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A Voucher Artifact for Bootstrapping Protocols
draft-ietf-anima-rfc8366bis-16

Document Type Active Internet-Draft (anima WG)
Authors Kent Watsen , Michael Richardson , Max Pritikin , Toerless Eckert , Qiufang Ma
Last updated 2025-10-20
Replaces draft-richardson-anima-rfc8366bis
RFC stream Internet Engineering Task Force (IETF)
Intended RFC status Proposed Standard
Formats
Yang Validation 6 errors, 0 warnings
Additional resources Mailing list discussion
Stream WG state WG Document
Document shepherd Sheng Jiang
IESG IESG state I-D Exists
Consensus boilerplate Yes
Telechat date (None)
Responsible AD (None)
Send notices to ludwig@clemm.org, shengjiang@bupt.edu.cn
draft-ietf-anima-rfc8366bis-16
ANIMA Working Group                                            K. Watsen
Internet-Draft                                           Watsen Networks
Intended status: Standards Track                           M. Richardson
Expires: 23 April 2026                                Sandelman Software
                                                             M. Pritikin
                                                           Cisco Systems
                                                               T. Eckert
                                             Futurewei Technologies Inc.
                                                                   Q. Ma
                                                                  Huawei
                                                         20 October 2025

             A Voucher Artifact for Bootstrapping Protocols
                     draft-ietf-anima-rfc8366bis-16

Abstract

   This document defines a strategy to securely assign a Pledge to an
   owner using an artifact signed, directly or indirectly, by the
   Pledge's manufacturer.  This artifact is known as a "voucher".

   This document defines an artifact format as a YANG-defined JSON or
   CBOR document that has been signed using a variety of cryptographic
   systems.

   The voucher artifact is normally generated by the Pledge's
   manufacturer (i.e., the Manufacturer Authorized Signing Authority
   (MASA)).

   This document updates RFC8366, includes a number of desired
   extensions into the YANG.  The voucher request defined in RFC8995 is
   also now included in this document, as well as other YANG extensions
   needed for variants of BRSKI/RFC8995.

About This Document

   This note is to be removed before publishing as an RFC.

   Status information for this document may be found at
   https://datatracker.ietf.org/doc/draft-ietf-anima-rfc8366bis/.

   Discussion of this document takes place on the anima Working Group
   mailing list (mailto:anima@ietf.org), which is archived at
   https://mailarchive.ietf.org/arch/browse/anima/.  Subscribe at
   https://www.ietf.org/mailman/listinfo/anima/.

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   Source for this draft and an issue tracker can be found at
   https://github.com/anima-wg/voucher.

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 23 April 2026.

Copyright Notice

   Copyright (c) 2025 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents (https://trustee.ietf.org/
   license-info) in effect on the date of publication of this document.
   Please review these documents carefully, as they describe your rights
   and restrictions with respect to this document.  Code Components
   extracted from this document must include Revised BSD License text as
   described in Section 4.e of the Trust Legal Provisions and are
   provided without warranty as described in the Revised BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   5
   3.  Requirements Language . . . . . . . . . . . . . . . . . . . .   6
   4.  Survey of Voucher Types . . . . . . . . . . . . . . . . . . .   7
   5.  Changes since RFC8366 . . . . . . . . . . . . . . . . . . . .   9
     5.1.  Attempts and motivation to extend RFC8366 . . . . . . . .   9
     5.2.  Informational Model changes since RFC8366 . . . . . . . .  10
   6.  Signature mechanisms  . . . . . . . . . . . . . . . . . . . .  10
     6.1.  CMS Format Voucher Artifact . . . . . . . . . . . . . . .  11
   7.  Voucher Artifact  . . . . . . . . . . . . . . . . . . . . . .  12
     7.1.  Tree Diagram  . . . . . . . . . . . . . . . . . . . . . .  13
     7.2.  Examples  . . . . . . . . . . . . . . . . . . . . . . . .  13

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     7.3.  YANG Module . . . . . . . . . . . . . . . . . . . . . . .  14
     7.4.  ietf-voucher SID values . . . . . . . . . . . . . . . . .  21
     7.5.  Voucher Extensions  . . . . . . . . . . . . . . . . . . .  23
     7.6.  Manufacturer Private extensions . . . . . . . . . . . . .  24
   8.  Voucher Request Artifact  . . . . . . . . . . . . . . . . . .  24
     8.1.  Tree Diagram  . . . . . . . . . . . . . . . . . . . . . .  24
     8.2.  "ietf-voucher-request" Module . . . . . . . . . . . . . .  25
     8.3.  ietf-voucher-request SID values . . . . . . . . . . . . .  31
   9.  Design Considerations . . . . . . . . . . . . . . . . . . . .  32
     9.1.  Renewals Instead of Revocations . . . . . . . . . . . . .  32
     9.2.  Voucher Per Pledge  . . . . . . . . . . . . . . . . . . .  33
   10. Security Considerations . . . . . . . . . . . . . . . . . . .  33
     10.1.  Clock Sensitivity  . . . . . . . . . . . . . . . . . . .  34
     10.2.  Protect Voucher PKI in HSM . . . . . . . . . . . . . . .  34
     10.3.  Test Domain Certificate Validity When Signing  . . . . .  34
     10.4.  YANG Module Security Considerations  . . . . . . . . . .  34
   11. IANA Considerations . . . . . . . . . . . . . . . . . . . . .  35
     11.1.  The IETF XML Registry  . . . . . . . . . . . . . . . . .  35
     11.2.  The YANG Module Names Registry . . . . . . . . . . . . .  35
     11.3.  The Media Types Registry . . . . . . . . . . . . . . . .  36
     11.4.  The SMI Security for S/MIME CMS Content Type Registry  .  36
     11.5.  Extensions Registry  . . . . . . . . . . . . . . . . . .  36
   12. References  . . . . . . . . . . . . . . . . . . . . . . . . .  37
     12.1.  Normative References . . . . . . . . . . . . . . . . . .  37
     12.2.  Informative References . . . . . . . . . . . . . . . . .  39
   Appendix A.  Examples . . . . . . . . . . . . . . . . . . . . . .  42
     A.1.  Key pairs associated with examples  . . . . . . . . . . .  42
     A.2.  Example CMS signed voucher request  . . . . . . . . . . .  47
     A.3.  Example CMS signed voucher from MASA  . . . . . . . . . .  48
     A.4.  Example JWS signed voucher from MASA  . . . . . . . . . .  49
   Acknowledgements  . . . . . . . . . . . . . . . . . . . . . . . .  50
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  50

1.  Introduction

   This document defines a strategy to securely assign a candidate
   device (Pledge) to an owner using an artifact signed, directly or
   indirectly, by the Pledge's manufacturer, i.e., the Manufacturer
   Authorized Signing Authority (MASA).  This artifact is known as the
   "voucher".

   The voucher artifact is a JSON [RFC8259] document that conforms with
   a data model described by YANG [RFC7950].  It may also be serialized
   to CBOR [CBOR].  It is encoded using the rules defined in [RFC7951]
   or [RFC9254], and is signed using (by default) a CMS structure
   [RFC5652].

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   The primary purpose of a voucher is to securely convey a trust anchor
   that a Pledge can use to authenticate subsequent interactions.  The
   trust anchor may be in the form of a certificate (the "pinned-domain-
   cert" attribute), a hash of a certificate, or it can be a raw public
   key (in constrained use cases).

   This trust anchor represents the authority of the owner of a network.
   Communicating this trust anchor securely to the Pledge is the job of
   the voucher artifact.  The act of communicating this trust anchor is
   known as pinning the trust anchor, as the Pledge can then use the
   resulting anchor to authenticate other actors who are part of the
   network.  The collection of all these actors is collectively known as
   the network domain.  (This is not related to the domain name system,
   but rather the term is of mathematical origin)

   A voucher may be useful in several contexts, but the driving
   motivation herein is to support secure onboarding mechanisms.  This
   is accomplished by assigning an owner to the Pledge, enabling it to
   authenticate the network that it is connected to.

   [RFC8366] originally defined just the voucher artifact, leaving the
   Voucher Request artifiact that is important to BRSKI to be defined in
   [BRSKI].  This document includes both Voucher and Voucher-Request,
   and therefore updates [BRSKI].

   YANG is not easily extended except by updating the YANG definition.
   Since [RFC8366] was written, the pattern is to publish YANG modules
   as two documents: one with only the YANG module, and the other one
   with usage, motivation and further explanation.  This allows the YANG
   module to be updated without replacing all of the context.  This
   document does not follow that pattern, but future updates may update
   only the YANG.

   This document also introduces an experimental mechanism to support
   future extensions without requiring the YANG module to be replaced.
   This includes both new IETF Standard mechanisms, as well as a
   facility for manufacturer private extensions.

   The lifetimes of vouchers may vary.  In some onboarding protocols,
   the vouchers may include a nonce restricting them to a single use,
   whereas the vouchers in other onboarding protocols may have an
   indicated lifetime.  In order to support long lifetimes, this
   document recommends using short lifetimes with programmatic renewal,
   see Section 9.1.

   Some onboarding protocols using the voucher artifact defined in this
   document include: [ZERO-TOUCH], [SECUREJOIN], [BRSKI] and [cBRSKI].

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2.  Terminology

   This document uses the following terms:

   (Voucher) Artifact:  Used throughout to represent the voucher as
      instantiated in the form of a signed datastructure.

   Bootstrapping:  The process where a Pledge obtains cryptographic key
      material to identify and trust future interactions within a
      specific domain network.  Based on imprinted key material provided
      during the manufacturing process (see: Imprint).

   Domain:  The set of entities or infrastructure under common
      administrative control.  The goal of the onboarding protocol is to
      enable a Pledge to join a domain and obtain domain specific
      security credentials.

   Imprint:  The process where a device obtains the cryptographic key
      material to identify and trust future interactions generally as
      part of the manufacturing.  This term is taken from Konrad
      Lorenz's work in biology with new ducklings: "during a critical
      period, the duckling would assume that anything that looks like a
      mother duck is in fact their mother" [Stajano99theresurrecting].
      An equivalent for a device is to obtain the fingerprint of the
      manufacturer's root certification authority (root ca) certificate.
      A device that imprints on an attacker suffers a similar fate to a
      duckling that imprints on a hungry wolf.  Imprinting is a term
      from psychology and ethology, as described in [imprinting].

   Join Registrar (and Coordinator):  A representative of the domain
      that is configured, perhaps autonomically, to decide whether a new
      device is allowed to join the domain.  The administrator of the
      domain interfaces with a join registrar (and Coordinator) to
      control this process.  Typically, a join registrar is "inside" its
      domain.  For simplicity, this document often refers to this as
      just "registrar".

   MASA (Manufacturer Authorized Signing Authority):  The entity that,
      for the purpose of this document, issues and signs the vouchers
      for a manufacturer's Pledges.  In some onboarding protocols, the
      MASA may have an Internet presence and be integral to the
      onboarding process, whereas in other protocols the MASA may be an
      offline service that has no active role in the onboarding process.

   Malicious Registrar:  An on-path active attacker that presents itself
      as a legitimate registrar, but which is in fact under the control
      of an attacker.

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   Onboarding:  Onboarding describes the process to provide necessary
      operational data to a Pledge and to complete the process of
      bringing the Pledge into an operational state.  This data may be
      configuration data, or also application-specific cryptographic key
      material (application-specific security credentials).

   Owner:  The entity that controls the private key of the trust anchor
      conveyed by the voucher.  Typically, this is indicated by the
      "pinned-domain-cert" data item.

   Pledge:  The prospective component/device attempting to find and
      securely join a domain.  When shipped or in factory reset mode, it
      only trusts authorized representatives of the manufacturer.

   Registrar:  See join registrar.

   TOFU (Trust on First Use):  When a Pledge makes no security decisions
      but rather simply trusts the first domain entity it is contacted
      by.  Used similarly to [RFC7435].  This is also known as the
      "resurrecting duckling" model.

   Voucher:  A short form for Voucher Artifact.  It refers to the signed
      statement from the MASA service that indicates to a Pledge the
      cryptographic identity of the domain it should trust.  When
      clarity is needed, it may be preceeded by the type of the
      signature, such as CMS, JWS or COSE.

   Voucher Data:  The raw (serialized) representation of the YANG
      without any enclosing signature.  Current formats include JSON and
      CBOR.

   Voucher Request:  A signed artifact sent from the Pledge to the
      Registrar, or from the Registrar to the MASA for Voucher
      acquisition.

   Pledge Voucher Request (PVR):  A signed artifact sent from the Pledge
      to the Registrar.  It is a specific form of Voucher Request.

   Registrar Voucher Request (RVR):  A signed artifact sent from the
      Registrar to the MASA.  It is a specific form of Voucher Request.

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.

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4.  Survey of Voucher Types

   A voucher is a cryptographically protected statement to the Pledge
   authorizing a zero-touch onboarding with the join registrar of the
   domain.  The specific information a voucher provides is influenced by
   the onboarding use case.

   The voucher can convey the following information to the join
   registrar and Pledge:

   Assertion Basis:  Indicates the method that protects the onboarding
      (this is distinct from the voucher signature that protects the
      voucher itself).  Methods include manufacturer-asserted ownership
      verification, assured logging operations, or reliance on Pledge
      behavior such as secure or measured boot.  The join registrar uses
      this information to make a determination as to whether to accept
      the Pledge into the network.  Only some methods are normatively
      defined in this document.  Other methods are left for future work.

   Authentication of Join Registrar:  Indicates how the Pledge can
      authenticate the join registrar.  This document defines a
      mechanism to pin the domain certificate, or a raw public key.
      Pinning a symmetric key, or "CN-ID" or "DNS-ID" information (as
      defined in [RFC6125]) is left for future work.

   Anti-Replay Protections:  Time- or nonce-based information to
      constrain the voucher to time periods or bootstrapping attempts.

   A number of onboarding scenarios can be met using differing
   combinations of this information.  All scenarios address the primary
   threat of an on-path active attacker (or MiTM) impersonating the
   registrar.  If successful, this would gain control over the Pledge.
   The following combinations are "types" of vouchers:

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   +=========+===========+========+===========+========+========+=====+
   |Voucher  | Assertion |        | Registrar |        |Validity|     |
   |Type     |           |        |        ID |        |        |     |
   +=========+===========+========+===========+========+========+=====+
   |         |    Logged |Verified|     Trust |CN-ID or|     RTC|Nonce|
   |         |           |        |    Anchor |  DNS-ID|        |     |
   +---------+-----------+--------+-----------+--------+--------+-----+
   |Audit    |         X |        |         X |        |        |    X|
   |voucher  |           |        |           |        |        |     |
   +---------+-----------+--------+-----------+--------+--------+-----+
   |Nonceless|         X |        |         X |        |       X|     |
   |Audit    |           |        |           |        |        |     |
   +---------+-----------+--------+-----------+--------+--------+-----+
   |Owner    |         X |       X|         X |        |       X|    X|
   |Audit    |           |        |           |        |        |     |
   +---------+-----------+--------+-----------+--------+--------+-----+
   |Owner ID |           |       X|         X |       X|       X|     |
   +---------+-----------+--------+-----------+--------+--------+-----+
   |Bearer   |         X |        |  wildcard |wildcard|optional|  opt|
   |voucher  |           |        |           |        |        |     |
   +---------+-----------+--------+-----------+--------+--------+-----+

                    Table 1: Overview of voucher types

   NOTE: All voucher types include a 'Pledge ID serial-number' (not
   shown here for space reasons).

   Audit Voucher:  An Audit Voucher is named after the logging assertion
      mechanisms that the registrar then "audits" to enforce local
      policy.  The registrar mitigates a malicious registrar by auditing
      that an unknown malicious registrar does not appear in the log
      entries.  This does not directly prevent a malicious registrar but
      provides a response mechanism that ensures the on-path-attack is
      unsuccessful.  An advantage is that actual ownership knowledge
      (i.e., sales integration providing an indication of who purchased
      the device) is not required on the MASA service.

   Nonceless Audit Voucher:  An Audit Voucher with a validity period
      statement, but no guarantee of freshness.  Fundamentally, it is
      the same as an Audit Voucher except that it can be issued in
      advance to support network partitions or to provide a permanent
      voucher for remote deployments.  Being issued in advance of the
      Pledge being online, the Pledge can not rely on a nonce to be
      included for freshness.  This compromise in reducing the freshness
      allows for the resulting voucher can be carried across air-gapped
      infrastructure.  In addition, as there is no end to the validity
      period, the voucher can be used after the manufacturer (and its
      delegates) has gone out of business.

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   Ownership Audit Voucher:  An Audit Voucher where the MASA service has
      verified the registrar as the authorized owner.  The MASA service
      mitigates a MiTM registrar by refusing to generate Audit Vouchers
      for unauthorized registrars.  The registrar uses audit techniques
      to supplement the MASA.  This provides an ideal sharing of policy
      decisions and enforcement between the vendor and the owner.

   Ownership ID Voucher:  Named after inclusion of the Pledge's CN-ID or
      DNS-ID within the voucher.  The MASA service mitigates a MiTM
      registrar by identifying the specific registrar (via WebPKI)
      authorized to own the Pledge.

   Bearer Voucher:  A Bearer Voucher is named after the inclusion of a
      registrar ID wildcard.  Because the registrar identity is not
      indicated, this voucher type must be treated as a secret and
      protected from exposure as any 'bearer' of the voucher can claim
      the Pledge.  This variation is included in the above table in
      order to clearly show how other voucher types differ.  This
      specification does not support bearer vouchers at this time.
      There are other specifications in the industry which are
      equivalent though.  Publishing a nonceless bearer voucher
      effectively turns the specified pledge into a "TOFU" device with
      minimal mitigation against MiTM registrars.  Bearer vouchers are
      therefore out of scope.

5.  Changes since RFC8366

5.1.  Attempts and motivation to extend RFC8366

   [RFC8366] was published in 2018 during the development of [BRSKI],
   [ZERO-TOUCH] and other work-in-progress efforts.  Since then the
   industry has matured significantly, and the in-the-field activity
   which this document supports has become known as _onboarding_ rather
   than _bootstrapping_.

   The focus of [BRSKI] was onboarding of ISP and Enterprise owned wired
   routing and switching equipment, with IoT devices being a less
   important aspect.  [ZERO-TOUCH] has focused upon onboarding of CPE
   equipment like cable modems and other larger IoT devices, again with
   smaller IoT devices being of less import.

   Since [BRSKI] was published there is now a mature effort to do
   application-level onboarding of constrained IoT devices defined by
   the Thread Group and the Fairhair Alliance (now OCF) [fairhair].  The
   [cBRSKI] document has defined a version of [BRSKI] that is useable
   over constrained IEEE 802.15.4 6LoWPAN networks using CoAP and DTLS,
   while [I-D.ietf-lake-authz] provides for using CoAP and EDHOC on even
   more constrained devices with very constrained networks.

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   [PRM] has created a new methodology for onboarding that does not
   depend upon a synchronous connection between the Pledge and the
   Registrar.  This mechanism uses a mobile Registrar Agent that works
   to collect and transfer signed artifacts via physical travel from one
   network to another.

   Both [cBRSKI] and [PRM] require extensions to the Voucher Request and
   the resulting Voucher.  The new attribtes are required to carry the
   additional attributes and describe the extended semantics.  In
   addition [cBRSKI] uses the serialization mechanism described in
   [RFC9254] to produce significantly more compact artifacts.

   When the process to define [cBRSKI] and [PRM] was started, there was
   a belief that the appropriate process was to use the [RFC8040]
   _augment_ mechanism to further extend both the voucher request
   [BRSKI] and voucher [RFC8366] artifacts.  However, [PRM] needs to
   extend an enumerated type with additional values and _augment_ can
   not do this, so that was initially the impetus for this document.

   An attempt was then made to determine what would happen if one wanted
   to have a constrained version of the [PRM] voucher artifact.  The
   result was invalid YANG, with multiple definitions of the core
   attributes from the [RFC8366] voucher artifact.  After some
   discussion, it was determined that the _augment_ mechanism did not
   work, nor did it work better when [RFC8040] yang-data was replaced
   with the [RFC8791] structure mechanisms.

   After significant discussion the decision was made to simply roll all
   of the needed extensions into this document.

5.2.  Informational Model changes since RFC8366

   This document therefore represents a merge of YANG definitions from
   [RFC8366], the voucher-request from [BRSKI], and extensions to each
   of these from [cBRSKI], [CLOUD] and [PRM].  The difficulty with this
   approach is that the semantics of the definitions needed for the
   other documents is not included in this document, but rather in the
   respective other documents.

6.  Signature mechanisms

   Three signature systems have been defined for vouchers and voucher-
   requests.

   [cBRSKI] defines a mechanism that uses COSE RFC9052, with the voucher
   data encoded using [RFC9254].  However, as the SID process requires
   up-to-date YANG, the SID values for this mechanism are presented in
   this document.

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   [jBRSKI] defines a mechanism that uses JSON [RFC8259] and [JWS].

   The CMS signing mechanism first defined in [RFC8366] continues to be
   defined here.

6.1.  CMS Format Voucher Artifact

   The IETF evolution of PKCS#7 is CMS [RFC5652].  A CMS-signed voucher,
   the default type, contains a ContentInfo structure with the voucher
   content.  An OID for JSON-encoded voucher is allocated in
   Section 11.4, and it is to be placed in the eContentType field in the
   ContentInfo.

   The signing structure is a CMS SignedData structure, as specified by
   Section 5.1 of [RFC5652], encoded using ASN.1 Distinguished Encoding
   Rules (DER), as specified in ITU-T X.690 [ITU-T.X690.2015].

   [RFC5652] mandates that SignedAttributes MUST be present when the
   content type is not id-data.  This mitigates attacks on CMS as
   described in [I-D.vangeest-lamps-cms-euf-cma-signeddata].  Decoders
   MUST verify that SignedAttributes are present.

   To facilitate interoperability, Section 11.3 the media type
   "application/voucher-cms+json" and the filename extension ".vcj" were
   registered by [RFC8366].

   The CMS structure MUST contain a 'signerInfo' structure, as described
   in Section 5.1 of [RFC5652], containing the signature generated over
   the content using a private key trusted by the recipient.  Normally,
   the recipient is the Pledge and the signer is the MASA.  In the
   Voucher Request, the signer is the Pledge, or the Registrar.

   Note that Section 5.1 of [RFC5652] includes a discussion about how to
   validate a CMS object, which is really a PKCS7 object (cmsVersion=1).
   Intermediate systems (such the Bootstrapping Remote Secure Key
   Infrastructures [BRSKI] registrar) that might need to evaluate the
   voucher in flight MUST be prepared for such an older format.  No
   signaling of the format version is necessary, as the manufacturer
   knows the capabilities of the Pledge and will use an appropriate
   format voucher for each Pledge.

   The CMS structure SHOULD also contain all of the certificates leading
   up to and including the signer's trust anchor certificate known to
   the recipient.  The inclusion of the trust anchor is unusual in many
   applications, but third parties cannot accurately audit the
   transaction without it.

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   The CMS structure MAY also contain revocation objects for any
   intermediate certificate authorities (CAs) between the voucher issuer
   and the trust anchor known to the recipient.  However, the use of
   CRLs and other validity mechanisms is discouraged, as the Pledge is
   unlikely to be able to perform online checks and is unlikely to have
   a trusted clock source.  As described below, the use of short-lived
   vouchers and/or a Pledge-provided nonce provides a freshness
   guarantee.

7.  Voucher Artifact

   The voucher's primary purpose is to securely assign a Pledge to an
   owner.  The voucher informs the Pledge which entity it should
   consider to be its owner.

   This document defines a voucher that is JSON-encoded, and CMS signed
   encoding of the data defined in the YANG module Section 7.3.  Also,
   this document defines voucher data that is CBOR-encoded based on the
   same YANG model.  The CBOR-encoded (signed) voucher based on this
   CBOR voucher data is defined in [cBRSKI].

   The voucher data format is described here as a practical basis for
   some uses (such as in NETCONF), but more to clearly indicate what
   vouchers look like in practice.  This description also serves to
   validate the YANG data model.

   [RFC8366] defined a media type and a filename extension for the CMS-
   encoded JSON type.  The media type for JOSE format vouchers is
   defined in [jBRSKI] and the media type for COSE format vouchers is
   defined in [cBRSKI].  Both include respective filename extensions.

   The Media Type is used by the Pledge (requesting to the Registrar)
   and by the Registrar (requesting to the MASA) to signal what voucher
   format is expected.  Other aspects of the voucher, such as it being
   nonce-less or which kind of pinned anchor is used, is not part of the
   Media Type.

   Only the format of voucher that is expected is signaled in the form
   of a (MIME) Media Content-Type in the HTTP Accept: header.

   For vouchers stored/transferred via methods like a USB storage device
   (USB key), the voucher format is usually signaled by a filename
   extension.

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7.1.  Tree Diagram

   The following tree diagram illustrates a high-level view of a voucher
   document.  The notation used in this diagram is described in
   [RFC8340].  Each node in the diagram is fully described by the YANG
   module in Section 7.3.  Please review the YANG module for a detailed
   description of the voucher format.

   module: ietf-voucher

     structure voucher:
       +-- voucher
          +-- created-on?                        yang:date-and-time
          +-- extensions*                        union
          +-- manufacturer-private?              binary
          +-- assertion?                         enumeration
          +-- serial-number                      string
          +-- idevid-issuer?                     binary
          +-- (pinning)?
          |  +--:(pinned-domain-cert)
          |  |  +-- pinned-domain-cert?          binary
          |  +--:(pinned-domain-pubk)
          |  |  +-- pinned-domain-pubk?          binary
          |  +--:(pinned-domain-pubk-sha256)
          |     +-- pinned-domain-pubk-sha256?   binary
          +-- domain-cert-revocation-checks?     boolean
          +-- last-renewal-date?                 yang:date-and-time
          +-- (nonceless)?
          |  +--:(expires-on)
          |  |  +-- expires-on?                  yang:date-and-time
          |  +--:(nonce)
          |     +-- nonce?                       binary
          +-- est-domain?                        ietf:uri
          +-- additional-configuration-url?      ietf:uri

7.2.  Examples

   This section provides voucher data examples for illustration
   purposes.  These examples conform to the encoding rules defined in
   [RFC8259].

   The following example illustrates an ephemeral voucher (uses a
   nonce).  The MASA generated this voucher using the 'logged' assertion
   type, knowing that it would be suitable for the Pledge making the
   request.

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   {
     "ietf-voucher:voucher": {
       "created-on": "2016-10-07T19:31:42Z",
       "assertion": "logged",
       "serial-number": "JADA123456789",
       "idevid-issuer": "base64encodedvalue==",
       "pinned-domain-cert": "base64encodedvalue==",
       "nonce": "base64encodedvalue=="
     }
   }

   The following example illustrates a non-ephemeral voucher (no nonce).
   While the voucher itself expires after two weeks, it presumably can
   be renewed for up to a year.  The MASA generated this voucher using
   the 'verified' assertion type, which should satisfy all Pledges.

   {
     "ietf-voucher:voucher": {
       "created-on": "2016-10-07T19:31:42Z",
       "expires-on": "2016-10-21T19:31:42Z",
       "assertion": "verified",
       "serial-number": "JADA123456789",
       "idevid-issuer": "base64encodedvalue==",
       "pinned-domain-cert": "base64encodedvalue==",
       "domain-cert-revocation-checks": true,
       "last-renewal-date": "2017-10-07T19:31:42Z"
     }
   }

   [jBRSKI], Section 8 contains examples of vouchers encoded in JSON,
   and signed with [JWS]. [cBRSKI], Section 9 contains examples of
   vouchers encoded in CBOR, and signed with [COSE].

7.3.  YANG Module

   <CODE BEGINS>
   =============== NOTE: '\' line wrapping per RFC 8792 ================

   module ietf-voucher {
     yang-version 1.1;
     namespace "urn:ietf:params:xml:ns:yang:ietf-voucher";
     prefix vch;

     import ietf-yang-types {
       prefix yang;
       reference
         "RFC 6991: Common YANG Data Types";
     }

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     import ietf-inet-types {
       prefix ietf;
       reference
         "RFC 6991: Common YANG Data Types";
     }
     import ietf-yang-structure-ext {
       prefix sx;
     }

     organization
       "IETF ANIMA Working Group";
     contact
       "WG Web:   <https://datatracker.ietf.org/wg/anima/>
        WG List:  <mailto:anima@ietf.org>
        Author:   Kent Watsen
                  <mailto:kent+ietf@watsen.net>
        Author:   Michael Richardson
                  <mailto:mcr+ietf@sandelman.ca>
        Author:   Max Pritikin
                  <mailto:pritikin@cisco.com>
        Author:   Toerless Eckert
                  <mailto:tte@cs.fau.de>
        Author:   Qiufang Ma
                  <mailto:maqiufang1@huawei.com>";
     description
       "This module defines the format for a voucher, which is
        produced by a pledge's manufacturer or delegate (MASA)
        to securely assign a pledge to an 'owner', so that the
        pledge may establish a secure connection to the owner's
        network infrastructure.

        Copyright (c) 2024 IETF Trust and the persons identified as
        authors of the code.  All rights reserved.

        Redistribution and use in source and binary forms, with or
        without modification, is permitted pursuant to, and subject to
        the license terms contained in, the Revised BSD License set
        forth in Section 4.c of the IETF Trust's Legal Provisions
        Relating to IETF Documents
        (https://trustee.ietf.org/license-info).

        This version of this YANG module is part of RFC XXXX
        (https://www.rfc-editor.org/info/rfcXXXX); see the RFC itself
        for full legal notices.

        RFCEDITOR: please replace XXXX with the RFC number assigned.

        The key words 'MUST', 'MUST NOT', 'REQUIRED', 'SHALL', 'SHALL

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        NOT', 'SHOULD', 'SHOULD NOT', 'RECOMMENDED', 'NOT RECOMMENDED',
        'MAY', and 'OPTIONAL' in this document are to be interpreted as
        described in BCP 14 (RFC 2119) (RFC 8174) when, and only when,
        they appear in all capitals, as shown here.";

     revision 2023-01-10 {
       description
         "updated to support new assertion enumerated type";
       reference
         "RFC XXXX Voucher Profile for Bootstrapping Protocols";
     }

     grouping voucher-artifact-grouping {
       description
         "Grouping to allow reuse/extensions in future work.";
       container voucher {
         description
           "A voucher assigns a pledge to an owner using
            the (pinned-domain-cert) value.";
         leaf created-on {
           type yang:date-and-time;
           description
             "A value indicating the date this voucher was created.
              This node is primarily for human consumption and auditing.
              Future work MAY create verification requirements based on
              this node.";
         }
         leaf-list extensions {
           type union {
             type uint64; // when serialized to CBOR with SID
             type string; // when serialized to CBOR or JSON
           }
           description
             "A list of extension names that are used in this Voucher
              file.  Each name is registered with the IANA.  Standard
              extensions are described in an RFC, while vendor \
                                                             proprietary
              ones are not.";
         }
         leaf manufacturer-private {
           type binary;
           description
             "In CBOR serialization, this is a CBOR bstr containing \
                                                     any valid CBOR that
              the manufacturer wishes to share with it's Pledge.  In \
                                                    JSON serializations,
              this contains additional JSON instead, and it is \
                                                    base64URL encoded.";

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         }
         leaf assertion {
           type enumeration {
             enum verified {
               value 0;
               description
                 "Indicates that the ownership has been positively
                  verified by the MASA (e.g., through sales channel
                  integration).";
             }
             enum logged {
               value 1;
               description
                 "Indicates that the voucher has been issued after
                  minimal verification of ownership or control.  The
                  issuance has been logged for detection of
                  potential security issues (e.g., recipients of
                  vouchers might verify for themselves that unexpected
                  vouchers are not in the log).  This is similar to
                  unsecured trust-on-first-use principles but with the
                  logging providing a basis for detecting unexpected
                  events.";
             }
             enum proximity {
               value 2;
               description
                 "Indicates that the voucher has been issued after
                  the MASA verified a proximity proof provided by the
                  device and target domain.  The issuance has been
                  logged for detection of potential security issues.";
             }
             enum agent-proximity {
               value 3;
               description
                 "Mostly identical to proximity, but
                  indicates that the voucher has been issued
                  after the MASA has verified a statement that
                  a registrar agent has made contact with the device.";
             }
           }
           description
             "The assertion is a statement from the MASA regarding how
              the owner was verified.  This statement enables pledges
              to support more detailed policy checks.  Pledges MUST
              ensure that the assertion provided is acceptable, per
              local policy, before processing the voucher.";
         }
         leaf serial-number {

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           type string;
           mandatory true;
           description
             "The serial-number of the hardware.  When processing a
              voucher, a pledge MUST ensure that its serial-number
              matches this value.  If no match occurs, then the
              pledge MUST NOT process this voucher.";
         }
         leaf idevid-issuer {
           type binary;
           description
             "The Authority Key Identifier OCTET STRING (as defined in
              Section 4.2.1.1 of RFC 5280) from the pledge's IDevID
              certificate.  Optional since some serial-numbers are
              already unique within the scope of a MASA.
              Inclusion of the statistically unique key identifier
              ensures statistically unique identification of the
              hardware.
              When processing a voucher, a pledge MUST ensure that its
              IDevID Authority Key Identifier matches this value.  If no
              match occurs, then the pledge MUST NOT process this
              voucher.
              When issuing a voucher, the MASA MUST ensure that this
              field is populated for serial-numbers that are not
              otherwise unique within the scope of the MASA.";
         }
         choice pinning {
           description
             "One of these attributes is used by the pledge to
              specify the registrar, and how the pledge would like
              the registrar's identity to be pinned";
           leaf pinned-domain-cert {
             type binary;
             description
               "An X.509 v3 certificate structure, as specified by
                RFC 5280, using Distinguished Encoding Rules (DER)
                encoding, as defined in ITU-T X.690.

                This certificate is used by a pledge to trust a Public \
                                                                     Key
                Infrastructure in order to verify a domain certificate
                supplied to the pledge separately by the bootstrapping
                protocol.  The domain certificate MUST have this
                certificate somewhere in its chain of certificates.
                This certificate MAY be an end-entity certificate,
                including a self-signed entity.";
             reference
               "RFC 5280:

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                  Internet X.509 Public Key Infrastructure Certificate
                  and Certificate Revocation List (CRL) Profile.
                ITU-T X.690:
                   Information technology - ASN.1 encoding rules:
                   Specification of Basic Encoding Rules (BER),
                   Canonical Encoding Rules (CER) and Distinguished
                   Encoding Rules (DER).";
           }
           leaf pinned-domain-pubk {
             type binary;
             description
               "The pinned-domain-pubk may replace the
                pinned-domain-cert in constrained uses of
                the voucher. The pinned-domain-pubk
                is the Raw Public Key of the Registrar.
                This field is encoded as a Subject Public Key Info block
                as specified in RFC7250, in section 3.
                The ECDSA algorithm MUST be supported.
                The EdDSA algorithm as specified in
                draft-ietf-tls-rfc4492bis-17 SHOULD be supported.
                Support for the DSA algorithm is not recommended.
                Support for the RSA algorithm is a MAY.";
           }
           leaf pinned-domain-pubk-sha256 {
             type binary;
             description
               "The pinned-domain-pubk-sha256 is a second
                alternative to pinned-domain-cert.  In many cases the
                public key of the domain has already been transmitted
                during the key agreement process, and it is wasteful
                to transmit the public key another two times.
                The use of a hash of public key info, at 32-bytes for
                sha256 is a significant savings compared to an RSA
                public key, but is only a minor savings compared to
                a 256-bit ECDSA public-key.
                Algorithm agility is provided by extensions to this
                specification which can define a new leaf for another
                hash type.";
           }
         }
         leaf domain-cert-revocation-checks {
           type boolean;
           description
             "A processing instruction to the pledge that it MUST (true)
              or MUST NOT (false) verify the revocation status for the
              pinned domain certificate.  If this field is not set, then
              normal PKIX behavior applies to validation of the domain
              certificate.";

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         }
         leaf last-renewal-date {
           type yang:date-and-time;
           // this does not work, the XPath does not evaluate
           // must '../nonceless/expires-on';
           description
             "The date that the MASA projects to be the last date it
              will renew a voucher on. This field is merely
              informative; it is not processed by pledges.

              Circumstances may occur after a voucher is generated that
              may alter a voucher's validity period.  For instance,
              a vendor may associate validity periods with support
              contracts, which may be terminated or extended
              over time.";
         }
         choice nonceless {
           description
             "Either a nonce must be present, or an expires-on header";
           leaf expires-on {
             type yang:date-and-time;
             description
               "A value indicating when this voucher expires.  The \
                                                                 node is
                optional as not all pledges support expirations, such as
                pledges lacking a reliable clock.

                If this field exists, then the pledges MUST ensure that
                the expires-on time has not yet passed. A pledge without
                an accurate clock cannot meet this requirement.

                The expires-on value MUST NOT exceed the expiration date
                of any of the listed 'pinned-domain-cert' certificates.\
                                                                      ";
           }
           leaf nonce {
             type binary {
               length "8..32";
             }
             description
               "A value that can be used by a pledge in some \
                                                           bootstrapping
                protocols to enable anti-replay protection.  This node \
                                                                      is
                optional because it is not used by all bootstrapping
                protocols.

                When present, the pledge MUST compare the provided nonce

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                value with another value that the pledge randomly
                generated and sent to a bootstrap server in an earlier
                bootstrapping message.  If the value is present, but
                the values do not match, then the pledge MUST NOT \
                                                                 process
                this voucher.";
           }
         }
         leaf est-domain {
           type ietf:uri;
           description
             "The est-domain is a URL from which the Pledge should
                continue doing enrollment rather than with the
                Cloud Registrar.
                The pinned-domain-cert contains a trust-anchor
                which is to be used to authenticate the server
                found at this URI.
               ";
         }
         leaf additional-configuration-url {
           type ietf:uri;
           description
             "The additional-configuration attribute contains a
                URL to which the Pledge can retrieve additional
                configuration information.
                The contents of this URL are manufacturer specific.
                This is intended to do things like configure
                a VoIP phone to point to the correct hosted
                PBX, for example.";
         }
       }
     }

     // Top-level statement
     sx:structure voucher {
       uses voucher-artifact-grouping;
     }
   }
   <CODE ENDS>

7.4.  ietf-voucher SID values

   [RFC9254] explains how to serialize YANG into CBOR, and for this a
   series of SID values are required.  While [CORESID] defines the
   management process for these values, due to the immaturity of the
   tooling around this YANG-SID mechanism, the following values are
   considered normative.

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         SID Assigned to
   --------- --------------------------------------------------
        2451 data /ietf-voucher:voucher/voucher
        2452 data /ietf-voucher:voucher/voucher/assertion
        2453 data /ietf-voucher:voucher/voucher/created-on
        2454 data .../domain-cert-revocation-checks
        2455 data /ietf-voucher:voucher/voucher/expires-on
        2456 data /ietf-voucher:voucher/voucher/idevid-issuer
        2457 data /ietf-voucher:voucher/voucher/last-renewal-date
        2458 data /ietf-voucher:voucher/nonce
        2459 data /ietf-voucher:voucher/voucher/pinned-domain-cert
        2460 data /ietf-voucher:voucher/voucher/pinned-domain-pubk
        2461 data .../pinned-domain-pubk-sha256
        2462 data /ietf-voucher:voucher/voucher/serial-number
        2463 data .../additional-configuration-url
        2464 data /ietf-voucher:voucher/voucher/est-domain
        2465 data .../manufacturer-private
        2466 data /ietf-voucher:voucher/voucher/extensions

   The "assertion" attribute is an enumerated type in [RFC8366], but no
   values were provided as part of the enumeration.  This document
   provides enumerated values as part of the YANG module.

   In the JSON serialization, the literal strings from the enumerated
   types are used so there is no ambiguity.

   In the CBOR serialization, a small integer is used, and the
   enumeration values are repeated here for convenience.  However, the
   YANG module should be considered authoritative.  No IANA registry is
   provided or necessary because the YANG module (and this document)
   would be extended when there are new entries required.

                       +=========+=================+
                       | Integer | Assertion Type  |
                       +=========+=================+
                       | 0       | verified        |
                       +---------+-----------------+
                       | 1       | logged          |
                       +---------+-----------------+
                       | 2       | proximity       |
                       +---------+-----------------+
                       | 3       | agent-proximity |
                       +---------+-----------------+

                           Table 2: CBOR integers
                            for the "assertion"
                               attribute enum

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7.5.  Voucher Extensions

   An unstated assumption in [RFC8366] was that vouchers could be
   extended in proprietary ways by manufacturers.  This allows for
   manufacturers to communicate new things from the MASA to the Pledge,
   and since both are under control of the same entity, it seemed
   perfectly fine, even though it would violate the strict definition of
   the YANG model.

   The JSON serialization of vouchers implicitely accomodates the above,
   since the voucher is just a map (or dictionary).  Map keys are just
   strings, and creating unique strings is easy to do by including the
   manufacturer's domain name.

   In CBOR serialization [RFC9254], the situation is not so easy.  The
   delta encoding for keys requires new keys to use the absolute Tag(47)
   for new entities.  An extension might need to use the Private Use SID
   values, or acquire SID values for their own use.

   Where the process has become complex is when making standard
   extensions, as has happened recently, resulting in this document.
   The processes which were anticipated to be useful, (the "augment"
   mechanism) turned out not to be, see Section 5.1.

   Instead, a process similiar to what was done by [RFC8520] has been
   adopted.  In this, extensions are listed in a leaf named
   "extensions".  In JSON serialization, these extensions require a
   unique name, and this MUST be allocated by IANA.  The name MUST be
   the same as the YANG extension module name.  The "extensions" list
   attribute definied in this model allows for new standard extensions
   to be defined.  Items within that list are strings (in JSON
   serialization), or integers (in CBOR serialization), as defined by
   the Voucher Extension Registry.

   Extensions are full YANG modules, which are subject to the SID
   allocation process described in [RFC9254].  When an extension is
   serialized, the extension is placed in a sub-map in the value
   section.  In JSON serialization, the key is the name of the
   extension, prefixed by the string "extension:".  In CBOR
   serialization, the key is the SID which is allocated as the module
   SID.  This will typically require the absolute Tag(47) to be applied
   to this key.

   Note that this differs from the mechanism described in [RFC8520] in
   that a sub-map is not used.  Instead keys are created by combining
   the module name and the attribute as a string.  The [RFC8520]
   mechanism uses more bytes, but is also not easily translateable to
   CBOR.

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   As the Voucher Request artifact is created by YANG augment of the
   voucher artifact, any extension defined for the voucher is also valid
   for a Voucher Request.

7.6.  Manufacturer Private extensions

   A manufacturer might need to communicate content in the voucher (or
   in the voucher request), which are never subject to standardization.
   While they can use the voucher extensions mechanism defined in
   Section 7.5, it does require allocation of a SID in order to do
   minimal-sized encoding.  Note that [RFC9254] does not strictly
   require use of SIDs: instead of a SID value, the full string name can
   always be used.  But this would significantly increase the size of
   the voucher data.

   Instead, a manufacturer MAY use the manufacturer-private leaf to put
   any content they wish.  In CBOR serialization, if a plain CBOR map
   would be used, it would be subject to delta encoding: so use of this
   leaf requires that the contents are bstr-encoded [RFC8949],
   Section 3.1 (Major type 2).  In JSON serialization, delta-encoding
   does not get in the way, and the manufacturer MAY use any encoding
   that is convenient for them, but base64URL encoding [RFC4648],
   Section 5 is RECOMMENDED.

8.  Voucher Request Artifact

   [BRSKI], Section 3 defined a Voucher-Request Artifact as an augmented
   artifact from the Voucher Artifact originally defined in [RFC8366].
   That definition has been moved to this document, and translated from
   YANG-DATA [RFC8040] to the SX:STRUCTURE extension [RFC8791].

8.1.  Tree Diagram

   The following tree diagram illustrates a high-level view of a voucher
   request document.  The notation used in this diagram is described in
   [RFC8340].  Each node in the diagram is fully described by the YANG
   module in Section 8.2.

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   module: ietf-voucher-request

     structure voucher:
       +-- voucher
          +-- created-on?
          |       yang:date-and-time
          +-- extensions*                                union
          +-- manufacturer-private?                      binary
          +-- assertion?                                 enumeration
          +-- serial-number                              string
          +-- idevid-issuer?                             binary
          +-- (pinning)?
          |  +--:(pinned-domain-cert)
          |  |  +-- pinned-domain-cert?                  binary
          |  +--:(pinned-domain-pubk)
          |  |  +-- pinned-domain-pubk?                  binary
          |  +--:(pinned-domain-pubk-sha256)
          |     +-- pinned-domain-pubk-sha256?           binary
          +-- domain-cert-revocation-checks?             boolean
          +-- last-renewal-date?
          |       yang:date-and-time
          +-- (nonceless)?
          |  +--:(expires-on)
          |  |  +-- expires-on?
          |  |          yang:date-and-time
          |  +--:(nonce)
          |     +-- nonce?                               binary
          +-- est-domain?                                ietf:uri
          +-- additional-configuration-url?              ietf:uri
          +-- prior-signed-voucher-request?              binary
          +-- (registrar-identity)?
          |  +--:(proximity-registrar-cert)
          |  |  +-- proximity-registrar-cert?            binary
          |  +--:(proximity-registrar-pubk)
          |  |  +-- proximity-registrar-pubk?            binary
          |  +--:(proximity-registrar-pubk-sha256)
          |     +-- proximity-registrar-pubk-sha256?     binary
          +-- agent-signed-data?                         binary
          +-- agent-provided-proximity-registrar-cert?   binary
          +-- agent-sign-cert?                           binary

8.2.  "ietf-voucher-request" Module

   The ietf-voucher-request YANG module is derived from the ietf-voucher
   module.

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   <CODE BEGINS>
   =============== NOTE: '\' line wrapping per RFC 8792 ================

   module ietf-voucher-request {
     yang-version 1.1;
     namespace "urn:ietf:params:xml:ns:yang:ietf-voucher-request";
     prefix vcr;

     import ietf-yang-structure-ext {
       prefix sx;
     }
     import ietf-voucher {
       prefix vch;
       description
         "This module defines the format for a voucher,
          which is produced by a pledge's manufacturer or
          delegate (MASA) to securely assign a pledge to
          an 'owner', so that the pledge may establish a secure
          connection to the owner's network infrastructure";
       reference
         "RFC XXXX: Voucher Artifact for
          Bootstrapping Protocols";
     }

     organization
       "IETF ANIMA Working Group";
     contact
       "WG Web:   <https://datatracker.ietf.org/wg/anima/>
        WG List:  <mailto:anima@ietf.org>
        Author:   Kent Watsen
                  <mailto:kent+ietf@watsen.net>
        Author:   Michael Richardson
                  <mailto:mcr+ietf@sandelman.ca>
        Author:   Max Pritikin
                  <mailto:pritikin@cisco.com>
        Author:   Toerless Eckert
                  <mailto:tte@cs.fau.de>
        Author:   Qiufang Ma
                  <mailto:maqiufang1@huawei.com>";
     description
       "This module defines the format for a voucher request.
        It is a superset of the voucher itself.
        It provides content to the MASA for consideration
        during a voucher request.

        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

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        described in BCP 14 (RFC 2119) (RFC 8174) when, and only when,
        they appear in all capitals, as shown here.

         Copyright (c) 2024 IETF Trust and the persons identified as
         authors of the code.  All rights reserved.

         Redistribution and use in source and binary forms, with or
         without modification, is permitted pursuant to, and subject to
         the license terms contained in, the Revised BSD License set
         forth in Section 4.c of the IETF Trust's Legal Provisions
         Relating to IETF Documents
         (https://trustee.ietf.org/license-info).

         This version of this YANG module is part of RFC XXXX
         (https://www.rfc-editor.org/info/rfcXXXX); see the RFC itself
         for full legal notices.

        RFCEDITOR: please replace XXXX with the RFC number assigned.

         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 (RFC 2119) (RFC 8174) when, and only when,
         they appear in all capitals, as shown here.";

     revision 2023-01-10 {
       description
         "Initial version";
       reference
         "RFC XXXX: Bootstrapping Remote Secure Key Infrastructure";
     }

     grouping voucher-request-grouping {
       description
         "Grouping to allow reuse/extensions in future work.";
       uses vch:voucher-artifact-grouping {
         refine "voucher/created-on" {
           mandatory false;
         }
         refine "voucher/last-renewal-date" {
           description
             "A last-renewal-date field
              is not valid in a voucher request, and
              any occurrence MUST be ignored";
         }
         refine "voucher/domain-cert-revocation-checks" {
           description
             "The domain-cert-revocation-checks field

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              is not valid in a voucher request, and
              any occurrence MUST be ignored";
         }
         refine "voucher/assertion" {
           mandatory false;
           description
             "Any assertion included in registrar voucher
              requests SHOULD be ignored by the MASA.";
         }
         augment "voucher" {
           description
             "Adds leaf nodes appropriate for requesting vouchers.";
           leaf prior-signed-voucher-request {
             type binary;
             description
               "If it is necessary to change a voucher, or re-sign and
                forward a voucher that was previously provided along a
                protocol path, then the previously signed voucher SHOULD
                be included in this field.

                For example, a pledge might sign a voucher request
                with a proximity-registrar-cert, and the registrar
                then includes it as the prior-signed-voucher-request
                field.  This is a simple mechanism for a chain of
                trusted parties to change a voucher request, while
                maintaining the prior signature information.

                The Registrar and MASA MAY examine the prior signed
                voucher information for the
                purposes of policy decisions. For example this
                information could be useful to a MASA to determine
                that both pledge and registrar agree on proximity
                assertions. The MASA SHOULD remove all
                prior-signed-voucher-request information when
                signing a voucher for imprinting so as to minimize
                the final voucher size.";
           }
           choice registrar-identity {
             description
               "One of these three attributes will be used to pin the \
                                                    registrar identity";
             leaf proximity-registrar-cert {
               type binary;
               description
                 "An X.509 v3 certificate structure as specified by
                  RFC 5280, Section 4 encoded using the ASN.1
                  distinguished encoding rules (DER), as specified
                  in [ITU.X690.1994].

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                  The first certificate in the Registrar TLS server
                  certificate_list sequence  (the end-entity TLS
                  certificate, see [RFC8446]) presented by the Registrar
                  to the Pledge.
                  This MUST be populated in a Pledge's voucher request
                  when a proximity assertion is requested.";
             }
             leaf proximity-registrar-pubk {
               type binary;
               description
                 "The proximity-registrar-pubk replaces
                  the proximity-registrar-cert in constrained uses of
                  the voucher-request.
                  The proximity-registrar-pubk is the
                  Raw Public Key of the Registrar. This field is encoded
                  as specified in RFC7250, section 3.
                  The ECDSA algorithm MUST be supported.
                  The EdDSA algorithm as specified in
                  draft-ietf-tls-rfc4492bis-17 SHOULD be supported.
                  Support for the DSA algorithm is not recommended.
                  Support for the RSA algorithm is a MAY, but due to
                  size is discouraged.";
             }
             leaf proximity-registrar-pubk-sha256 {
               type binary;
               description
                 "The proximity-registrar-pubk-sha256
                  is an alternative to both
                  proximity-registrar-pubk and pinned-domain-cert.
                  In many cases the public key of the domain has already
                  been transmitted during the key agreement protocol,
                  and it is wasteful to transmit the public key another
                  two times.
                  The use of a hash of public key info, at 32-bytes for
                  sha256 is a significant savings compared to an RSA
                  public key, but is only a minor savings compared to
                  a 256-bit ECDSA public-key.
                  Algorithm agility is provided by extensions to this
                  specification which may define a new leaf for another
                  hash type.";
             }
           }
           leaf agent-signed-data {
             type binary;
             description
               "The agent-signed-data field contains a data artifact \
                                                                provided
                by the Registrar-Agent to the Pledge for inclusion \

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                                                                into the
                voucher request.

                This artifact is signed by the Registrar-Agent and \
                                                                contains
                data, which can be verified by the pledge and the \
                                                              registrar.
                This data contains the pledge's serial-number and a \
                                                              created-on
                information of the agent-signed-data.

                The format is intentionally defined as binary to allow
                the document using this leaf to determine the encoding.\
                                                                      ";
           }
           leaf agent-provided-proximity-registrar-cert {
             type binary;
             description
               "An X.509 v3 certificate structure, as specified by
                RFC 5280, Section 4, encoded using the ASN.1
                distinguished encoding rules (DER), as specified
                in ITU X.690.
                The first certificate in the registrar TLS server
                certificate_list sequence (the end-entity TLS
                certificate; see RFC 8446) presented by the
                registrar to the registrar-agent and provided to
                the pledge.
                This MUST be populated in a pledge's voucher-request
                when an agent-proximity assertion is requested.";
             reference
               "ITU X.690: Information Technology - ASN.1 encoding
                rules: Specification of Basic Encoding Rules (BER),
                Canonical Encoding Rules (CER) and Distinguished
                Encoding Rules (DER)
                RFC 5280: Internet X.509 Public Key Infrastructure
                Certificate and Certificate Revocation List (CRL)
                Profile
                RFC 8446: The Transport Layer Security (TLS)
                Protocol Version 1.3";
           }
           leaf agent-sign-cert {
             type binary;
             description
               "An X.509 v3 certificate structure, as specified by
                RFC 5280, Section 4, encoded using the ASN.1
                distinguished encoding rules (DER), as specified
                in ITU X.690.
                This certificate can be used by the pledge,

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                the registrar, and the MASA to verify the signature
                of agent-signed-data. It is an optional component
                for the pledge-voucher request.
                This MUST be populated in a registrar's
                voucher-request when an agent-proximity assertion
                is requested.";
             reference
               "ITU X.690: Information Technology - ASN.1 encoding
                rules: Specification of Basic Encoding Rules (BER),
                Canonical Encoding Rules (CER) and Distinguished
                Encoding Rules (DER)
                RFC 5280: Internet X.509 Public Key Infrastructure
                Certificate and Certificate Revocation List (CRL)
                Profile";
           }
         }
       }
     }

     // Top-level statement
     sx:structure voucher {
       uses voucher-request-grouping;
     }
   }
   <CODE ENDS>

8.3.  ietf-voucher-request SID values

   [RFC9254] explains how to serialize YANG into CBOR, and for this a
   series of SID values are required.  While [CORESID] defines the
   management process for these values, due to the immaturity of the
   tooling around this YANG-SID mechanisms, the following values are
   considered normative.

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         SID Assigned to
   --------- --------------------------------------------------
        2501 data /ietf-voucher-request:voucher/voucher
        2502 data /ietf-voucher-request:voucher/voucher/assertion
        2503 data /ietf-voucher-request:voucher/voucher/created-on
        2504 data .../domain-cert-revocation-checks
        2505 data /ietf-voucher-request:voucher/voucher/expires-on
        2506 data .../idevid-issuer
        2507 data .../last-renewal-date
        2508 data /ietf-voucher-request:voucher/nonce
        2509 data .../pinned-domain-cert
        2510 data .../prior-signed-voucher-request
        2511 data .../proximity-registrar-cert
        2512 data .../proximity-registrar-pubk-sha256
        2513 data .../proximity-registrar-pubk
        2514 data .../serial-number
        2515 data .../agent-provided-proximity-registrar-cert
        2516 data .../agent-sign-cert
        2517 data .../agent-signed-data
        2518 data .../pinned-domain-pubk
        2519 data .../pinned-domain-pubk-sha256
        2520 data .../additional-configuration-url
        2521 data /ietf-voucher-request:voucher/est-domain
        2522 data /ietf-voucher-request:voucher/expires-on
        2523 data /ietf-voucher-request:voucher/voucher/extensions
        2524 data .../manufacturer-private

   The "assertion" attribute is an enumerated type, and has values as
   defined in Table 2.

9.  Design Considerations

9.1.  Renewals Instead of Revocations

   The lifetimes of vouchers may vary.  In some onboarding protocols,
   the vouchers may be created and consumed immediately, whereas in
   other onboarding solutions, there may be a significant time delay
   between when a voucher is created and when it is consumed.  In cases
   when there is a time delay, there is a need for the Pledge to ensure
   that the assertions made when the voucher was created are still
   valid.

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   A revocation artifact is generally used to verify the continued
   validity of an assertion such as a PKIX certificate, web token, or a
   "voucher".  With this approach, a potentially long-lived assertion is
   paired with a reasonably fresh revocation status check to ensure that
   the assertion is still valid.  However, this approach increases
   solution complexity, as it introduces the need for additional
   protocols and code paths to distribute and process the revocations.

   Addressing the shortcomings of revocations, this document recommends
   instead the use of lightweight renewals of short-lived non-revocable
   vouchers.  That is, rather than issue a long-lived voucher, where the
   'expires-on' leaf is set to some distant date, the expectation is for
   the MASA to instead issue a short-lived voucher, where the 'expires-
   on' leaf is set to a relatively near date, along with a promise
   (reflected in the 'last-renewal-date' field) to reissue the voucher
   again when needed.  Importantly, while issuing the initial voucher
   may incur heavyweight verification checks ("Are you who you say you
   are?"  "Does the Pledge actually belong to you?"), reissuing the
   voucher should be a lightweight process, as it ostensibly only
   updates the voucher's validity period.  With this approach, there is
   only the one artifact, and only one code path is needed to process
   it; there is no possibility of a Pledge choosing to skip the
   revocation status check because, for instance, the OCSP Responder is
   not reachable.

   While this document recommends issuing short-lived vouchers, the
   voucher artifact does not restrict the ability to create long-lived
   voucher, if required; however, no revocation method is described.

   Note that a voucher may be signed by a chain of intermediate CAs
   leading up to the trust anchor CA known by the Pledge.  Even though
   the voucher itself is not revocable, it is still revoked, per se, if
   one of the intermediate CA certificates is revoked.

9.2.  Voucher Per Pledge

   The solution described herein originally enabled a single voucher to
   apply to many Pledges, using lists of regular expressions to
   represent ranges of serial-numbers.  However, it was determined that
   blocking the renewal of a voucher that applied to many devices would
   be excessive when only the ownership for a single Pledge needed to be
   blocked.  Thus, the voucher format now only supports a single serial-
   number to be listed.

10.  Security Considerations

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10.1.  Clock Sensitivity

   An attacker could use an expired voucher to gain control over a
   device that has no understanding of time.  The device cannot trust
   NTP as a time reference, as an attacker could control the NTP stream.

   There are three things to defend against this: 1) devices are
   required to verify that the expires-on field has not yet passed, 2)
   devices without access to time can use nonces to get ephemeral
   vouchers, and 3) vouchers without expiration times may be used, which
   will appear in the audit log, informing the security decision.

   This document defines a voucher format that contains time values for
   expirations, which require an accurate clock in order to be processed
   correctly.  Vendors planning on issuing vouchers with expiration
   values must ensure that devices have an accurate clock when shipped
   from manufacturing facilities and take steps to prevent clock
   tampering.  If it is not possible to ensure clock accuracy, then
   vouchers with time values for expirations should not be issued.

10.2.  Protect Voucher PKI in HSM

   Pursuant the recommendation made in Section 6.1 for the MASA to be
   deployed as an online voucher signing service, it is RECOMMENDED that
   the MASA's private key used for signing vouchers is protected by a
   hardware security module (HSM).

10.3.  Test Domain Certificate Validity When Signing

   If a domain certificate is compromised, then any outstanding vouchers
   for that domain could be used by the attacker.  In this case, the
   domain administrator is clearly expected to initiate revocation of
   any domain identity certificates (as is normal in PKI solutions).

   Similarly, they are expected to contact the MASA to indicate that an
   outstanding (presumably short lifetime) voucher should be blocked
   from automated renewal.  Protocols for voucher distribution are
   RECOMMENDED to check for revocation of domain identity certificates
   before the signing of vouchers.

10.4.  YANG Module Security Considerations

   The YANG modules specified in this document define the schema for
   data that is subsequently encapsulated by secure signed-data
   structure, such as the CMS signed-data described in Section 6.1.  As
   such, all of the YANG modeled data is protected from modification.

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   Implementations should be aware that the signed data is only
   protected from external modification; the data is still visible.
   This potential disclosure of information doesn't affect security so
   much as privacy.  In particular, adversaries can glean information
   such as which devices belong to which organizations and which CRL
   Distribution Point and/or OCSP Responder URLs are accessed to
   validate the vouchers.  When privacy is important, the CMS signed-
   data content type SHOULD be encrypted, either by conveying it via a
   mutually authenticated secure transport protocol (e.g., TLS
   [RFC5246]) or by encapsulating the signed-data content type with an
   enveloped-data content type (Section 6 of [RFC5652]), though details
   for how to do this are outside the scope of this document.

   The use of YANG to define data structures, via the 'yang-data'
   statement, is relatively new and distinct from the traditional use of
   YANG to define an API accessed by network management protocols such
   as NETCONF [RFC6241] and RESTCONF [RFC8040].  For this reason, these
   guidelines do not follow template described by Section 3.7 of
   [YANG-GUIDE].

11.  IANA Considerations

11.1.  The IETF XML Registry

   This document registers two URIs in the "IETF XML Registry"
   [RFC3688].

   IANA has registered the following:

      URI:  urn:ietf:params:xml:ns:yang:ietf-voucher
      Registrant Contact:  The ANIMA WG of the IETF.
      XML:  N/A, the requested URI is an XML namespace.

   This reference should be updated to point to this document.

11.2.  The YANG Module Names Registry

   This document registers two YANG module in the "YANG Module Names"
   registry [RFC6020].

   IANA has registred the following:

      name:  ietf-voucher
      namespace:  urn:ietf:params:xml:ns:yang:ietf-voucher
      prefix:  vch
      reference:  RFC 8366

   This reference should be updated to point to this document.

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11.3.  The Media Types Registry

   IANA has registered the media type: application/voucher-cms+json, and
   this registration should be updated to point to this document.

11.4.  The SMI Security for S/MIME CMS Content Type Registry

   IANA has registered the OID 1.2.840.113549.1.9.16.1.40, id-ct-
   animaJSONVoucher.  This registration should be updated to point to
   this document.

11.5.  Extensions Registry

   IANA is asked to create a registry of extensions as follows:

     Registry name: Voucher Extensions Registry
     Registry policy: First Come First Served
     Reference: an optional document
     Extension name: UTF-8-encoded string, not to exceed 40 characters.
     Extension SID: the module SID value as allocated

   Each extension MUST follow the rules specified in this specification.
   As is usual, the IANA issues early allocations in accordance with
   [RFC7120].

   Note that the SID module value is allocated as part of a [CORESID]
   process.  This may be from a SID range managed by IANA, or from any
   other MegaRange.  Future work may allow for PEN based allocations.
   IANA does not need to separately allocate a SID value for this
   column.

   Extension name strings for standards track documents are single
   words, given by the YANG Module Name.  They do not contain dots.  For
   vendor proprietary extensions, the string SHOULD be made unique by
   putting the extension name in the form a fully-qualified domain name
   (FQDN) [RFC3696], such as "fuubar.example.com"

   Vendor proprietary extensions do not need to be registered with IANA,
   but vendors MAY do so.

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   Designated Experts should review for standards track documents for
   clarity, but the process is essentially tied to WG and IESG process:
   There are no choices in the extension names (which is always the YANG
   module name), or SID value (which is from another IANA process).  For
   non-standards track extensions, the Designated Expert should review
   whatever document is provided, if any.  The stability of the
   reference may be of concern.  The Designated Expert should determine
   if the work overlaps with existing efforts; and if so suggest
   merging.  However, as registration is optional, the Designated Expert
   should not block any registrations.

12.  References

12.1.  Normative References

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

   [CBOR]     Internet Standard 94,
              <https://www.rfc-editor.org/info/std94>.
              At the time of writing, this STD comprises the following:

              Bormann, C. and P. Hoffman, "Concise Binary Object
              Representation (CBOR)", STD 94, RFC 8949,
              DOI 10.17487/RFC8949, December 2020,
              <https://www.rfc-editor.org/info/rfc8949>.

   [cBRSKI]   Richardson, M., Van der Stok, P., Kampanakis, P., and E.
              Dijk, "Constrained Bootstrapping Remote Secure Key
              Infrastructure (cBRSKI)", Work in Progress, Internet-
              Draft, draft-ietf-anima-constrained-voucher-29, 18 October
              2025, <https://datatracker.ietf.org/doc/html/draft-ietf-
              anima-constrained-voucher-29>.

   [CLOUD]    Friel, O., Shekh-Yusef, R., and M. Richardson,
              "Bootstrapping Remote Secure Key Infrastructure (BRSKI)
              Cloud Registrar", Work in Progress, Internet-Draft, draft-
              ietf-anima-brski-cloud-19, 9 September 2025,
              <https://datatracker.ietf.org/doc/html/draft-ietf-anima-
              brski-cloud-19>.

   [CORESID]  Veillette, M., Ed., Pelov, A., Ed., Petrov, I., Ed.,
              Bormann, C., and M. Richardson, "YANG Schema Item
              iDentifier (YANG SID)", RFC 9595, DOI 10.17487/RFC9595,
              July 2024, <https://www.rfc-editor.org/rfc/rfc9595>.

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   [IDEVID]   IEEE Standard, "IEEE 802.1AR Secure Device Identifier",
              2018, <https://1.ieee802.org/security/802-1ar/>.

   [ITU-T.X690.2015]
              International Telecommunication Union, "Information
              Technology - ASN.1 encoding rules: Specification of Basic
              Encoding Rules (BER), Canonical Encoding Rules (CER) and
              Distinguished Encoding Rules (DER)", ITU-T Recommendation
              X.690, ISO/IEC 8825-1, August 2015,
              <https://www.itu.int/rec/T-REC-X.690/>.

   [jBRSKI]   Werner, T. and M. Richardson, "JWS signed Voucher
              Artifacts for Bootstrapping Protocols", Work in Progress,
              Internet-Draft, draft-ietf-anima-jws-voucher-16, 15
              January 2025, <https://datatracker.ietf.org/doc/html/
              draft-ietf-anima-jws-voucher-16>.

   [PRM]      Fries, S., Werner, T., Lear, E., and M. Richardson, "BRSKI
              with Pledge in Responder Mode (BRSKI-PRM)", Work in
              Progress, Internet-Draft, draft-ietf-anima-brski-prm-23, 3
              June 2025, <https://datatracker.ietf.org/doc/html/draft-
              ietf-anima-brski-prm-23>.

   [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/rfc/rfc2119>.

   [RFC5652]  Housley, R., "Cryptographic Message Syntax (CMS)", STD 70,
              RFC 5652, DOI 10.17487/RFC5652, September 2009,
              <https://www.rfc-editor.org/rfc/rfc5652>.

   [RFC6020]  Bjorklund, M., Ed., "YANG - A Data Modeling Language for
              the Network Configuration Protocol (NETCONF)", RFC 6020,
              DOI 10.17487/RFC6020, October 2010,
              <https://www.rfc-editor.org/rfc/rfc6020>.

   [RFC7120]  Cotton, M., "Early IANA Allocation of Standards Track Code
              Points", BCP 100, RFC 7120, DOI 10.17487/RFC7120, January
              2014, <https://www.rfc-editor.org/rfc/rfc7120>.

   [RFC7950]  Bjorklund, M., Ed., "The YANG 1.1 Data Modeling Language",
              RFC 7950, DOI 10.17487/RFC7950, August 2016,
              <https://www.rfc-editor.org/rfc/rfc7950>.

   [RFC7951]  Lhotka, L., "JSON Encoding of Data Modeled with YANG",
              RFC 7951, DOI 10.17487/RFC7951, August 2016,
              <https://www.rfc-editor.org/rfc/rfc7951>.

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   [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/rfc/rfc8174>.

   [RFC8259]  Bray, T., Ed., "The JavaScript Object Notation (JSON) Data
              Interchange Format", STD 90, RFC 8259,
              DOI 10.17487/RFC8259, December 2017,
              <https://www.rfc-editor.org/rfc/rfc8259>.

   [RFC8791]  Bierman, A., Björklund, M., and K. Watsen, "YANG Data
              Structure Extensions", RFC 8791, DOI 10.17487/RFC8791,
              June 2020, <https://www.rfc-editor.org/rfc/rfc8791>.

   [RFC9148]  van der Stok, P., Kampanakis, P., Richardson, M., and S.
              Raza, "EST-coaps: Enrollment over Secure Transport with
              the Secure Constrained Application Protocol", RFC 9148,
              DOI 10.17487/RFC9148, April 2022,
              <https://www.rfc-editor.org/rfc/rfc9148>.

   [RFC9254]  Veillette, M., Ed., Petrov, I., Ed., Pelov, A., Bormann,
              C., and M. Richardson, "Encoding of Data Modeled with YANG
              in the Concise Binary Object Representation (CBOR)",
              RFC 9254, DOI 10.17487/RFC9254, July 2022,
              <https://www.rfc-editor.org/rfc/rfc9254>.

   [ZERO-TOUCH]
              Watsen, K., Farrer, I., and M. Abrahamsson, "Secure Zero
              Touch Provisioning (SZTP)", RFC 8572,
              DOI 10.17487/RFC8572, April 2019,
              <https://www.rfc-editor.org/rfc/rfc8572>.

12.2.  Informative References

   [COSE]     Internet Standard 96,
              <https://www.rfc-editor.org/info/std96>.
              At the time of writing, this STD comprises the following:

              Schaad, J., "CBOR Object Signing and Encryption (COSE):
              Structures and Process", STD 96, RFC 9052,
              DOI 10.17487/RFC9052, August 2022,
              <https://www.rfc-editor.org/info/rfc9052>.

              Schaad, J., "CBOR Object Signing and Encryption (COSE):
              Countersignatures", STD 96, RFC 9338,
              DOI 10.17487/RFC9338, December 2022,
              <https://www.rfc-editor.org/info/rfc9338>.

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   [fairhair] Open Connectivity Foundation, "Fairhair Specification", 1
              November 2019,
              <https://openconnectivity.org/developer/specifications/
              fairhair/>.

   [I-D.ietf-lake-authz]
              Selander, G., Mattsson, J. P., Vučinić, M., Fedrecheski,
              G., and M. Richardson, "Lightweight Authorization using
              Ephemeral Diffie-Hellman Over COSE (ELA)", Work in
              Progress, Internet-Draft, draft-ietf-lake-authz-05, 7 July
              2025, <https://datatracker.ietf.org/doc/html/draft-ietf-
              lake-authz-05>.

   [I-D.vangeest-lamps-cms-euf-cma-signeddata]
              Van Geest, D. and F. Strenzke, "Best Practices for CMS
              SignedData with Regards to Signed Attributes", Work in
              Progress, Internet-Draft, draft-vangeest-lamps-cms-euf-
              cma-signeddata-02, 20 October 2025,
              <https://datatracker.ietf.org/doc/html/draft-vangeest-
              lamps-cms-euf-cma-signeddata-02>.

   [imprinting]
              Wikipedia, "Wikipedia article: Imprinting (psychology)", 1
              October 2025, <https://en.wikipedia.org/w/
              index.php?title=Imprinting_(psychology)&oldid=1314466188>.

   [JWS]      Jones, M., Bradley, J., and N. Sakimura, "JSON Web
              Signature (JWS)", RFC 7515, DOI 10.17487/RFC7515, May
              2015, <https://www.rfc-editor.org/rfc/rfc7515>.

   [RFC3688]  Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688,
              DOI 10.17487/RFC3688, January 2004,
              <https://www.rfc-editor.org/rfc/rfc3688>.

   [RFC3696]  Klensin, J., "Application Techniques for Checking and
              Transformation of Names", RFC 3696, DOI 10.17487/RFC3696,
              February 2004, <https://www.rfc-editor.org/rfc/rfc3696>.

   [RFC4648]  Josefsson, S., "The Base16, Base32, and Base64 Data
              Encodings", RFC 4648, DOI 10.17487/RFC4648, October 2006,
              <https://www.rfc-editor.org/rfc/rfc4648>.

   [RFC5246]  Dierks, T. and E. Rescorla, "The Transport Layer Security
              (TLS) Protocol Version 1.2", RFC 5246,
              DOI 10.17487/RFC5246, August 2008,
              <https://www.rfc-editor.org/rfc/rfc5246>.

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   [RFC6125]  Saint-Andre, P. and J. Hodges, "Representation and
              Verification of Domain-Based Application Service Identity
              within Internet Public Key Infrastructure Using X.509
              (PKIX) Certificates in the Context of Transport Layer
              Security (TLS)", RFC 6125, DOI 10.17487/RFC6125, March
              2011, <https://www.rfc-editor.org/rfc/rfc6125>.

   [RFC6241]  Enns, R., Ed., Bjorklund, M., Ed., Schoenwaelder, J., Ed.,
              and A. Bierman, Ed., "Network Configuration Protocol
              (NETCONF)", RFC 6241, DOI 10.17487/RFC6241, June 2011,
              <https://www.rfc-editor.org/rfc/rfc6241>.

   [RFC7435]  Dukhovni, V., "Opportunistic Security: Some Protection
              Most of the Time", RFC 7435, DOI 10.17487/RFC7435,
              December 2014, <https://www.rfc-editor.org/rfc/rfc7435>.

   [RFC8040]  Bierman, A., Bjorklund, M., and K. Watsen, "RESTCONF
              Protocol", RFC 8040, DOI 10.17487/RFC8040, January 2017,
              <https://www.rfc-editor.org/rfc/rfc8040>.

   [RFC8340]  Bjorklund, M. and L. Berger, Ed., "YANG Tree Diagrams",
              BCP 215, RFC 8340, DOI 10.17487/RFC8340, March 2018,
              <https://www.rfc-editor.org/rfc/rfc8340>.

   [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/rfc/rfc8366>.

   [RFC8520]  Lear, E., Droms, R., and D. Romascanu, "Manufacturer Usage
              Description Specification", RFC 8520,
              DOI 10.17487/RFC8520, March 2019,
              <https://www.rfc-editor.org/rfc/rfc8520>.

   [RFC8792]  Watsen, K., Auerswald, E., Farrel, A., and Q. Wu,
              "Handling Long Lines in Content of Internet-Drafts and
              RFCs", RFC 8792, DOI 10.17487/RFC8792, June 2020,
              <https://www.rfc-editor.org/rfc/rfc8792>.

   [SECUREJOIN]
              Richardson, M., "6tisch Zero-Touch Secure Join protocol",
              Work in Progress, Internet-Draft, draft-ietf-6tisch-
              dtsecurity-zerotouch-join-04, 8 July 2019,
              <https://datatracker.ietf.org/doc/html/draft-ietf-6tisch-
              dtsecurity-zerotouch-join-04>.

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   [Stajano99theresurrecting]
              Stajano, F. and R. Anderson, "The Resurrecting Duckling:
              Security Issues for Ad-Hoc Wireless Networks", 1999, <http
              s://www.cl.cam.ac.uk/research/dtg/www/files/publications/
              public/files/tr.1999.2.pdf>.

   [YANG-GUIDE]
              Bierman, A., "Guidelines for Authors and Reviewers of
              Documents Containing YANG Data Models", BCP 216, RFC 8407,
              DOI 10.17487/RFC8407, October 2018,
              <https://www.rfc-editor.org/rfc/rfc8407>.

Appendix A.  Examples

A.1.  Key pairs associated with examples

   The following voucher request has been produced using the IDevID
   [IDEVID] public (certificate) and private key.  They are included so
   that other developers can match the same output.

   The private RSA key:

   -----BEGIN EC PRIVATE KEY-----
   MHcCAQEEIBHNh6r8QRevRuo+tEmBJeFjQKf6bpFA/9NGoltv+9sNoAoGCCqGSM49
   AwEHoUQDQgAEA6N1Q4ezfMAKmoecrfb0OBMc1AyEH+BATkF58FsTSyBxs0SbSWLx
   FjDOuwB9gLGn2TsTUJumJ6VPw5Z/TP4hJw==
   -----END EC PRIVATE KEY-----

   The IDevID certificate (public key):

   -----BEGIN CERTIFICATE-----
   MIIBrzCCATWgAwIBAgIEHxj+5zAKBggqhkjOPQQDAjAmMSQwIgYDVQQDDBtoaWdo
   d2F5LXRlc3QuZXhhbXBsZS5jb20gQ0EwIBcNMjEwNDI3MTgyOTMwWhgPMjk5OTEy
   MzEwMDAwMDBaMBwxGjAYBgNVBAUTETAwLUQwLUU1LUYyLTAwLTAyMFkwEwYHKoZI
   zj0CAQYIKoZIzj0DAQcDQgAEA6N1Q4ezfMAKmoecrfb0OBMc1AyEH+BATkF58FsT
   SyBxs0SbSWLxFjDOuwB9gLGn2TsTUJumJ6VPw5Z/TP4hJ6NZMFcwHQYDVR0OBBYE
   FEWIzJaWAGQ3sLojZWRkVAgGbFatMAkGA1UdEwQCMAAwKwYIKwYBBQUHASAEHxYd
   aGlnaHdheS10ZXN0LmV4YW1wbGUuY29tOjk0NDMwCgYIKoZIzj0EAwIDaAAwZQIw
   YirbvjT3G8uF3iaOQwD5DYjId6jdPAhAVLzsPbbccCvDf8oZIZqgq8VRjqrfNt6L
   AjEAsl1Z+EfH7QOXqMDHqIH6qIbtZ2Q3UXpunKOCTW2tvPM1np1qom1/fyUcA+/w
   uptx
   -----END CERTIFICATE-----

   The Certification Authority that created the IDevID:

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   =============== NOTE: '\' line wrapping per RFC 8792 ================

   Certificate:
       Data:
           Version: 3 (0x2)
           Serial Number: 1016146354 (0x3c9129b2)
           Signature Algorithm: sha256WithRSAEncryption
           Issuer: CN = highway-test.example.com CA
           Validity
               Not Before: Apr  5 19:36:57 2021 GMT
               Not After : May  6 05:36:57 2021 GMT
           Subject: CN = highway-test.example.com CA
           Subject Public Key Info:
               Public Key Algorithm: rsaEncryption
                   Public-Key: (3072 bit)
                   Modulus:
                       00:b4:7b:27:42:49:9f:ed:85:47:74:ff:f6:50:cd:
                       5d:22:1a:64:38:22:f8:09:d2:d6:f3:60:d8:98:7f:
                       e5:84:52:1e:d9:ce:96:b4:dc:a6:43:74:67:27:d9:
                       9d:42:7d:bf:1a:43:92:9b:d1:dd:34:9b:41:d2:e3:
                       d5:59:b3:40:fc:b3:c9:e1:58:84:3f:87:f7:06:45:
                       25:26:4c:bf:a1:45:72:a0:0a:5b:86:41:d7:8e:be:
                       d3:38:b5:aa:66:69:bd:3a:fd:e9:b5:b8:a2:79:c4:
                       f0:a5:3c:9e:91:94:32:1e:9c:b0:7f:25:46:5b:76:
                       1d:86:23:85:b0:62:45:5c:a8:6f:fb:c5:26:e1:dd:
                       a8:f2:68:ab:c5:8c:b4:58:b4:2e:96:49:fa:fe:d2:
                       ea:a5:11:68:c2:8d:f4:58:ab:30:bd:dd:1b:29:97:
                       00:18:6f:59:40:9c:3a:2a:e4:96:25:bb:12:f4:1a:
                       11:72:6d:31:f6:b4:e1:cc:d8:9a:0c:aa:a8:aa:a4:
                       64:e3:f1:06:1c:c0:09:df:62:ba:04:cb:70:b0:c4:
                       f7:ca:35:22:ea:a9:c7:52:e1:ce:27:fb:6c:52:39:
                       b7:22:b3:5d:97:cb:0a:9f:75:a3:af:16:ef:e6:b2:
                       1b:6a:c3:0b:1d:15:fd:b8:d8:e7:8a:f6:f4:99:1c:
                       23:97:4b:80:e9:79:a3:85:16:f8:dd:bd:77:ef:3a:
                       3c:8e:e7:75:56:67:36:3a:dd:42:7b:84:2f:64:2f:
                       13:0e:fa:b0:3b:11:13:7e:ae:78:a6:2f:46:dd:4b:
                       11:88:e4:7b:19:ab:21:2d:1f:34:ba:61:cd:51:84:
                       a5:ec:6a:c1:90:20:70:e3:aa:f4:01:fd:0c:6e:cd:
                       04:47:99:31:70:79:6c:af:41:78:c1:04:2a:43:78:
                       84:8a:fe:c3:3d:f2:41:c8:2a:a1:10:e0:b7:b4:4f:
                       4e:e6:26:79:ac:49:64:cf:57:1e:2e:e3:2f:58:bd:
                       6f:30:00:67:d7:8b:d6:13:60:bf
                   Exponent: 65537 (0x10001)
           X509v3 extensions:
               X509v3 Basic Constraints: critical
                   CA:TRUE
               X509v3 Key Usage: critical
                   Certificate Sign, CRL Sign

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               X509v3 Subject Key Identifier:
                   33:12:45:B7:1B:10:BE:F3:CB:64:E5:4C:50:80:7C:9D:88:\
                                                                65:74:40
               X509v3 Authority Key Identifier:
                   33:12:45:B7:1B:10:BE:F3:CB:64:E5:4C:50:80:7C:9D:88:\
                                                                65:74:40
       Signature Algorithm: sha256WithRSAEncryption
       Signature Value:
           05:37:28:85:37:39:71:87:ec:5c:f0:51:19:55:4a:b7:e0:2a:
           e6:61:30:d4:e2:2b:ad:7a:db:12:fc:8a:a6:6e:15:82:80:10:
           fa:5d:67:60:e8:54:14:e3:89:d6:4e:60:89:98:5b:ab:fe:32:
           26:aa:02:35:68:4e:c6:2e:ce:08:36:d1:ea:a0:97:3d:76:38:
           6e:9d:4b:6f:33:d2:fa:c2:7e:b0:59:bc:75:97:17:d1:1b:c5:
           c4:58:ae:7b:7e:87:e5:87:2b:8b:6b:10:16:70:7c:c8:65:c7:
           d0:62:5d:f3:b5:06:af:03:8b:32:dd:88:f0:07:2b:5d:61:58:
           61:35:54:a6:ce:95:81:a2:6e:fa:b5:aa:25:e1:41:53:9d:e7:
           4b:7e:93:88:79:6b:dd:a3:6e:9a:0d:bd:85:b4:2d:66:b9:cc:
           01:13:f1:b5:d5:91:cc:86:5e:a7:c8:4a:8f:4d:9d:f8:17:31:
           32:7d:50:d5:c2:79:a0:41:a0:69:83:33:16:14:35:26:10:3b:
           23:eb:60:d9:28:68:99:d5:55:61:89:b5:35:5d:8b:fe:b1:96:
           32:69:3e:8b:c2:a2:4e:e1:d8:76:04:3c:87:91:5d:66:9e:81:
           a5:bf:18:2e:3e:39:da:4f:68:57:46:d2:1d:aa:81:51:3b:33:
           72:da:e9:7d:12:b6:a1:fc:c7:1d:c1:9c:bd:92:e8:1b:d2:06:
           e8:0b:82:2a:4f:23:5a:7a:fa:7b:86:a0:d7:c1:46:e7:04:47:
           77:11:cd:da:7c:50:32:d2:6f:fd:1e:0a:df:cf:b1:20:d2:86:
           ce:40:5a:27:61:49:2f:71:f5:04:ac:eb:c6:03:70:a4:70:13:
           4a:af:41:35:83:dc:55:c0:29:7f:12:4f:d0:f1:bb:f7:61:4a:
           9f:8d:61:b0:5e:89:46:49:e3:27:8b:42:82:5e:af:14:d5:d9:
           91:69:3d:af:11:70:5b:a3:92:3b:e3:c8:2a:a4:38:e5:88:f2:
           6f:09:f4:e5:04:3b
   -----BEGIN CERTIFICATE-----
   MIIELTCCApWgAwIBAgIEPJEpsjANBgkqhkiG9w0BAQsFADAmMSQwIgYDVQQDDBto
   aWdod2F5LXRlc3QuZXhhbXBsZS5jb20gQ0EwHhcNMjEwNDA1MTkzNjU3WhcNMjEw
   NTA2MDUzNjU3WjAmMSQwIgYDVQQDDBtoaWdod2F5LXRlc3QuZXhhbXBsZS5jb20g
   Q0EwggGiMA0GCSqGSIb3DQEBAQUAA4IBjwAwggGKAoIBgQC0eydCSZ/thUd0//ZQ
   zV0iGmQ4IvgJ0tbzYNiYf+WEUh7Zzpa03KZDdGcn2Z1Cfb8aQ5Kb0d00m0HS49VZ
   s0D8s8nhWIQ/h/cGRSUmTL+hRXKgCluGQdeOvtM4tapmab06/em1uKJ5xPClPJ6R
   lDIenLB/JUZbdh2GI4WwYkVcqG/7xSbh3ajyaKvFjLRYtC6WSfr+0uqlEWjCjfRY
   qzC93RsplwAYb1lAnDoq5JYluxL0GhFybTH2tOHM2JoMqqiqpGTj8QYcwAnfYroE
   y3CwxPfKNSLqqcdS4c4n+2xSObcis12XywqfdaOvFu/mshtqwwsdFf242OeK9vSZ
   HCOXS4DpeaOFFvjdvXfvOjyO53VWZzY63UJ7hC9kLxMO+rA7ERN+rnimL0bdSxGI
   5HsZqyEtHzS6Yc1RhKXsasGQIHDjqvQB/QxuzQRHmTFweWyvQXjBBCpDeISK/sM9
   8kHIKqEQ4Le0T07mJnmsSWTPVx4u4y9YvW8wAGfXi9YTYL8CAwEAAaNjMGEwDwYD
   VR0TAQH/BAUwAwEB/zAOBgNVHQ8BAf8EBAMCAQYwHQYDVR0OBBYEFDMSRbcbEL7z
   y2TlTFCAfJ2IZXRAMB8GA1UdIwQYMBaAFDMSRbcbEL7zy2TlTFCAfJ2IZXRAMA0G
   CSqGSIb3DQEBCwUAA4IBgQAFNyiFNzlxh+xc8FEZVUq34CrmYTDU4iutetsS/Iqm
   bhWCgBD6XWdg6FQU44nWTmCJmFur/jImqgI1aE7GLs4INtHqoJc9djhunUtvM9L6
   wn6wWbx1lxfRG8XEWK57foflhyuLaxAWcHzIZcfQYl3ztQavA4sy3YjwBytdYVhh

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   NVSmzpWBom76taol4UFTnedLfpOIeWvdo26aDb2FtC1mucwBE/G11ZHMhl6nyEqP
   TZ34FzEyfVDVwnmgQaBpgzMWFDUmEDsj62DZKGiZ1VVhibU1XYv+sZYyaT6LwqJO
   4dh2BDyHkV1mnoGlvxguPjnaT2hXRtIdqoFROzNy2ul9Erah/McdwZy9kugb0gbo
   C4IqTyNaevp7hqDXwUbnBEd3Ec3afFAy0m/9Hgrfz7Eg0obOQFonYUkvcfUErOvG
   A3CkcBNKr0E1g9xVwCl/Ek/Q8bv3YUqfjWGwXolGSeMni0KCXq8U1dmRaT2vEXBb
   o5I748gqpDjliPJvCfTlBDs=
   -----END CERTIFICATE-----

   The private key for the Certification Authority that created the
   IDevID:

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   -----BEGIN RSA PRIVATE KEY-----
   MIIG5AIBAAKCAYEAtHsnQkmf7YVHdP/2UM1dIhpkOCL4CdLW82DYmH/lhFIe2c6W
   tNymQ3RnJ9mdQn2/GkOSm9HdNJtB0uPVWbNA/LPJ4ViEP4f3BkUlJky/oUVyoApb
   hkHXjr7TOLWqZmm9Ov3ptbiiecTwpTyekZQyHpywfyVGW3YdhiOFsGJFXKhv+8Um
   4d2o8mirxYy0WLQulkn6/tLqpRFowo30WKswvd0bKZcAGG9ZQJw6KuSWJbsS9BoR
   cm0x9rThzNiaDKqoqqRk4/EGHMAJ32K6BMtwsMT3yjUi6qnHUuHOJ/tsUjm3IrNd
   l8sKn3Wjrxbv5rIbasMLHRX9uNjnivb0mRwjl0uA6XmjhRb43b137zo8jud1Vmc2
   Ot1Ce4QvZC8TDvqwOxETfq54pi9G3UsRiOR7GashLR80umHNUYSl7GrBkCBw46r0
   Af0Mbs0ER5kxcHlsr0F4wQQqQ3iEiv7DPfJByCqhEOC3tE9O5iZ5rElkz1ceLuMv
   WL1vMABn14vWE2C/AgMBAAECggGAAUF6HHP2sOhkfuPpCtbi9wHIALv9jdPxuu/J
   kgYRysHnhQxy7/85CO8eaKCS/4twcPZXZs4nA96wro73RRCCOz/k/7Rl9yszBNAm
   WgXer3iUO5jW2jBLF6ssPRDGhr/lmSt7HNCUENTV99BcKhcl4iCk+b2Ap9JCklRc
   8cU9Rk/Ft7K/eoLYUhd4Wn+IIbXfPRx2qp89Erj0SaZDNPq79BY9wiRS09iyfkiX
   /wRoJwsOLrSfunQYDOdlSs+XAs+NKeKmB6chmPhP+sYTXx+zFj+36NRjq2dxkYSH
   hB9peJ5yzTDhLQpagV5D36VXQsqHawvgEu6cQAfcZ4Iqmnura7zYBysfk4YzzizO
   rsc9rYGP10UO5W0EpKR/IcNfMGwtDbHe1/7z+0JSVDe/ldht8YrwX3ogd5rNbhlf
   lUE+D7rof8E8g6Uz4TWI8dpMDaXCzjgz6q2iiW770R5xCphLFbuNh/SnbkYNYNEo
   k8AN+Fx+w3EO7Cg4aaETB76iNXVBAoHBAOibavF4IYurjni39Z/6vIhO31F7VdNj
   x9gZ9Om6MmZNFSbU8PLyoQEyI46ygf8TO/BSfiHyUMncohmXWsoUXiFZV412aVqk
   HgZg+MWsKuYuTmGk/CouYQzd7RtrLl8TpPncXhsJIZ48ppcVGnMHnWZmTLj/Kqf6
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   Kc/94hmeR6TljINMSn0EI9nlJ5FkY2BDmzgeAD9/kNBbPHRjIyMa5Ow7rHO4Lt09
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   S9jVch5pKqmWvDYYrBXmmCe9Ju0RnBCgOIuGUiCPjEFAy+myLdgQ0A==
   -----END RSA PRIVATE KEY-----

   The MASA certificate that signs the voucher:

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   -----BEGIN CERTIFICATE-----
   MIIBcDCB9qADAgECAgQLhwoxMAoGCCqGSM49BAMCMCYxJDAiBgNVBAMMG2hpZ2h3
   YXktdGVzdC5leGFtcGxlLmNvbSBDQTAeFw0yMTA0MTMyMTQwMTZaFw0yMzA0MTMy
   MTQwMTZaMCgxJjAkBgNVBAMMHWhpZ2h3YXktdGVzdC5leGFtcGxlLmNvbSBNQVNB
   MFkwEwYHKoZIzj0CAQYIKoZIzj0DAQcDQgAEqgQVo0S54kT4yfkbBxumdHOcHrps
   qbOpMKmiMln3oB1HAW25MJV+gqi4tMFfSJ0iEwt8kszfWXK4rLgJS2mnpaMQMA4w
   DAYDVR0TAQH/BAIwADAKBggqhkjOPQQDAgNpADBmAjEArsthLdRcjW6GqgsGHcbT
   YLoyczYl0yOFSYcczpQjeRqeQVUkHRUioUi7CsCrPBNzAjEAhjxns5Wi4uX5rfkd
   nME0Mnj1z+rVRwOfAL/QWctRwpgEgSSKURNQsXWyL52otPS5
   -----END CERTIFICATE-----

   The private key for MASA certificate signs the voucher:

   -----BEGIN EC PRIVATE KEY-----
   MHcCAQEEIFhdd0eDdzip67kXx72K+KHGJQYJHNy8pkiLJ6CcvxMGoAoGCCqGSM49
   AwEHoUQDQgAEqgQVo0S54kT4yfkbBxumdHOcHrpsqbOpMKmiMln3oB1HAW25MJV+
   gqi4tMFfSJ0iEwt8kszfWXK4rLgJS2mnpQ==
   -----END EC PRIVATE KEY-----

A.2.  Example CMS signed voucher request

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   MIIGjQYJKoZIhvcNAQcCoIIGfjCCBnoCAQExDTALBglghkgBZQMEAgEwggOl
   BgkqhkiG9w0BBwGgggOWBIIDknsiaWV0Zi12b3VjaGVyLXJlcXVlc3Q6dm91
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   Q0FaYWdBd0lCQWdJRVlGYTZaVEFLQmdncWhrak9QUVFEQWpCdE1SSXdFQVlL
   Q1pJbWlaUHlMR1FCR1JZQ1kyRXhHVEFYQmdvSmtpYUprL0lzWkFFWkZnbHpZ
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   R1NNNDlBd0VIQTBJQUJKWmxVSEkwdXAvbDNlWmY5dkNCYitsSW5vRU1FZ2M3
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   TWNCZ2dyQmdFRkJRY0RBZ1lJS3dZQkJRVUhBd0V3RGdZRFZSMFBBUUgvQkFR
   REFnZUFNQW9HQ0NxR1NNNDlCQU1DQTJnQU1HVUNNUUNkU1pSSjgzTU5SQ3ph
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   SM49AgEGCCqGSM49AwEHA0IABAOjdUOHs3zACpqHnK329DgTHNQMhB/gQE5B
   efBbE0sgcbNEm0li8RYwzrsAfYCxp9k7E1CbpielT8OWf0z+ISejWTBXMB0G
   A1UdDgQWBBRFiMyWlgBkN7C6I2VkZFQIBmxWrTAJBgNVHRMEAjAAMCsGCCsG
   AQUFBwEgBB8WHWhpZ2h3YXktdGVzdC5leGFtcGxlLmNvbTo5NDQzMAoGCCqG
   SM49BAMCA2gAMGUCMGIq27409xvLhd4mjkMA+Q2IyHeo3TwIQFS87D223HAr
   w3/KGSGaoKvFUY6q3zbeiwIxALJdWfhHx+0Dl6jAx6iB+qiG7WdkN1F6bpyj
   gk1trbzzNZ6daqJtf38lHAPv8LqbcTGCAQQwggEAAgEBMC4wJjEkMCIGA1UE
   AwwbaGlnaHdheS10ZXN0LmV4YW1wbGUuY29tIENBAgQfGP7nMAsGCWCGSAFl
   AwQCAaBpMBgGCSqGSIb3DQEJAzELBgkqhkiG9w0BBwEwHAYJKoZIhvcNAQkF
   MQ8XDTIyMDcxMDIxMDgxOFowLwYJKoZIhvcNAQkEMSIEIFc4jO6OnilTLkM/
   fcc9p5au4ANjvJvjRXsAKK6+RcTvMAoGCCqGSM49BAMCBEcwRQIhAOjoOdgh
   Sr+Hk2r2APsfs1+QJba0uRf/+zXA70yb6mRCAiB9aS6Wj8kBcWEvvfsDue41
   KWo0ukOBQxdPGpJqg+GAMw==

A.3.  Example CMS signed voucher from MASA

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   MIIGPQYJKoZIhvcNAQcCoIIGLjCCBioCAQExDTALBglghkgBZQMEAgEwggOU
   BgkqhkiG9w0BBwGgggOFBIIDgXsiaWV0Zi12b3VjaGVyOnZvdWNoZXIiOnsi
   YXNzZXJ0aW9uIjoibG9nZ2VkIiwiY3JlYXRlZC1vbiI6IjIwMjItMDctMTBU
   MTc6MDg6MTguNzIwLTA0OjAwIiwic2VyaWFsLW51bWJlciI6IjAwLUQwLUU1
   LUYyLTAwLTAyIiwibm9uY2UiOiI0dlRzcHBTMkNlcUJ6aEVkb2lmTTJnIiwi
   cGlubmVkLWRvbWFpbi1jZXJ0IjoiTUlJQ0VEQ0NBWmFnQXdJQkFnSUVZRmE2
   WlRBS0JnZ3Foa2pPUFFRREFqQnRNUkl3RUFZS0NaSW1pWlB5TEdRQkdSWUNZ
   MkV4R1RBWEJnb0praWFKay9Jc1pBRVpGZ2x6WVc1a1pXeHRZVzR4UERBNkJn
   TlZCQU1NTTJadmRXNTBZV2x1TFhSbGMzUXVaWGhoYlhCc1pTNWpiMjBnVlc1
   emRISjFibWNnUm05MWJuUmhhVzRnVW05dmRDQkRRVEFlRncweU1URXhNalF4
   T1RRek1EVmFGdzB5TXpFeE1qUXhPVFF6TURWYU1GTXhFakFRQmdvSmtpYUpr
   L0lzWkFFWkZnSmpZVEVaTUJjR0NnbVNKb21UOGl4a0FSa1dDWE5oYm1SbGJH
   MWhiakVpTUNBR0ExVUVBd3daWm05MWJuUmhhVzR0ZEdWemRDNWxlR0Z0Y0d4
   bExtTnZiVEJaTUJNR0J5cUdTTTQ5QWdFR0NDcUdTTTQ5QXdFSEEwSUFCSlps
   VUhJMHVwL2wzZVpmOXZDQmIrbElub0VNRWdjN1JvK1haQ3RqQUkwQ0QxZkpm
   SlIvaEl5eURtSFd5WWlORmJSQ0g5ZnlhcmZremdYNHAwelRpenFqUGpBOE1D
   b0dBMVVkSlFFQi93UWdNQjRHQ0NzR0FRVUZCd01jQmdnckJnRUZCUWNEQWdZ
   SUt3WUJCUVVIQXdFd0RnWURWUjBQQVFIL0JBUURBZ2VBTUFvR0NDcUdTTTQ5
   QkFNQ0EyZ0FNR1VDTVFDZFNaUko4M01OUkN6YTMrdk9CYTAxaDRxWnYybEto
   ZCtEZmhCNFlEaHZHcGtXb2xaZUhId05iN0F0QkNNdGJVd0NNSG9OeG9payt4
   VzdBdDFoWEVocDMvTWNYaUFkem5aYnBWcSt4SkVaaWhYVTM2SUJqdllnV0RG
   OWl2cXhKcERieXc9PSJ9faCCAXQwggFwMIH2oAMCAQICBAuHCjEwCgYIKoZI
   zj0EAwIwJjEkMCIGA1UEAwwbaGlnaHdheS10ZXN0LmV4YW1wbGUuY29tIENB
   MB4XDTIxMDQxMzIxNDAxNloXDTIzMDQxMzIxNDAxNlowKDEmMCQGA1UEAwwd
   aGlnaHdheS10ZXN0LmV4YW1wbGUuY29tIE1BU0EwWTATBgcqhkjOPQIBBggq
   hkjOPQMBBwNCAASqBBWjRLniRPjJ+RsHG6Z0c5weumyps6kwqaIyWfegHUcB
   bbkwlX6CqLi0wV9InSITC3ySzN9ZcrisuAlLaaeloxAwDjAMBgNVHRMBAf8E
   AjAAMAoGCCqGSM49BAMCA2kAMGYCMQCuy2Et1FyNboaqCwYdxtNgujJzNiXT
   I4VJhxzOlCN5Gp5BVSQdFSKhSLsKwKs8E3MCMQCGPGezlaLi5fmt+R2cwTQy
   ePXP6tVHA58Av9BZy1HCmASBJIpRE1CxdbIvnai09LkxggEEMIIBAAIBATAu
   MCYxJDAiBgNVBAMMG2hpZ2h3YXktdGVzdC5leGFtcGxlLmNvbSBDQQIEC4cK
   MTALBglghkgBZQMEAgGgaTAYBgkqhkiG9w0BCQMxCwYJKoZIhvcNAQcBMBwG
   CSqGSIb3DQEJBTEPFw0yMjA3MTAyMTA4MThaMC8GCSqGSIb3DQEJBDEiBCBA
   77EhoAybh5R6kK89jDefpxRy8Q6rDo1cnlwgvCzXbzAKBggqhkjOPQQDAgRH
   MEUCIQD4RnuXwKvYVvwamwVq3VYv7dXcM7bzLg7FXTkhvYqPzwIgXTJxVV5a
   cLMAroeHgThS5JU5QA2PJMLGF82UcSNTsEY=

A.4.  Example JWS signed voucher from MASA

   These examples are folded according to the [RFC8792] Single Backslash
   rule.

Watsen, et al.            Expires 23 April 2026                [Page 49]
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   {
     "payload": "eyJpZXRmLXZvdWNoZXI6dm91Y2hlciI6eyJhc3NlcnRpb24iOiJwcm\
   94aW1pdHkiLCJzZXJpYWwtbnVtYmVyIjoiY2FmZmUtOTg3NDUiLCJub25jZSI6IjYyYT\
   JlNzY5M2Q4MmZjZGEyNjI0ZGU1OGZiNjcyMmU1IiwiY3JlYXRlZC1vbiI6IjIwMjUtMT\
   AtMTVUMDA6MDA6MDBaIiwicGlubmVkLWRvbWFpbi1jZXJ0IjoiTUlJQmd6Q0NBU3FnQX\
   dJQkFnSUdBV09XZTBSRk1Bb0dDQ3FHU000OUJBTUNNRFV4RXpBUkJnTlZCQW9NQ2sxNV\
   FuVnphVzVsYzNNeERUQUxCZ05WQkFjTUJGTnBkR1V4RHpBTkJnTlZCQU1NQmxSbGMzUk\
   RRVEFlRncweE9EQTFNalV3T0RRM016QmFGdzB5T0RBMU1qVXdPRFEzTXpCYU1EVXhFek\
   FSQmdOVkJBb01DazE1UW5WemFXNWxjM014RFRBTEJnTlZCQWNNQkZOcGRHVXhEekFOQm\
   dOVkJBTU1CbFJsYzNSRFFUQlpNQk1HQnlxR1NNNDlBZ0VHQ0NxR1NNNDlBd0VIQTBJQU\
   JIOUVCdXVXVjdJS09ya040YjdsYTVJb2J5dFduV1p3Rm5QdHVsMDlhd3dVSEZQZStOWW\
   M1WjVwdUo2ZEFuK0FrVzFnY1poQlhWR0JBM0crSXlSV1VXU2pKakFrTUJJR0ExVWRFd0\
   VCL3dRSU1BWUJBZjhDQVFBd0RnWURWUjBQQVFIL0JBUURBZ0lFTUFvR0NDcUdTTTQ5Qk\
   FNQ0EwY0FNRVFDSURlWlc2SWZjeUsvLzBBVFk2S21NYjRNMFFJU1FTZFVGVjdQNzlLWV\
   ZJWVVBaUJRMVYrd0xSM1Uzd2NJWnhHSE1ISGx0N2M3ZzFDaFdNRVkveEFoU1NZaWlnPT\
   0ifX0",
     "signatures": [
       {
         "protected": "eyJ4NWMiOlsiTUlJQmNEQ0I5cUFEQWdFQ0FnUUxod294TUFv\
   R0NDcUdTTTQ5QkFNQ01DWXhKREFpQmdOVkJBTU1HMmhwWjJoM1lYa3RkR1Z6ZEM1bGVH\
   RnRjR3hsTG1OdmJTQkRRVEFlRncweU1UQTBNVE15TVRRd01UWmFGdzB5TXpBME1UTXlN\
   VFF3TVRaYU1DZ3hKakFrQmdOVkJBTU1IV2hwWjJoM1lYa3RkR1Z6ZEM1bGVHRnRjR3hs\
   TG1OdmJTQk5RVk5CTUZrd0V3WUhLb1pJemowQ0FRWUlLb1pJemowREFRY0RRZ0FFcWdR\
   Vm8wUzU0a1Q0eWZrYkJ4dW1kSE9jSHJwc3FiT3BNS21pTWxuM29CMUhBVzI1TUpWK2dx\
   aTR0TUZmU0owaUV3dDhrc3pmV1hLNHJMZ0pTMm1ucGFNUU1BNHdEQVlEVlIwVEFRSC9C\
   QUl3QURBS0JnZ3Foa2pPUFFRREFnTnBBREJtQWpFQXJzdGhMZFJjalc2R3Fnc0dIY2JU\
   WUxveWN6WWwweU9GU1ljY3pwUWplUnFlUVZVa0hSVWlvVWk3Q3NDclBCTnpBakVBaGp4\
   bnM1V2k0dVg1cmZrZG5NRTBNbmoxeityVlJ3T2ZBTC9RV2N0UndwZ0VnU1NLVVJOUXNY\
   V3lMNTJvdFBTNSJdLCJ0eXAiOiJ2b3VjaGVyLWp3cytqc29uIiwiYWxnIjoiRVMyNTYi\
   fQ",
         "signature": "s_gJM_4qzz1bxDtqh6Ybip42J_0_Y4CMdrMFb8lpPsAhDHVR\
   AESNRL3n6M_F8dGQHm1fu66x83cK9E5cPtEdag"
       }
     ]
   }

                       Figure 1: Example JWS Voucher

Acknowledgements

   The authors would like to thank for following for lively discussions
   on list and in the halls (ordered by last name): William Atwood,
   Michael H. Behringer, Esko Dijk, Steffen Fries, Sheng Jiang, Thomas
   Werner.

Authors' Addresses

Watsen, et al.            Expires 23 April 2026                [Page 50]
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   Kent Watsen
   Watsen Networks
   Email: kent+ietf@watsen.net

   Michael C. Richardson
   Sandelman Software
   Email: mcr+ietf@sandelman.ca, https://orcid.org/0000-0002-0773-8388
   URI:   http://www.sandelman.ca/

   Max Pritikin
   Cisco Systems
   Email: pritikin@cisco.com

   Toerless Eckert
   Futurewei Technologies Inc.
   2330 Central Expy
   Santa Clara,  95050
   United States of America
   Email: tte@cs.fau.de

   Qiufang Ma
   Huawei
   101 Software Avenue, Yuhua District
   Nanjing
   210012
   China
   Email: maqiufang1@huawei.com

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