]> Watsen Networks

kent+ietf@watsen.net

Sandelman Software

mcr+ietf@sandelman.ca https://orcid.org/0000-0002-0773-8388 https://www.sandelman.ca/

IoTconsultancy.nl

esko.dijk@iotconsultancy.nl

Futurewei Technologies Inc.

2330 Central Expy Santa Clara 95050 United States of America tte@cs.fau.de

Huawei

101 Software Avenue, Yuhua District Nanjing 210012 China maqiufang1@huawei.com

Operations ANIMA Working Group voucher This document defines a strategy to securely assign a candidate device (Pledge) to an Owner using a digital 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 which is represented by the Manufacturer Authorized Signing Authority (MASA). This document obsoletes RFC8366: it includes a number of desired extensions into the YANG module. The Voucher Request YANG module defined in RFC8995 is also updated and now included in this document, as well as other YANG extensions needed for variants of RFC8995. About This Document Status information for this document may be found at . Discussion of this document takes place on the anima Working Group mailing list (), which is archived at . Subscribe at . Source for this draft and an issue tracker can be found at .

Introduction This document defines a strategy to securely assign a candidate device (Pledge) to an Owner using a digital artifact signed, directly or indirectly, by the Pledge's manufacturer. This artifact is known as the "Voucher". Its purpose is to securely convey to the Pledge a trust anchor that represents the authority of the Owner. The Pledge's manufacturer is represented by the Manufacturer Authorized Signing Authority (MASA), the entity that has digitally signed the Voucher Artifact. Capitalized terms such as Pledge, Owner, Domain, Onboarding and MASA are defined in . explains why Onboarding protocols need such an artifact and why alternative approaches are undesirable. This document defines the Voucher Artifact and the Voucher Request Artifact only. How these artifacts are conveyed and details of their security parameters are not defined here, but rather in the Onboarding protocols that use them. Such protocols include , , and . The Voucher Artifact is a JSON or CBOR document that conforms with a data model described by YANG . It is encoded using the rules defined in or , and is signed using (by default) a CMS structure . This document obsoletes and updates . It adds the Attributes needed by the variants of that were developed since was published into the Voucher YANG module, it includes and updates the Voucher Request YANG module that was defined in , and it adds a mechanism for future extensions that avoids further revisions of the YANG modules. The motivation for these changes, and the detailed list of changes, are given in . The remainder of this document is organized as follows. defines the terms that are used throughout. surveys the information that a Voucher can carry, and the combinations of that information that constitute different types of Voucher. and detail the changes relative to and . describes the default signature mechanism (CMS) for Voucher Artifacts. and give the normative definitions of the two artifacts, including their tree diagrams, YANG modules and SID values. and discuss the design considerations and the security considerations, respectively.

Motivation This section is informative. It explains the problems that Voucher-based Onboarding solves, and why the alternative approaches are undesirable.

Onboarding without a Voucher When a device is sold to a new owner, the device normally has no way to verify the identity of that new owner, nor to limit its own configurability to that new owner. Instead, such devices (Pledges) employ one or more of the following problematic mechanisms:

1. They permit configuration without any security or password, or they require a well-known "default" password.
2. They limit configuration to mechanisms that require some degree of physical control over the device, such as permitting configuration only across a serial "console" port, or requiring pairing via Bluetooth.
3. They are delivered with some form of "bearer token", such as a unique QR or similar code that is delivered together with the device and that has to be scanned to authenticate against the device.

All these mechanisms expose various security or operational problems, making them insufficient for the typical professional deployment of equipment such as is required in industrial, enterprise, defense and other markets for networking equipment or other IoT equipment. In these deployment scenarios, physical installation has to be performed by non-experts. This limits installation to physical wiring (power and possibly networking), without any knowledge of network configuration or digital security. Such installers should not be required to handle Bluetooth pairing, which is often physically difficult or impossible once the device is in its target location, nor should the Pledge be expected to have the open network connectivity that pairing may require. They should not need to locate, understand and safely retain bearer tokens, which are placed at arbitrary positions in or on packaging that has most likely already been discarded. They should not need to determine whether a network connection is free of harmful (e.g., attacking or spying) software that discovers and invades unconfigured devices via their default passwords, and so on. In one evaluation, professional video surveillance cameras deployed at scale cost $500 on average, but required installation by networking/security experts cost more than $1000 on average. By comparison, simple physical installation by non-experts into a building network that was potentially infested with harmful software cost less than $500.

Staging as a remedy? To overcome the provisioning limitations of pre-voucher protocol solutions, a common approach in the industry is so-called "staging". Instead of being shipped directly from the manufacturer or seller to the ultimate deployment location, Pledges are shipped to a so-called "staging" location, where they are provisioned by networking/security experts. There, the Pledge is connected only to a staging network that is known to be free of attackers, and is provisioned with the configuration necessary to operate at the target deployment location -- at least to the extent that subsequent attacks or unintentional misconfiguration by a non-owner are no longer possible. Staging is expensive and slow. It is also considered impractical in many market segments, not only because of the number of low-cost Pledges and the high ratio of installation cost to Pledge cost (as in the surveillance camera example above), but also because of international shipping, certification and import/export issues for hardware. For example, specialized equipment for networking, security and other business purposes is often not shipped internationally at all. Instead, it is composed of locally sourced standard hardware components, such as "x86" hardware with well-defined secure hardware such as a TPM and IDevID, and this generic hardware is then "personalized" to become the specialized device through automated, online download of the complete product software suite over international network connections. This leaves only the problem of initial, mutually trusted connectivity between such a Pledge and the remote provisioning system to be solved -- which is exactly what protocols using Vouchers aim to achieve.

Onboarding with a Voucher The Voucher is a digital artifact (a digital data structure) that is created and cryptographically signed by an agent of the Pledge's manufacturer, called the Manufacturer Authorized Signing Authority (MASA). The Voucher's most important element is a trust anchor that identifies the intended Owner of the Pledge. This trust anchor is typically a certificate (the 'pinned-domain-cert' Attribute), but it can also be a hash of a certificate, or a raw public key in constrained use cases. Securely communicating this trust anchor to the Pledge is the job of the Voucher Artifact, and the act of communicating it is known as pinning the trust anchor. The rationale for this approach is that the only trust anchors an unconfigured Pledge can be expected to carry in its software are those of the manufacturer, or of third-party entities designated by the manufacturer to support the Voucher process. Consequently, a Voucher identifying the Owner has to be signed by such a MASA. How the MASA determines who the Owner of a Pledge is, is left to the Onboarding protocol mechanisms using the Voucher. Once the Pledge has received such a Voucher via some protocol utilizing a Voucher, the Pledge can permit configuration only by entities that can cryptographically authenticate themselves as belonging to the Owner, for example by proving ownership of the pinned trust anchor, or of a certificate signed by the trust anchor either directly or via an intermediate CA. The collection of all devices that share the same Owner's trust anchor is known as the Domain. explains how the pinned trust anchor is used to form an overlay management Autonomic Control Plane (ACP) network, using authenticated IPsec (or other) tunnels. IoT devices can use it for mutually authenticated (D)TLS or EDHOC connections, although authorization is best left to mechanisms such as . The Voucher itself does not specify the procedures by which it is communicated. That is the responsibility of the Onboarding protocols that use Voucher Artifacts. In "Secure Zero Touch Provisioning" , protocol mechanisms are defined through which a Pledge can automatically discover an SZTP server and "register" with it. The Pledge accepts configuration from that SZTP server only after the server has presented a valid Voucher identifying the Pledge's Owner. In "Bootstrapping Remote Secure Key Infrastructure" and its derivative protocols, the Pledge discovers and connects to a BRSKI "Registrar" belonging to the Owner and requests a Voucher using a variant of the Voucher called a "Voucher Request" artifact, which is also defined in this document. Having received a Voucher in return, the Pledge can authenticate the Registrar as its new Owner. The Pledge then expects to be "enrolled" with keying material: it receives the trust anchors of the Owner's PKI Domain, as well as a so-called LDevID certificate (operational certificate) from that Domain. SZTP and BRSKI are only two examples of existing protocol families that use Vouchers. They follow different design philosophies and thereby illustrate why the Voucher is not tied to, and not specified solely within, a single protocol family.

What the Voucher does and does not provide Use of the Voucher as specified in this document does not guarantee interoperability between an arbitrary Pledge and an arbitrary configuration/provisioning/enrollment/Onboarding server; that is instead the responsibility of the protocols using Vouchers. What the use of a Voucher-based Onboarding protocol does enable is the ability to enroll and provision Pledges without the operational and security challenges of pre-voucher i.e. legacy mechanisms. Pledges supporting Voucher-based protocols can be physically installed by personnel who are neither security experts nor networking experts and who only need to know how to wire up and physically install the Pledge. Network-based (i.e., non-physical) attacks that rely on taking control of an unconfigured Pledge are eliminated, as is the non-malicious enrollment of a Pledge into a non-Owner network, which is a common problem in multi-tenant and multi-dwelling environments.

Terminology 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 when, and only when, they appear in all capitals, as shown here. This document uses and defines the following terms, which are also used in related documents. The terms are listed in alphabetical order.

Artifact:

See "Voucher Artifact".

Attribute:

A single named data element that can be stored in Voucher Data. The element's name and data type are defined by one of the YANG models as defined in this document.

Bootstrapping:

See "Onboarding". This term was used in , but has been supplanted by the term Onboarding.

Domain:

The set of entities or infrastructure under common administrative control, sharing the trust anchor that is conveyed by the Voucher. The goal of the Onboarding protocol is to enable a Pledge to join a Domain and obtain domain-specific security credentials. This term is not related to "DNS domain" although a Domain might be associated to a specific DNS domain.

IDevID (Initial Device Identifier):

A device identity credential, defined by , that is installed (i.e. imprinted) in the Pledge by its manufacturer during production and that the Pledge uses to identify itself to a Domain that it attempts to join. It consists of an X.509 certificate that contains the Pledge's serial number, together with the associated private key.

Join Registrar (and Coordinator):

A representative of the Domain that is configured 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".

LDevID (Locally Significant Device Identifier):

A secure device identity credential, defined by , that is issued to the Pledge by the Domain that it has joined and that the Pledge uses to identify itself within that Domain. It is also called an operational certificate.

MASA (Manufacturer Authorized Signing Authority):

The entity that, for the purpose of this document, issues and signs the Vouchers for a manufacturer's Pledges and keeps logs of Pledge ownership. 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 towards the Pledge. This attacker's goal is to trick the Pledge to trust its malicious Domain and let it onboard into that Domain. The attacker then has control over the Pledge and may then perform various follow-up actions such as operating the device at another location in a network under the attacker's control, or attempting further device exploits to compromise its software. After the software is compromised, the Pledge could be instructed by the attacker to onboard another time but now with a real Registrar of a target Domain being attacked. This way, a compromised Pledge could become trusted in the attacker's target Domain. describes more details of this attack and its mitigations.

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 include configuration data, but the specific focus of this document is providing data that identifies a Domain-specific trust anchor that the Pledge can trust for it to carry out the remainder of the onboarding process (see also: Pinning). Application-specific security credentials or network access credentials may also be provided during the onboarding process. When was first published, the industry had not yet concluded on a term to describe this process and a number of terms were used, among which the term "bootstrapping" that used. The industry has since preferred the term "onboarding", and this document uses that term.

Owner:

The entity that controls the private key of the trust anchor conveyed by the Voucher. Typically, the Owner is indicated by the 'pinned-domain-cert' Attribute.

Pinning:

The act of securely communicating a trust anchor to a Pledge by conveying it in a Voucher. The trust anchor that is communicated this way is said to be pinned.

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.

Pledge Voucher Request (PVR):

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

Registrar:

See Join Registrar. This term is not related to the term DNS Registrar .

Registrar Voucher Request (RVR):

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

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 . This is also known as the "resurrecting duckling" model .

Trust Anchor:

A public key, or a certificate that contains a public key, that a Pledge is configured to trust as an authoritative source when it validates the credentials that other entities present to it; see also . The Voucher conveys the trust anchor of the Owner's Domain to the Pledge.

Voucher:

A Voucher Artifact that is a 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 preceded by the type of the signature, such as CMS, JWS or COSE.

Voucher Artifact:

Used throughout this document to represent a Voucher or Voucher Request as instantiated in the form of a signed datastructure. The payload of the signed datastructure is called the Voucher Data.

Voucher Data:

The raw (serialized) representation of the YANG data elements of a Voucher (Request) without any enclosing signature. Current serialization 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. When clarity is needed, it may be preceded by the type of the signature, such as CMS, JWS or COSE.

Zero-touch:

Describes an Onboarding process that requires no manual configuration of the Pledge at its deployment location, beyond the physical installation of the Pledge.

Survey of Voucher Types This section is informative. It surveys the information that a Voucher can carry, and the combinations of that information -- the "Voucher types" -- that existing Onboarding protocols use. The normative definition of the Voucher Artifact, and of the Attributes that are mentioned here, is given in . 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 to the 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 boot or measured boot (which is an attested boot process involving 'measurements' as defined by .) 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 ) is left for future work.

Anti-Replay Protections:

Time- or nonce-based information to constrain the Voucher to specific time periods or Onboarding attempts.

Voucher lifetimes vary between Onboarding protocols. Some protocols include a nonce in the Voucher, restricting it to a single use, whereas Vouchers in other protocols have an indicated lifetime. When longer validity periods are important, this document recommends using short lifetimes with programmatic renewal, see . How short the lifetimes can be depends upon the means of conveyance of the Voucher, so the exact times are specified in the Onboarding protocol itself. 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, the attacker would gain control over the Pledge. The following combinations are "types" of Vouchers: Overview of Voucher types

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

NOTE: The "RTC" column denotes Voucher validation using a Real-Time Clock. NOTE: All Voucher types include a "Pledge ID serial-number" (column not shown for space reasons).

Audit Voucher:

An audit Voucher is named after the logging assertion mechanisms that the Registrar then "audits" to enforce its local policy. The Registrar mitigates the risk of a Malicious Registrar by auditing that no unknown Registrar, or known Malicious Registrar, appears in the MASA's log entries for the Pledge. 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 cannot rely on a nonce to be included for freshness. This compromise in reducing the freshness allows for the resulting Voucher to be carried across air-gapped infrastructure. In addition, if the validity period has been set sufficiently long, the Voucher can be used after the manufacturer (and its delegates) has gone out of business.

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 PKIX ) 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.

Changes since RFC8366 This document obsoletes .

Motivation for revising RFC8366 originally defined the Voucher as the only Voucher Artifact, leaving the Voucher Request that is used in BRSKI to be defined in . This document includes both Voucher and Voucher Request thereby obsoleting , and Updating . A number of variations of have been developed since the publication of , and these variations require new Attributes be added to the Voucher and Voucher Request. At the low-level, that is the JSON (or CBOR) mechanical level, this was thought to be trivial as the artifacts are JSON (or CBOR) maps, and adding new keys seemed easy. However, the use of YANG for the information model does not make it as trivial as was thought. In the end, YANG is not easily extended except by updating the YANG module definition, and that update is the major reason for the publication of this document. The process that led to this conclusion is described in . This document introduces a mechanism to support future extensions without requiring the YANG module to be revised. This includes both a new IETF standard mechanism for extensions modeled after the mechanism present in , as well as a facility for manufacturer proprietary extensions.

History of New Protocols Since RFC8366 was published in 2018 during the development of , 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 was Onboarding of ISP and Enterprise owned wired routing and switching equipment, with IoT devices being a less important aspect. has focused upon Onboarding of CPE equipment like cable modems and other larger IoT devices, again with smaller IoT devices being of lesser importance. Since 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) . The document has defined a version of that is usable over constrained IEEE 802.15.4 6LoWPAN networks using CoAP and DTLS, while provides for using CoAP and EDHOC on even more constrained devices with very constrained networks. 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. uses the serialization mechanism described in to produce significantly more compact artifacts.

Challenges with revisions to YANG When the process to define and was started, there was a belief that the appropriate process was to use the augment mechanism to further extend both the Voucher Request and Voucher artifacts. However, needs to extend an enumerated type with additional values and augment cannot 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 Voucher Artifact. The result was invalid YANG, with multiple definitions of the core Attributes from the Voucher Artifact. After some discussion, it was determined that the augment mechanism did not work for this use case, nor did it work better when the "yang-data" extension was replaced with the "structure" extension. After significant discussion the decision was made to simply roll all of the needed extensions into this document.

Detailed changes since RFC8366 , and require extensions to the Voucher Request and the resulting Voucher. New Attributes are required to carry the additional data and describe the extended semantics. The following Attributes are new, and the document that they support is noted: To the Voucher Request:

agent-signed-data:

agent-provided-proximity-registrar-cert:

agent-sign-cert:

assertion(agent-proximity):

proximity-registrar-pubk:

proximity-registrar-pubk-sha256:

To the Voucher:

additional-configuration-url:

est-domain:

extensions:

Added to aid in future extensions

manufacturer-proprietary:

Added to allow for controlled experiments and custom extensions

pinned-domain-pubk:

pinned-domain-pubk-sha256:

Updates to RFC8995 This document represents a merge of YANG definitions of the Voucher from , the Voucher Request from , and extensions to each of these from , and . The difficulty with this approach is that the semantics of the definitions needed for the other documents are not included in this document, but rather in the respective other documents.

Updates to the use of idevid-issuer The voucher-request module definition that was in Sections 3.2 (tree diagram) and 3.4 (YANG module) is now included in this document. There is a change to it: the 'idevid-issuer' Attribute MUST be included in a Registrar Voucher Request (RVR). Like the 'serial-number' value in the RVR, the 'idevid-issuer' value in the RVR is to be taken from the Pledge's (IDevID) client certificate. In some variations of BRSKI, such as , there is no direct TLS connection between Pledge and Registrar. Therefore, the Pledge's IDevID certificate cannot be extracted from the TLS connection, so those variations define a different channel binding process and may deviate from the above requirement. A Registrar MUST apply the following rules for the value of the 'idevid-issuer' Attribute in the given order:

1. If the Authority Key Identifier (AKI) field is present in the Pledge's (IDevID) client certificate, the Registrar copies the full data element as specified in .
2. Otherwise, the Registrar generates the full data element in the format specified in , using the SHA-1 hash of the public key of the Pledge's IDevID client certificate. This is defined as method 1 in .

Clarifications on the use of idevid-issuer and define the 'idevid-issuer' Attribute for the 'voucher' and 'voucher-request' modules (respectively), but they only summarily explain when to use it, and why it is used. The 'idevid-issuer' Attribute is provided so that the serial number to which the issued Voucher pertains can be relative to the entity that issued the Pledge's IDevID. In most cases there is a one to one relationship between the trust anchor that signs Vouchers (and is trusted by the Pledge), and the Certification Authority that signs the IDevID. In that case, the 'serial-number' in the Voucher Data must refer to the same device as the serial number that is in the IDevID certificate (in the 'serialNumber' element of type 'X520SerialNumber' per ). However, there are situations where the one to one relationship may be broken. This occurs whenever a manufacturer has a common MASA, but different products (on different assembly lines) are produced with identical serial numbers. A system of serial numbers which is just a simple counter is a good example of this. A system of serial numbers where there is some prefix relating the product type does not fit into this, even if the lower digits are a counter. Another situation occurs when multiple manufacturers share a common MASA. In this case, any given serial number in the IDevID certificate may not be unique across all manufacturers. It is not possible for the Pledge or the Registrar to know which situation applies. And because one of the situations may apply, or may occur in the future, there needs to be a contingency to allow uniquely identifying a Pledge regardless of the current or future situation. This is realized by the 'idevid-issuer' Attribute. It is clarified next, whether or not to include the 'idevid-issuer' in the PVR, in the RVR and in the Voucher. Analysis of the situation shows that the Pledge never needs to include 'idevid-issuer' Attribute in its PVR, because the Pledge's IDevID certificate is available to the Registrar, and the Authority Key Identifier needed to fill this Attribute is contained within that IDevID certificate. The Pledge therefore has no need to repeat this. For the RVR, now normatively requires that the 'idevid-issuer' Attribute be included. For the Voucher, as detailed in , the 'idevid-issuer' Attribute MUST be included by a MASA in case the MASA issues a Voucher with a serial number that is known to be not unique within the scope of all the serial numbers represented by the MASA. If this rule does not apply, the MASA SHOULD NOT include the 'idevid-issuer' Attribute in order to achieve a smaller Voucher size.

Clarifications on the format of idevid-issuer and were not fully clear on the required binary format of the 'idevid-issuer' Attribute. This gave rise to incompatible implementations. This section clarifies the format of the 'idevid-issuer' Attribute, which contains the full Authority Key Identifier from an IDevID certificate. The entire Authority Key Identifier object from the certificate i.e. the 'extnValue' OCTET STRING is to be included, comprising the ASN.1 DER encoding of the 'AuthorityKeyIdentifier' structure as defined in . This includes the ASN.1 DER encoding of the SEQUENCE as well as the OCTET STRING element (tagged 0) that is named 'keyIdentifier' with type 'KeyIdentifier'. Note that per , only the first optional element named 'keyIdentifier' is expected to be found in an IDevID certificate, not the 'authorityCertIssuer' or the 'authorityCertSerialNumber'. However, because of the above requirement to include the full 'extnValue' OCTET STRING, even if the non-expected elements would be present, they would be included in the 'idevid-issuer' value in a Voucher Request or Voucher.

Errata closed The above updates to addresses errata .

Signature mechanisms Three signature systems have been defined for Voucher Artifacts. defines a mechanism that uses COSE , with the Voucher Data encoded using YANG-CBOR . However, as the SID allocation process requires up-to-date YANG, the SID values for this mechanism are presented in this document. defines a mechanism that uses JSON and . The CMS signing mechanism first defined in continues to be defined in this document.

CMS Format Voucher Artifact The CMS data structure consists of the ContentInfo defined in , which contains a single SignedData structure. The SignedData structure is specified by Section 5.1 of , encoded using ASN.1 Distinguished Encoding Rules (DER), as specified in ITU-T X.690 . The SignedData structure contains a single EncapsulatedContentInfo structure, defined in . An object identifier (OID) for JSON-encoded Voucher Data is allocated in . This OID is placed in the 'eContentType' field in the EncapsulatedContentInfo, with the OID defined as follows: The use of PKCS#7 (CMSVersion=1) in the SignedData structure is deprecated by this document. mandates that SignedAttributes MUST be present when the content type is not 'id-data'. This mitigates attacks on CMS as described in . Decoders MUST verify that SignedAttributes is present. To facilitate interoperability, per the media type "application/voucher-cms+json" and the filename extension ".vcj" were registered by . The CMS SignedData structure MUST contain a 'signerInfo' structure, as described in , containing the signature generated over the content using a private key trusted by the recipient. In a Voucher, the recipient is the Pledge and the signer is the MASA. In the Voucher Request, the signer is the Pledge (in the PVR), or the Registrar (in the RVR). Note that includes a discussion about how to validate a CMS object. This object may have a particular CMSVersion (see ). Intermediate systems (such as the Bootstrapping Remote Secure Key Infrastructures Registrar) that might need to evaluate the object in flight MUST be prepared for any version of this format. No signaling of the format version (CMSVersion) 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. The CMS structure MAY also contain revocation objects for any intermediate Certification 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 in the next section, the use of short-lived Vouchers and/or a Pledge-provided nonce provides a freshness guarantee.

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 Artifact that is a CMS-signed encoding of the JSON-encoded Voucher Data as defined by the YANG module . 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 . 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. defined a media type and a filename extension for the CMS-encoded JSON type. The media type for JOSE format Vouchers is defined in and the media type for COSE format Vouchers is defined in . 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 nonceless or which kind of pinned anchor is used, are not part of the media type. Only the format of Voucher that is expected is signaled in the form of a (MIME) media 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. The Attributes pinned-domain-pubk (proximity-registrar-pubk for a PVR) and pinned-domain-pubk-sha256 (proximity-registrar-pubk-sha256 for a PVR) are involved in the process of pinning/identifying a raw public key, instead of a certificate, for such devices. Should the SHA-256 hash algorithm ever need to be replaced in the future, then a new YANG module will be published with new leafs, obsoleting the pinned-domain-pubk-sha256 and proximity-registrar-pubk-sha256 Attributes. In the event that more than one of pinned-domain-pubk-sha256, pinned-domain-pubk or pinned-domain-cert Attributes are present in a Voucher, then the Pledge SHALL prioritize the matching proximity-* entry which it used in its voucher-request artifact, ignoring the others. If the Voucher is nonceless, then the Pledge SHALL consider the first of the above Attributes that it understands, in the order given above.

Algorithm Choices for Voucher Artifacts When designing Pledge devices, manufacturers choose algorithms and signature formats - which they also need to support in their MASA. As explained in , the Pledge is a creation of the manufacturer, and thus the manufacturer (represented by the MASA) has knowledge of the capabilities of the Pledge. Specifically, the manufacturer knows what signature algorithm the Pledge is going to use (to sign a PVR or to validate a Voucher), and can verify this, thus there is no need (or opportunity) to negotiate the algorithm or signature (CMS, JWS, COSE) scheme. The exact choice of format (CMS, JWS or CBOR) and algorithm depends upon the target operational community for the Voucher. For that reason, this document does not specify any mandatory to implement algorithms but leaves that specification to the Onboarding protocols that make use of Voucher Artifacts. specifies mandatory to implement algorithms for current Autonomic Network Infrastructure (ANI) uses. is future work for quantum-safe (PQ) algorithms for ANIs. and specify mandatory to implement algorithms for IoT use cases involving constrained devices. A certain class of constrained devices defined in minimizes the code size of the code for ASN.1 processing, PKIX processing and Voucher/PVR processing, which determines and constrains the algorithm and format choices. Another class of cBRSKI constrained devices minimizes just the sizes of Voucher and PVR, a benefit on constrained networks, and these devices have different constraints on the algorithm and format choices. Public keys in the pinned-domain-pubk or proximity-registrar-pubk Attributes are encoded as a DER-encoded SubjectPublicKeyInfo structure, as specified in . This structure identifies the key's algorithm by an OID, so it can carry any public key type for which a SubjectPublicKeyInfo encoding is defined. Examples are RSA and ECDSA as listed in , EdDSA and ML-DSA . Should a manufacturer decide to stop supporting some algorithm that their manufactured Pledges rely on, they will need to execute a transition operation for any inventory (Pledges) that exists in warehouses or within the supply chain, to ensure that these devices can still be onboarded in the new situation. One transition strategy is to recall these Pledges, replace the firmware and update the IDevID certificates present in the recalled devices. This is not ideal; a better transition strategy could be defined as part of an Onboarding protocol such that a physical recall is not required.

Tree Diagram The following tree diagram illustrates a high-level view of a Voucher document. The notation used in this diagram is described in . Each node in the diagram is fully described by the YANG module in . Please review the YANG module for a detailed description of the Voucher format.

Examples This section provides Voucher Data examples for illustration purposes. These examples conform to the JSON encoding rules defined in . 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. The following example illustrates a non-ephemeral Voucher (containing no nonce, or "nonceless"). 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. The final two examples illustrate a Voucher that includes an (example) extension per . The hypothetical YANG module name of the extension is 'example-my-extension'. First, a JSON serialization is shown. Next, a CBOR serialization is shown in CBOR diagnostic notation. This uses again the extension module 'example-my-extension' and refers to it using its SID value 305823299950. Note that for this example, long binary strings are abbreviated using the ellipsis (...) notation. contains examples of Vouchers encoded in JSON, and signed with . contains examples of Vouchers encoded in CBOR, and signed with . Further examples of CMS-signed Vouchers are given in .

YANG Module "ietf-voucher" During development of this merged YANG module, advice was given to better organize mutually exclusive Attributes such as 'pinned-domain-cert' vs 'pinned-domain-pubk', or 'expires-on' vs 'nonce'. Unfortunately, does not explain how and why choice statements are assigned SID values, and the tooling as of the end of 2025 is inconsistent with both the document, and the intuitive notions as to how this should work. As the simplest way forward, the no choice statements are used, allowing the SID values to be generated correctly. Normative requirements are instead included in the description of the Attributes in the YANG files. As a result, the SID values presented in and are to be considered normative, rather than relying exclusively on the ".sid" file generated from the YANG modules. The presented SID values are believed to be correct, but future reprocessing of the YANG module to a ".sid" file could result in changes as the tooling is fixed. Any such changes will be recorded as errata on this document. WG List: Author: Kent Watsen Author: Michael Richardson Author: Toerless Eckert Author: Qiufang Ma Author: Esko Dijk "; 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) 2023-2026 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. 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."; // RFCEDITOR: please replace XXXX in this entire code fragment // with the RFC number assigned and remove this notice. // Please also update references in the description {{}} to the // RFC numbers for the documents. revision 2025-12-18 { description "Updates and additions described by RFC XXXX, includes mechanism for constrained BRSKI {{I-D.ietf-anima-constrained-voucher}}, Pledge in Responder Mode {{I-D.ietf-anima-brski-prm}}, and BRSKI-CLOUD {{I-D.ietf-anima-brski-cloud}}"; reference "RFC XXXX: A Voucher Artifact for Onboarding Protocols"; } revision 2018-05-09 { description "Initial version"; reference "RFC 8366: Voucher Profile for Bootstrapping Protocols"; } grouping voucher-artifact { description "Grouping to allow reuse/extensions in future work."; 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. Typically, names are registered with the IANA. Standard extensions are described in an RFC, while vendor proprietary ones are not."; } leaf manufacturer-proprietary { type binary; description "In CBOR serialization, this is a CBOR bstr containing any valid CBOR that the manufacturer wishes to share with its Pledge. In JSON serializations, this contains additional JSON instead, and it is base64URL encoded. Since a Voucher could be logged or stored by a Registrar or another intermediate, this Attribute MUST NOT contain any data that requires confidentiality."; } 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 { 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. In the Voucher, it is optional as some manufacturers know that all serial-numbers are unique within the scope of a MASA. In the Voucher Request, whether it is mandatory or optional depends on which protocol is used, such as RFC8995 and variations. 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."; } // The MASA typically includes only one of the below // pinned-domain-* Attributes in a Voucher. 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.X690]. 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 onboarding 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: Internet X.509 Public Key Infrastructure Certificate and Certificate Revocation List (CRL) Profile. ITU-T.X690: 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."; } 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."; } // End of pinned-domain-* Attributes block 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."; } leaf last-renewal-date { type yang:date-and-time; must '../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."; } // The MASA MUST NOT include both of the below // Attributes expires-on and nonce in a Voucher. 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. A MASA that includes this Attribute MUST NOT include the 'nonce' Attribute."; } leaf nonce { type binary { length "8..32"; } description "A value that can be used by a Pledge in some onboarding protocols to enable anti-replay protection. This node is optional because it is not used by all onboarding protocols. When present, the Pledge MUST compare the provided nonce value with another value that the Pledge randomly generated and sent to a bootstrap server in an earlier onboarding message. If the value is present, but the values do not match, then the Pledge MUST NOT process this Voucher. A nonce value MUST be a cryptographically strong random value as detailed in RFC 4086. A MASA that includes this Attribute MUST NOT include the 'expires-on' Attribute."; } // End of expires-on / nonce Attributes block 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. The URL MUST NOT contain any data (such as authen- tication tokens) that requires confidentiality."; } } // Top-level statement sx:structure voucher { uses voucher-artifact; } } ]]>

ietf-voucher SID values explains how to serialize YANG into CBOR, and for this a series of SID values are required. The below SID values are assigned to the 'ietf-voucher' YANG module elements and are considered normative. The right column shows the schema-node path expression for the YANG data node to which the SID value is assigned. The 'assertion' Attribute is an enumerated type in , 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. CBOR integers for the 'assertion' Attribute enum value

CBOR Integer	Assertion Type
0	verified
1	logged
2	proximity
3	agent-proximity

Voucher Extensions An unstated assumption in 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 implicitly accommodates 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 DNS domain name. In CBOR serialization , the situation is not so easy when SID keys are used. An extension might need to use "Private range" 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 YANG "augment" mechanism), turned out not to be, see . Instead, a process similar to what was done by has been adopted. In the Voucher Data, any extensions are listed in a list Attribute named 'extensions'. In JSON serialization, these extensions each require a unique name, and therefore an IANA registration for these names is provided and FQDN-based uniqueness is used in certain cases (see ). The name MUST be the same as the YANG extension module name. The 'extensions' list Attribute allows for new standard extensions to be defined without changes to the 'ietf-voucher' YANG module. Items within that list are either strings (in JSON serialization), or integers (in CBOR serialization using SIDs). If the extension is registered with IANA, then both name and SID are always defined in the Voucher Extensions registry (see ). Extensions are full YANG modules, which are subject to the SID allocation process described in . When an extension is serialized, the extension is placed in a sub-map in the value of a new key/value pair in the 'voucher' container element. In JSON serialization, the corresponding key is the name of the extension, prefixed by the string "extension:". In CBOR serialization, the corresponding key is the SID which is allocated as the YANG extension module SID. This will typically require the absolute SID value Tag(47) to be applied to this key (see or the final example in ). Note that this differs from the mechanism described in : there, a sub-map is not used. Instead, keys are created by combining the module name and the Attribute as a string, as a result of using the YANG "augment" mechanism. The mechanism uses more bytes, but is also not easily translatable to CBOR. As the Voucher Request YANG module is created by YANG augment of the Voucher YANG module, any extension defined for the Voucher is also valid for a Voucher Request.

Manufacturer Proprietary 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 , it does require allocation of a SID value in order to do minimal-sized encoding in case of CBOR Voucher Data. Note that 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-proprietary' Attribute to put any content they wish, as long as this content does not require confidentiality. In CBOR serialization, if a plain CBOR map would be used, it would be subject to delta encoding: so use of this Attribute requires that the contents are bstr-encoded Section of RFC 8949 (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 is RECOMMENDED.

Voucher Request Artifact defined a "voucher-request" Artifact as an augmented Artifact from the "voucher" Artifact originally defined in . That definition has been moved to this document, and translated from the "yang-data" extension to the "sx:structure" extension . In the event that more than one of the Attributes proximity-registrar-pubk-sha256, proximity-registrar-pubk or proximity-registrar-cert are present in a Voucher Request, then the Registrar and MASA SHALL consider them in the order presented here. The presence of more than one of these Attributes is legal as it may allow a Pledge to operate in both constrained and non-constrained networks. However, on constrained networks it wastes significant amounts of space, and it is discouraged in those environments.

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 . Each node in the diagram is fully described by the YANG module in .

Example An example of a CMS-signed Voucher Request is given in .

YANG Module "ietf-voucher-request" The 'ietf-voucher-request' YANG module is derived from the 'ietf-voucher' module. WG List: Author: Kent Watsen Author: Michael Richardson Author: Toerless Eckert Author: Qiufang Ma Author: Esko Dijk "; 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 procedure and subsequent Voucher creation. Copyright (c) 2023-2026 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. 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."; // RFCEDITOR: please replace XXXX in this entire code fragment // with the RFC number assigned and remove this notice. // Please also update references in the description {{}} to the // RFC numbers for the documents. revision 2025-12-18 { description "Updates and additions described by RFC XXXX, includes mechanism for constrained BRSKI {{I-D.ietf-anima-constrained-voucher}}, Pledge in Responder Mode {{I-D.ietf-anima-brski-prm}}, and BRSKI-CLOUD {{I-D.ietf-anima-brski-cloud}}"; reference "RFC XXXX: A Voucher Artifact for Onboarding Protocols"; } revision 2021-05-20 { description "Initial version"; reference "RFC 8995: Bootstrapping Remote Secure Key Infrastructure (BRSKI)"; } grouping voucher-request { description "Grouping to allow reuse/extensions in future work."; uses vch:voucher-artifact { refine "last-renewal-date" { description "A last-renewal-date field MUST NOT be present in a Voucher Request, and any occurrence MUST be ignored"; } refine "domain-cert-revocation-checks" { description "The domain-cert-revocation-checks field MUST NOT be present in a Voucher Request, and any occurrence MUST be ignored"; } refine "assertion" { description "Any assertion included in Registrar Voucher Requests SHOULD be ignored by the MASA."; } refine "idevid-issuer" { description "The idevid-issuer field MUST be included in a Registrar Voucher Request (RVR) (unless specified otherwise) per Section 6.1 of RFC XXXX."; } } leaf prior-signed-voucher-request { type binary; description "If it is necessary to change a Voucher, or re-sign and forward a Voucher Request 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 Request information for the purposes of policy decisions. The MASA SHOULD remove all prior-signed-voucher-request information when signing a Voucher for onboarding so as to minimize the final Voucher size and to ensure privacy/security sensitive information does not leak into the Voucher."; } 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-T.X690]. The first certificate in the Registrar TLS server certificate_list sequence (the end-entity TLS certificate, see RFC 9846) 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."; } 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 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-T.X690]. The first certificate in the Registrar TLS server certificate_list sequence (the end-entity TLS certificate; see RFC 9846) 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-T.X690: 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 9846: 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-T.X690]. This certificate can be used by the Pledge, the Registrar, and the MASA to verify the signature of agent-signed-data. It is an optional component for the Pledge's Voucher Request. This MUST be populated in a Registrar's Voucher Request when an agent-proximity assertion is requested."; reference "ITU-T.X690: 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: called "voucher" to match RFC8995 sx:structure voucher { uses voucher-request; } } ]]>

ietf-voucher-request SID values explains how to serialize YANG into CBOR, and for this a series of SID values are required. The below SID values are assigned to the 'ietf-voucher-request' YANG module elements and are considered normative. The right column shows the schema-node path expression for the YANG data node to which the SID value is assigned. The 'assertion' Attribute is an enumerated type, and has values as defined in .

Design Considerations

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. A revocation artifact (such as an OCSP staple , or CRL ) is generally used to verify the continued validity of an assertion such as a PKIX certificate , web token, or 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' Attribute is set to some distant date, the expectation is for the MASA to instead issue a short-lived Voucher, where the 'expires-on' Attribute is set to a relatively near date, along with a promise (reflected in the 'last-renewal-date' Attribute) 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?"), renewal does not repeat all those checks: rather, the checks upon renewal are to confirm that the relationship established earlier still holds. The MASA always verifies the RVR, to ensure that the requesting Registrar still has access to the Domain's private key; it checks the revocation status of the Domain identity certificate (see ); and it applies any policy that has changed since the previous Voucher issuance, such as a Domain owner's request to block further renewals or the expiry of a support contract. Renewal has therefore lower overhead than the initial issuance and can be fully automated in most cases. The renewal request is created by the Registrar, using a freshly signed Registrar Voucher Request (RVR), including the old Voucher in the prior-signed-voucher-request Attribute. The Registrar signs the new request. 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. The exact definition of "short-lived" is up to the different Onboarding mechanisms. So, while this document recommends issuing short-lived Vouchers, the Voucher Artifact does not restrict the ability to create long-lived Vouchers, 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.

Change of a Pinned Trust Anchor A Voucher pins a specific Domain trust anchor, such as a Domain CA or a specific Registrar, identified by a specific public key. If that trust anchor changes after the Voucher was issued but before the Pledge has used it, for example because the Domain CA is rekeyed, the Voucher can no longer be used to onboard the Pledge into the Domain. In that case, the remedy is for the Registrar to request a new Voucher from the MASA that pins the new trust anchor. With short-lived Vouchers this is handled automatically: a Pledge that fails its Onboarding attempt would retry later, causing a fresh Voucher to be generated by the MASA pinning the new Domain trust anchor. With long-lived Vouchers, the Domain owner needs to track which outstanding Vouchers pin the old trust anchor and needs to request the manufacturer/MASA to have these Vouchers re-issued. Change of the pinned trust anchor in a long-lived Voucher is an exceptional case: normally, a long-lived Voucher pins always a stable identity in the domain such as a Domain CA, which is not expected to change during the Voucher's validity period. However, security-related concerns may sometimes require the rekeying of a Domain CA earlier than expected. See for considerations related to such cases. Note that recommends using short-lived Vouchers whenever possible.

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.

Signed, Not Encrypted Voucher Artifacts are, by design, signed but not encrypted. The security of a Voucher Artifact is based on its authenticity and integrity, not on the secrecy of its contents. The Voucher Data Attributes are all designed so that they could be exposed in public while not compromising the security of the Onboarding process. Leaving a Voucher Artifact unencrypted also allows parties other than the Pledge or MASA to inspect it. For example, a Registrar can verify and log a Voucher before forwarding it to the Pledge, and the network owner can audit what information is being exchanged between Pledge and manufacturer. Confidentiality of Voucher Artifacts in transit, where needed, is the responsibility of the Onboarding protocol. See for more detailed information on the transport security used by the different Onboarding protocols and related privacy considerations for exposed Voucher Artifacts.

Security Considerations

Clock Accuracy in a Pledge An attacker could use an expired nonceless Voucher to gain control over a device (Pledge) that has no understanding of the current time. While there are ways to secure Network Time Protocol (NTP), they are not as yet common, and like unsecured NTP they rely on the device having access to a network. As the purpose of the Voucher is usually to onboard the device onto a network, the device cannot make use of NTP as a time reference until it is onboarded. Even after Onboarding, the device still cannot rely on unauthenticated NTP, as the attacker could control the NTP stream. There are three defenses against this attack: 1) a device with an accurate clock is required to verify that the 'expires-on' Attribute's time has not yet passed, 2) a device without an accurate clock uses a nonce to get a fresh ephemeral Voucher, and 3) a device is required to verify that the trust anchor indicated in the Voucher matches the Registrar it is communicating with. The third prevents Onboarding into a Domain controlled by an attacker which is different to the Domain indicated in the Voucher. This limits attacks to Owners who had valid Vouchers in the past. If a device can be convinced that it is living in some past, then a former Owner could "repossess" the device using an expired Voucher. This document defines a Voucher that optionally contains an expiration time, which requires an accurate clock on the device in order to be processed correctly. Manufacturers issuing Vouchers with an expiration time need to ensure that the devices targeted have an accurate clock when shipped from manufacturing facilities and need to take measures to prevent clock tampering. If it is not possible to ensure clock accuracy and tamper-proofness, then the expiration time values in Vouchers will provide little protection.

Nonceless Vouchers A nonceless Voucher cannot be validated by a Pledge for freshness, other than by inspecting the 'expires-on' Attribute and comparing its value against the Pledge's internal clock. See the previous section for considerations on the accuracy of this clock and the risks of relying on NTP for acquiring the current time. A nonceless Voucher can be reused by a Registrar to answer a Pledge's PVR any number of times within its validity period. This can be a benefit for a Domain owner if repeated Onboarding into a Domain is required, but it equally allows an attacker that came into possession of a nonceless Voucher to attempt a great number of Onboarding attempts with the indicated Pledge. Still, such repeated attacks are unlikely to succeed because the Voucher explicitly identifies only one Domain where the Pledge can be onboarded into - which is not the attacker's Domain in this scenario.

Protecting the MASA Signing Key and the MASA CA Key As the MASA needs to be able to respond to Voucher signing requests, its private key used for signing Vouchers is online. This key is associated to its End-Entity certificate, which is a short-lived certificate, re-generated frequently. The private key MUST be stored such that it cannot be exported and each use of the key is subject to access control. A hardware security module (HSM) is one way to achieve this. There are many ways to organize the PKI that is used to sign Vouchers. describes a number of different scenarios. In some of them, there are long-term keys kept offline, implementing a Certification Authority (CA). This can be as advanced as an FIPS-certified resin-filled HSM, or as simple as a USB key stored in a locked cabinet. The trust anchor configured into the Pledge is the long-term offline anchor.

Test Domain Certificate Validity When Signing If a Domain CA certificate is compromised, then any outstanding Vouchers for that Domain could be used by an attacker. In this case, the Domain administrator is clearly expected to initiate revocation of any Domain identity certificates (as is normal in PKIX solutions). Similarly, they are expected to contact the manufacturer to indicate that ayn outstanding (presumably short lifetime) Vouchers should be blocked from automated renewal by the MASA. Protocols doing Voucher distribution are RECOMMENDED to check for revocation of Domain identity certificates before doing the signing of Vouchers. After the above mitigation steps have been taken, Onboarding of Pledges into the Domain can continue after new Vouchers are issued by the MASA that pin the new Domain trust anchor, as described in .

YANG Module Security Considerations The YANG modules in this document define only groupings and abstract data structures using the "sx:structure" extension . These are not intended to be accessed via YANG-based management protocols such as NETCONF or RESTCONF . Therefore, per Section 3.7 of , the YANG security considerations template does not apply. Modules that reuse the groupings defined in this document outside of a signed Voucher or Voucher Request artifact, need to identify the corresponding security implications. The YANG modules specified in this document define the schema for data that is subsequently encapsulated by secure signed-data structures, such as the CMS signed-data described in . As such, all of the YANG-modeled data is protected from modification. Implementers should be aware that the signed data is only protected from external modification; the data is still visible. This potential disclosure of this information doesn't affect security so much as privacy. When used with or , all Voucher Artifacts are conveyed using TLS , so there is no exposure of information apart from the endpoints of the TLS sessions. When used with , information can be exposed in the last hop between Registrar-Agent and Pledge, where unsecured HTTP can be used. When a Voucher is in CMS format, it can disclose information via the signer's certificate chain about which organization a device belongs to and which CRL Distribution Point and/or OCSP Responder URLs are accessed to check the revocation status of certificates. Note that specifies the use of format artifacts rather than CMS, so there are no CRLs to disclose in that case. uses a wide variety of transports, some of which offer physical privacy for data, and others which do not. To mitigate this, specifies a way to encrypt using CMS.

IANA Considerations

The IETF XML Registry This document updates two URIs in the "IETF XML Registry" : urn:ietf:params:xml:ns:yang:ietf-voucher and urn:ietf:params:xml:ns:yang:ietf-voucher-request: IANA is requested to update this registration to point to THIS-DOCUMENT.

The YANG Module Names Registry IANA is requested to update the ietf-voucher and ietf-voucher-request registrations in the "YANG Module Names" registry within the "YANG Parameters" registry group to point to this document. For the ietf-voucher-request entry, the prefix should be updated to "vcr".

The Media Types Registry IANA is requested to update the registration of media type: application/voucher-cms+json to change the Published Specification to THIS-DOCUMENT.

The SMI Security for S/MIME CMS Content Type Registry IANA is requested to update the registration for the OID 1.2.840.113549.1.9.16.1.40, 'id-ct-animaJSONVoucher'. This registration should be updated to point to this document.

The Voucher Extensions Registry IANA is asked to create a registry of Voucher extensions within the Bootstrapping Remote Secure Key Infrastructures (BRSKI) Parameters as follows. The name is: Voucher Extensions, and the Registration Policy is Expert Review.

• Extension name:

  UTF-8-encoded string, at most 40 characters.

  Extension SID:

  the YANG module SID value that defines the extension per .

  Reference:

  an optional document reference (URL, or other pointer)

Note that the Extension SID value is allocated as part of a process. This may be from a SID range managed by IANA, or from any other MegaRange. allows for PEN-based allocations. IANA does not need to separately allocate a SID value for this column. Extension name strings for documents in the IETF Document Stream and IRTF Document Stream are given by the YANG module name: they do not contain dots. For vendor proprietary extensions (including Independent Submission Stream documents), the resulting string still needs to be unique. This can be done by making the YANG module name unique, basing it on a fully-qualified domain name (FQDN) . For example, using a string "fuubar.example.com-mud-thing" rather than "fuubar-mud-thing" if the vendor owns the FQDN "fuubar.example.com". Vendor proprietary extensions do not need to be registered with IANA, but vendors are encouraged to do so. Note that a 'vendor' may also be a standards development organization that develops extensions. Designated Experts should review the referenced document for clarity of purpose and to facilitate the checks below. For IETF/IRTF Document Stream registrations, an expert does not review or change the registered values themselves, as these are tied to IETF processes:

• There are no choices in the Extension name: it is always the YANG module name.
• There is no choice in the Extension SID value: it follows from another IANA process (as explained above).

For documents outside the IETF/IRTF Document Streams, the Designated Expert should pay special attention to the stability of the reference, which may be a concern. For example, a URL pointing to the website of a standards development organization may change from time to time. Also, a Designated Expert could suggest a shorter FQDN in case the Extension name string exceeds the character limit. The Designated Expert should determine if the work overlaps with an existing IETF WG effort, suggesting to the registrant how the work could become part of an (IETF) standard. However, as extension registration is optional, the Designated Expert should not block any vendor registrations if no consolidated extension is pursued by the registrant.

The IETF YANG-SID Ranges Registry IANA is requested to register the following entries in the IETF YANG-SID Ranges registry: Registered SID ranges

Entry Point	Size	Module Name	Reference
2450	50	ietf-voucher	[This-Document]
2500	50	ietf-voucher-request	[This-Document]

The IETF YANG-SID Modules Registry IANA is requested to register the following YANG module in the IETF YANG-SID Modules registry, per :

• YANG module name: ietf-voucher
• URI for the ".yang" file: a pointer to the file defined in
• URI for the ".sid" file: a pointer to the file defined in
• Number of SIDs: 17

and also the following YANG module:

• YANG module name: ietf-voucher-request
• URI for the ".yang" file: a pointer to the file defined in
• URI for the ".sid" file: a pointer to the file defined in
• Number of SIDs: 24

YANG references RFC-editor, please remove this section. This section just lists references present in YANG modules which otherwise do not get included in the references, like . Also , Common YANG Data Types. Also , Randomness Requirements for Security. (Normative reference)

References Normative References This memo profiles the X.509 v3 certificate and X.509 v2 certificate revocation list (CRL) for use in the Internet. An overview of this approach and model is provided as an introduction. The X.509 v3 certificate format is described in detail, with additional information regarding the format and semantics of Internet name forms. Standard certificate extensions are described and two Internet-specific extensions are defined. A set of required certificate extensions is specified. The X.509 v2 CRL format is described in detail along with standard and Internet-specific extensions. An algorithm for X.509 certification path validation is described. An ASN.1 module and examples are provided in the appendices. [STANDARDS-TRACK] This document describes the Cryptographic Message Syntax (CMS). This syntax is used to digitally sign, digest, authenticate, or encrypt arbitrary message content. [STANDARDS-TRACK] YANG is a data modeling language used to model configuration and state data manipulated by the Network Configuration Protocol (NETCONF), NETCONF remote procedure calls, and NETCONF notifications. [STANDARDS-TRACK] This document amends the IANA guidance on the uniqueness of YANG module and submodule names. The document updates RFC 6020 to clarify how modules and their revisions are handled by IANA. YANG is a data modeling language used to model configuration data, state data, Remote Procedure Calls, and notifications for network management protocols. This document describes the syntax and semantics of version 1.1 of the YANG language. YANG version 1.1 is a maintenance release of the YANG language, addressing ambiguities and defects in the original specification. There are a small number of backward incompatibilities from YANG version 1. This document also specifies the YANG mappings to the Network Configuration Protocol (NETCONF). JavaScript Object Notation (JSON) is a lightweight, text-based, language-independent data interchange format. It was derived from the ECMAScript Programming Language Standard. JSON defines a small set of formatting rules for the portable representation of structured data. This document removes inconsistencies with other specifications of JSON, repairs specification errors, and offers experience-based interoperability guidance. YANG (RFC 7950) is a data modeling language used to model configuration data, state data, parameters and results of Remote Procedure Call (RPC) operations or actions, and notifications. This document defines encoding rules for YANG in the Concise Binary Object Representation (CBOR) (RFC 8949). The Concise Binary Object Representation (CBOR) is a data format whose design goals include the possibility of extremely small code size, fairly small message size, and extensibility without the need for version negotiation. These design goals make it different from earlier binary serializations such as ASN.1 and MessagePack. This document obsoletes RFC 7049, providing editorial improvements, new details, and errata fixes while keeping full compatibility with the interchange format of RFC 7049. It does not create a new version of the format. YANG Schema Item iDentifiers (YANG SIDs) are globally unique 63-bit unsigned integers used to identify YANG items. SIDs provide a more compact method for identifying those YANG items that can be used efficiently, notably in constrained environments (RFC 7228). This document defines the semantics, registration processes, and assignment processes for YANG SIDs for IETF-managed YANG modules. To enable the implementation of these processes, this document also defines a file format used to persist and publish assigned YANG SIDs. Sandelman Software Works vanderstok consultancy Cisco Systems IoTconsultancy.nl This document defines the Constrained Bootstrapping Remote Secure Key Infrastructure (cBRSKI) protocol, which provides a solution for secure zero-touch onboarding of resource-constrained (IoT) devices into the network of a domain owner. This protocol is designed for constrained networks, which may have limited data throughput or may experience frequent packet loss. cBRSKI is a variant of the BRSKI protocol, which uses an artifact signed by the device manufacturer called the "voucher" which enables a new device and the owner's network to mutually authenticate. While the BRSKI voucher data is encoded in JSON, cBRSKI uses a compact CBOR-encoded voucher. The BRSKI voucher data definition is extended with new data types that allow for smaller voucher sizes. The Enrollment over Secure Transport (EST) protocol, used in BRSKI, is replaced with EST-over- CoAPS; and HTTPS used in BRSKI is replaced with DTLS-secured CoAP (CoAPS). This document Updates RFC 8995 and RFC 9148. Siemens AG Sandelman Software Works This document introduces a variant of the RFC8366 voucher artifact in which CMS is replaced by the JSON Object Signing and Encryption (JOSE) mechanism described in RFC7515. This supports deployments in which JOSE is preferred over CMS. In addition to specifying the format, the "application/voucher-jws+json" media type is registered and examples are provided. International Telecommunication Union International Telecommunication Union This document specifies automated bootstrapping of an Autonomic Control Plane. To do this, a Secure Key Infrastructure is bootstrapped. This is done using manufacturer-installed X.509 certificates, in combination with a manufacturer's authorizing service, both online and offline. We call this process the Bootstrapping Remote Secure Key Infrastructure (BRSKI) protocol. Bootstrapping a new device can occur when using a routable address and a cloud service, only link-local connectivity, or limited/disconnected networks. Support for deployment models with less stringent security requirements is included. Bootstrapping is complete when the cryptographic identity of the new key infrastructure is successfully deployed to the device. The established secure connection can be used to deploy a locally issued certificate to the device as well. Siemens AG Siemens AG Cisco Systems Sandelman Software Works This document defines enhancements to Bootstrapping Remote Secure Key Infrastructure (BRSKI, RFC8995) as BRSKI with Pledge in Responder Mode (BRSKI-PRM). BRSKI-PRM supports the secure bootstrapping of devices, referred to as pledges, into a domain where direct communication with the registrar is either limited or not possible at all. To facilitate interaction between a pledge and a domain registrar the registrar-agent is introduced as new component. The registrar-agent supports the reversal of the interaction model from a pledge-initiated mode, to a pledge-responding mode, where the pledge is in a server role. To establish the trust relation between pledge and registrar, BRSKI-PRM relies on object security rather than transport security. This approach is agnostic to enrollment protocols that connect a domain registrar to a key infrastructure (e.g., domain Certification Authority). Cisco Ciena Sandelman Software Works Bootstrapping Remote Secure Key Infrastructures (BRSKI) defines how to onboard a device securely into an operator-maintained infrastructure. It assumes that there is local network infrastructure for the device to discover. On networks without that, there is nothing present to help onboard the device. This document extends BRSKI and defines behavior for bootstrapping devices for deployments where no local infrastructure is available, such as in a home or remote office. This document defines how the device can use a well-defined "call-home" mechanism to find the operator-maintained infrastructure. This document defines how to contact a well-known Cloud Registrar, and two ways in which the device may be redirected towards the operator-maintained infrastructure. The Cloud Registrar enables discovery of the operator-maintained infrastructure, and may enable establishment of trust with operator-maintained infrastructure that does not support BRSKI mechanisms. This document updates RFC 8995 (BRSKI). IEEE This document describes YANG mechanisms for defining abstract data structures with YANG. This document defines encoding rules for representing configuration data, state data, parameters of Remote Procedure Call (RPC) operations or actions, and notifications defined using YANG as JavaScript Object Notation (JSON) text. Autonomic functions need a control plane to communicate, which depends on some addressing and routing. This Autonomic Control Plane should ideally be self-managing and be as independent as possible of configuration. This document defines such a plane and calls it the "Autonomic Control Plane", with the primary use as a control plane for autonomic functions. It also serves as a "virtual out-of-band channel" for Operations, Administration, and Management (OAM) communications over a network that provides automatically configured, hop-by-hop authenticated and encrypted communications via automatically configured IPv6 even when the network is not configured or is misconfigured. In many standards track documents several words are used to signify the requirements in the specification. These words are often capitalized. This document defines these words as they should be interpreted in IETF documents. This document specifies an Internet Best Current Practices for the Internet Community, and requests discussion and suggestions for improvements. RFC 2119 specifies common key words that may be used in protocol specifications. This document aims to reduce the ambiguity by clarifying that only UPPERCASE usage of the key words have the defined special meanings. University of the Bundeswehr Munich NVIDIA Sandelman Software Works Ericsson RFC 7925 offers guidance to developers on using TLS/DTLS 1.2 for Internet of Things (IoT) devices with resource constraints. This document is a companion to RFC 7925, defining TLS/DTLS 1.3 profiles for IoT devices. Additionally, it updates RFC 7925 with respect to the X.509 certificate profile and ciphersuite requirements. Discussion Venues This note is to be removed before publishing as an RFC. Source for this draft and an issue tracker can be found at https://github.com/thomas-fossati/draft-tls13-iot. This document specifies a new certificate type and two TLS extensions for exchanging raw public keys in Transport Layer Security (TLS) and Datagram Transport Layer Security (DTLS). The new certificate type allows raw public keys to be used for authentication. This document defines a collection of common data types to be used with the YANG data modeling language. It includes several new type definitions and obsoletes RFC 6991. Security systems are built on strong cryptographic algorithms that foil pattern analysis attempts. However, the security of these systems is dependent on generating secret quantities for passwords, cryptographic keys, and similar quantities. The use of pseudo-random processes to generate secret quantities can result in pseudo-security. A sophisticated attacker may find it easier to reproduce the environment that produced the secret quantities and to search the resulting small set of possibilities than to locate the quantities in the whole of the potential number space. Choosing random quantities to foil a resourceful and motivated adversary is surprisingly difficult. This document points out many pitfalls in using poor entropy sources or traditional pseudo-random number generation techniques for generating such quantities. It recommends the use of truly random hardware techniques and shows that the existing hardware on many systems can be used for this purpose. It provides suggestions to ameliorate the problem when a hardware solution is not available, and it gives examples of how large such quantities need to be for some applications. This document specifies an Internet Best Current Practices for the Internet Community, and requests discussion and suggestions for improvements. Informative References This document describes an IANA maintained registry for IETF standards which use Extensible Markup Language (XML) related items such as Namespaces, Document Type Declarations (DTDs), Schemas, and Resource Description Framework (RDF) Schemas. This document specifies version 1.3 of the Transport Layer Security (TLS) protocol. TLS allows client/server applications to communicate over the Internet in a way that is designed to prevent eavesdropping, tampering, and message forgery. This document obsoletes RFC 8446, which specified TLS 1.3. This document obsoletes RFC 5246 (specifying TLS 1.2) and RFCs 5077, 6961, 7627, and 8422, all of which pertain to TLS 1.2 or earlier, and updates RFCs 5705 and 6066. This document also specifies new requirements for TLS 1.2 implementations. Many application technologies enable secure communication between two entities by means of Internet Public Key Infrastructure Using X.509 (PKIX) certificates in the context of Transport Layer Security (TLS). This document specifies procedures for representing and verifying the identity of application services in such interactions. [STANDARDS-TRACK] The Network Configuration Protocol (NETCONF) defined in this document provides mechanisms to install, manipulate, and delete the configuration of network devices. It uses an Extensible Markup Language (XML)-based data encoding for the configuration data as well as the protocol messages. The NETCONF protocol operations are realized as remote procedure calls (RPCs). This document obsoletes RFC 4741. [STANDARDS-TRACK] This document defines the concept "Opportunistic Security" in the context of communications protocols. Protocol designs based on Opportunistic Security use encryption even when authentication is not available, and use authentication when possible, thereby removing barriers to the widespread use of encryption on the Internet. This document describes an HTTP-based protocol that provides a programmatic interface for accessing data defined in YANG, using the datastore concepts defined in the Network Configuration Protocol (NETCONF). This document captures the current syntax used in YANG module tree diagrams. The purpose of this document is to provide a single location for this definition. This syntax may be updated from time to time based on the evolution of the YANG language. 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 document that has been signed using a Cryptographic Message Syntax (CMS) structure. Other YANG-derived formats are possible. The voucher artifact is normally generated by the pledge's manufacturer (i.e., the Manufacturer Authorized Signing Authority (MASA)). This document only defines the voucher artifact, leaving it to other documents to describe specialized protocols for accessing it. This document presents a technique to securely provision a networking device when it is booting in a factory-default state. Variations in the solution enable it to be used on both public and private networks. The provisioning steps are able to update the boot image, commit an initial configuration, and execute arbitrary scripts to address auxiliary needs. The updated device is subsequently able to establish secure connections with other systems. For instance, a device may establish NETCONF (RFC 6241) and/or RESTCONF (RFC 8040) connections with deployment-specific network management systems. This document defines two strategies for handling long lines in width-bounded text content. One strategy, called the "single backslash" strategy, is based on the historical use of a single backslash ('\') character to indicate where line-folding has occurred, with the continuation occurring with the first character that is not a space character (' ') on the next line. The second strategy, called the "double backslash" strategy, extends the first strategy by adding a second backslash character to identify where the continuation begins and is thereby able to handle cases not supported by the first strategy. Both strategies use a self-describing header enabling automated reconstitution of the original content. In network protocol exchanges, it is often useful for one end of a communication to know whether the other end is in an intended operating state. This document provides an architectural overview of the entities involved that make such tests possible through the process of generating, conveying, and evaluating evidentiary Claims. It provides a model that is neutral toward processor architectures, the content of Claims, and protocols. Many application technologies enable secure communication between two entities by means of Transport Layer Security (TLS) with Internet Public Key Infrastructure using X.509 (PKIX) certificates. This document specifies procedures for representing and verifying the identity of application services in such interactions. This document obsoletes RFC 6125. Concise Binary Object Representation (CBOR) is a data format designed for small code size and small message size. There is a need to be able to define basic security services for this data format. This document defines the CBOR Object Signing and Encryption (COSE) protocol. This specification describes how to create and process signatures, message authentication codes, and encryption using CBOR for serialization. This specification additionally describes how to represent cryptographic keys using CBOR. This document, along with RFC 9053, obsoletes RFC 8152. Concise Binary Object Representation (CBOR) is a data format designed for small code size and small message size. CBOR Object Signing and Encryption (COSE) defines a set of security services for CBOR. This document defines a countersignature algorithm along with the needed header parameters and CBOR tags for COSE. This document updates RFC 9052. JSON Web Signature (JWS) represents content secured with digital signatures or Message Authentication Codes (MACs) using JSON-based data structures. Cryptographic algorithms and identifiers for use with this specification are described in the separate JSON Web Algorithms (JWA) specification and an IANA registry defined by that specification. Related encryption capabilities are described in the separate JSON Web Encryption (JWE) specification. This document provides guidelines for authors and reviewers of specifications containing YANG data models, including IANA-maintained YANG modules. Recommendations and procedures are defined, which are intended to increase interoperability and usability of Network Configuration Protocol (NETCONF) and RESTCONF protocol implementations that utilize YANG modules. This document obsoletes RFC 8407; it also updates RFC 8126 by providing additional guidelines for writing the IANA considerations for RFCs that specify IANA-maintained YANG modules. Open Connectivity Foundation n.d. This specification defines a framework for authentication and authorization in Internet of Things (IoT) environments called ACE-OAuth. The framework is based on a set of building blocks including OAuth 2.0 and the Constrained Application Protocol (CoAP), thus transforming a well-known and widely used authorization solution into a form suitable for IoT devices. Existing specifications are used where possible, but extensions are added and profiles are defined to better serve the IoT use cases. The Domain Name System (DNS) is defined in literally dozens of different RFCs. The terminology used by implementers and developers of DNS protocols, and by operators of DNS systems, has changed in the decades since the DNS was first defined. This document gives current definitions for many of the terms used in the DNS in a single document. This document updates RFC 2308 by clarifying the definitions of "forwarder" and "QNAME". It obsoletes RFC 8499 by adding multiple terms and clarifications. Comprehensive lists of changed and new definitions can be found in Appendices A and B. A trust anchor represents an authoritative entity via a public key and associated data. The public key is used to verify digital signatures, and the associated data is used to constrain the types of information for which the trust anchor is authoritative. A relying party uses trust anchors to determine if a digitally signed object is valid by verifying a digital signature using the trust anchor's public key, and by enforcing the constraints expressed in the associated data for the trust anchor. This document describes some of the problems associated with the lack of a standard trust anchor management mechanism and defines requirements for data formats and push-based protocols designed to address these problems. This document is not an Internet Standards Track specification; it is published for informational purposes. This memo specifies a component-based architecture for Manufacturer Usage Descriptions (MUDs). The goal of MUD is to provide a means for end devices to signal to the network what sort of access and network functionality they require to properly function. The initial focus is on access control. Later work can delve into other aspects. This memo specifies two YANG modules, IPv4 and IPv6 DHCP options, a Link Layer Discovery Protocol (LLDP) TLV, a URL, an X.509 certificate extension, and a means to sign and verify the descriptions. Ericsson AB Ericsson AB INRIA INRIA Sandelman Software Works Ephemeral Diffie-Hellman Over COSE (EDHOC) is a lightweight authenticated key exchange protocol intended for use in constrained scenarios. This document specifies Lightweight Authorization using EDHOC (ELA). The procedure allows authorizing enrollment of new devices using the extension point defined in EDHOC. ELA is applicable to zero-touch onboarding of new devices to a constrained network leveraging trust anchors installed at manufacture time. CryptoNext Security MTG AG The Cryptographic Message Syntax (CMS) has different signature verification behaviour based on whether signed attributes are present or not. This results in a potential existential forgery vulnerability in CMS and protocols which use CMS. This document describes the vulnerability and lists best practices and mitigations for such a vulnerability. The Hypertext Transfer Protocol (HTTP) is a stateless application-level protocol for distributed, collaborative, hypertext information systems. This document describes the overall architecture of HTTP, establishes common terminology, and defines aspects of the protocol that are shared by all versions. In this definition are core protocol elements, extensibility mechanisms, and the "http" and "https" Uniform Resource Identifier (URI) schemes. This document updates RFC 3864 and obsoletes RFCs 2818, 7231, 7232, 7233, 7235, 7538, 7615, 7694, and portions of 7230. Sandelman Software The imminent arrival of a Cryptographically Relevant Quantum Computer (CRQC) makes algorithms such as RSA, ECDSA and EdDSA vulnerable to attack. A transition to Quantum-Safe (PQ) algorithms is occurring. This document provides specific requirements (Mandatory to Implement) for Autonomic Network Infrastructure (ANI/ACP) and AgenticAI manufacturers and operators to be able to seamlessly transition to Quantum Safe algorithms. The advent of a cryptographically relevant quantum computer (CRQC) would render state-of-the-art, traditional public key algorithms deployed today obsolete, as the mathematical assumptions underpinning their security would no longer hold. To address this, protocols and infrastructure must transition to post-quantum algorithms, which are designed to resist both traditional and quantum attacks. This document explains why engineers need to be aware of and understand post-quantum cryptography (PQC), and it details the impact of CRQCs on existing systems and the challenges involved in transitioning to post-quantum algorithms. Unlike previous cryptographic updates, this shift may require significant protocol redesign due to the unique properties of post-quantum algorithms. This document describes elliptic curve signature scheme Edwards-curve Digital Signature Algorithm (EdDSA). The algorithm is instantiated with recommended parameters for the edwards25519 and edwards448 curves. An example implementation and test vectors are provided. This document specifies algorithm identifiers and ASN.1 encoding formats for elliptic curve constructs using the curve25519 and curve448 curves. The signature algorithms covered are Ed25519 and Ed448. The key agreement algorithms covered are X25519 and X448. The encoding for public key, private key, and Edwards-curve Digital Signature Algorithm (EdDSA) structures is provided. Digital signatures are used within X.509 certificates and Certificate Revocation Lists (CRLs), and to sign messages. This document specifies the conventions for using FIPS 204, the Module-Lattice-Based Digital Signature Algorithm (ML-DSA) in Internet X.509 certificates and CRLs. The conventions for the associated signatures, subject public keys, and private key are also described. This document describes the commonly used base 64, base 32, and base 16 encoding schemes. It also discusses the use of line-feeds in encoded data, use of padding in encoded data, use of non-alphabet characters in encoded data, use of different encoding alphabets, and canonical encodings. [STANDARDS-TRACK] This document specifies a protocol useful in determining the current status of a digital certificate without requiring Certificate Revocation Lists (CRLs). Additional mechanisms addressing PKIX operational requirements are specified in separate documents. This document obsoletes RFCs 2560 and 6277. It also updates RFC 5912. The Registration Data Access Protocol (RDAP) is used by Regional Internet Registries (RIRs) and Domain Name Registries (DNRs) to provide access to their resource registration information. The core specifications for RDAP define basic search functionality, but there are various search options related to IP addresses, IP prefixes, and Autonomous System Numbers (ASNs), which are provided by RIRs via their WHOIS services, but for which there is no corresponding RDAP functionality. This document extends RDAP to support those search options. Sandelman Software Works Siemens AG This document describes a number of operational modes that a BRSKI Manufacturer Authorized Signing Authority (MASA) may take on. Each mode is defined, and then each mode is given a relevance within an over applicability of what kind of organization the MASA is deployed into. This document does not change any protocol mechanisms. YANG-CBOR (RFC 9254, "Encoding of Data Modeled with YANG in the Concise Binary Object Representation (CBOR)") defines YANG Schema Item iDentifiers (YANG SIDs), globally unique 63-bit unsigned integers used to identify YANG items. RFC 9595 ("YANG Schema Item iDentifier (YANG SID)") defines ways to allocate these SIDs using IANA registries. The present specification employs these SID allocation mechanisms to allocate ranges of 100 000 SIDs (representation size 64 bits) to each holder of an IANA Private Enterprise Number (PEN) of a value below 1 000 000. Holders of PENs of values smaller than 100 000 are also allocated ranges of 10 000 SIDs (representation size 32 bits).

Examples

Key pairs associated with examples The following Voucher Request has been produced using the IDevID public (certificate) and private key. They are included so that other developers can match the same output. The private RSA key: The IDevID certificate (public key): The Certification Authority that created the IDevID: The private key for the Certification Authority that created the IDevID: The MASA certificate that signs the Voucher: The private key for the MASA certificate that signs the Voucher:

Example CMS-signed Voucher Request

Example CMS-signed Voucher from MASA

Example JWS-signed Voucher from MASA These examples are folded according to the Single Backslash rule.

Example JWS Voucher

SID Allocations It is temporarily included for review purposes, following the guidelines in .

SID Allocations for Voucher

SID Allocations for Voucher Request

Acknowledgements The authors would like to thank the following people for lively discussions on list and in the halls (ordered by last name): , , , , . This document received directorate reviews from , , and . It was shepherded by . and were instrumental in creating the original .