control systems
need to be introduced to each other. If a registrar exists it will
have no Internet connectivity (as above), until the home becomes
owned by the first owner. There might never be a registrar though.
The basement case is important because the assumption is that the
_installer_ may have poor or no LTE connectivity in that location.
The installer will have to exit the basement, perhaps even return to
their truck, in order to have network connectivity for their
provisioning device (a smartphone equivalent).
1.2. Additional Motivation
The Wi-Fi Alliance has released the Device Provisioning Protocol
[dpp]. The specification is available only via "free" registation.
The specification relies on being able to send and receive 802.11
Public Action frames, as well as Generic Advertisement Service (GAS)
Public Action frames. Access to send new layer-2 frames is generally
restricted in most smartphone operating systems (iOS, Android). At
present there are no known public APIs that a generic application
writer could use, and therefore the smart-phone side of the DPP can
only be implemented at present by the vendors of those operating
systems.
As both dominant vendors have competing proprietary mechanisms, it is
unclear if generic applications will be produced soon. It is
probably impractical for a vendor an a smart-appliance to
independantly produce an application that can do proper DPP in 2019.
As one of the common goals of this document and DPP is that there
need not be an application-per-device only one DPP application need
exist. Until such time as such an application becomes universal it
is a goal of this document to lay the groundwork for a transition to
full use of DPP by leveraging the QR code infrastructure that DPP
depends upon.
In addition to the above concern, DPP is primary concerned about
provisioning WiFi credentials to devices. DPP can provision access
points themselves, but it lacks any kind of manufacturer integration.
BRSKI provides this integration, and therefore an audit trail history
for the device.
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The smarkaklink enrollment process described in this document is
about securely initializing the administrative connection with a
device that is the WiFi Access Point.
2. Terminology
The following terminology is copied from
[I-D.ietf-anima-bootstrapping-keyinfra]
enrollment: The process where a device presents key material to a
network and acquires a network specific identity. For example when a
certificate signing request is presented to a certification authority
and a certificate is obtained in response.
pledge: The prospective device, which has an identity installed at
the factory.
IDevID: a manufacturer signed keypair (different from the QRkey)
which is generated at the factory. This is the 802.1AR artifact
which is mandated by [I-D.ietf-anima-bootstrapping-keyinfra].
The following new terminology has been added
smarkaphone: The prospective administrator device, usually a
smartphone equipped with a QR capable camera, wifi and 3G
connectivity.
adolescent router (AR): a home router or device containing a
registrar. The device does not yet have network connectivity, and
has no administrator. It is considered not a "baby" device in the
same way that the pledge is, but it is not yet an adult. A better
term would be welcome.
SelfDevID: a public/private key pair generated by the smartpledge,
formed into a self-signed PKIX certificate. The private key part
remains always on the smartpledge, but like other secondary device
keys, should be encrypted for backup purposes. {EDNOTE: any
references to Apple or Android APIs/specifications here?}
QRkey: a unique, raw ECDSA or EdDSA key pair generated in (or for)
the adolescent router at the factory, and stored in the
configuration portion of the firmware. The public portion is
printed in a QRcode. This key is not formed into a certificate of
any kind.
smarkaklink: the name of this protocol.
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adolescent router (AR): a home router or device containing a
registrar. The device does not yet have network connectivity, and
has no administrator.
2.1. History and Origin of the name
This document was originally called the "smartpledge" variation of
BRSKI. This name was intended to indicate that the variation is one
where the BRSKI role of Pledge is taken on by the smartphone device.
While the end-goal is to have the smartphone enrolled into a PKI
hosted by the fully-grown Router, the activities of each device do
not map into the BRSKI roles at the beginning. In fact, they are
reversed with the Adolescent Router being the Pledge. Review of this
document suggested that removing the word pledge would help.
The new name "smarkaklink" is intended to sound like the sound that
two (wine, beer) glasses make after a toast is made.
3. Requirements Language
In this document, the key words "MUST", "MUST NOT", "REQUIRED",
"SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY",
and "OPTIONAL" are to be interpreted as described in BCP 14, RFC 2119
[RFC2119] and indicate requirement levels for compliant STuPiD
implementations.
4. Assumptions and Required Setup
The first assumption is that intended device owner is active and is
present. The device owner has a smart-phone that is capable of using
Wi-Fi or being wired into the adolescent router (AR).
The smartpledge application generates a self-signed certificate with
public/private keypair that it knows. It may generate a unique
certificate for each manufacturer. This certificate is called the
SelfDevID.
The second assumption is that the device has a QR code printed on the
outside of the unit, and/or provided with the packaging/
documentation. The QR code is as specified in section 5.3 of [dpp],
with the additions specified in Section 6.1
The third assumption is that the AR, at manufacturing time, has the
anchor for it's MASA (same assumption as for BRSKI pledge's). In
addition, like the BRSKI pledge, the AR has an IDevID certificate
(and associated private key) signed by the manufacturer.
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The fourth assumption is that the key in the "K:" attribute
Section 6.1 is a different public key pair. It MUST be different
from the key used in the IDevID. This key is called the DPP-Keypair.
5. Protocol Overview
This is the overview of the process. {EDNOTE: there are many details
here that belong in the next section. The goal in this section is to
consisely explain the interaction among the components. Clearly this
text currently fails in that regard}
5.1. Scan the QR code
The operator of the smartphone invokes the smarkaklink application,
and scans the QR code on the AR. The smartphone learns the ESSID,
Public-Key, mac-address, smarkaklink URL, and link-local address of
the AR.
5.2. Enroll with the manufacturer
The smartphone uses it's 3G, or other WiFi internet access to connect
to the manufacturer with TLS. The manufacturer is identified with
the smartpledge URL.
The operator of the smartphone may need to move to another location
to get connectivity. It is desireable that an operator be able to
scan many QR codes before moving, performing this operation in a
batch. There may be multiple devices from the same manufacturer, and
the smarkalink application SHOUld enroll with the manufacturer a
single time for all devices.
The smartphone does an HTTP POST to the provided URL using it's
generated certificate as it's ClientCertificate. As described in
Section 7, the manufacturer MAY respond with a 302 result code, and
have the end user go through a web browser based process to enroll.
After that process, a redirection will occur using OAUTH2.
The result should finally be a 201 result code, and at that URL is a
new certificate signed by the manufacturer.
5.3. Connect to BRSKI join network
The application then reconnects the Wi-Fi interface of the smartphone
to the ESSID of the AR. This involves normal 802.11 station
attachment. The given ESSID explicitely has no WPA or other security
required on it.
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There will be no DHCPv4 on this network. This simplifies the
operation of the devices that are enrolling, but it also makes the
network uninteresting to other random users that may stumble upon the
open ESSID.
A IPv6 Router Solicitation may elicit an answer (confirming the
device is there), but it is acceptable for there to be no prefix
information. An IPv6 Neighbour Discovery is done for the IPv6 Link-
Local address of the AR. Receipt of an answer confirms that the
ESSID is correct and present.
(XXX - not using GRASP here. Could use GRASP, but QR code is better)
5.4. Connect to Adolescent Registrar (AR)
The smarkaklink application then makes a direct (no proxy) TLS
connection to port 8443 (!XXX!) of the AR, on the IPv6 Link-Local
address given. This is as in section 5.1 of
[I-D.ietf-anima-bootstrapping-keyinfra]. The smartphone uses it's
SelfDevID as the TLS ClientCertificate, as the smartphone and
smarkaklink will not have a manufacturer signed IDevID.
Additionally, the AR will use it's IDevID certificate as the
ServerCertificate of the TLS conncetion. As with other BRSKI IDevID,
it will have a MASA URL extension, as described in
[I-D.ietf-anima-bootstrapping-keyinfra] section 2.3.2.
The Adolescent Registrar acts in the role of pledge!
5.5. Pledge Requests Voucher-Request from the Adolescent Registrar
The smartphone generates a random nonce _SPnonce_. To this is added
SOMETHING-that-is-time-unique, to create a _voucher-request
challenge_. This is placed in the voucher-challenge-nonce field.
Using the public-key of the AR that was scanned from the QR code, the
smartphone encrypts the challenge using CMS (or COSE?).
NOTE: DPP has a round with the SHA256 of the device's key to make
sure that the correct device has been chosen. The TLS connection
effectively provides the same privacy that the Bx keys provided.
The resulting object is POST'ed to the new BRSKI endpoint:
/.well-known/est/requestvoucherrequest
[or should it be named: /.well-known/est/requestvoucherchallenge
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]
5.6. AR processing of voucher-request, request.
The AR processes this POST. First it uses the private key that is
associated with it's QR printed public key to decrypt the voucher-
request challenge. Included in this challenge is a nonce, and also
the link-local address of the smartphone.
The AR SHOULD verify that the link-local address matches the
originating address of the connection on which the request is
received.
The AR then forms a voucher-request identically to as described in
section 5.2 of [I-D.ietf-anima-bootstrapping-keyinfra]. Note that
the AR uses it's IDevID to sign the voucher-request. This is the
same key used to terminate the TLS connection.
Note: It MUST be different from the public key printed in the QR
code.
In addition to the randomly generated nonce that the AR generates to
place in the the voucher-request, into the nonce field, it also
includes the _SPnonce_ in a new _voucher-challenge-nonce_ field.
{EDNOTE: hash of nonce?}
This voucher-request is then _returned_ during the POST operation to
the smartphone. (This is in constrast that in ANIMA the voucher-
request is sent by the device to the Registrar, or the MASA)
5.6.1. Additions to Voucher-Request
QUESTION: should the _voucher-challenge-nonce_ be provided directly
in the voucher-request, or should only a hash of the nonce be used?
The nonce is otherwise not disclosed, and a MITM on the initial TLS
connection would get to see the nonce. A hash of the nonce validates
the nonce as easily.
5.7. Smartphone validates connection
The smartphone then examines the resulting voucher-request. The
smartphone validates that the voucher-request is signed by the same
public key as was seen in the TLS ServerCertificate.
The smartphone then examines the contents of the voucher-request, and
looks for the _voucher-challenge-nonce_. As this nonce was encrypted
to the AR, the only way that the resulting nonce could be correct is
if the correct private key was present on the AR to decrypt it.
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Succesful verification of the _voucher-challenge-nonce_ (or the hash
of it, see below) results in the smartphone moving it's end of the
connection from provisional to validated.
5.8. Smart-Phone connects to MASA
The smarkaklink application running on the smartphone then examines
the MASA URL provided in the TLS ServerCertificate of the AR. The
smarkaklink application then connects to that URL using it's 3G/LTE
connection, taking on the temporary role of Registrar.
A wrapped voucher-request is formed by the smartphone in the same way
as described in section 5.4 of
[I-D.ietf-anima-bootstrapping-keyinfra]. The prior-signed-voucher-
request is filled in with the voucher-request that was created by the
AR in the previous step.
The proximity-registrar-cert of the wrapped voucher-request is set to
be the SelfDevID certificate of the smartphone. The voucher-request
is to be signed by the SelfDevID.
The voucher-request is POST'ed to the MASA using the same URL that is
used for Registrar/MASA operation:
/.well-known/est/requestvoucher
5.9. MASA processing
The MASA processing occurs as specified in section 5.5 of
[I-D.ietf-anima-bootstrapping-keyinfra] as before. The MASA MUST
also copy the _voucher-challenge-nonce_ into the resulting voucher.
5.10. Smartpledge processing of voucher
The smartphone will receive a voucher that contains it's IDevID as
the _pinned-domain-cert_, and the _voucher-challenge-nonce_ that it
created will also be present. The smartphone SHOULD verify the
signature on the artifact, but may be unable to validate that the
certificate used has a relationship to the TLS ServerCertificate used
by the MASA. (This limitation exists in ANIMA as well).
The smartphone will then POST the resulting voucher to the AR using
the URL
/.well-known/est/voucher
If an existing TLS connection is still available, it MAY be reused.
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If a TLS session-resumption ticket (see [RFC8446] section 2.2 for TLS
1.3, and [RFC5077] for TLS 1.2) has been obtained, it SHOULD be used
if the TLS connection needs to be rebuilt. This is particularly
useful in the disconnected use case explained in Section 1.1.
5.11. Adolescent Registrar (AR) receives voucher
When the AR receives the voucher, it validates that it is signed by
it's manufacturer. This process is the same as section 5.5.1 of
[I-D.ietf-anima-bootstrapping-keyinfra].
Again note that the AR is acting in the role of a pledge.
Inside the voucher, the pinned-domain-cert is examined. It should
match the TLS ClientCertificate that the smartphone used to connect.
This is the SelfDevID.
At this point the AR has validated the identity of the smartphone,
and the AR moves it's end of the connection from provisional to
validated.
5.12. Adolescent Registrar (AR) grows up
The roles are now changed.
If necessary, the AR generates a new key pair as it's Domain CA key.
It MAY generate intermediate CA certificates and a seperate Registrar
certificate, but this is discouraged for home network use.
The AR is now considered a full registrar. The AR now takes on the
role of Registrar.
5.13. Smartphone enrolls
At this stage of the smarkaklink protocol, the typical BRSKI exchange
is over. A Secure Transport has been established between the
smartphone and the fully-grown AR. The smartphone now takes on the
role of secured pledge, or EST client.
The smartphone MUST now request the full list of CA Certificates, as
per [RFC7030] section 4.1. As the Registrar's CA certificate has
just been generated, the smartphone has no other way of knowing it.
The smartphone MUST now also generate a CSR request as per
[I-D.ietf-anima-bootstrapping-keyinfra] section 5.8.3. The
smartpledge MAY reuse the SelfDevID key pair for this purpose. (XXX
- maybe there are good reasons not to reuse?)
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The Registrar SHOULD grant administrator privileges to the smartphone
via the certificate that is issued. This may be done via special
attributes in the issued certificate, or it may pin the certificate
in a database. Which method to use is a local matter.
The TLS/EST connection MUST remain open at this point. This is
connection one.
5.14. Validation of connection
The smartphone MUST now open a new HTTPS connection to the Registrar
(AR), using it's newly issued certificate. (XXX should this be on a
different IP, or a different port? If so, how is this indicated?)
The smartphone MUST validate that the new connection's TLS Server
certificate can be validated by the Registrar's new CA certificate.
The registrar MUST validate that the smartphone's ClientCertificate
is validated by the Registrar's CA. The smartphone SHOULD perform a
POST operation on this new connection to the
[I-D.ietf-anima-bootstrapping-keyinfra] Enrollment Status Telemetry
mechanism, see section 5.8.3.
Upon success, the original TLS/EST connection (one) MAY now be
closed.
Should the validations above fail, then the original EST connection
MUST be used to GET a value from the
/.well-known/est/enrollstatus
from the Registrar. The contents of this value SHOULD then be sent
to the MASA, using a POST to the enrollstatus, and including the
reply from the AR in a new attribute, "adolescent-registrar-reason".
6. Protocol Details
6.1. Quick Response Code (QR code)
Section 5.3 of [dpp] describes the contents for an [iso18004] image.
It specifies content that starts with DPP:, and the contains a series
of semi-colon (;) deliminated section with a single letter and colon.
This markup is terminated with a double semi-colon.
Although no amending formula is defined in DPP 1.0, this document is
defining two extensions. This requires amending the ABNF from
section 5.2.1 as follows:
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dpp-qr = "DPP:" [channel-list ";"] [channel-list ";"]
[mac ";"] [information ";"] public-key
[";" llv6-addr ] [";" mudurl ]
[";" smarkaklink ] [";" essid ] ";;"
llv6-addr = "L:" 8*hex-octet
essid = "E:" *(%x20-3A / %x3C-7E) ; semicolon not allowed
smarkaklink = "S:" *(%x20-3A / %x3C-7E) ; semicolon not allowed
mudurl = "D:" *(%x20-3A / %x3C-7E) ; semicolon not allowed
While the ABNF defined in the [dpp] document assumes a specific order
(C:, M:, I:, K:), this specification relaxes this so that the tags
can come in any order. However, in order to make interoperation with
future DPP-only clients as seamless as possible, the extensions
suggested here are placed at the end of the list. This is consistent
with the Postel Principle.
It is intended that parts of this protocol could be performed by an
actual DPP implementation, should it become possible to implement DPP
using current smartphone operating systems in an unprivileged way.
6.1.1. The Smarkaklink Attribute
The _smarkaklink_ attribute indicates that the device is capable of
the protocol specified in this document. The contents of the
smarkaklink attribute contains part or all of an IRI which identifies
the manufacturer of the device.
It SHOULD contain the _iauthority_ of an IRI as specified in section
2.2 of [RFC3987]. The scheme is implicitely "https://", with an
ipath of "/.well-known/est/smarkaklink". This implicit form exists
to save bytes in the QR code.
If the string contains any "/" characters, then it is not an
_iauthority_, but an entire IRI. This takes many more characters,
but is useful in a variety of debugging situations, and also provides
for new innovations.
Short URLs are important to fit into typical QR code space.
6.1.2. Link-Layer Address Attribute
The _llv6-addr_ attribute is optional. When present, it specifies
the IPv6 Link-Local address at which the adolescent router is
listening. If not specified, then the link-local address may be
formed according to the historical (privacy-violating) process
described in [RFC4291] Appendix A. The _llv6-addr_ attribute is
present so that devices that have implemented [RFC7217] stable
addresses can express that address clearly.
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6.1.3. ESSID Name Attribute
The _essid_ attribute provides the name of the 802.11 network on
which the enrollment will occur. If this attribute is absent, then
it defaults to "BRSKI".
6.2. Enrollment using EST
TBD
7. Smart Pledge enrollment with manufacturer
While it is assumed that there will be many makers of Smarkaklink
applications, a goal of this specification is to eliminate the need
for an "app" per device, providing onboarding mechanism for a variety
of devices from a single app.
Given the secondary goal of a transition to use of Device
Provisioning Protocol (DPP), the smarkaklink application may have to
be provided as part of the smart phone system, as a system service.
This is due to the need to send/receive wifi management frames from
DPP. As such each vendor of a smart device will need to produce a
smarkaklink app, and it will be impossible for the vendor of the
Registrar device (or other DPP capable IoT device) to provide an app
on their own.
Having stated this goal, it is understood that initially the app may
well come from the manufacturer of the Registrar, but this protocol
is designed on the assumption that there is no such vertical
integration.
So, there can be no initial relationship between the Smart Pledge and
the manufacturer of the Registrar.
But, in a traditional [I-D.ietf-anima-bootstrapping-keyinfra]
scenario the pledge would have been provided with an IDevID at
manufacturing time. While an IDevID could have been built-in to the
SmartPledge "app", such a key would not be private if it was built-
in. A key could be generated by the app upon installation. It could
be self-signed, it could be signed by the maker of the app, or it
could be signed by another party.
o a self-signed certificate is just a container for a public key.
For the purposes of the trust relationship with the Registrar, it
would be sufficient.
o a certificate signed by the maker of the app (or the maker of the
smart-phone) would carry no specific trust beyond what a self-
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signed certificate would have. Any linking in the certificate to
a network expressable identity (such as layer-2 address) would
simply be a privacy violation.
o a certificate signed by another party would similarly have little
additional relevance, unless the third party is the manufacturer
of the Registrar!
The smarkaklink enrollment process uses a combination of the first
and third choice. The involvement of the manufacturer at this step
affords an opporuntity to do sales-channel integration with the
manufacturer. The manufacturer can associate an account with the
user using a wide variety of OAUTH2 [RFC6749] processes. In
addition, based upon the URL provided the manufacturer can do
redirection along a value-added reseller process. For instance, the
manufacturer of a home router could redirect the pledge to the ISP
that resold the router.
While [RFC7030] describes a Certificate Signing Request in order to
have a certificate assigned, the actual contents of the certificate
are not interesting at all, and the process of attempting to come up
with a meaningful contents tends to cause more interoperability
issues than having nothing.
The Smarkaklink takes the _smartpledge attribute_ from the QR code,
forming a URL as describe above. An HTTPS POST is performed to this
URL, with the JSON body of:
{
"mac" : <mac-address>
}
The HTTPS POST MUST be performed with freshly created self-signed
certificate. If the smarkaklink application has previously
communicated with this URL, it MAY skip this step and use a
previously returned certificate. Doing so has a privacy implication
discussed below, but is appropriate when enrolling many devices from
the same manufacturer into the same network.
The smarkaklink client should be prepared for three cases:
o A certificate is immediately returned.
o A 201 status code is returned, and Location: header is provided.
A GET request to that location will retrieve the certificate.
o A 302 redirection occurs with some initiation of an OAUTH2 process
to establish some additional authorization.
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o Any other error (4xx and 5xx) are typically unrecoverable errors.
In the third case, the 302 response SHOULD take the smarkaklink
operator to the given URL in an interactive browser. The operator
SHOULD be given access to their normal set of cookies and third-party
logins such that they can use appropriate third party (Google,
Facebook, Github, Live.com, etc.) logins to help validate the
operator as a real person, and not a malware. Such logins are
optional, and it is a manufacturer choice as to what integrations
they want to make.
After the OAUTH2 process, the SmartPledge will be redirected back to
the MASA and a 201 status code will be returned when successful as
above.
7.1. minimal Smart Pledge enrollment
A manufacturer who has not built-in any restrictions on the identity
that the smarkaklink uses, MAY return the same self-signed
certificate that the smartpledge used to connect with.
8. Threat Analysis
The following attacks have been considered.
8.1. Wrong Administrator
Neighbours with similar setups wind up managing each other's network
(by mistake).
8.2. Rogue Administrator
Uninitialized networks can be adopted by 'wardrivers' who search for
networks that have no administrator.
8.3. Attack from Internal device
A compromised device inside the home can be used by an attack to take
control of the home router.
8.4. Attack from camera enabled robot
A robot (such as a home vacuum cleaner) could be compromised, and
then used by an attacker to observe and/or scan the router QRcode.
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8.5. Attack from manipulator enabled robot
A robot (for instance, a toy) could be compromised, and then used by
an attacker to push the WPA and/or factory reset button on the
router.
9. Security Considerations
XXX: Go through the list of attacks above, and explain how each has
been mitigated.
Go through the list of concerns in ANIMA and EST-RFC7030 and indicate
if there are additional concerns, or if a concern does not apply.
10. IANA Considerations
TBD.
11. Acknowledgements
This work was supported by the Canadian Internet Registration
Authority https://cira.ca/blogs/cira-labs/about-cira-labs.
12. References
12.1. Normative References
[dpp] "Device Provisioning Protocol Specification", n.d.,
<https://www.wi-fi.org/downloads-registered-guest/Device_P
rovisioning_Protocol_Draft_Technical_Specification_Package
_v0_0_23_0.zip/31255>.
[I-D.ietf-anima-bootstrapping-keyinfra]
Pritikin, M., Richardson, M., Behringer, M., Bjarnason,
S., and K. Watsen, "Bootstrapping Remote Secure Key
Infrastructures (BRSKI)", draft-ietf-anima-bootstrapping-
keyinfra-18 (work in progress), January 2019.
[iso18004]
"Information technology --- Automatic identification and
data capture techniques --- Bar code symbology --- QR
Codes (ISO/IEC 18004:2015)", n.d.,
<https://github.com/yansikeim/QR-Code/blob/master/
ISO%20IEC%2018004%202015%20Standard.pdf>.
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[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>.
[RFC3987] Duerst, M. and M. Suignard, "Internationalized Resource
Identifiers (IRIs)", RFC 3987, DOI 10.17487/RFC3987,
January 2005, <https://www.rfc-editor.org/info/rfc3987>.
[RFC7030] Pritikin, M., Ed., Yee, P., Ed., and D. Harkins, Ed.,
"Enrollment over Secure Transport", RFC 7030,
DOI 10.17487/RFC7030, October 2013,
<https://www.rfc-editor.org/info/rfc7030>.
12.2. Informative References
[RFC4291] Hinden, R. and S. Deering, "IP Version 6 Addressing
Architecture", RFC 4291, DOI 10.17487/RFC4291, February
2006, <https://www.rfc-editor.org/info/rfc4291>.
[RFC5077] Salowey, J., Zhou, H., Eronen, P., and H. Tschofenig,
"Transport Layer Security (TLS) Session Resumption without
Server-Side State", RFC 5077, DOI 10.17487/RFC5077,
January 2008, <https://www.rfc-editor.org/info/rfc5077>.
[RFC6749] Hardt, D., Ed., "The OAuth 2.0 Authorization Framework",
RFC 6749, DOI 10.17487/RFC6749, October 2012,
<https://www.rfc-editor.org/info/rfc6749>.
[RFC7217] Gont, F., "A Method for Generating Semantically Opaque
Interface Identifiers with IPv6 Stateless Address
Autoconfiguration (SLAAC)", RFC 7217,
DOI 10.17487/RFC7217, April 2014,
<https://www.rfc-editor.org/info/rfc7217>.
[RFC8446] Rescorla, E., "The Transport Layer Security (TLS) Protocol
Version 1.3", RFC 8446, DOI 10.17487/RFC8446, August 2018,
<https://www.rfc-editor.org/info/rfc8446>.
Appendix A. Resulting DPP QR code specification
This is a merge of the additions from section Section 6.1 and section
5.2.1 of [dpp]:
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dpp-qr = "DPP:" [channel-list ";"]
[";" llv6-addr ] [";" mudurl ]
[";" smarkaklink ] [";" essid ] ";;"
llv6-addr = "L:" 8*hex-octet
essid = "E:" *(%x20-3A / %x3C-7E) ; semicolon not allowed
smarkaklink = "S:" *(%x20-3A / %x3C-7E) ; semicolon not allowed
mudurl = "D:" *(%x20-3A / %x3C-7E) ; semicolon not allowed
pkex-bootstrap-info = [information]
channel-list = "C:" class-and-channels *("," class-and-channels)
class-and-channels = class "/" channel *("," channel)
class = 1*3DIGIT
channel = 1*3DIGIT
mac = "M:" 6hex-octet ; MAC address
hex-octet = 2HEXDIG
information = "I:" *(%x20-3A / %x3C-7E) ; semicolon not allowed
public-key = "K:" *PKCHAR
; DER of ASN.1 SubjectPublicKeyInfo encoded in
; "base64" as per [14]
PKCHAR = ALPHA / DIGIT / %x2b / %x2f / %x3d
llv6-addr = "L:" 8*hex-octet
essid = "E:" *(%x21-3A / %x3C-7E) ; semicolon not allowed
smartpledge = "S:" *(%x21-3A / %x3C-7E) ; semicolon not allowed
Appendix B. Swagger.IO definition of API
This is a work-in-progress definition of the smarkaklink to MASA API
in the form of Swagger.IO format:
---
swagger: "2.0"
info:
description: |
The smartpledge API is described in detail in
draft-richardson-anima-smartpledge. This API is
a variation of BRSKI (draft-ietf-anima-bootstrapping-keyinfra)
which provides an initial bootstrap of the
Secure Home Gateway registrar.
version: 1.0.0
title: Secure Home Gateway secure enrollment API (smartpledge-BRSKI)
contact:
email: securehomegateway@cira.ca
license:
name: Apache 2.0
url: http://www.apache.org/licenses/LICENSE-2.0.html
host: virtserver.swaggerhub.com
basePath: /CIRALabs/smartpledge/1.0.0
tags:
- name: est
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description: Enrollment over Secure Transport
schemes:
- https
paths:
/voucherrequest:
get:
tags:
- developers
summary: searches inventory
description: |
By passing in the appropriate options, you can search for
available inventory in the system
operationId: searchInventory
produces:
- application/json
parameters:
- name: searchString
in: query
description: |
pass an optional search string for looking up inventory
required: false
type: string
- name: skip
in: query
description: number of records to skip for pagination
required: false
type: integer
minimum: 0
format: int32
- name: limit
in: query
description: maximum number of records to return
required: false
type: integer
maximum: 50
minimum: 0
format: int32
responses:
200:
description: search results matching criteria
schema:
type: array
items:
$ref: '#/definitions/InventoryItem'
400:
description: bad input parameter
post:
tags:
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- admins
summary: adds an inventory item
description: Adds an item to the system
operationId: addInventory
consumes:
- application/json
produces:
- application/json
parameters:
- in: body
name: inventoryItem
description: Inventory item to add
required: false
schema:
$ref: '#/definitions/InventoryItem'
responses:
201:
description: item created
400:
description: invalid input, object invalid
409:
description: an existing item already exists
definitions:
InventoryItem:
type: object
required:
- id
- manufacturer
- name
- releaseDate
properties:
id:
type: string
format: uuid
example: d290f1ee-6c54-4b01-90e6-d701748f0851
name:
type: string
example: Widget Adapter
releaseDate:
type: string
format: date-time
example: 2016-08-29T09:12:33.001Z
manufacturer:
$ref: '#/definitions/Manufacturer'
Manufacturer:
required:
- name
properties:
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name:
type: string
example: ACME Corporation
homePage:
type: string
format: url
example: https://www.acme-corp.com
phone:
type: string
example: 408-867-5309
Authors' Addresses
Michael Richardson
Sandelman Software Works
Email: mcr+ietf@sandelman.ca
Jacques Latour
CIRA Labs
Email: Jacques.Latour@cira.ca
Faud Khan
Twelve Dot Systems
Email: faud.khan@twelvedot.com
Abhishek Joshi
Twelve Dot Systems
Email: abhishek.joshi@twelvedot.com
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