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Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 anima Working Group M. Richardson 3 Internet-Draft Sandelman Software Works 4 Intended status: Standards Track P. van der Stok 5 Expires: February 10, 2022 vanderstok consultancy 6 P. Kampanakis 7 Cisco Systems 8 August 09, 2021 10 Constrained Join Proxy for Bootstrapping Protocols 11 draft-ietf-anima-constrained-join-proxy-03 13 Abstract 15 This document defines a protocol to securely assign a Pledge to a 16 domain, represented by a Registrar, using an intermediary node 17 between Pledge and Registrar. This intermediary node is known as a 18 "constrained Join Proxy". 20 This document extends the work of [RFC8995] by replacing the Circuit- 21 proxy between Pledge and Registrar by a stateless/stateful 22 constrained (CoAP) Join Proxy. It relays join traffic from the 23 Pledge to the Registrar. 25 Status of This Memo 27 This Internet-Draft is submitted in full conformance with the 28 provisions of BCP 78 and BCP 79. 30 Internet-Drafts are working documents of the Internet Engineering 31 Task Force (IETF). Note that other groups may also distribute 32 working documents as Internet-Drafts. The list of current Internet- 33 Drafts is at https://datatracker.ietf.org/drafts/current/. 35 Internet-Drafts are draft documents valid for a maximum of six months 36 and may be updated, replaced, or obsoleted by other documents at any 37 time. It is inappropriate to use Internet-Drafts as reference 38 material or to cite them other than as "work in progress." 40 This Internet-Draft will expire on February 10, 2022. 42 Copyright Notice 44 Copyright (c) 2021 IETF Trust and the persons identified as the 45 document authors. All rights reserved. 47 This document is subject to BCP 78 and the IETF Trust's Legal 48 Provisions Relating to IETF Documents 49 (https://trustee.ietf.org/license-info) in effect on the date of 50 publication of this document. Please review these documents 51 carefully, as they describe your rights and restrictions with respect 52 to this document. Code Components extracted from this document must 53 include Simplified BSD License text as described in Section 4.e of 54 the Trust Legal Provisions and are provided without warranty as 55 described in the Simplified BSD License. 57 Table of Contents 59 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 60 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4 61 3. Requirements Language . . . . . . . . . . . . . . . . . . . . 4 62 4. Join Proxy functionality . . . . . . . . . . . . . . . . . . 4 63 5. Join Proxy specification . . . . . . . . . . . . . . . . . . 5 64 5.1. Statefull Join Proxy . . . . . . . . . . . . . . . . . . 5 65 5.2. Stateless Join Proxy . . . . . . . . . . . . . . . . . . 7 66 5.3. Stateless Message structure . . . . . . . . . . . . . . . 8 67 6. Comparison of stateless and statefull modes . . . . . . . . . 9 68 7. Discovery . . . . . . . . . . . . . . . . . . . . . . . . . . 10 69 7.1. Join-Proxy discovers Registrar . . . . . . . . . . . . . 11 70 7.1.1. CoAP discovery . . . . . . . . . . . . . . . . . . . 11 71 7.1.2. Autonomous Network . . . . . . . . . . . . . . . . . 11 72 7.1.3. 6tisch discovery . . . . . . . . . . . . . . . . . . 11 73 7.2. Pledge discovers Join Proxy . . . . . . . . . . . . . . . 12 74 7.2.1. Autonomous Network . . . . . . . . . . . . . . . . . 12 75 7.2.2. CoAP discovery . . . . . . . . . . . . . . . . . . . 12 76 7.2.3. 6tisch discovery . . . . . . . . . . . . . . . . . . 12 77 7.3. Join Proxy discovers Registrar join port . . . . . . . . 12 78 7.3.1. CoAP discovery . . . . . . . . . . . . . . . . . . . 12 79 8. Security Considerations . . . . . . . . . . . . . . . . . . . 13 80 9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 13 81 9.1. Resource Type registry . . . . . . . . . . . . . . . . . 13 82 10. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 14 83 11. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 14 84 12. Changelog . . . . . . . . . . . . . . . . . . . . . . . . . . 14 85 12.1. 02 to 03 . . . . . . . . . . . . . . . . . . . . . . . . 14 86 12.2. 01 to 02 . . . . . . . . . . . . . . . . . . . . . . . . 14 87 12.3. 00 to 01 . . . . . . . . . . . . . . . . . . . . . . . . 14 88 12.4. 00 to 00 . . . . . . . . . . . . . . . . . . . . . . . . 14 89 13. References . . . . . . . . . . . . . . . . . . . . . . . . . 15 90 13.1. Normative References . . . . . . . . . . . . . . . . . . 15 91 13.2. Informative References . . . . . . . . . . . . . . . . . 16 92 Appendix A. Stateless Proxy payload examples . . . . . . . . . . 17 93 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 18 95 1. Introduction 97 Enrolment of new nodes into networks with enrolled nodes present is 98 described in [RFC8995] ("BRSKI") and makes use of Enrolment over 99 Secure Transport (EST) [RFC7030] with [RFC8366] vouchers to securely 100 enroll devices. BRSKI connects a new joining device (called Pledge) 101 to "Registrars" via a Join Proxy. 103 The specified solutions use https and may be too large in terms of 104 code space or bandwidth required for constrained devices. 105 Constrained devices possibly part of constrained networks [RFC7228] 106 typically implement the IPv6 over Low-Power Wireless personal Area 107 Networks (6LoWPAN) [RFC4944] and Constrained Application Protocol 108 (CoAP) [RFC7252]. 110 CoAP can be run with the Datagram Transport Layer Security (DTLS) 111 [RFC6347] as a security protocol for authenticity and confidentiality 112 of the messages. This is known as the "coaps" scheme. A constrained 113 version of EST, using Coap and DTLS, is described in 114 [I-D.ietf-ace-coap-est]. The [I-D.ietf-anima-constrained-voucher] 115 extends [I-D.ietf-ace-coap-est] with BRSKI artefacts such as voucher, 116 request voucher, and the protocol extensions for constrained Pledges. 118 DTLS is a client-server protocol relying on the underlying IP layer 119 to perform the routing between the DTLS Client and the DTLS Server. 120 However, the new Pledge will not be IP routable until it is 121 authenticated to the network. A new Pledge can only initially use a 122 link-local IPv6 address to communicate with a neighbour on the same 123 link [RFC6775] until it receives the necessary network configuration 124 parameters. However, before the Pledge can receive these 125 configuration parameters, it needs to authenticate itself to the 126 network to which it connects. 128 During enrollment, a DTLS connection is required between Pledge and 129 Registrar. 131 This document specifies a new form of Join Proxy and protocol to act 132 as intermediary between Pledge and Registrar to relay DTLS messages 133 between Pledge and Registrar. Two versions of the Join Proxy are 134 specified: 136 1 A stateful Join Proxy that locally stores IP addresses 137 during the connection. 138 2 A stateless Join Proxy that where the connection state 139 is stored in the messages. 141 This document is very much inspired by text published earlier in 142 [I-D.kumar-dice-dtls-relay]. 144 [I-D.richardson-anima-state-for-joinrouter] outlined the various 145 options for building a join proxy. [RFC8995] adopted only the 146 Circuit Proxy method (1), leaving the other methods as future work. 147 This document standardizes the CoAP/DTLS (method 4). 149 2. Terminology 151 The following terms are defined in [RFC8366], and are used 152 identically as in that document: artifact, imprint, domain, Join 153 Registrar/Coordinator (JRC), Manufacturer Authorized Signing 154 Authority (MASA), Pledge, Trust of First Use (TOFU), and Voucher. 156 The term "installation network" refers to all devices in the 157 installation and the network connections between them. The term 158 "installation IP_address" refers to the set of adresses which are 159 routable over the whole installation network. 161 3. Requirements Language 163 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 164 "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and 165 "OPTIONAL" in this document are to be interpreted as described in 166 BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all 167 capitals, as shown here. 169 4. Join Proxy functionality 171 As depicted in the Figure 1, the Pledge (P), in an LLN mesh can be 172 more than one hop away from the Registrar (R) and not yet 173 authenticated into the network. 175 In this situation, the Pledge can only communicate one-hop to its 176 nearest neighbour, the Join Proxy (J) using their link-local IPv6 177 addresses. However, the Pledge (P) needs to communicate with end-to- 178 end security with a Registrar to authenticate and get the relevant 179 system/network parameters. If the Pledge (P), knowing the IP-address 180 of the Registrar, initiates a DTLS connection to the Registrar, then 181 the packets are dropped at the Join Proxy (J) since the Pledge (P) is 182 not yet admitted to the network or there is no IP routability to 183 Pledge (P) for any returned messages from the Registrar. 185 ++++ multi-hop 186 |R |---- mesh +--+ +--+ 187 | | \ |J |........|P | 188 ++++ \-----| | | | 189 +--+ +--+ 190 Registrar Join Proxy Pledge 192 Figure 1: multi-hop enrolment. 194 Without routing the Pledge (P) cannot establish a secure connection 195 to the Registrar (R) over multiple hops in the network. 197 Furthermore, the Pledge (P) cannot discover the IP address of the 198 Registrar (R) over multiple hops to initiate a DTLS connection and 199 perform authentication. 201 To overcome the problems with non-routability of DTLS packets and/or 202 discovery of the destination address of the Registrar, the Join Proxy 203 is introduced. This Join Proxy functionality is configured into all 204 authenticated devices in the network which may act as a Join Proxy 205 for Pledges. The Join Proxy allows for routing of the packets from 206 the Pledge using IP routing to the intended Registrar. An 207 authenticated Join Proxy can discover the routable IP address of the 208 Registrar over multiple hops. The following Section 5 specifies the 209 two Join Proxy modes. A comparison is presented in Section 6. 211 5. Join Proxy specification 213 A Join Proxy can operate in two modes: 215 o Statefull mode 217 o Stateless mode 219 A Join Proxy MUST implement one of the two modes. A Join Proxy MAY 220 implement both, with an unspecified mechanism to switch between the 221 two modes. 223 5.1. Statefull Join Proxy 225 In stateful mode, the Join Proxy forwards the DTLS messages to the 226 Registrar. 228 Assume that the Pledge does not know the IP address of the Registrar 229 it needs to contact. The Join Proxy has has been enrolled via the 230 Registrar and learns the IP address and port of the Registrar, for 231 example by using the discovery mechanism described in Section 7. The 232 Pledge first discovers (see Section 7) and selects the most 233 appropriate Join Proxy. (Discovery can also be based upon [RFC8995] 234 section 4.1, or via DNS-SD service discovery [RFC6763]). The Pledge 235 initiates its request as if the Join Proxy is the intended Registrar. 236 The Join Proxy receives the message at a discoverable "Join" port. 237 The Join Proxy constructs an IP packet by copying the DTLS payload 238 from the message received from the Pledge, and provides source and 239 destination addresses to forward the message to the intended 240 Registrar. The Join Proxy maintains a 4-tuple array to translate the 241 DTLS messages received from the Registrar and forward it back to the 242 Pledge. 244 In Figure 2 the various steps of the message flow are shown, with 245 5684 being the standard coaps port: 247 +------------+------------+-------------+--------------------------+ 248 | Pledge | Join Proxy | Registrar | Message | 249 | (P) | (J) | (R) | Src_IP:port | Dst_IP:port| 250 +------------+------------+-------------+-------------+------------+ 251 | --ClientHello--> | IP_P:p_P | IP_Ja:p_J | 252 | --ClientHello--> | IP_Jb:p_Jb| IP_R:5684 | 253 | | | | 254 | <--ServerHello-- | IP_R:5684 | IP_Jb:p_Jb | 255 | : | | | 256 | <--ServerHello-- : | IP_Ja:p_J | IP_P:p_P | 257 | : : | | | 258 | [DTLS messages] | : | : | 259 | : : | : | : | 260 | --Finished--> : | IP_P:p_P | IP_Ja:p_J | 261 | --Finished--> | IP_Jb:p_Jb| IP_R:5684 | 262 | | | | 263 | <--Finished-- | IP_R:5684 | IP_Jb:p_Jb | 264 | <--Finished-- | IP_Ja:p_J | IP_P:p_P | 265 | : : | : | : | 266 +---------------------------------------+-------------+------------+ 267 IP_P:p_P = Link-local IP address and port of Pledge (DTLS Client) 268 IP_R:5684 = Routable IP address and coaps port of Registrar 269 IP_Ja:P_J = Link-local IP address and join port of Join Proxy 270 IP_Jb:p_Rb = Routable IP address and client port of Join proxy 272 Figure 2: constrained statefull joining message flow with Registrar 273 address known to Join Proxy. 275 5.2. Stateless Join Proxy 277 The stateless Join Proxy aims to minimize the requirements on the 278 constrained Join Proxy device. Stateless operation requires no 279 memory in the Join Proxy device, but may also reduce the CPU impact 280 as the device does not need to search through a state table. 282 If an untrusted Pledge that can only use link-local addressing wants 283 to contact a trusted Registrar, and the Registrar is more than one 284 hop away, it sends its DTLS messages to the Join Proxy. 286 When a Pledge attempts a DTLS connection to the Join Proxy, it uses 287 its link-local IP address as its IP source address. This message is 288 transmitted one-hop to a neighbouring (Join Proxy) node. Under 289 normal circumstances, this message would be dropped at the neighbour 290 node since the Pledge is not yet IP routable or is not yet 291 authenticated to send messages through the network. However, if the 292 neighbour device has the Join Proxy functionality enabled, it routes 293 the DTLS message to its Registrar of choice. 295 The Join Proxy sends a "new" JPY message which includes the DTLS data 296 as payload. 298 The JPY message payload consists of two parts: 300 o Header (H) field: consisting of the source link-local address and 301 port of the Pledge (P), and 303 o Contents (C) field: containing the original DTLS payload. 305 On receiving the JPY message, the Registrar (or proxy) retrieves the 306 two parts. 308 The Registrar transiently stores the Header field information. The 309 Registrar uses the Contents field to execute the Registrar 310 functionality. However, when the Registrar replies, it also extends 311 its DTLS message with the header field in a JPY message and sends it 312 back to the Join Proxy. The Registrar SHOULD NOT assume that it can 313 decode the Header Field, it should simply repeat it when responding. 314 The Header contains the original source link-local address and port 315 of the Pledge from the transient state stored earlier and the 316 Contents field contains the DTLS payload. 318 On receiving the JPY message, the Join Proxy retrieves the two parts. 319 It uses the Header field to route the DTLS message containing the 320 DTLS payload retrieved from the Contents field to the Pledge. 322 In this scenario, both the Registrar and the Join Proxy use 323 discoverable "Join" ports, which may be the default ports. 325 The Figure 3 depicts the message flow diagram: 327 +--------------+------------+---------------+-----------------------+ 328 | Pledge | Join Proxy | Registrar | Message | 329 | (P) | (J) | (R) |Src_IP:port|Dst_IP:port| 330 +--------------+------------+---------------+-----------+-----------+ 331 | --ClientHello--> | IP_P:p_P |IP_Ja:p_Ja | 332 | --JPY[H(IP_P:p_P),--> | IP_Jb:p_Jb|IP_R:p_Ra | 333 | C(ClientHello)] | | | 334 | <--JPY[H(IP_P:p_P),-- | IP_R:p_Ra |IP_Jb:p_Jb | 335 | C(ServerHello)] | | | 336 | <--ServerHello-- | IP_Ja:p_Ja|IP_P:p_P | 337 | : | | | 338 | [ DTLS messages ] | : | : | 339 | : | : | : | 340 | --Finished--> | IP_P:p_P |IP_Ja:p_Ja | 341 | --JPY[H(IP_P:p_P),--> | IP_Jb:p_Jb|IP_R:p_Ra | 342 | C(Finished)] | | | 343 | <--JPY[H(IP_P:p_P),-- | IP_R:p_Ra |IP_Jb:p_Jb | 344 | C(Finished)] | | | 345 | <--Finished-- | IP_Ja:p_Ja|IP_P:p_P | 346 | : | : | : | 347 +-------------------------------------------+-----------+-----------+ 348 IP_P:p_P = Link-local IP address and port of the Pledge 349 IP_R:p_Ra = Routable IP address and join port of Registrar 350 IP_Ja:p_Ja = Link-local IP address and join port of Join Proxy 351 IP_Jb:p_Jb = Routable IP address and port of Join Proxy 353 JPY[H(),C()] = Join Proxy message with header H and content C 355 Figure 3: constrained stateless joining message flow. 357 5.3. Stateless Message structure 359 The JPY message is constructed as a payload with media-type 360 aplication/cbor 362 Header and Contents fields togther are one cbor array of 5 elements: 364 1. header field: containing a CBOR array [RFC7049] with the Pledge 365 IPv6 Link Local address as a cbor byte string, the Pledge's UDP 366 port number as a CBOR integer, the IP address family (IPv4/IPv6) 367 as a cbor integer, and the proxy's ifindex or other identifier 368 for the physical port as cbor integer. The header field is not 369 DTLS encrypted. 371 2. Content field: containing the DTLS payload as a CBOR byte string. 373 The join_proxy cannot decrypt the DTLS payload and has no knowledge 374 of the transported media type. 376 JPY_message = 377 [ 378 ip : bstr, 379 port : int, 380 family : int, 381 index : int 382 payload : bstr 383 ] 385 Figure 4: CDDL representation of JPY message 387 The content fields are DTLS encrypted. In CBOR diagnostic notation 388 the payload JPY[H(IP_P:p_P)], will look like: 390 [h'IP_p', p_P, family, ident, h'DTLS-payload'] 392 Examples are shown in Appendix A. 394 6. Comparison of stateless and statefull modes 396 The stateful and stateless mode of operation for the Join Proxy have 397 their advantages and disadvantages. This section should enable to 398 make a choice between the two modes based on the available device 399 resources and network bandwidth. 401 +-------------+----------------------------+------------------------+ 402 | Properties | Stateful mode | Stateless mode | 403 +-------------+----------------------------+------------------------+ 404 | State |The Join Proxy needs | No information is | 405 | Information |additional storage to | maintained by the Join | 406 | |maintain mapping between | Proxy. Registrar needs | 407 | |the address and port number | to store the packet | 408 | |of the Pledge and those | header. | 409 | |of the Registrar. | | 410 +-------------+----------------------------+------------------------+ 411 |Packet size |The size of the forwarded |Size of the forwarded | 412 | |message is the same as the |message is bigger than | 413 | |original message. |the original,it includes| 414 | | |additional IP-addresses | 415 +-------------+----------------------------+------------------------+ 416 |Specification|The Join Proxy needs |New JPY message to | 417 |complexity |additional functionality |encapsulate DTLS payload| 418 | |to maintain state |The Registrar | 419 | |information, and specify |and the Join Proxy | 420 | |the source and destination |have to understand the | 421 | |addresses of the DTLS |JPY message in order | 422 | |handshake messages |to process it. | 423 +-------------+----------------------------+------------------------+ 424 | Ports | Join Proxy needs |Join Proxy and Registrar| 425 | | discoverable "Join" port |need discoverable | 426 | | | "Join" ports | 427 +-------------+----------------------------+------------------------+ 429 Figure 5: Comparison between stateful and stateless mode 431 7. Discovery 433 It is assumed that Join Proxy seamlessly provides a coaps connection 434 between Pledge and Registrar. In particular this section replaces 435 section 4.1 of [RFC8995]. 437 The discovery follows two steps with two alternatives for step 1: 439 1. Two alternatives: 441 a. The Pledge is one hop away from the Registrar. The Pledge 442 discovers the link-local address of the Registrar as described in 443 [I-D.ietf-ace-coap-est]. From then on, it follows the BRSKI process 444 as described in [I-D.ietf-ace-coap-est] and 445 [I-D.ietf-anima-constrained-voucher], using link-local addresses. 447 b. The Pledge is more than one hop away from a relevant Registrar, 448 and discovers the link-local address and join port of a Join Proxy. 449 The Pledge then follows the BRSKI procedure using the link-local 450 address of the Join Proxy. 452 1. Once enrolled, the Join Proxy discovers the join port of the 453 Registrar. 455 Once a Pledge is enrolled, it may function as Join Proxy. The Join 456 Proxy functions are advertised as descibed below. In principle, the 457 Join Proxy functions are offered via a "join" port, and not the 458 standard coaps port. Also the Registrar offers a "join" port to 459 which the stateless join proxy sends the JPY message. The Join Proxy 460 and Registrar show the extra join port number when reponding to a 461 /.well-known/core discovery request addressed to the standard coap/ 462 coaps port. 464 Three discovery cases are discussed: Join_proxy discovers Registrar, 465 Pledge discovers Registrar, and Pledge discovers Join-proxy. Each 466 discovery case considers threa alternatives: coap discovery, 6tisch 467 discovery and GRASP discovery. 469 7.1. Join-Proxy discovers Registrar 471 In this section, the Pledge and Join Proxy are assumed to communicate 472 via Link-Local addresses. This section describes the discovery of 473 the Registrar by the Join-Proxy. 475 7.1.1. CoAP discovery 477 The discovery of the coaps Registrar, using coap discovery, by the 478 Join Proxy follows section 6 of [I-D.ietf-ace-coap-est]. 480 7.1.2. Autonomous Network 482 In the context of autonomous networks, the Join Proxy uses the DULL 483 GRASP M_FLOOD mechanism to announce itself. Section 4.1.1 of 484 [RFC8995] discusses this in more detail. The Registrar announces 485 itself using ACP instance of GRASP using M_FLOOD messages. 486 Autonomous Network Join Proxies MUST support GRASP discovery of 487 Registrar as decribed in section 4.3 of [RFC8995] . 489 7.1.3. 6tisch discovery 491 The discovery of Registrar by the Join-Proxy uses the enhanced 492 beacons as discussed in [I-D.ietf-6tisch-enrollment-enhanced-beacon]. 494 7.2. Pledge discovers Join Proxy 496 7.2.1. Autonomous Network 498 The Pledge MUST listen for GRASP M_FLOOD [I-D.ietf-anima-grasp] 499 announcements of the objective: "AN_Proxy". See section 500 Section 4.1.1 [RFC8995] for the details of the objective. 502 7.2.2. CoAP discovery 504 In the context of a coap network without Autonomous Network support, 505 discovery follows the standard coap policy. The Pledge can discover 506 a Join Proxy by sending a link-local multicast message to ALL CoAP 507 Nodes with address FF02::FD. Multiple or no nodes may respond. The 508 handling of multiple responses and the absence of responses follow 509 section 4 of [RFC8995]. 511 The join port of the Join Proxy is discovered by sending a GET 512 request to "/.well-known/core" including a resource type (rt) 513 parameter with the value "brski-proxy" [RFC6690]. Upon success, the 514 return payload will contain the join port. 516 The example below shows the discovery of the join port of the Join 517 Proxy. 519 REQ: GET coap://[FF02::FD]/.well-known/core?rt=brski-proxy 521 RES: 2.05 Content 522 ; rt="brski-proxy" 524 Port numbers are assumed to be the default numbers 5683 and 5684 for 525 coap and coaps respectively (sections 12.6 and 12.7 of [RFC7252] when 526 not shown in the response. Discoverable port numbers are usually 527 returned for Join Proxy resources in the of the payload (see 528 section 5.1 of [I-D.ietf-ace-coap-est]). 530 7.2.3. 6tisch discovery 532 Not applicable. 534 7.3. Join Proxy discovers Registrar join port 536 7.3.1. CoAP discovery 538 The stateless Join Proxy can discover the join port of the Registrar 539 by sending a GET request to "/.well-known/core" including a resource 540 type (rt) parameter with the value "join-proxy" [RFC6690]. Upon 541 success, the return payload will contain the join Port of the 542 Registrar. 544 REQ: GET coap://[IP_address]/.well-known/core?rt=join-proxy 546 RES: 2.05 Content 547 ; rt="join-proxy" 549 The discoverable port numbers are usually returned for Join Proxy 550 resources in the of the payload (see section 5.1 of 551 [I-D.ietf-ace-coap-est]). 553 8. Security Considerations 555 It should be noted here that the contents of the CBOR map used to 556 convey return address information is not protected. However, the 557 communication is between the Proxy and a known registrar are over the 558 already secured portion of the network, so are not visible to 559 eavesdropping systems. 561 All of the concerns in [RFC8995] section 4.1 apply. The Pledge can 562 be deceived by malicious Join_Proxy announcements. The Pledge will 563 only join a network to which it receives a valid [RFC8366] voucher 564 [I-D.ietf-anima-constrained-voucher]. 566 If the communicatione between Join-Proxy and Registrar passed over an 567 unsecure network, then an attacker could change the cbor array, 568 causing the Pledge to send traffic to another node. If the such 569 scenario needed to be supported, then it would be reasonable for the 570 Proxy to encrypt the CBOR array using a locally generated symmetric 571 key. The Registrar would not be able to examine the result, but it 572 does not need to do so. This is a topic for future work. 574 9. IANA Considerations 576 This document needs to create a registry for key indices in the CBOR 577 map. It should be given a name, and the amending formula should be 578 IETF Specification. 580 9.1. Resource Type registry 582 This specification registers a new Resource Type (rt=) Link Target 583 Attributes in the "Resource Type (rt=) Link Target Attribute Values" 584 subregistry under the "Constrained RESTful Environments (CoRE) 585 Parameters" registry. 587 rt="brski-proxy". This BRSKI resource is used to query and return 588 the supported BRSKI port of the Join Proxy. 590 rt="join-proxy". This BRSKI resource is used to query and return 591 the supported BRSKI port of the Registrar. 593 10. Acknowledgements 595 Many thanks for the comments by Brian Carpenter and Esko Dijk. 597 11. Contributors 599 Sandeep Kumar, Sye loong Keoh, and Oscar Garcia-Morchon are the co- 600 authors of the draft-kumar-dice-dtls-relay-02. Their draft has 601 served as a basis for this document. Much text from their draft is 602 copied over to this draft. 604 12. Changelog 606 12.1. 02 to 03 608 * Terminology updated 609 * Several clarifications on discovery and routability 610 * DTLS payload introduced 612 12.2. 01 to 02 614 o Discovery of Join Proxy and Registrar ports 616 12.3. 00 to 01 618 o Registrar used throughout instead of EST server 620 o Emphasized additional Join Proxy port for Join Proxy and Registrar 622 o updated discovery accordingly 624 o updated stateless Join Proxy JPY header 626 o JPY header described with CDDL 628 o Example simplified and corrected 630 12.4. 00 to 00 632 o copied from vanderstok-anima-constrained-join-proxy-05 634 13. References 636 13.1. Normative References 638 [I-D.ietf-6tisch-enrollment-enhanced-beacon] 639 (editor), D. D. and M. Richardson, "Encapsulation of 640 6TiSCH Join and Enrollment Information Elements", draft- 641 ietf-6tisch-enrollment-enhanced-beacon-14 (work in 642 progress), February 2020. 644 [I-D.ietf-ace-coap-est] 645 Stok, P. V. D., Kampanakis, P., Richardson, M. C., and S. 646 Raza, "EST over secure CoAP (EST-coaps)", draft-ietf-ace- 647 coap-est-18 (work in progress), January 2020. 649 [I-D.ietf-anima-constrained-voucher] 650 Richardson, M., Stok, P. V. D., Kampanakis, P., and E. 651 Dijk, "Constrained Voucher Artifacts for Bootstrapping 652 Protocols", draft-ietf-anima-constrained-voucher-13 (work 653 in progress), July 2021. 655 [I-D.ietf-anima-grasp] 656 Bormann, C., Carpenter, B., and B. Liu, "GeneRic Autonomic 657 Signaling Protocol (GRASP)", draft-ietf-anima-grasp-15 658 (work in progress), July 2017. 660 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 661 Requirement Levels", BCP 14, RFC 2119, 662 DOI 10.17487/RFC2119, March 1997, 663 . 665 [RFC6347] Rescorla, E. and N. Modadugu, "Datagram Transport Layer 666 Security Version 1.2", RFC 6347, DOI 10.17487/RFC6347, 667 January 2012, . 669 [RFC7049] Bormann, C. and P. Hoffman, "Concise Binary Object 670 Representation (CBOR)", RFC 7049, DOI 10.17487/RFC7049, 671 October 2013, . 673 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 674 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 675 May 2017, . 677 [RFC8366] Watsen, K., Richardson, M., Pritikin, M., and T. Eckert, 678 "A Voucher Artifact for Bootstrapping Protocols", 679 RFC 8366, DOI 10.17487/RFC8366, May 2018, 680 . 682 [RFC8995] Pritikin, M., Richardson, M., Eckert, T., Behringer, M., 683 and K. Watsen, "Bootstrapping Remote Secure Key 684 Infrastructure (BRSKI)", RFC 8995, DOI 10.17487/RFC8995, 685 May 2021, . 687 13.2. Informative References 689 [I-D.kumar-dice-dtls-relay] 690 Kumar, S. S., Keoh, S. L., and O. Garcia-Morchon, "DTLS 691 Relay for Constrained Environments", draft-kumar-dice- 692 dtls-relay-02 (work in progress), October 2014. 694 [I-D.richardson-anima-state-for-joinrouter] 695 Richardson, M. C., "Considerations for stateful vs 696 stateless join router in ANIMA bootstrap", draft- 697 richardson-anima-state-for-joinrouter-03 (work in 698 progress), September 2020. 700 [RFC4944] Montenegro, G., Kushalnagar, N., Hui, J., and D. Culler, 701 "Transmission of IPv6 Packets over IEEE 802.15.4 702 Networks", RFC 4944, DOI 10.17487/RFC4944, September 2007, 703 . 705 [RFC6690] Shelby, Z., "Constrained RESTful Environments (CoRE) Link 706 Format", RFC 6690, DOI 10.17487/RFC6690, August 2012, 707 . 709 [RFC6763] Cheshire, S. and M. Krochmal, "DNS-Based Service 710 Discovery", RFC 6763, DOI 10.17487/RFC6763, February 2013, 711 . 713 [RFC6775] Shelby, Z., Ed., Chakrabarti, S., Nordmark, E., and C. 714 Bormann, "Neighbor Discovery Optimization for IPv6 over 715 Low-Power Wireless Personal Area Networks (6LoWPANs)", 716 RFC 6775, DOI 10.17487/RFC6775, November 2012, 717 . 719 [RFC7030] Pritikin, M., Ed., Yee, P., Ed., and D. Harkins, Ed., 720 "Enrollment over Secure Transport", RFC 7030, 721 DOI 10.17487/RFC7030, October 2013, 722 . 724 [RFC7228] Bormann, C., Ersue, M., and A. Keranen, "Terminology for 725 Constrained-Node Networks", RFC 7228, 726 DOI 10.17487/RFC7228, May 2014, 727 . 729 [RFC7252] Shelby, Z., Hartke, K., and C. Bormann, "The Constrained 730 Application Protocol (CoAP)", RFC 7252, 731 DOI 10.17487/RFC7252, June 2014, 732 . 734 Appendix A. Stateless Proxy payload examples 736 The examples show the request "GET coaps://192.168.1.200:5965/est/ 737 crts" to a Registrar. The header generated between Join-Proxy and 738 Registrar and from Registrar to Join-Proxy are shown in detail. The 739 DTLS payload is not shown. 741 The request from Join Proxy to Registrar looks like: 743 85 # array(5) 744 50 # bytes(16) 745 FE800000000000000000FFFFC0A801C8 # 746 19 BDA7 # unsigned(48551) 747 0A # unsigned(10) 748 00 # unsigned(0) 749 58 2D # bytes(45) 750 752 In CBOR Diagnostic: 754 [h'FE800000000000000000FFFFC0A801C8', 48551, 10, 0, 755 h''] 757 The response is: 759 85 # array(5) 760 50 # bytes(16) 761 FE800000000000000000FFFFC0A801C8 # 762 19 BDA7 # unsigned(48551) 763 0A # unsigned(10) 764 00 # unsigned(0) 765 59 026A # bytes(618) 766 768 In CBOR diagnostic: 770 [h'FE800000000000000000FFFFC0A801C8', 48551, 10, 0, 771 h''] 773 Authors' Addresses 775 Michael Richardson 776 Sandelman Software Works 778 Email: mcr+ietf@sandelman.ca 780 Peter van der Stok 781 vanderstok consultancy 783 Email: consultancy@vanderstok.org 785 Panos Kampanakis 786 Cisco Systems 788 Email: pkampana@cisco.com