Constrained Join Proxy for Bootstrapping Protocols
draft-ietf-anima-constrained-join-proxy-02
anima Working Group M. Richardson
Internet-Draft Sandelman Software Works
Intended status: Standards Track P. van der Stok
Expires: August 8, 2021 vanderstok consultancy
P. Kampanakis
Cisco Systems
February 04, 2021
Constrained Join Proxy for Bootstrapping Protocols
draft-ietf-anima-constrained-join-proxy-02
Abstract
This document defines a protocol to securely assign a pledge to a
domain, represented by a Registrar, using an intermediary node
between pledge and Registrar. This intermediary node is known as a
"constrained Join Proxy".
This document extends the work of
[I-D.ietf-anima-bootstrapping-keyinfra] by replacing the Circuit-
proxy by a stateless/stateful constrained (CoAP) Join Proxy. It
transports join traffic from the pledge to the Registrar without
requiring per-client state.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
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This Internet-Draft will expire on August 8, 2021.
Copyright Notice
Copyright (c) 2021 IETF Trust and the persons identified as the
document authors. All rights reserved.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4
3. Requirements Language . . . . . . . . . . . . . . . . . . . . 4
4. Join Proxy functionality . . . . . . . . . . . . . . . . . . 4
5. Join Proxy specification . . . . . . . . . . . . . . . . . . 5
5.1. Statefull Join Proxy . . . . . . . . . . . . . . . . . . 5
5.2. Stateless Join Proxy . . . . . . . . . . . . . . . . . . 6
5.3. Stateless Message structure . . . . . . . . . . . . . . . 8
6. Comparison of stateless and statefull modes . . . . . . . . . 9
7. Discovery . . . . . . . . . . . . . . . . . . . . . . . . . . 10
7.1. Pledge discovery of Registrar . . . . . . . . . . . . . . 11
7.1.1. CoAP discovery . . . . . . . . . . . . . . . . . . . 11
7.1.2. Autonomous Network . . . . . . . . . . . . . . . . . 11
7.1.3. 6tisch discovery . . . . . . . . . . . . . . . . . . 11
7.2. Pledge discovers Join Proxy . . . . . . . . . . . . . . . 11
7.2.1. Autonomous Network . . . . . . . . . . . . . . . . . 12
7.2.2. CoAP discovery . . . . . . . . . . . . . . . . . . . 12
7.3. Join Proxy discovers Registrar join port . . . . . . . . 12
7.3.1. CoAP discovery . . . . . . . . . . . . . . . . . . . 12
8. Security Considerations . . . . . . . . . . . . . . . . . . . 13
9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 13
9.1. Resource Type registry . . . . . . . . . . . . . . . . . 13
10. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 14
11. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 14
12. Changelog . . . . . . . . . . . . . . . . . . . . . . . . . . 14
12.1. 01 to 02 . . . . . . . . . . . . . . . . . . . . . . . . 14
12.2. 00 to 01 . . . . . . . . . . . . . . . . . . . . . . . . 14
12.3. 00 to 00 . . . . . . . . . . . . . . . . . . . . . . . . 14
13. References . . . . . . . . . . . . . . . . . . . . . . . . . 14
13.1. Normative References . . . . . . . . . . . . . . . . . . 14
13.2. Informative References . . . . . . . . . . . . . . . . . 16
Appendix A. Stateless Proxy payload examples . . . . . . . . . . 17
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 17
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1. Introduction
Enrolment of new nodes into networks with enrolled nodes present is
described in [I-D.ietf-anima-bootstrapping-keyinfra] ("BRSKI") and
makes use of Enrolment over Secure Transport (EST) [RFC7030] with
[RFC8366] vouchers to securely enroll devices. BRSKI connects new
devices ("pledges") to "Registrars" via a Join Proxy.
The specified solutions use https and may be too large in terms of
code space or bandwidth required for constrained devices.
Constrained devices possibly part of constrained networks [RFC7228]
typically implement the IPv6 over Low-Power Wireless personal Area
Networks (6LoWPAN) [RFC4944] and Constrained Application Protocol
(CoAP) [RFC7252].
CoAP can be run with the Datagram Transport Layer Security (DTLS)
[RFC6347] as a security protocol for authenticity and confidentiality
of the messages. This is known as the "coaps" scheme. A constrained
version of EST, using Coap and DTLS, is described in
[I-D.ietf-ace-coap-est]. The {I-D.ietf-anima-constrained-voucher}
describes the BRSKI extensions to the Registrar.
DTLS is a client-server protocol relying on the underlying IP layer
to perform the routing between the DTLS Client and the DTLS Server.
However, the new "joining" device will not be IP routable until it is
authenticated to the network. A new "joining" device can only
initially use a link-local IPv6 address to communicate with a
neighbour node using neighbour discovery [RFC6775] until it receives
the necessary network configuration parameters. However, before the
device can receive these configuration parameters, it needs to
authenticate itself to the network to which it connects. IPv6
routing is necessary to establish a connection between joining device
and the Registrar.
A DTLS connection is required between Pledge and Registrar.
This document specifies a new form of Join Proxy and protocol to act
as intermediary between joining device and Registrar to establish a
connection between joining device and Registrar.
This document is very much inspired by text published earlier in
[I-D.kumar-dice-dtls-relay].
[I-D.richardson-anima-state-for-joinrouter] outlined the various
options for building a join proxy.
[I-D.ietf-anima-bootstrapping-keyinfra] adopted only the Circuit
Proxy method (1), leaving the other methods as future work. This
document standardizes the CoAP/DTLS (method 4).
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2. Terminology
The following terms are defined in [RFC8366], and are used
identically as in that document: artifact, imprint, domain, Join
Registrar/Coordinator (JRC), Manufacturer Authorized Signing
Authority (MASA), pledge, Trust of First Use (TOFU), and Voucher.
3. Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in
BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
4. Join Proxy functionality
As depicted in the Figure 1, the joining Device, or pledge (P), in an
LLN mesh can be more than one hop away from the Registrar (R) and not
yet authenticated into the network.
In this situation, it can only communicate one-hop to its nearest
neighbour, the Join Proxy (J) using their link-local IPv6 addresses.
However, the Pledge (P) needs to communicate with end-to-end security
with a Registrar hosting the Registrar (R) to authenticate and get
the relevant system/network parameters. If the Pledge (P) initiates
a DTLS connection to the Registrar whose IP address has been pre-
configured, then the packets are dropped at the Join Proxy (J) since
the Pledge (P) is not yet admitted to the network or there is no IP
routability to Pledge (P) for any returned messages.
++++ multi-hop
|R |---- mesh +--+ +--+
| | \ |J |........|P |
++++ \-----| | | |
+--+ +--+
Registrar Join Proxy Pledge
"Joining" Device
Figure 1: multi-hop enrolment.
Without routing the Pledge (P) cannot establish a secure connection
to the Registrar (R) in the network assuming appropriate credentials
are exchanged out-of-band, e.g. a hash of the Pledge (P)'s raw public
key could be provided to the Registrar (R).
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Furthermore, the Pledge (P) may be unaware of the IP address of the
Registrar (R) to initiate a DTLS connection and perform
authentication.
To overcome the problems with non-routability of DTLS packets and/or
discovery of the destination address of the EST Server to contact,
the Join Proxy is introduced. This Join Proxy functionality is
configured into all authenticated devices in the network which may
act as the Join Proxy for newly joining nodes. The Join Proxy allows
for routing of the packets from the Pledge using IP routing to the
intended Registrar.
5. Join Proxy specification
A Join Proxy can operate in two modes:
o Statefull mode
o Stateless mode
5.1. Statefull Join Proxy
In stateful mode, the joining node forwards the DTLS messages to the
Registrar.
Assume that the Pledge does not know the IP address of the Registrar
it needs to contact. The Join Proxy has has been enrolled via the
Registrar and consequently knows the IP address and port of the
Registrar. The Pledge first discovers and selects the most
appropriate Join Proxy. (Discovery can be based upon
[I-D.ietf-anima-bootstrapping-keyinfra] section 4.3, or via DNS-SD
service discovery [RFC6763]). The Pledge initiates its request as if
the Join Proxy is the intended Registrar. The Join Proxy receives
the message at a discoverable "Join" port. The Join Proxy changes
the IP packet (without modifying the DTLS message) by modifying both
the source and destination addresses to forward the message to the
intended Registrar. The Join Proxy maintains a 4-tuple array to
translate the DTLS messages received from the Registrar and forward
it to the EST Client. This is a form of Network Address translation,
where the Join Proxy acts as a forward proxy. In Figure 2 the
various steps of the message flow are shown, with 5684 being the
standard coaps port:
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+------------+------------+-------------+--------------------------+
| Pledge | Join Proxy | Registrar | Message |
| (P) | (J) | (R) | Src_IP:port | Dst_IP:port|
+------------+------------+-------------+-------------+------------+
| --ClientHello--> | IP_P:p_P | IP_Ja:p_J |
| --ClientHello--> | IP_Jb:p_Jb| IP_R:5684 |
| | | |
| <--ServerHello-- | IP_R:5684 | IP_Jb:p_Jb |
| : | | |
| <--ServerHello-- : | IP_Ja:p_J | IP_P:p_P |
| : : | | |
| : : | : | : |
| : : | : | : |
| --Finished--> : | IP_P:p_P | IP_Ja:p_J |
| --Finished--> | IP_Jb:p_Jb| IP_R:5684 |
| | | |
| <--Finished-- | IP_R:5684 | IP_Jb:p_Jb |
| <--Finished-- | IP_Ja:p_J | IP_P:p_P |
| : : | : | : |
+---------------------------------------+-------------+------------+
IP_P:p_P = Link-local IP address and port of Pledge (DTLS Client)
IP_R:5684 = Global IP address and coaps port of Registrar
IP_Ja:P_J = Link-local IP address and join port of Join Proxy
IP_Jb:p_Rb = Global IP address and client port of Join proxy
Figure 2: constrained statefull joining message flow with Registrar
address known to Join Proxy.
5.2. Stateless Join Proxy
The stateless Join Proxy aims to minimize the requirements on the
constrained Join Proxy device. Stateless operation requires no
memory in the Join Proxy device, but may also reduce the CPU impact
as the device does not need to search through a state table.
If an untrusted Pledge that can only use link-local addressing wants
to contact a trusted Registrar, and the Registrar is more than one
hop away, it sends the DTLS message to the Join Proxy.
When a Pledge attempts a DTLS connection to the Join Proxy, it uses
its link-local IP address as its IP source address. This message is
transmitted one-hop to a neighbouring (Join Proxy) node. Under
normal circumstances, this message would be dropped at the neighbour
node since the Pledge is not yet IP routable or is not yet
authenticated to send messages through the network. However, if the
neighbour device has the Join Proxy functionality enabled, it routes
the DTLS message to its Registrar of choice.
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The Join Proxy extends this message into a new type of message called
Join ProxY (JPY) message and sends it on to the Registrar.
The JPY message payload consists of two parts:
o Header (H) field: consisting of the source link-local address and
port of the Pledge (P), and
o Contents (C) field: containing the original DTLS message.
On receiving the JPY message, the Registrar retrieves the two parts.
The Registrar transiently stores the Header field information. The
Registrar uses the Contents field to execute the Registrar
functionality. However, when the Registrar replies, it also extends
its DTLS message with the header field in a JPY message and sends it
back to the Join Proxy. The Registrar SHOULD NOT assume that it can
decode the Header Field, it should simply repeat it when responding.
The Header contains the original source link-local address and port
of the pledge from the transient state stored earlier and the
Contents field contains the DTLS message.
On receiving the JPY message, the Join Proxy retrieves the two parts.
It uses the Header field to route the DTLS message retrieved from the
Contents field to the Pledge.
In this scenario, both the Registrar and the Join Proxy use
discoverable "Join" ports.
The Figure 3 depicts the message flow diagram:
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+--------------+------------+---------------+-----------------------+
| EST Client | Join Proxy | Registrar | Message |
| (P) | (J) | (R) |Src_IP:port|Dst_IP:port|
+--------------+------------+---------------+-----------+-----------+
| --ClientHello--> | IP_P:p_P |IP_Ja:p_Ja |
| --JPY[H(IP_P:p_P),--> | IP_Jb:p_Jb|IP_R:p_Ra |
| C(ClientHello)] | | |
| <--JPY[H(IP_P:p_P),-- | IP_R:p_Ra |IP_Jb:p_Jb |
| C(ServerHello)] | | |
| <--ServerHello-- | IP_Ja:p_Ja|IP_P:p_P |
| : | | |
| : | : | : |
| | : | : |
| --Finished--> | IP_P:p_P |IP_Ja:p_Ja |
| --JPY[H(IP_P:p_P),--> | IP_Jb:p_Jb|IP_R:p_Ra |
| C(Finished)] | | |
| <--JPY[H(IP_P:p_P),-- | IP_R:p_Ra |IP_Jb:p_Jb |
| C(Finished)] | | |
| <--Finished-- | IP_Ja:p_Ja|IP_P:p_P |
| : | : | : |
+-------------------------------------------+-----------+-----------+
IP_P:p_P = Link-local IP address and port of the Pledge
IP_R:p_Ra = Global IP address and join port of Registrar
IP_Ja:p_Ja = Link-local IP address and join port of Join Proxy
IP_Jb:p_Jb = Global IP address and port of Join Proxy
JPY[H(),C()] = Join Proxy message with header H and content C
Figure 3: constrained stateless joining message flow.
5.3. Stateless Message structure
The JPY message is constructed as a payload with media-type
aplication/cbor
Header and Contents fields togther are one cbor array of 5 elements:
1. header field: containing a CBOR array [RFC7049] with the pledge
IPv6 Link Local address as a cbor byte string, the pledge's UDP
port number as a CBOR integer, the IP address family (IPv4/IPv6)
as a cbor integer, and the proxy's ifindex or other identifier
for the physical port as cbor integer. The header field is not
DTLS encrypted.
2. Content field: containing the DTLS encrypted payload as a CBOR
byte string.
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The join_proxy cannot decrypt the DTLS ecrypted payload and has no
knowledge of the transported media type.
JPY_message =
[
ip : bstr,
port : int,
family : int,
index : int
payload : bstr
]
Figure 4: CDDL representation of JPY message
The content fields are DTLS encrypted. In CBOR diagnostic notation
the payload JPY[H(IP_P:p_P)], will look like:
[h'IP_p', p_P, family, ident, h'DTLS-content']
Examples are shown in Appendix A.
6. Comparison of stateless and statefull modes
The stateful and stateless mode of operation for the Join Proxy have
their advantages and disadvantages. This section should enable to
make a choice between the two modes based on the available device
resources and network bandwidth.
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+-------------+----------------------------+------------------------+
| Properties | Stateful mode | Stateless mode |
+-------------+----------------------------+------------------------+
| State |The Join Proxy needs | No information is |
| Information |additional storage to | maintained by the Join |
| |maintain mapping between | Proxy. Registrar needs |
| |the address and port number | to store the packet |
| |of the pledge and those | header. |
| |of the Registrar. | |
+-------------+----------------------------+------------------------+
|Packet size |The size of the forwarded |Size of the forwarded |
| |message is the same as the |message is bigger than |
| |original message. |the original,it includes|
| | |additional source and |
| | |destination addresses. |
+-------------+----------------------------+------------------------+
|Specification|The Join Proxy needs |New JPY message to |
|complexity |additional functionality |encapsulate DTLS message|
| |to maintain state |The Registrar |
| |information, and modify |and the Join Proxy |
| |the source and destination |have to understand the |
| |addresses of the DTLS |JPY message in order |
| |handshake messages |to process it. |
+-------------+----------------------------+------------------------+
| Ports | Join Proxy needs |Join Proxy and Registrar|
| | discoverable "Join" port |need discoverable |
| | | "Join" ports |
+-------------+----------------------------+------------------------+
Figure 5: Comparison between stateful and stateless mode
7. Discovery
It is assumed that Join Proxy seamlessly provides a coaps connection
between Pledge and coaps Registrar. In particular this section
replaces section 4.2 of [I-D.ietf-anima-bootstrapping-keyinfra].
The discovery follows two steps:
1. The pledge is one hop away from the Registrar. The pledge
discovers the link-local address of the Registrar as described in
{I-D.ietf-ace-coap-est}. From then on, it follows the BRSKI
process as described in {I-D.ietf-ace-coap-est}, using link-local
addresses.
2. The pledge is more than one hop away from a relevant Registrar,
and discovers the link-local address and join port of a Join
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Proxy. The pledge then follows the BRSKI procedure using the
link-local address of the Join Proxy.
3. The stateless Join Proxy discovers the join port of the Registrar
Once a pledge is enrolled, it may function as Join Proxy. The Join
Proxy functions are advertised as descibed below. In principle, the
Join Proxy functions are offered via a "join" port, and not the
standard coaps port. Also the Registrar offer a "join" port to which
the stateless join proxy sends the JPY message. The Join Proxy and
Registrar MUST show the extra join port number when reponding to the
.well-known/core request addressed to the standard coap/coaps port.
Three discovery cases are discussed: coap discovery, 6tisch discovery
and GRASP discovery.
7.1. Pledge discovery of Registrar
The Pledge and Join Proxy are assumed to communicate via Link-Local
addresses.
7.1.1. CoAP discovery
The discovery of the coaps Registrar, using coap discovery, by the
Join Proxy follows section 6 of [I-D.ietf-ace-coap-est]. The
extension to discover the additional port needed by the stateless
proxy is described in Section 7.2.2.
7.1.2. Autonomous Network
In the context of autonomous networks, the Join Proxy uses the DULL
GRASP M_FLOOD mechanism to announce itself. Section 4.1.1 of
[I-D.ietf-anima-bootstrapping-keyinfra] discusses this in more
detail. The Registrar announces itself using ACP instance of GRASP
using M_FLOOD messages. Autonomous Network Join Proxies MUST support
GRASP discovery of Registrar as decribed in section 4.3 of
[I-D.ietf-anima-bootstrapping-keyinfra] .
7.1.3. 6tisch discovery
The discovery of Registrar by the pledge uses the enhanced beacons as
discussed in [I-D.ietf-6tisch-enrollment-enhanced-beacon].
7.2. Pledge discovers Join Proxy
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7.2.1. Autonomous Network
The pledge MUST listen for GRASP M_FLOOD [I-D.ietf-anima-grasp]
announcements of the objective: "AN_Proxy". See section
Section 4.1.1 [I-D.ietf-anima-bootstrapping-keyinfra] for the details
of the objective.
7.2.2. CoAP discovery
In the context of a coap network without Autonomous Network support,
discovery follows the standard coap policy. The Pledge can discover
a Join Proxy by sending a link-local multicast message to ALL CoAP
Nodes with address FF02::FD. Multiple or no nodes may respond. The
handling of multiple responses and the absence of responses follow
section 4 of [I-D.ietf-anima-bootstrapping-keyinfra].
The join port of the Join Proxy is discovered by sending a GET
request to "/.well-known/core" including a resource type (rt)
parameter with the value "brski-proxy" [RFC6690]. Upon success, the
return payload will contain the join port.
The example below shows the discovery of the join port of the Join
Proxy.
REQ: GET coap://[FF02::FD]/.well-known/core?rt=brski-proxy
RES: 2.05 Content
<coaps://[IP_address]:join-port>; rt="brski-proxy"
Port numbers are assumed to be the default numbers 5683 and 5684 for
coap and coaps respectively (sections 12.6 and 12.7 of [RFC7252] when
not shown in the response. Discoverable port numbers are usually
returned for Join Proxy resources in the <href> of the payload (see
section 5.1 of [I-D.ietf-ace-coap-est]).
7.3. Join Proxy discovers Registrar join port
7.3.1. CoAP discovery
The stateless Join Proxy can discover the join port of the Registrar
by sending a GET request to "/.well-known/core" including a resource
type (rt) parameter with the value "join-proxy" [RFC6690]. Upon
success, the return payload will contain the join Port of the
Registrar.
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REQ: GET coap://[IP_address]/.well-known/core?rt=brski-proxy
RES: 2.05 Content
<coaps://[IP_address]:join-port>; rt="join-proxy"
The discoverable port numbers are usually returned for Join Proxy
resources in the <href> of the payload (see section 5.1 of
[I-D.ietf-ace-coap-est]).
8. Security Considerations
It should be noted here that the contents of the CBOR map used to
convey return address information is not protected. However, the
communication is between the Proxy and a known registrar are over the
already secured portion of the network, so are not visible to
eavesdropping systems.
All of the concerns in [I-D.ietf-anima-bootstrapping-keyinfra]
section 4.1 apply. The pledge can be deceived by malicious AN_Proxy
announcements. The pledge will only join a network to which it
receives a valid [RFC8366] voucher.
If the proxy/Registrar was not over a secure network, then an
attacker could change the cbor array, causing the pledge to send
traffic to another node. If the such scenario needed to be
supported, then it would be reasonable for the Proxy to encrypt the
CBOR array using a locally generated symmetric key. The Registrar
would not be able to examine the result, but it does not need to do
so. This is a topic for future work.
9. IANA Considerations
This document needs to create a registry for key indices in the CBOR
map. It should be given a name, and the amending formula should be
IETF Specification.
9.1. Resource Type registry
This specification registers a new Resource Type (rt=) Link Target
Attributes in the "Resource Type (rt=) Link Target Attribute Values"
subregistry under the "Constrained RESTful Environments (CoRE)
Parameters" registry.
rt="brski-proxy". This BRSKI resource is used to query and return
the supported BRSKI port of the Join Proxy.
rt="join-proxy". This BRSKI resource is used to query and return
the supported BRSKI port of the Registrar.
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10. Acknowledgements
Many thanks for the comments by Brian Carpenter and Esko Dijk.
11. Contributors
Sandeep Kumar, Sye loong Keoh, and Oscar Garcia-Morchon are the co-
authors of the draft-kumar-dice-dtls-relay-02. Their draft has
served as a basis for this document. Much text from their draft is
copied over to this draft.
12. Changelog
12.1. 01 to 02
o Discovery of Join Proxy and Registrar ports
12.2. 00 to 01
o Registrar used throughout instead of EST server
o Emphasized additional Join Proxy port for Join Proxy and Registrar
o updated discovery accordingly
o updated stateless Join Proxy JPY header
o JPY header described with CDDL
o Example simplified and corrected
12.3. 00 to 00
o copied from vanderstok-anima-constrained-join-proxy-05
13. References
13.1. Normative References
[I-D.ietf-6tisch-enrollment-enhanced-beacon]
Dujovne, D. and M. Richardson, "IEEE 802.15.4 Information
Element encapsulation of 6TiSCH Join and Enrollment
Information", draft-ietf-6tisch-enrollment-enhanced-
beacon-14 (work in progress), February 2020.
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[I-D.ietf-ace-coap-est]
Stok, P., Kampanakis, P., Richardson, M., and S. Raza,
"EST over secure CoAP (EST-coaps)", draft-ietf-ace-coap-
est-18 (work in progress), January 2020.
[I-D.ietf-anima-bootstrapping-keyinfra]
Pritikin, M., Richardson, M., Eckert, T., Behringer, M.,
and K. Watsen, "Bootstrapping Remote Secure Key
Infrastructures (BRSKI)", draft-ietf-anima-bootstrapping-
keyinfra-45 (work in progress), November 2020.
[I-D.ietf-anima-constrained-voucher]
Richardson, M., Stok, P., and P. Kampanakis, "Constrained
Voucher Artifacts for Bootstrapping Protocols", draft-
ietf-anima-constrained-voucher-09 (work in progress),
November 2020.
[I-D.ietf-anima-grasp]
Bormann, C., Carpenter, B., and B. Liu, "A Generic
Autonomic Signaling Protocol (GRASP)", draft-ietf-anima-
grasp-15 (work in progress), July 2017.
[I-D.ietf-core-multipart-ct]
Fossati, T., Hartke, K., and C. Bormann, "Multipart
Content-Format for CoAP", draft-ietf-core-multipart-ct-04
(work in progress), August 2019.
[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>.
[RFC6347] Rescorla, E. and N. Modadugu, "Datagram Transport Layer
Security Version 1.2", RFC 6347, DOI 10.17487/RFC6347,
January 2012, <https://www.rfc-editor.org/info/rfc6347>.
[RFC7049] Bormann, C. and P. Hoffman, "Concise Binary Object
Representation (CBOR)", RFC 7049, DOI 10.17487/RFC7049,
October 2013, <https://www.rfc-editor.org/info/rfc7049>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>.
[RFC8366] Watsen, K., Richardson, M., Pritikin, M., and T. Eckert,
"A Voucher Artifact for Bootstrapping Protocols",
RFC 8366, DOI 10.17487/RFC8366, May 2018,
<https://www.rfc-editor.org/info/rfc8366>.
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13.2. Informative References
[I-D.kumar-dice-dtls-relay]
Kumar, S., Keoh, S., and O. Garcia-Morchon, "DTLS Relay
for Constrained Environments", draft-kumar-dice-dtls-
relay-02 (work in progress), October 2014.
[I-D.richardson-anima-state-for-joinrouter]
Richardson, M., "Considerations for stateful vs stateless
join router in ANIMA bootstrap", draft-richardson-anima-
state-for-joinrouter-03 (work in progress), September
2020.
[RFC4944] Montenegro, G., Kushalnagar, N., Hui, J., and D. Culler,
"Transmission of IPv6 Packets over IEEE 802.15.4
Networks", RFC 4944, DOI 10.17487/RFC4944, September 2007,
<https://www.rfc-editor.org/info/rfc4944>.
[RFC6690] Shelby, Z., "Constrained RESTful Environments (CoRE) Link
Format", RFC 6690, DOI 10.17487/RFC6690, August 2012,
<https://www.rfc-editor.org/info/rfc6690>.
[RFC6763] Cheshire, S. and M. Krochmal, "DNS-Based Service
Discovery", RFC 6763, DOI 10.17487/RFC6763, February 2013,
<https://www.rfc-editor.org/info/rfc6763>.
[RFC6775] Shelby, Z., Ed., Chakrabarti, S., Nordmark, E., and C.
Bormann, "Neighbor Discovery Optimization for IPv6 over
Low-Power Wireless Personal Area Networks (6LoWPANs)",
RFC 6775, DOI 10.17487/RFC6775, November 2012,
<https://www.rfc-editor.org/info/rfc6775>.
[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>.
[RFC7228] Bormann, C., Ersue, M., and A. Keranen, "Terminology for
Constrained-Node Networks", RFC 7228,
DOI 10.17487/RFC7228, May 2014,
<https://www.rfc-editor.org/info/rfc7228>.
[RFC7252] Shelby, Z., Hartke, K., and C. Bormann, "The Constrained
Application Protocol (CoAP)", RFC 7252,
DOI 10.17487/RFC7252, June 2014,
<https://www.rfc-editor.org/info/rfc7252>.
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Appendix A. Stateless Proxy payload examples
The examples show the get coaps://[192.168.1.200]:5965/est/crts to a
Registrar. The header generated between Client and registrar and
from registrar to client are shown in detail. The DTLS encrypted
code is not shown.
The request from Join Proxy to Registrar looks like:
85 # array(5)
50 # bytes(16)
00000000000000000000FFFFC0A801C8 #
19 BDA7 # unsigned(48551)
0A # unsigned(10)
00 # unsigned(0)
58 2D # bytes(45)
<cacrts DTLS encrypted request>
In CBOR Diagnostic:
[h'00000000000000000000FFFFC0A801C8', 48551, 10, 0,
h'<cacrts DTLS encrypted request>']
The response is:
85 # array(5)
50 # bytes(16)
00000000000000000000FFFFC0A801C8 #
19 BDA7 # unsigned(48551)
0A # unsigned(10)
00 # unsigned(0)
59 026A # bytes(618)
<cacrts DTLS encrypted response>
In CBOR diagnostic:
[h'00000000000000000000FFFFC0A801C8', 48551, 10, 0,
h'<cacrts DTLS encrypted response>']
Authors' Addresses
Michael Richardson
Sandelman Software Works
Email: mcr+ietf@sandelman.ca
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Peter van der Stok
vanderstok consultancy
Email: consultancy@vanderstok.org
Panos Kampanakis
Cisco Systems
Email: pkampana@cisco.com
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