]> Watsen Networks

kent+ietf@watsen.net

Sandelman Software

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

Cisco Systems

pritikin@cisco.com

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 Pledge to an Owner using an artifact signed, directly or indirectly, by the Pledge's manufacturer. This artifact is known as a "Voucher". This document defines an artifact format as a YANG-defined JSON or CBOR document that has been signed using a variety of cryptographic systems. The Voucher Artifact is normally generated by the Pledge's manufacturer (i.e., the Manufacturer Authorized Signing Authority (MASA)). This document updates RFC8366: 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 BRSKI/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 an artifact signed, directly or indirectly, by the Pledge's manufacturer, i.e., the Manufacturer Authorized Signing Authority (MASA). This artifact is known as the "Voucher". The Voucher Artifact is a JSON document that conforms with a data model described by YANG . It may also be serialized to CBOR . It is encoded using the rules defined in or , and is signed using (by default) a CMS structure . The primary purpose of a Voucher is to securely convey a trust anchor that a Pledge can use to authenticate subsequent interactions. The trust anchor may be in the form of a certificate (the 'pinned-domain-cert' Attribute), a hash of a certificate, or it can be a raw public key (in constrained use cases). This trust anchor represents the authority of the Owner of a network. Communicating this trust anchor securely to the Pledge is the job of the Voucher Artifact. The act of communicating this trust anchor is known as pinning the trust anchor, as the Pledge can then use the resulting anchor to authenticate other actors who are part of the network. The collection of all these actors is collectively known as the Domain. (This is not related to the domain name system, but rather the term is of mathematical origin) A Voucher may be useful in several contexts, but the driving motivation herein is to support secure Onboarding mechanisms. This is accomplished by assigning an Owner to the Pledge, enabling it to authenticate the network that it is connected to. 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, and therefore updates . YANG is not easily extended except by updating the YANG module definition. Since was written, the common pattern is to publish YANG modules as two documents: one with only the YANG module, and the other one with usage, motivation and further explanation. This allows the YANG module to be updated without replacing all of the context. This document does not follow that pattern, but future documents may update only the YANG module. 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 private extensions. The lifetimes of Vouchers may vary. In some Onboarding protocols, the Vouchers may include a nonce restricting them to a single use, whereas the Vouchers in other Onboarding protocols may have an indicated lifetime. In order to support long lifetimes, this document recommends using short lifetimes with programmatic renewal, see . Some Onboarding protocols using the Voucher Artifact defined in this document include: , , and .

Terminology This document uses and defines the following terms. They are used in this document and related documents.

(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.

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:

The process where a Pledge obtains cryptographic key material to identify and trust future interactions within a specific Domain network. Based on imprinted key material provided during the manufacturing process (see: Imprint). This term was used in , but has been supplanted by the term Onboarding.

Domain:

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

Imprint:

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

Join Registrar (and Coordinator):

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

MASA (Manufacturer Authorized Signing Authority):

The entity that, for the purpose of this document, issues and signs the Vouchers for a manufacturer's Pledges 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.

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 specifically deals with application-specific cryptographic key material (application-specific security credentials). Since , this term has replaced the term Bootstrapping.

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.

Pledge:

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

Registrar:

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

TOFU (Trust on First Use):

When a Pledge makes no security decisions but rather simply trusts the first Domain entity it is contacted by. Used similarly to . This is also known as the "resurrecting duckling" model .

Voucher:

A Voucher Artifact, not a Voucher Request, 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 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.

Pledge Voucher Request (PVR):

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

Registrar Voucher Request (RVR):

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

Requirements Language The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in BCP 14 when, and only when, they appear in all capitals, as shown here.

Survey of Voucher Types A Voucher is a cryptographically protected statement to the Pledge authorizing a zero-touch Onboarding with the Join Registrar of the Domain. The specific information a Voucher provides is influenced by the Onboarding use case. The Voucher can convey the following information to the Join Registrar and 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 or measured boot. The Join Registrar uses this information to make a determination as to whether to accept the Pledge into the network. Only some methods are normatively defined in this document. Other methods are left for future work.

Authentication of Join Registrar:

Indicates how the Pledge can authenticate the Join Registrar. This document defines a mechanism to pin the Domain certificate, or a raw public key. Pinning a symmetric key, or CN-ID () or DNS-ID information (as defined in ) is left for future work.

Anti-Replay Protections:

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

A number of Onboarding scenarios can be met using differing combinations of this information. All scenarios address the primary threat of an on-path active attacker (or MiTM) impersonating the Registrar. If successful, this would gain control over the Pledge. The following combinations are "types" of Vouchers: 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 can not 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

Attempts and motivation to extend 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. Both and require extensions to the Voucher Request and the resulting Voucher. The new Attributes are required to carry the additional data and describe the extended semantics. In addition uses the serialization mechanism described in to produce significantly more compact artifacts. 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 can not do this, so that was initially the impetus for this document. An attempt was then made to determine what would happen if one wanted to have a constrained version of the 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 mechanisms. After significant discussion the decision was made to simply roll all of the needed extensions into this document.

Informational Model changes since RFC8366 This document therefore represents a merge of YANG definitions 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 is not included in this document, but rather in the respective other documents.

Signature mechanisms Three signature systems have been defined for Vouchers Artifacts. defines a mechanism that uses COSE , with the Voucher Data encoded using . 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 here.

CMS Format Voucher Artifact The IETF evolution of PKCS#7 is CMS . A CMS-signed Voucher, the default type, contains a ContentInfo structure with the Voucher Data. An OID for JSON-encoded Voucher Data is allocated in , and it is to be placed in the 'eContentType' field in the ContentInfo. The signing structure is a CMS SignedData structure, as specified by Section 5.1 of , encoded using ASN.1 Distinguished Encoding Rules (DER), as specified in ITU-T X.690 . 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 are present. To facilitate interoperability, the media type "application/voucher-cms+json" and the filename extension ".vcj" were registered by . The CMS structure MUST contain a 'signerInfo' structure, as described in Section 5.1 of , containing the signature generated over the content using a private key trusted by the recipient. Normally, the recipient is the Pledge and the signer is the MASA. In the Voucher Request, the signer is the Pledge (in the PVR), or the Registrar (in the RVR). Note that Section 5.1 of includes a discussion about how to validate a CMS object, which is really a PKCS7 object (cmsVersion=1). Intermediate systems (such as the Bootstrapping Remote Secure Key Infrastructures Registrar) that might need to evaluate the Voucher in flight MUST be prepared for such an older format. No signaling of the format version is necessary, as the manufacturer knows the capabilities of the Pledge and will use an appropriate format Voucher for each Pledge. The CMS structure SHOULD also contain all of the certificates leading up to and including the signer's trust anchor certificate known to the recipient. The inclusion of the trust anchor is unusual in many applications, but third parties cannot accurately audit the transaction without it. The CMS structure MAY also contain revocation objects for any intermediate certificate authorities (CAs) between the Voucher issuer and the trust anchor known to the recipient. However, the use of CRLs and other validity mechanisms is discouraged, as the Pledge is unlikely to be able to perform online checks and is unlikely to have a trusted clock source. As described below, the use of short-lived Vouchers and/or a Pledge-provided nonce provides a freshness guarantee.

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.

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 .

YANG Module 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 choice mechanisms that were introduced have been commented out in the YANG, allowing the SID values to be generated correctly. 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: Max Pritikin 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 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. revision 2023-01-10 { description "Updates and additions described by RFC XXXX"; reference "RFC XXXX A Voucher Profile for Bootstrapping Protocols"; } revision 2018-05-09 { description "Initial version"; reference "RFC 8366: Voucher Profile for Bootstrapping Protocols"; } grouping voucher-artifact-grouping { 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. Each name is registered with the IANA. Standard extensions are described in an RFC, while vendor proprietary ones are not."; } leaf manufacturer-private { type binary; description "In CBOR serialization, this is a CBOR bstr containing any valid CBOR that the manufacturer wishes to share with its pledge. In JSON serializations, this contains additional JSON instead, and it is base64URL encoded."; } 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. Optional since some serial-numbers are already unique within the scope of a MASA. Inclusion of the statistically unique key identifier ensures statistically unique identification of the hardware. When processing a voucher, a pledge MUST ensure that its IDevID Authority Key Identifier matches this value. If no match occurs, then the pledge MUST NOT process this voucher. When issuing a voucher, the MASA MUST ensure that this field is populated for serial-numbers that are not otherwise unique within the scope of the MASA."; } // choice pinning { // description "One of these attributes is used by the // MASA to pin the registrar identity"; leaf pinned-domain-cert { type binary; description "An X.509 v3 certificate structure, as specified by RFC 5280, using Distinguished Encoding Rules (DER) encoding, as defined in ITU-T X.690. This certificate is used by a pledge to trust a Public Key Infrastructure in order to verify a domain certificate supplied to the pledge separately by the bootstrapping protocol. The domain certificate MUST have this certificate somewhere in its chain of certificates. This certificate MAY be an end-entity certificate, including a self-signed entity."; reference "RFC 5280: Internet X.509 Public Key Infrastructure Certificate and Certificate Revocation List (CRL) Profile. ITU-T X.690: Information technology - ASN.1 encoding rules: Specification of Basic Encoding Rules (BER), Canonical Encoding Rules (CER) and Distinguished Encoding Rules (DER)."; } leaf pinned-domain-pubk { type binary; description "The pinned-domain-pubk may replace the pinned-domain-cert in constrained uses of the voucher. The pinned-domain-pubk is the Raw Public Key of the registrar. This field is encoded as a Subject Public Key Info block as specified in RFC7250, in section 3. The ECDSA algorithm MUST be supported. The EdDSA algorithm as specified in draft-ietf-tls-rfc4492bis-17 SHOULD be supported. Support for the DSA algorithm is not recommended. Support for the RSA algorithm is a MAY."; } leaf pinned-domain-pubk-sha256 { type binary; description "The pinned-domain-pubk-sha256 is a second alternative to pinned-domain-cert. In many cases the public key of the domain has already been transmitted during the key agreement process, and it is wasteful to transmit the public key another two times. The use of a hash of public key info, at 32-bytes for sha256 is a significant savings compared to an RSA public key, but is only a minor savings compared to a 256-bit ECDSA public-key. Algorithm agility is provided by extensions to this specification which can define a new leaf for another hash type."; } // } choice pinning removed 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."; } //choice nonceless { // description "Either a nonce must be present, // or an expires-on header"; leaf expires-on { type yang:date-and-time; description "A value indicating when this voucher expires. The node is optional as not all pledges support expirations, such as pledges lacking a reliable clock. If this field exists, then the pledges MUST ensure that the expires-on time has not yet passed. A pledge without an accurate clock cannot meet this requirement. The expires-on value MUST NOT exceed the expiration date of any of the listed 'pinned-domain-cert' certificates."; } leaf nonce { type binary { length "8..32"; } description "A value that can be used by a pledge in some bootstrapping protocols to enable anti-replay protection. This node is optional because it is not used by all bootstrapping protocols. When present, the pledge MUST compare the provided nonce value with another value that the pledge randomly generated and sent to a bootstrap server in an earlier bootstrapping message. If the value is present, but the values do not match, then the pledge MUST NOT process this voucher."; } // } choice nonceless leaf est-domain { type ietf:uri; description "The est-domain is a URL from which the pledge should continue doing enrollment rather than with the cloud registrar. The pinned-domain-cert contains a trust-anchor which is to be used to authenticate the server found at this URI."; } leaf additional-configuration-url { type ietf:uri; description "The additional-configuration attribute contains a URL to which the pledge can retrieve additional configuration information. The contents of this URL are manufacturer specific. This is intended to do things like configure a VoIP phone to point to the correct hosted PBX, for example."; } } // Top-level statement sx:structure voucher { uses voucher-artifact-grouping; } } ]]>

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 XPath expression for the YANG data node to which the SID value is assigned. In the XPath, the ellipsis (...) notation is used to abbreviate the structure path '/ietf-voucher:voucher' to let each entry fit on one line. 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 accomodates the above, since the Voucher is just a map (or dictionary). Map keys are just strings, and creating unique strings is easy to do by including the manufacturer's 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 this name MUST be allocated by IANA. 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); both are always defined in the entries of 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 Private Extensions A manufacturer might need to communicate content in the Voucher (or in the Voucher Request), which are never subject to standardization. While they can use the Voucher extensions mechanism defined in , 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-private' Attribute to put any content they wish. In CBOR serialization, if a plain CBOR map would be used, it would be subject to delta encoding: so use of this Attribute requires that the contents are bstr-encoded (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 .

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 .

"ietf-voucher-request" Module The 'ietf-voucher-request' YANG module is derived from the 'ietf-voucher' module. WG List: Author: Kent Watsen Author: Michael Richardson Author: Max Pritikin 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 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. revision 2023-01-10 { description "Updates and additions described by RFC XXXX"; reference "RFC XXXX: A Voucher Artifact for Bootstrapping Protocols"; } revision 2021-05-20 { description "Initial version"; reference "RFC 8995: Bootstrapping Remote Secure Key Infrastructure (BRSKI)"; } grouping voucher-request-grouping { description "Grouping to allow reuse/extensions in future work."; uses vch:voucher-artifact-grouping { refine "last-renewal-date" { description "A last-renewal-date field is not valid in a voucher request, and any occurrence MUST be ignored"; } refine "domain-cert-revocation-checks" { description "The domain-cert-revocation-checks field is not valid 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."; } } 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 information for the purposes of policy decisions. The MASA SHOULD remove all prior-signed-voucher-request information when signing a voucher for imprinting so as to minimize the final voucher size."; } leaf proximity-registrar-cert { type binary; description "An X.509 v3 certificate structure as specified by RFC 5280, Section 4 encoded using the ASN.1 distinguished encoding rules (DER), as specified in [ITU.X690.1994]. The first certificate in the Registrar TLS server certificate_list sequence (the end-entity TLS certificate, see [RFC8446]) presented by the Registrar to the Pledge. This MUST be populated in a Pledge's voucher request when a proximity assertion is requested."; } leaf proximity-registrar-pubk { type binary; description "The proximity-registrar-pubk replaces the proximity-registrar-cert in constrained uses of the voucher-request. The proximity-registrar-pubk is the Raw Public Key of the Registrar. This field is encoded as specified in RFC7250, section 3. The ECDSA algorithm MUST be supported. The EdDSA algorithm as specified in draft-ietf-tls-rfc4492bis-17 SHOULD be supported. Support for the DSA algorithm is not recommended. Support for the RSA algorithm is a MAY, but due to size is discouraged."; } leaf proximity-registrar-pubk-sha256 { type binary; description "The proximity-registrar-pubk-sha256 is an alternative to both proximity-registrar-pubk and pinned-domain-cert. In many cases the public key of the domain has already been transmitted during the key agreement protocol, and it is wasteful to transmit the public key another two times. The use of a hash of public key info, at 32-bytes for sha256 is a significant savings compared to an RSA public key, but is only a minor savings compared to a 256-bit ECDSA public-key. Algorithm agility is provided by extensions to this specification which may define a new leaf for another hash type."; } leaf agent-signed-data { type binary; description "The agent-signed-data field contains a data artifact provided by the Registrar-Agent to the Pledge for inclusion into the voucher request. This artifact is signed by the Registrar-Agent and contains data, which can be verified by the pledge and the registrar. This data contains the pledge's serial-number and a created-on information of the agent-signed-data. The format is intentionally defined as binary to allow the document using this leaf to determine the encoding."; } leaf agent-provided-proximity-registrar-cert { type binary; description "An X.509 v3 certificate structure, as specified by RFC 5280, Section 4, encoded using the ASN.1 distinguished encoding rules (DER), as specified in ITU X.690. The first certificate in the registrar TLS server certificate_list sequence (the end-entity TLS certificate; see RFC 8446) presented by the registrar to the registrar-agent and provided to the pledge. This MUST be populated in a pledge's voucher-request when an agent-proximity assertion is requested."; reference "ITU X.690: Information Technology - ASN.1 encoding rules: Specification of Basic Encoding Rules (BER), Canonical Encoding Rules (CER) and Distinguished Encoding Rules (DER) RFC 5280: Internet X.509 Public Key Infrastructure Certificate and Certificate Revocation List (CRL) Profile RFC 8446: The Transport Layer Security (TLS) Protocol Version 1.3"; } leaf agent-sign-cert { type binary; description "An X.509 v3 certificate structure, as specified by RFC 5280, Section 4, encoded using the ASN.1 distinguished encoding rules (DER), as specified in ITU X.690. This certificate can be used by the pledge, the registrar, and the MASA to verify the signature of agent-signed-data. It is an optional component for the pledge-voucher request. This MUST be populated in a registrar's voucher-request when an agent-proximity assertion is requested."; reference "ITU X.690: Information Technology - ASN.1 encoding rules: Specification of Basic Encoding Rules (BER), Canonical Encoding Rules (CER) and Distinguished Encoding Rules (DER) RFC 5280: Internet X.509 Public Key Infrastructure Certificate and Certificate Revocation List (CRL) Profile"; } } // Top-level statement: called "voucher" to match RFC8995 sx:structure voucher { uses voucher-request-grouping; } } ]]>

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 XPath expression for the YANG data node to which the SID value is assigned. In the XPath, the ellipsis (...) notation is used to abbreviate the structure path '/ietf-voucher-request:voucher' to let each entry fit on one line. 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 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?"), reissuing the Voucher should be a lightweight process, as it ostensibly only updates the Voucher's validity period. With this approach, there is only the one Artifact, and only one code path is needed to process it; there is no possibility of a Pledge choosing to skip the revocation status check because, for instance, the OCSP Responder () is not reachable. While this document recommends issuing short-lived Vouchers, the Voucher Artifact does not restrict the ability to create long-lived 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.

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.

Security Considerations

Clock Sensitivity An attacker could use an expired Voucher to gain control over a device that has no understanding of time. The device cannot trust NTP as a time reference, as an attacker could control the NTP stream. There are three things to defend against this: 1) devices are required to verify that the 'expires-on' Attribute has not yet passed, 2) devices without access to time can use nonces to get ephemeral Vouchers, and 3) Vouchers without expiration times may be used, which will appear in the audit log, informing the security decision. This document defines a Voucher format that contains time values for expirations, which require an accurate clock in order to be processed correctly. Vendors planning on issuing Vouchers with expiration values must ensure that devices have an accurate clock when shipped from manufacturing facilities and take steps to prevent clock tampering. If it is not possible to ensure clock accuracy, then Vouchers with time values for expirations should not be issued.

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

Test Domain Certificate Validity When Signing If a Domain certificate is compromised, then any outstanding Vouchers for that Domain could be used by the attacker. In this case, the Domain administrator is clearly expected to initiate revocation of any Domain identity certificates (as is normal in PKIX solutions). Similarly, they are expected to contact the MASA to indicate that an outstanding (presumably short lifetime) Voucher should be blocked from automated renewal. Protocols for Voucher distribution are RECOMMENDED to check for revocation of Domain identity certificates before the signing of Vouchers.

YANG Module Security Considerations The YANG modules specified in this document define the schema for data that is subsequently encapsulated by secure signed-data structure, such as the CMS signed-data described in . As such, all of the YANG modeled data is protected from modification. Implementations should be aware that the signed data is only protected from external modification; the data is still visible. This potential disclosure of information doesn't affect security so much as privacy. In particular, adversaries can glean information such as which devices belong to which organizations and which CRL Distribution Point and/or OCSP Responder URLs are accessed to validate the Vouchers. When privacy is important, the CMS signed-data content type SHOULD be encrypted, either by conveying it via a mutually authenticated secure transport protocol (e.g., TLS ) or by encapsulating the signed-data content type with an enveloped-data content type (Section 6 of ), though details for how to do this are outside the scope of this document. The use of YANG to define data structures, via the "yang-data" statement, is relatively new and distinct from the traditional use of YANG to define an API accessed by network management protocols such as NETCONF and RESTCONF . For this reason, these guidelines do not follow the template described by Section 3.7 of .

IANA Considerations

The IETF XML Registry This document registers two URIs in the "IETF XML Registry" . IANA has registered the following:

• URI:

  urn:ietf:params:xml:ns:yang:ietf-voucher

  Registrant Contact:

  The ANIMA WG of the IETF.

  XML:

  N/A, the requested URI is an XML namespace.

This reference should be updated to point to this document.

The YANG Module Names Registry This document registers two YANG module in the "YANG Module Names" registry . IANA has registered the following:

• name:

  ietf-voucher

  namespace:

  urn:ietf:params:xml:ns:yang:ietf-voucher

  prefix:

  vch

  reference:

  RFC 8366

This reference should be updated to point to this document.

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

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

The Voucher Extensions Registry IANA is asked to create a registry of Voucher extensions as follows:

• Registry name:

  Voucher Extensions Registry

  Registry policy:

  First Come First Served

  Reference:

  an optional document

  Extension name:

  UTF-8-encoded string, not to exceed 40 characters.

  Extension SID:

  the YANG module SID value that defines the extension per .

Each extension MUST follow the rules specified in this specification. As is usual, the IANA issues early allocations in accordance with . Note that the SID module value is allocated as part of a process. This may be from a SID range managed by IANA, or from any other MegaRange. Future work may allow for PEN based allocations. IANA does not need to separately allocate a SID value for this column. Extension name strings for standards track documents are single words, given by the YANG Module Name. They do not contain dots. For vendor proprietary extensions, the string SHOULD be made unique by putting the extension name in the form a fully-qualified domain name (FQDN) , such as "fuubar.example.com" Vendor proprietary extensions do not need to be registered with IANA, but vendors MAY do so. Designated Experts should review for standards track documents for clarity, but the process is essentially tied to WG and IESG process: There are no choices in the extension names (which is always the YANG module name), or SID value (which is from another IANA process). For non-standards track extensions, the Designated Expert should review whatever document is provided, if any. The stability of the reference may be of concern. The Designated Expert should determine if the work overlaps with existing efforts; and if so suggest merging. However, as registration is optional, the Designated Expert should not block any registrations.

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] 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. Enrollment over Secure Transport (EST) is used as a certificate provisioning protocol over HTTPS. Low-resource devices often use the lightweight Constrained Application Protocol (CoAP) for message exchanges. This document defines how to transport EST payloads over secure CoAP (EST-coaps), which allows constrained devices to use existing EST functionality for provisioning certificates. 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 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 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 Standard 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. 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. This memo describes the process for early allocation of code points by IANA from registries for which "Specification Required", "RFC Required", "IETF Review", or "Standards Action" policies apply. This process can be used to alleviate the problem where code point allocation is needed to facilitate desired or required implementation and deployment experience prior to publication of an RFC, which would normally trigger code point allocation. The procedures in this document are intended to apply only to IETF Stream documents. 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 1.2 of the Transport Layer Security (TLS) protocol. The TLS protocol provides communications security over the Internet. The protocol allows client/server applications to communicate in a way that is designed to prevent eavesdropping, tampering, or message forgery. [STANDARDS-TRACK] 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 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. 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. Sandelman Software Works This document describes a Zero-touch Secure Join (ZSJ) mechanism to enroll a new device (the "pledge") into a IEEE802.15.4 TSCH network using the 6tisch signaling mechanisms. The resulting device will obtain a domain specific credential that can be used with either 802.15.9 per-host pair keying protocols, or to obtain the network- wide key from a coordinator. The mechanism describe here is an augmentation to the one-touch mechanism described in [I-D.ietf-6tisch-minimal-security], and is a profile of the constrained voucher mechanism [I-D.ietf-anima-constrained-voucher]. This memo provides guidelines for authors and reviewers of specifications containing 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 6087. Wikipedia Open Connectivity Foundation 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. 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. Data centers are attached to the Internet or a backbone network by gateway routers. One data center typically has more than one gateway for commercial, load-balancing, and resiliency reasons. Other sites, such as access networks, also need to be connected across backbone networks through gateways. This document defines a mechanism using the BGP Tunnel Encapsulation attribute to allow data center gateway routers to advertise routes to the prefixes reachable in the site, including advertising them on behalf of other gateways at the same site. This allows segment routing to be used to identify multiple paths across the Internet or backbone network between different gateways. The paths can be selected for load-balancing, resilience, and quality purposes. 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 defines the semantics of HTTP/1.1 messages, as expressed by request methods, request header fields, response status codes, and response header fields, along with the payload of messages (metadata and body content) and mechanisms for content negotiation. 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] Many Internet applications have been designed to deduce top-level domains (or other domain name labels) from partial information. The introduction of new top-level domains, especially non-country-code ones, has exposed flaws in some of the methods used by these applications. These flaws make it more difficult, or impossible, for users of the applications to access the full Internet. This memo discusses some of the techniques that have been used and gives some guidance for minimizing their negative impact as the domain name environment evolves. This document draws summaries of the applicable rules together in one place and supplies references to the actual standards. This memo provides information for the Internet community.

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 MASA certificate 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

Acknowledgements The authors would like to thank the following people for lively discussions on list and in the halls (ordered by last name): , , , , , .