draft-ietf-anima-voucher-07.txt   rfc8366.txt 
ANIMA Working Group K. Watsen Internet Engineering Task Force (IETF) K. Watsen
Internet-Draft Juniper Networks Request for Comments: 8366 Juniper Networks
Intended status: Standards Track M. Richardson Category: Standards Track M. Richardson
Expires: July 28, 2018 Sandelman Software ISSN: 2070-1721 Sandelman Software
M. Pritikin M. Pritikin
Cisco Systems Cisco Systems
T. Eckert T. Eckert
Huawei Huawei
January 24, 2018 May 2018
Voucher Profile for Bootstrapping Protocols A Voucher Artifact for Bootstrapping Protocols
draft-ietf-anima-voucher-07
Abstract Abstract
This document defines a strategy to securely assign a pledge to an This document defines a strategy to securely assign a pledge to an
owner, using an artifact signed, directly or indirectly, by the owner using an artifact signed, directly or indirectly, by the
pledge's manufacturer. This artifact is known as a "voucher". pledge's manufacturer. This artifact is known as a "voucher".
This document defines an artifact format as a YANG-defined JSON This document defines an artifact format as a YANG-defined JSON
document that has been signed using a CMS structure. Other YANG- document that has been signed using a Cryptographic Message Syntax
derived formats are possible. The voucher artifact is normally (CMS) structure. Other YANG-derived formats are possible. The
generated by the pledge's manufacturer (i.e. the Manufacturer voucher artifact is normally generated by the pledge's manufacturer
Authorized Signing Authority). (i.e., the Manufacturer Authorized Signing Authority (MASA)).
This document only defines the voucher artifact, leaving it to other This document only defines the voucher artifact, leaving it to other
documents to describe specialized protocols for accessing it. documents to describe specialized protocols for accessing it.
Status of This Memo Status of This Memo
This Internet-Draft is submitted in full conformance with the This is an Internet Standards Track document.
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
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Drafts is at https://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months This document is a product of the Internet Engineering Task Force
and may be updated, replaced, or obsoleted by other documents at any (IETF). It represents the consensus of the IETF community. It has
time. It is inappropriate to use Internet-Drafts as reference received public review and has been approved for publication by the
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Internet Standards is available in Section 2 of RFC 7841.
This Internet-Draft will expire on July 28, 2018. Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at
https://www.rfc-editor.org/info/rfc8366.
Copyright Notice Copyright Notice
Copyright (c) 2018 IETF Trust and the persons identified as the Copyright (c) 2018 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
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described in the Simplified BSD License. described in the Simplified BSD License.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Requirements Language . . . . . . . . . . . . . . . . . . . . 4 3. Requirements Language . . . . . . . . . . . . . . . . . . . . 5
4. Survey of Voucher Types . . . . . . . . . . . . . . . . . . . 5 4. Survey of Voucher Types . . . . . . . . . . . . . . . . . . . 5
5. Voucher artifact . . . . . . . . . . . . . . . . . . . . . . 7 5. Voucher Artifact . . . . . . . . . . . . . . . . . . . . . . 7
5.1. Tree Diagram . . . . . . . . . . . . . . . . . . . . . . 7 5.1. Tree Diagram . . . . . . . . . . . . . . . . . . . . . . 8
5.2. Examples . . . . . . . . . . . . . . . . . . . . . . . . 8 5.2. Examples . . . . . . . . . . . . . . . . . . . . . . . . 8
5.3. YANG Module . . . . . . . . . . . . . . . . . . . . . . . 9 5.3. YANG Module . . . . . . . . . . . . . . . . . . . . . . . 9
5.4. CMS format voucher artifact . . . . . . . . . . . . . . . 14 5.4. CMS Format Voucher Artifact . . . . . . . . . . . . . . . 15
6. Design Considerations . . . . . . . . . . . . . . . . . . . . 15 6. Design Considerations . . . . . . . . . . . . . . . . . . . . 16
6.1. Renewals instead of Revocations . . . . . . . . . . . . . 15 6.1. Renewals Instead of Revocations . . . . . . . . . . . . . 16
6.2. Voucher Per Pledge . . . . . . . . . . . . . . . . . . . 16 6.2. Voucher Per Pledge . . . . . . . . . . . . . . . . . . . 17
7. Security Considerations . . . . . . . . . . . . . . . . . . . 16 7. Security Considerations . . . . . . . . . . . . . . . . . . . 17
7.1. Clock Sensitivity . . . . . . . . . . . . . . . . . . . . 16 7.1. Clock Sensitivity . . . . . . . . . . . . . . . . . . . . 17
7.2. Protect Voucher PKI in HSM . . . . . . . . . . . . . . . 17 7.2. Protect Voucher PKI in HSM . . . . . . . . . . . . . . . 17
7.3. Test Domain Certificate Validity when Signing . . . . . . 17 7.3. Test Domain Certificate Validity When Signing . . . . . . 17
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 17 7.4. YANG Module Security Considerations . . . . . . . . . . . 18
8.1. The IETF XML Registry . . . . . . . . . . . . . . . . . . 17 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 18
8.2. The YANG Module Names Registry . . . . . . . . . . . . . 18 8.1. The IETF XML Registry . . . . . . . . . . . . . . . . . . 18
8.3. The IETF MIME Registry . . . . . . . . . . . . . . . . . 18 8.2. The YANG Module Names Registry . . . . . . . . . . . . . 19
8.4. The SMI Security for S/MIME CMS Content Type Registry . 19 8.3. The Media Types Registry . . . . . . . . . . . . . . . . 19
9. References . . . . . . . . . . . . . . . . . . . . . . . . . 19 8.4. The SMI Security for S/MIME CMS Content Type Registry . . 20
9.1. Normative References . . . . . . . . . . . . . . . . . . 19 9. References . . . . . . . . . . . . . . . . . . . . . . . . . 20
9.2. Informative References . . . . . . . . . . . . . . . . . 20 9.1. Normative References . . . . . . . . . . . . . . . . . . 20
Appendix A. Acknowledgements . . . . . . . . . . . . . . . . . . 22 9.2. Informative References . . . . . . . . . . . . . . . . . 21
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 22 Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . 23
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 23
1. Introduction 1. Introduction
This document defines a strategy to securely assign a candidate This document defines a strategy to securely assign a candidate
device (pledge) to an owner, using an artifact signed, directly or device (pledge) to an owner using an artifact signed, directly or
indirectly, by the pledge's manufacturer, i.e. the Manufacturer indirectly, by the pledge's manufacturer, i.e., the Manufacturer
Authorized Signing Authority (MASA). This artifact is known as the Authorized Signing Authority (MASA). This artifact is known as the
voucher. "voucher".
The voucher artifact is a JSON [RFC7159] document, conforming to a The voucher artifact is a JSON [RFC8259] document that conforms with
data model described by YANG [RFC7950], encoded using the rules a data model described by YANG [RFC7950], is encoded using the rules
defined in [RFC7159], and signed using (by default) a CMS structure defined in [RFC8259], and is signed using (by default) a CMS
[RFC5652]. structure [RFC5652].
A voucher's primary purpose is to securely convey to a pledge a The primary purpose of a voucher is to securely convey a certificate,
certificate, the "pinned-domain-cert", that the pledge can then use the "pinned-domain-cert", that a pledge can use to authenticate
to authenticate subsequent interactions. A voucher may be useful in subsequent interactions. A voucher may be useful in several
several contexts but the driving motivation herein is to support contexts, but the driving motivation herein is to support secure
secure bootstrapping mechanisms. Assigning ownership is important to bootstrapping mechanisms. Assigning ownership is important to
bootstrapping mechanisms so that the pledge can authenticate the bootstrapping mechanisms so that the pledge can authenticate the
network that is trying to take control of it. network that is trying to take control of it.
The lifetimes of vouchers may vary. In some bootstrapping protocols The lifetimes of vouchers may vary. In some bootstrapping protocols,
the vouchers may include a nonce restricting them to a single use, the vouchers may include a nonce restricting them to a single use,
whereas in others the vouchers may have an indicated lifetime. In whereas the vouchers in other bootstrapping protocols may have an
order to support long lifetimes this document recommends using short indicated lifetime. In order to support long lifetimes, this
lifetimes with programmatic renewal, see Section 6.1. document recommends using short lifetimes with programmatic renewal,
see Section 6.1.
This document only defines the voucher artifact, leaving it to other This document only defines the voucher artifact, leaving it to other
documents to describe specialized protocols for accessing it. Some documents to describe specialized protocols for accessing it. Some
bootstrapping protocols using the voucher artifact defined in this bootstrapping protocols using the voucher artifact defined in this
draft include: [I-D.ietf-netconf-zerotouch], document include: [ZERO-TOUCH], [SECUREJOIN], and [KEYINFRA]).
[I-D.ietf-6tisch-dtsecurity-secure-join], and
[I-D.ietf-anima-bootstrapping-keyinfra]).
2. Terminology 2. Terminology
This document uses the following terms (sorted by name): This document uses the following terms:
Artifact: The term "artifact" is used throughout to represent the Artifact: Used throughout to represent the voucher as instantiated
voucher as instantiated in the form of a signed structure. in the form of a signed structure.
Domain: The set of entities or infrastructure under common
administrative control. The goal of the bootstrapping protocol is
to enable a pledge to discover and join a domain.
Imprint: The process where a device obtains the cryptographic key Imprint: The process where a device obtains the cryptographic key
material to identify and trust future interactions with a network. material to identify and trust future interactions with a network.
This term is taken from Konrad Lorenz's work in biology with new This term is taken from Konrad Lorenz's work in biology with new
ducklings: "during a critical period, the duckling would assume ducklings: "during a critical period, the duckling would assume
that anything that looks like a mother duck is in fact their that anything that looks like a mother duck is in fact their
mother." An equivalent for a device is to obtain the fingerprint mother" [Stajano99theresurrecting]. An equivalent for a device is
of the network's root certification authority certificate. A to obtain the fingerprint of the network's root certification
device that imprints on an attacker suffers a similar fate to a authority certificate. A device that imprints on an attacker
duckling that imprints on a hungry wolf. Imprinting is a term suffers a similar fate to a duckling that imprints on a hungry
from psychology and ethnology, as describe in [imprinting]. The wolf. Imprinting is a term from psychology and ethology, as
analogy to Lorenz's work was first noted in described in [imprinting].
[Stajano99theresurrecting].
Domain: The set of entities or infrastructure under common
administrative control. The goal of the bootstrapping protocol is
to enable a Pledge to discover and join a domain.
Join Registrar (and Coordinator): A representative of the domain Join Registrar (and Coordinator): A representative of the domain
that is configured, perhaps autonomically, to decide whether a new that is configured, perhaps autonomically, to decide whether a new
device is allowed to join the domain. The administrator of the device is allowed to join the domain. The administrator of the
domain interfaces with a Join Registrar (and Coordinator) to domain interfaces with a join registrar (and Coordinator) to
control this process. Typically a Join Registrar is "inside" its control this process. Typically, a join registrar is "inside" its
domain. For simplicity this document often refers to this as just domain. For simplicity, this document often refers to this as
"Registrar". just "registrar".
MASA: The Manufacturer Authorized Signing Authority (MASA) is the MASA (Manufacturer Authorized Signing Authority): The entity that,
entity that, for the purpose of this document, signs the vouchers for the purpose of this document, signs the vouchers for a
for a manufacturer's pledges. In some bootstrapping protocols, manufacturer's pledges. In some bootstrapping protocols, the MASA
the MASA may have Internet presence and be integral to the may have an Internet presence and be integral to the bootstrapping
bootstrapping process, whereas in other protocols the MASA may be process, whereas in other protocols the MASA may be an offline
an offline service that has no active role in the bootstrapping service that has no active role in the bootstrapping process.
process.
Owner: The entity that controls the private key of the "pinned- Owner: The entity that controls the private key of the "pinned-
domain-cert" certificate conveyed by the voucher. domain-cert" certificate conveyed by the voucher.
Pledge: The prospective device attempting to find and securely join Pledge: The prospective device attempting to find and securely join
a domain. When shipped it only trusts authorized representatives a domain. When shipped, it only trusts authorized representatives
of the manufacturer. of the manufacturer.
Registrar See Join Registrar Registrar: See join registrar.
TOFU: Trust on First Use. This is where a Pledge device makes no TOFU (Trust on First Use): Where a pledge device makes no security
security decisions but rather simply trusts the first domain decisions but rather simply trusts the first domain entity it is
entity it is contacted by. Used similarly to [RFC7435]. This is contacted by. Used similarly to [RFC7435]. This is also known as
also known as the "resurrecting duckling" model. the "resurrecting duckling" model.
Voucher: A signed statement from the MASA service that indicates to Voucher: A signed statement from the MASA service that indicates to
a Pledge the cryptographic identity of the domain it should trust. a pledge the cryptographic identity of the domain it should trust.
3. Requirements Language 3. Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in BCP "OPTIONAL" in this document are to be interpreted as described in BCP
14 [RFC2119] [RFC8174] when, and only when, they appear in all 14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here. capitals, as shown here.
4. Survey of Voucher Types 4. Survey of Voucher Types
A voucher is a cryptographically protected statement to the Pledge A voucher is a cryptographically protected statement to the pledge
device authorizing a zero-touch "imprint" on the Join Registrar of device authorizing a zero-touch "imprint" on the join registrar of
the domain. The specific information a voucher provides is the domain. The specific information a voucher provides is
influenced by the bootstrapping use case. influenced by the bootstrapping use case.
The voucher can impart the following information to the Join The voucher can impart the following information to the join
Registrar and Pledge: registrar and pledge:
Assertion Basis: Indicates the method that protects the imprint Assertion Basis: Indicates the method that protects the imprint
(this is distinct from the voucher signature that protects the (this is distinct from the voucher signature that protects the
voucher itself). This might include manufacturer asserted voucher itself). This might include manufacturer-asserted
ownership verification, assured logging operations or reliance on ownership verification, assured logging operations, or reliance on
Pledge endpoint behavior such as secure root of trust of pledge endpoint behavior such as secure root of trust of
measurement. The Join Registrar might use this information. Only measurement. The join registrar might use this information. Only
some methods are normatively defined in this document. Other some methods are normatively defined in this document. Other
methods are left for future work. methods are left for future work.
Authentication of Join Registrar: Indicates how the Pledge can Authentication of Join Registrar: Indicates how the pledge can
authenticate the Join Registrar. This document defines a authenticate the join registrar. This document defines a
mechanism to pin the domain certificate. Pinning a symmetric key, mechanism to pin the domain certificate. Pinning a symmetric key,
a raw key, or [RFC6125] style "CN-ID" or "DNS- a raw key, or "CN-ID" or "DNS-ID" information (as defined in
ID" information is left for future work. [RFC6125]) is left for future work.
Anti-Replay Protections: Time or nonce based information to Anti-Replay Protections: Time- or nonce-based information to
constrain the voucher to time periods or bootstrap attempts. constrain the voucher to time periods or bootstrap attempts.
A number of bootstrapping scenarios can be met using differing A number of bootstrapping scenarios can be met using differing
combinations of this information. All scenarios address the primary combinations of this information. All scenarios address the primary
threat of a Man-in-The-Middle (MiTM) Registrar gaining control over threat of a Man-in-The-Middle (MiTM) registrar gaining control over
the Pledge device. The following combinations are "types" of the pledge device. The following combinations are "types" of
vouchers: vouchers:
|Assertion |Registrar ID | Validity | |Assertion |Registrar ID | Validity |
Voucher |Log-|Veri- |Trust |CN-ID or| RTC | Nonce | Voucher |Log-|Veri- |Trust |CN-ID or| RTC | Nonce |
Type | ged| fied |Anchor |DNS-ID | | | Type | ged| fied |Anchor |DNS-ID | | |
---------------------------------------------------------| ---------------------------------------------------------|
Audit | X | | X | | | X | Audit | X | | X | | | X |
-------------|----|-------|-------|--------|-----|-------| -------------|----|-------|-------|--------|-----|-------|
Nonceless | X | | X | | X | | Nonceless | X | | X | | X | |
Audit | | | | | | | Audit | | | | | | |
-------------|----|-------|-------|--------|-----|-------| -------------|----|-------|-------|--------|-----|-------|
Owner Audit | X | X | X | | X | X | Owner Audit | X | X | X | | X | X |
-------------|----|-------|-------|--------|-----|-------| -------------|----|-------|-------|--------|-----|-------|
Owner ID | | X | X | X | X | | Owner ID | | X | X | X | X | |
-------------|----|-------|----------------|-----|-------| -------------|----|-------|----------------|-----|-------|
Bearer | X | | wildcard | optional | Bearer | X | | wildcard | optional |
out-of-scope | | | | | out-of-scope | | | | |
-------------|----|-------|----------------|-------------| -------------|----|-------|----------------|-------------|
NOTE: All voucher types include a 'Pledge ID serial number' NOTE: All voucher types include a 'pledge ID serial-number'
(Not shown for space reasons) (not shown here for space reasons).
Audit Voucher: An Audit Voucher is named after the logging assertion Audit Voucher: An Audit Voucher is named after the logging assertion
mechanisms that the Registrar then "audits" to enforce local mechanisms that the registrar then "audits" to enforce local
policy. The Registrar mitigates a MiTM Registrar by auditing that policy. The registrar mitigates a MiTM registrar by auditing that
an unknown MiTM registrar does not appear in the log entries. an unknown MiTM registrar does not appear in the log entries.
This does not directly prevent the MiTM but provides a response This does not directly prevent the MiTM but provides a response
mechanism that ensures the MiTM is unsuccessful. This advantage mechanism that ensures the MiTM is unsuccessful. The advantage is
is that actual ownership knowledge is not required on the MASA that actual ownership knowledge is not required on the MASA
service. service.
Nonceless Audit Voucher: An Audit Voucher without a validity period Nonceless Audit Voucher: An Audit Voucher without a validity period
statement. Fundamentally the same as an Audit Voucher except that statement. Fundamentally, it is the same as an Audit Voucher
it can be issued in advance to support network partitions or to except that it can be issued in advance to support network
provide a permanent voucher for remote deployments. partitions or to provide a permanent voucher for remote
deployments.
Ownership Audit Voucher: An Audit Voucher where the MASA service has Ownership Audit Voucher: An Audit Voucher where the MASA service has
verified the Registrar as the authorized owner. The MASA service verified the registrar as the authorized owner. The MASA service
mitigates a MiTM Registrar by refusing to generate Audit Vouchers mitigates a MiTM registrar by refusing to generate Audit Vouchers
for unauthorized Registrars. The Registrar uses audit techniques for unauthorized registrars. The registrar uses audit techniques
to supplement the MASA. This provides a ideal sharing of policy to supplement the MASA. This provides an ideal sharing of policy
decisions and enforcement between the vendor and the owner. decisions and enforcement between the vendor and the owner.
Ownership ID Voucher: An Ownership ID Voucher is named after Ownership ID Voucher: Named after inclusion of the pledge's CN-ID or
inclusion of the Pledge's CN-ID or DNS-ID within the voucher. The DNS-ID within the voucher. The MASA service mitigates a MiTM
MASA service mitigates a MiTM Registrar by identifying the registrar by identifying the specific registrar (via WebPKI)
specific Registrar (via WebPKI) authorized to own the Pledge. authorized to own the pledge.
Bearer Voucher: A Bearer Voucher is named after the inclusion of a Bearer Voucher: A Bearer Voucher is named after the inclusion of a
Registrar ID wildcard. Because the Registrar identity is not registrar ID wildcard. Because the registrar identity is not
indicated this voucher type must be treated as a secret and indicated, this voucher type must be treated as a secret and
protected from exposure as any 'bearer' of the voucher can claim protected from exposure as any 'bearer' of the voucher can claim
the Pledge device. Publishing a nonceless bearer voucher the pledge device. Publishing a nonceless bearer voucher
effectively turns the specified Pledge into a "TOFU" device with effectively turns the specified pledge into a "TOFU" device with
minimal mitigation against MiTM Registrars. Bearer vouchers are minimal mitigation against MiTM registrars. Bearer vouchers are
out-of-scope. out of scope.
5. Voucher artifact 5. Voucher Artifact
The voucher's primary purpose is to securely assign a pledge to an The voucher's primary purpose is to securely assign a pledge to an
owner. The voucher informs the pledge which entity it should owner. The voucher informs the pledge which entity it should
consider to be its owner. consider to be its owner.
This document defines a voucher that is a JSON encoded instance of This document defines a voucher that is a JSON-encoded instance of
the YANG module defined in Section 5.3 that has been, by default, the YANG module defined in Section 5.3 that has been, by default, CMS
CMS-signed. signed.
This format is described here as a practical basis for some uses This format is described here as a practical basis for some uses
(such as in NETCONF), but more to make it clear what vouchers look (such as in NETCONF), but more to clearly indicate what vouchers look
like in practice. This description also serves to validate the YANG like in practice. This description also serves to validate the YANG
model. data model.
Future work is expected to define new mappings of the voucher to CBOR Future work is expected to define new mappings of the voucher to
(from JSON), and to change the signature container from CMS to JOSE Concise Binary Object Representation (CBOR) (from JSON) and to change
or COSE. XML or ASN.1 formats are also conceivable. the signature container from CMS to JSON Object Signing and
Encryption (JOSE) or CBOR Object Signing and Encryption (COSE). XML
or ASN.1 formats are also conceivable.
This document defines a MIME type and a filename extension for the This document defines a media type and a filename extension for the
CMS encoded JSON type. Future documents on additional formats would CMS-encoded JSON type. Future documents on additional formats would
define additional MIME types. Signaling is in the form of a MIME define additional media types. Signaling is in the form of a MIME
Content-Type, an HTTP Accept: header, or more mundane methods like Content-Type, an HTTP Accept: header, or more mundane methods like
use of a filename extension when a voucher is transfered on a USB use of a filename extension when a voucher is transferred on a USB
key. key.
5.1. Tree Diagram 5.1. Tree Diagram
The following tree diagram illustrates a high-level view of a voucher The following tree diagram illustrates a high-level view of a voucher
document. The notation used in this diagram is described in document. The notation used in this diagram is described in
[I-D.ietf-netmod-yang-tree-diagrams]). Each node in the diagram is [RFC8340]. Each node in the diagram is fully described by the YANG
fully described by the YANG module in Section 5.3. Please review the module in Section 5.3. Please review the YANG module for a detailed
YANG module for a detailed description of the voucher format. description of the voucher format.
module: ietf-voucher module: ietf-voucher
yang-data voucher-artifact: yang-data voucher-artifact:
+---- voucher +---- voucher
+---- created-on yang:date-and-time +---- created-on yang:date-and-time
+---- expires-on? yang:date-and-time +---- expires-on? yang:date-and-time
+---- assertion enumeration +---- assertion enumeration
+---- serial-number string +---- serial-number string
+---- idevid-issuer? binary +---- idevid-issuer? binary
+---- pinned-domain-cert binary +---- pinned-domain-cert binary
+---- domain-cert-revocation-checks? boolean +---- domain-cert-revocation-checks? boolean
+---- nonce? binary +---- nonce? binary
+---- last-renewal-date? yang:date-and-time +---- last-renewal-date? yang:date-and-time
5.2. Examples 5.2. Examples
This section provides voucher examples for illustration purposes. This section provides voucher examples for illustration purposes.
That these examples conform to the encoding rules defined in These examples conform to the encoding rules defined in [RFC8259].
[RFC7159].
The following example illustrates an ephemeral voucher (uses a The following example illustrates an ephemeral voucher (uses a
nonce). The MASA generated this voucher using the 'logged' assertion nonce). The MASA generated this voucher using the 'logged' assertion
type, knowing that it would be suitable for the pledge making the type, knowing that it would be suitable for the pledge making the
request. request.
{ {
"ietf-voucher:voucher": { "ietf-voucher:voucher": {
"created-on": "2016-10-07T19:31:42Z", "created-on": "2016-10-07T19:31:42Z",
"assertion": "logged", "assertion": "logged",
skipping to change at page 8, line 40 skipping to change at page 9, line 4
{ {
"ietf-voucher:voucher": { "ietf-voucher:voucher": {
"created-on": "2016-10-07T19:31:42Z", "created-on": "2016-10-07T19:31:42Z",
"assertion": "logged", "assertion": "logged",
"serial-number": "JADA123456789", "serial-number": "JADA123456789",
"idevid-issuer": "base64encodedvalue==", "idevid-issuer": "base64encodedvalue==",
"pinned-domain-cert": "base64encodedvalue==", "pinned-domain-cert": "base64encodedvalue==",
"nonce": "base64encodedvalue==" "nonce": "base64encodedvalue=="
} }
} }
The following example illustrates a non-ephemeral voucher (no nonce). The following example illustrates a non-ephemeral voucher (no nonce).
While the voucher itself expires after two weeks, it presumably can While the voucher itself expires after two weeks, it presumably can
be renewed for up to a year later. The MASA generated this voucher be renewed for up to a year. The MASA generated this voucher using
using the 'verified' assertion type, which should satisfy all the 'verified' assertion type, which should satisfy all pledges.
pledges.
{ {
"ietf-voucher:voucher": { "ietf-voucher:voucher": {
"created-on": "2016-10-07T19:31:42Z", "created-on": "2016-10-07T19:31:42Z",
"expires-on": "2016-10-21T19:31:42Z", "expires-on": "2016-10-21T19:31:42Z",
"assertion": "verified", "assertion": "verified",
"serial-number": "JADA123456789", "serial-number": "JADA123456789",
"idevid-issuer": "base64encodedvalue==", "idevid-issuer": "base64encodedvalue==",
"pinned-domain-cert": "base64encodedvalue==", "pinned-domain-cert": "base64encodedvalue==",
"domain-cert-revocation-checks": "true", "domain-cert-revocation-checks": "true",
"last-renewal-date": "2017-10-07T19:31:42Z" "last-renewal-date": "2017-10-07T19:31:42Z"
} }
} }
5.3. YANG Module 5.3. YANG Module
Following is a YANG [RFC7950] module formally describing the Following is a YANG [RFC7950] module formally describing the
voucher's JSON document structure. voucher's JSON document structure.
<CODE BEGINS> file "ietf-voucher@2018-01-24.yang" <CODE BEGINS> file "ietf-voucher@2018-05-09.yang"
module ietf-voucher { module ietf-voucher {
yang-version 1.1; yang-version 1.1;
namespace "urn:ietf:params:xml:ns:yang:ietf-voucher";
namespace prefix vch;
"urn:ietf:params:xml:ns:yang:ietf-voucher";
prefix "vch";
import ietf-yang-types { import ietf-yang-types {
prefix yang; prefix yang;
reference "RFC 6991: Common YANG Data Types"; reference "RFC 6991: Common YANG Data Types";
} }
import ietf-restconf { import ietf-restconf {
prefix rc; prefix rc;
description description
"This import statement is only present to access "This import statement is only present to access
the yang-data extension defined in RFC 8040."; the yang-data extension defined in RFC 8040.";
reference "RFC 8040: RESTCONF Protocol"; reference "RFC 8040: RESTCONF Protocol";
} }
organization organization
"IETF ANIMA Working Group"; "IETF ANIMA Working Group";
contact contact
"WG Web: <http://tools.ietf.org/wg/anima/> "WG Web: <https://datatracker.ietf.org/wg/anima/>
WG List: <mailto:anima@ietf.org> WG List: <mailto:anima@ietf.org>
Author: Kent Watsen Author: Kent Watsen
<mailto:kwatsen@juniper.net> <mailto:kwatsen@juniper.net>
Author: Max Pritikin
<mailto:pritikin@cisco.com>
Author: Michael Richardson
<mailto:mcr+ietf@sandelman.ca>
Author: Toerless Eckert
<mailto:tte+ietf@cs.fau.de>";
Author: Max Pritikin
<mailto:pritikin@cisco.com>
Author: Michael Richardson
<mailto:mcr+ietf@sandelman.ca>
Author: Toerless Eckert
<mailto:tte+ietf@cs.fau.de>";
description description
"This module defines the format for a voucher, which is produced by "This module defines the format for a voucher, which is produced by
a pledge's manufacturer or delegate (MASA) to securely assign a a pledge's manufacturer or delegate (MASA) to securely assign a
pledge to an 'owner', so that the pledge may establish a secure pledge to an 'owner', so that the pledge may establish a secure
connection to the owner's network infrastructure. connection to the owner's network infrastructure.
The key words 'MUST', 'MUST NOT', 'REQUIRED', 'SHALL', 'SHALL NOT', The key words 'MUST', 'MUST NOT', 'REQUIRED', 'SHALL', 'SHALL
'SHOULD', 'SHOULD NOT', 'RECOMMENDED', 'MAY', and 'OPTIONAL' in NOT', 'SHOULD', 'SHOULD NOT', 'RECOMMENDED', 'NOT RECOMMENDED',
the module text are to be interpreted as described in RFC 2119. '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.
Copyright (c) 2017 IETF Trust and the persons identified as Copyright (c) 2018 IETF Trust and the persons identified as
authors of the code. All rights reserved. authors of the code. All rights reserved.
Redistribution and use in source and binary forms, with or without Redistribution and use in source and binary forms, with or without
modification, is permitted pursuant to, and subject to the license modification, is permitted pursuant to, and subject to the license
terms contained in, the Simplified BSD License set forth in Section terms contained in, the Simplified BSD License set forth in Section
4.c of the IETF Trust's Legal Provisions Relating to IETF Documents 4.c of the IETF Trust's Legal Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info). (https://trustee.ietf.org/license-info).
This version of this YANG module is part of RFC XXXX; see the RFC This version of this YANG module is part of RFC 8366; see the RFC
itself for full legal notices."; itself for full legal notices.";
revision "2018-01-24" { revision 2018-05-09 {
description description
"Initial version"; "Initial version";
reference reference "RFC 8366: Voucher Profile for Bootstrapping Protocols";
"RFC XXXX: Voucher Profile for Bootstrapping Protocols";
} }
// Top-level statement // Top-level statement
rc:yang-data voucher-artifact { rc:yang-data voucher-artifact {
uses voucher-artifact-grouping; uses voucher-artifact-grouping;
} }
// Grouping defined for future augmentations // Grouping defined for future augmentations
grouping voucher-artifact-grouping { grouping voucher-artifact-grouping {
description description
"Grouping to allow reuse/extensions in future work."; "Grouping to allow reuse/extensions in future work.";
container voucher { container voucher {
description description
"A voucher assigns a pledge to an owner (pinned-domain-cert)."; "A voucher assigns a pledge to an owner (pinned-domain-cert).";
leaf created-on { leaf created-on {
type yang:date-and-time; type yang:date-and-time;
mandatory true; mandatory true;
description description
"A value indicating the date this voucher was created. This "A value indicating the date this voucher was created. This
node is primarily for human consumption and auditing. Future node is primarily for human consumption and auditing. Future
work MAY create verification requirements based on this work MAY create verification requirements based on this
node."; node.";
} }
leaf expires-on { leaf expires-on {
type yang:date-and-time; type yang:date-and-time;
must "not(../nonce)"; must 'not(../nonce)';
description description
"A value indicating when this voucher expires. The node is "A value indicating when this voucher expires. The node is
optional as not all pledges support expirations, such as optional as not all pledges support expirations, such as
pledges lacking a reliable clock. pledges lacking a reliable clock.
If this field exists, then the the pledges MUST ensure that If this field exists, then the pledges MUST ensure that
the expires-on time has not yet passed. A pledge without the expires-on time has not yet passed. A pledge without
an accurate clock cannot meet this requirement. an accurate clock cannot meet this requirement.
The expires-on value MUST NOT exceed the expiration date The expires-on value MUST NOT exceed the expiration date
of any of the listed 'pinned-domain-cert' certificates."; of any of the listed 'pinned-domain-cert' certificates.";
} }
leaf assertion { leaf assertion {
type enumeration { type enumeration {
enum verified { enum verified {
description description
"Indicates that the ownership has been positively "Indicates that the ownership has been positively
verified by the MASA (e.g., through sales channel verified by the MASA (e.g., through sales channel
integration)."; integration).";
} }
enum logged { enum logged {
description description
skipping to change at page 11, line 43 skipping to change at page 11, line 41
type enumeration { type enumeration {
enum verified { enum verified {
description description
"Indicates that the ownership has been positively "Indicates that the ownership has been positively
verified by the MASA (e.g., through sales channel verified by the MASA (e.g., through sales channel
integration)."; integration).";
} }
enum logged { enum logged {
description description
"Indicates that the voucher has been issued after "Indicates that the voucher has been issued after
minimal verification of ownership or control. The minimal verification of ownership or control. The
issuance has been logged for detection of issuance has been logged for detection of
potential security issues (e.g. recipients of potential security issues (e.g., recipients of
vouchers might verify for themselves that unexpected vouchers might verify for themselves that unexpected
vouchers are not in the log). This is similar to unsecured vouchers are not in the log). This is similar to
trust-on-first-use principles but with the logging unsecured trust-on-first-use principles but with the
providing a basis for detecting unexpected events."; logging providing a basis for detecting unexpected
events.";
} }
enum proximity { enum proximity {
description description
"Indicates that the voucher has been issued after "Indicates that the voucher has been issued after
the MASA verified a proximity proof provided by the the MASA verified a proximity proof provided by the
device and target domain. The issuance has been logged device and target domain. The issuance has been logged
for detection of potential security issues. This is for detection of potential security issues. This is
stronger than just logging, because it requires some stronger than just logging, because it requires some
verification that the pledge and owner are verification that the pledge and owner are
in communication, but is still dependent on analysis of in communication but is still dependent on analysis of
the logs to detect unexpected events."; the logs to detect unexpected events.";
} }
} }
mandatory true; mandatory true;
description description
"The assertion is a statement from the MASA regarding how "The assertion is a statement from the MASA regarding how
the owner was verified. This statement enables pledges the owner was verified. This statement enables pledges
to support more detailed policy checks. Pledges MUST to support more detailed policy checks. Pledges MUST
ensure that the assertion provided is acceptable, per ensure that the assertion provided is acceptable, per
local policy, before processing the voucher."; local policy, before processing the voucher.";
} }
leaf serial-number { leaf serial-number {
type string; type string;
mandatory true; mandatory true;
description description
"The serial number of the hardware. When processing a "The serial-number of the hardware. When processing a
voucher, a pledge MUST ensure that its serial number voucher, a pledge MUST ensure that its serial-number
matches this value. If no match occurs, then the matches this value. If no match occurs, then the
pledge MUST NOT process this voucher."; pledge MUST NOT process this voucher.";
} }
leaf idevid-issuer { leaf idevid-issuer {
type binary; type binary;
description description
"The RFC5280 4.2.1.1 Authority Key Identifier OCTET STRING "The Authority Key Identifier OCTET STRING (as defined in
from the pledge's IDevID certificate. Optional since some Section 4.2.1.1 of RFC 5280) from the pledge's IDevID
serial-numbers are already unique within the scope of a certificate. Optional since some serial-numbers are
MASA. Inclusion of the statistically unique key identifier already unique within the scope of a MASA.
Inclusion of the statistically unique key identifier
ensures statistically unique identification of the hardware. ensures statistically unique identification of the hardware.
When processing a voucher, a pledge MUST ensure that its When processing a voucher, a pledge MUST ensure that its
IDevID Authority Key Identifier matches this value. If no IDevID Authority Key Identifier matches this value. If no
match occurs, then the pledge MUST NOT process this voucher. match occurs, then the pledge MUST NOT process this voucher.
When issuing a voucher, the MASA MUST ensure that this field When issuing a voucher, the MASA MUST ensure that this field
is populated for serial numbers that are not otherwise unique is populated for serial-numbers that are not otherwise unique
within the scope of the MASA."; within the scope of the MASA.";
} }
leaf pinned-domain-cert { leaf pinned-domain-cert {
type binary; type binary;
mandatory true; mandatory true;
description description
"An X.509 v3 certificate structure, as specified by RFC 5280, "An X.509 v3 certificate structure, as specified by RFC 5280,
using distinguished encoding rules (DER) encoding, as defined using Distinguished Encoding Rules (DER) encoding, as defined
in ITU-T X.690. in ITU-T X.690.
This certificate is used by a pledge to trust a public key This certificate is used by a pledge to trust a Public Key
infrastructure, in order to verify a domain certificate Infrastructure in order to verify a domain certificate
supplied to the pledge separately by the bootstrapping supplied to the pledge separately by the bootstrapping
protocol. The domain certificate MUST have this certificate protocol. The domain certificate MUST have this certificate
somewhere in its chain of certificates. This certificate somewhere in its chain of certificates. This certificate
MAY be an end-entity certificate, including a self-signed MAY be an end-entity certificate, including a self-signed
entity."; entity.";
reference reference
"RFC 5280: "RFC 5280:
Internet X.509 Public Key Infrastructure Certificate Internet X.509 Public Key Infrastructure Certificate
and Certificate Revocation List (CRL) Profile. and Certificate Revocation List (CRL) Profile.
ITU-T X.690: ITU-T X.690:
skipping to change at page 13, line 27 skipping to change at page 13, line 26
reference reference
"RFC 5280: "RFC 5280:
Internet X.509 Public Key Infrastructure Certificate Internet X.509 Public Key Infrastructure Certificate
and Certificate Revocation List (CRL) Profile. and Certificate Revocation List (CRL) Profile.
ITU-T X.690: ITU-T X.690:
Information technology - ASN.1 encoding rules: Information technology - ASN.1 encoding rules:
Specification of Basic Encoding Rules (BER), Specification of Basic Encoding Rules (BER),
Canonical Encoding Rules (CER) and Distinguished Canonical Encoding Rules (CER) and Distinguished
Encoding Rules (DER)."; Encoding Rules (DER).";
} }
leaf domain-cert-revocation-checks { leaf domain-cert-revocation-checks {
type boolean; type boolean;
must "../expires-on";
description description
"A processing instruction to the pledge that it MUST verify "A processing instruction to the pledge that it MUST (true)
the revocation status for the domain certificate. This or MUST NOT (false) verify the revocation status for the
instruction is only available for vouchers that expire. If pinned domain certificate. If this field is not set, then
this field is not set, then normal PKIX behaviour applies normal PKIX behavior applies to validation of the domain
to validation of the domain certificate."; certificate.";
} }
leaf nonce { leaf nonce {
type binary { type binary {
length "8..32"; length "8..32";
} }
must "not(../expires-on)"; must 'not(../expires-on)';
description description
"A value that can be used by a pledge in some bootstrapping "A value that can be used by a pledge in some bootstrapping
protocols to enable anti-replay protection. This node is protocols to enable anti-replay protection. This node is
optional because it is not used by all bootstrapping optional because it is not used by all bootstrapping
protocols. protocols.
When present, the pledge MUST compare the provided nonce When present, the pledge MUST compare the provided nonce
value with another value that the pledge randomly generated value with another value that the pledge randomly generated
and sent to a bootstrap server in an earlier bootstrapping and sent to a bootstrap server in an earlier bootstrapping
message. If the values do not match, then the pledge MUST message. If the values do not match, then the pledge MUST
skipping to change at page 14, line 8 skipping to change at page 14, line 4
protocols to enable anti-replay protection. This node is protocols to enable anti-replay protection. This node is
optional because it is not used by all bootstrapping optional because it is not used by all bootstrapping
protocols. protocols.
When present, the pledge MUST compare the provided nonce When present, the pledge MUST compare the provided nonce
value with another value that the pledge randomly generated value with another value that the pledge randomly generated
and sent to a bootstrap server in an earlier bootstrapping and sent to a bootstrap server in an earlier bootstrapping
message. If the values do not match, then the pledge MUST message. If the values do not match, then the pledge MUST
NOT process this voucher."; NOT process this voucher.";
} }
leaf last-renewal-date { leaf last-renewal-date {
type yang:date-and-time; type yang:date-and-time;
must "../expires-on"; must '../expires-on';
description description
"The date that the MASA projects to be the last date it "The date that the MASA projects to be the last date it
will renew a voucher on. This field is merely informative, it will renew a voucher on. This field is merely informative;
is not processed by pledges. it is not processed by pledges.
Circumstances may occur after a voucher is generated that Circumstances may occur after a voucher is generated that
may alter a voucher's validity period. For instance, a may alter a voucher's validity period. For instance, a
vendor may associate validity periods with support contracts, vendor may associate validity periods with support contracts,
which may be terminated or extended over time."; which may be terminated or extended over time.";
} }
} // end voucher } // end voucher
} // end voucher-grouping } // end voucher-grouping
} }
<CODE ENDS> <CODE ENDS>
5.4. CMS Format Voucher Artifact
5.4. CMS format voucher artifact The IETF evolution of PKCS#7 is CMS [RFC5652]. A CMS-signed voucher,
The IETF evolution of PKCS#7 is CMS [RFC5652]. A CMS signed voucher,
the default type, contains a ContentInfo structure with the voucher the default type, contains a ContentInfo structure with the voucher
content. An eContentType of TBD1 indicates the content is a JSON- content. An eContentType of 40 indicates that the content is a JSON-
encoded voucher. encoded voucher.
The signing structure is a CMS SignedData structure, as specified by The signing structure is a CMS SignedData structure, as specified by
Section 5.1 of [RFC5652], encoded using ASN.1 distinguished encoding Section 5.1 of [RFC5652], encoded using ASN.1 Distinguished Encoding
rules (DER), as specified in ITU-T X.690 [ITU.X690.1994]. Rules (DER), as specified in ITU-T X.690 [ITU.X690.2015].
To facilitate interoperability, Section 8.3 in this document To facilitate interoperability, Section 8.3 in this document
registers the MIME type "application/voucher-cms+json" and the registers the media type "application/voucher-cms+json" and the
filename extension ".vcj". filename extension ".vcj".
The CMS structure MUST contain a 'signerInfo' structure, as described The CMS structure MUST contain a 'signerInfo' structure, as described
in Section 5.1 of [RFC5652], containing the signature generated over in Section 5.1 of [RFC5652], containing the signature generated over
the content using a private key trusted by the recipient. Normally the content using a private key trusted by the recipient. Normally,
the recipient is the pledge and the signer is the MASA. A possible the recipient is the pledge and the signer is the MASA. Another
other use could be as a "signed voucher request" format originating possible use could be as a "signed voucher request" format
from pledge or registrar toward the MASA. Within this document the originating from the pledge or registrar toward the MASA. Within
signer is assumed to be the MASA. this document, the signer is assumed to be the MASA.
Note that Section 5.1 of [RFC5652] includes a discussion about how to Note that Section 5.1 of [RFC5652] includes a discussion about how to
validate a CMS object which is really a PKCS7 object (cmsVersion=1). validate a CMS object, which is really a PKCS7 object (cmsVersion=1).
Intermediate systems (such the BRSKI Registrar) which might need to Intermediate systems (such the Bootstrapping Remote Secure Key
evaluate the voucher in flight MUST be prepared for such an older Infrastructures (BRSKI) registrar) that might need to evaluate the
format. No signaling is necessary, as the Manufacturer knows the voucher in flight MUST be prepared for such an older format. No
capabilities of the pledge, and will use an appropriate format signaling is necessary, as the manufacturer knows the capabilities of
voucher for each pledge. the pledge and will use an appropriate format voucher for each
pledge.
The CMS structure SHOULD also contain all the certificates leading up The CMS structure SHOULD also contain all of the certificates leading
to and including the signer's trust anchor certificate known to the up to and including the signer's trust anchor certificate known to
recipient. The inclusion of the trust anchor is unusual in many the recipient. The inclusion of the trust anchor is unusual in many
applications, but without it third parties can not accurately audit applications, but third parties cannot accurately audit the
the transaction. transaction without it.
The CMS structure MAY also contain revocation objects for any The CMS structure MAY also contain revocation objects for any
intermediate certificate authorities (CAs) between the voucher-issuer intermediate certificate authorities (CAs) between the voucher issuer
and the trust anchor known to the recipient. However, the use of and the trust anchor known to the recipient. However, the use of
CRLs and other validity mechanisms is discouraged, as the pledge is CRLs and other validity mechanisms is discouraged, as the pledge is
unlikely to be able to perform online checks, and is unlikely to have 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 a trusted clock source. As described below, the use of short-lived
vouchers and/or pledge provided nonce provides a freshness guarantee. vouchers and/or a pledge-provided nonce provides a freshness
guarantee.
6. Design Considerations 6. Design Considerations
6.1. Renewals instead of Revocations 6.1. Renewals Instead of Revocations
The lifetimes of vouchers may vary. In some bootstrapping protocols, The lifetimes of vouchers may vary. In some bootstrapping protocols,
the vouchers may be created and consumed immediately whereas, in the vouchers may be created and consumed immediately, whereas in
other bootstrapping solutions, there may be a significant time delay other bootstrapping solutions, there may be a significant time delay
between when a voucher is created and when it is consumed. In cases 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 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 that the assertions made when the voucher was created are still
valid. valid.
A revocation artifact is generally used to verify the continued A revocation artifact is generally used to verify the continued
validity of an assertion such as a PKIX certificate, web token, or a validity of an assertion such as a PKIX certificate, web token, or a
"voucher". With this approach, a potentially long-lived assertion is "voucher". With this approach, a potentially long-lived assertion is
paired with a reasonably fresh revocation status check to ensure that paired with a reasonably fresh revocation status check to ensure that
the assertion is still valid. However, this approach increases the assertion is still valid. However, this approach increases
solution complexity, as it introduces the need for additional solution complexity, as it introduces the need for additional
protocols and code paths to distribute and process the revocations. protocols and code paths to distribute and process the revocations.
Addressing the short-comings of revocations, this document recommends Addressing the shortcomings of revocations, this document recommends
instead the use of lightweight renewals of short-lived non-revocable instead the use of lightweight renewals of short-lived non-revocable
vouchers. That is, rather than issue a long-lived voucher, where the vouchers. That is, rather than issue a long-lived voucher, where the
'expires-on' leaf is set to some distant date, the expectation is for 'expires-on' leaf is set to some distant date, the expectation is for
the MASA to instead issue a short-lived voucher, where the 'expires- the MASA to instead issue a short-lived voucher, where the 'expires-
on' leaf is set to a relatively near date, along with a promise on' leaf is set to a relatively near date, along with a promise
(reflected in the 'last-renewal-date' field) to re-issue the voucher (reflected in the 'last-renewal-date' field) to reissue the voucher
again when needed. Importantly, while issuing the initial voucher again when needed. Importantly, while issuing the initial voucher
may incur heavyweight verification checks (are you who you say you may incur heavyweight verification checks ("Are you who you say you
are? does the pledge actually belong to you?), re-issuing the are?" "Does the pledge actually belong to you?"), reissuing the
voucher should be a lightweight process, as it ostensibly only voucher should be a lightweight process, as it ostensibly only
updates the voucher's validity period. With this approach, there is updates the voucher's validity period. With this approach, there is
only the one artifact, and only one code path is needed to process only the one artifact, and only one code path is needed to process
it, without any possibility for a pledge to choose to skip the it; there is no possibility of a pledge choosing to skip the
revocation status check because, for instance, the OCSP Responder is revocation status check because, for instance, the OCSP Responder is
not reachable. not reachable.
While this document recommends issuing short-lived vouchers, the While this document recommends issuing short-lived vouchers, the
voucher artifact does not restrict the ability to create a long-lived voucher artifact does not restrict the ability to create long-lived
vouchers, if required, however no revocation method is described. voucher, if required; however, no revocation method is described.
Note that a voucher may be signed by a chain of intermediate CAs Note that a voucher may be signed by a chain of intermediate CAs
leading up to the trust anchor certificate known by the pledge. Even leading up to the trust anchor certificate known by the pledge. Even
though the voucher itself is not revocable, it may still be revoked, though the voucher itself is not revocable, it may still be revoked,
per se, if one of the intermediate CA certificates is revoked. per se, if one of the intermediate CA certificates is revoked.
6.2. Voucher Per Pledge 6.2. Voucher Per Pledge
The solution described herein originally enabled a single voucher to The solution described herein originally enabled a single voucher to
apply to many pledges, using lists of regular expressions to apply to many pledges, using lists of regular expressions to
represent ranges of serial numbers. However, it was determined that represent ranges of serial-numbers. However, it was determined that
blocking the renewal of a voucher that applied to many devices would 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 be excessive when only the ownership for a single pledge needed to be
blocked. Thus, the voucher format now only supports a single serial- blocked. Thus, the voucher format now only supports a single serial-
number to be listed. number to be listed.
7. Security Considerations 7. Security Considerations
7.1. Clock Sensitivity 7.1. Clock Sensitivity
An attacker could use an expired voucher to gain control over a An attacker could use an expired voucher to gain control over a
device that has no understanding of time. The device can not trust device that has no understanding of time. The device cannot trust
NTP as a time reference, as an attacker could control the NTP stream. NTP as a time reference, as an attacker could control the NTP stream.
To defend against this there are three things: devices are required There are three things to defend against this: 1) devices are
to verify that the expires-on field has not yet passed. Devices required to verify that the expires-on field has not yet passed, 2)
without access to time can use nonces to get ephemeral vouchers. devices without access to time can use nonces to get ephemeral
Thirdly, vouchers without expiration times may be used, which will vouchers, and 3) vouchers without expiration times may be used, which
appear in the audit log, informing the security decision. will appear in the audit log, informing the security decision.
This document defines a voucher format that contains time values for This document defines a voucher format that contains time values for
expirations, which require an accurate clock in order to be processed expirations, which require an accurate clock in order to be processed
correctly. Vendors planning on issuing vouchers with expiration correctly. Vendors planning on issuing vouchers with expiration
values must ensure devices have an accurate clock when shipped from values must ensure that devices have an accurate clock when shipped
manufacturing facilities, and take steps to prevent clock tampering. from manufacturing facilities and take steps to prevent clock
If it is not possible to ensure clock accuracy then vouchers with tampering. If it is not possible to ensure clock accuracy, then
expirations should not be issued. vouchers with expirations should not be issued.
7.2. Protect Voucher PKI in HSM 7.2. Protect Voucher PKI in HSM
A voucher is signed by a CA, that may itself be signed by a chain of Pursuant the recommendation made in Section 6.1 for the MASA to be
CAs leading to a trust anchor known to a pledge. Revocation checking deployed as an online voucher signing service, it is RECOMMENDED that
of the intermediate certificates may be difficult in some scenarios. the MASA's private key used for signing vouchers is protected by a
The voucher format supports the existing PKIX revocation information hardware security module (HSM).
distribution within the limits of the current PKI technology (a PKCS7
structure can contain revocation objects as well), but pledges MAY
accept vouchers without checking X.509 certificate revocation (when
'domain-cert-revocation-checks' is false). Without revocation
checking, a compromised MASA keychain could be used to issue vouchers
ad infinitum without recourse. For this reason, MASA implementations
wanting to support such deployments SHOULD ensure that all the CA
private keys used for signing the vouchers are protected by hardware
security modules (HSMs).
7.3. Test Domain Certificate Validity when Signing 7.3. Test Domain Certificate Validity When Signing
If a domain certificate is compromised, then any outstanding vouchers If a domain certificate is compromised, then any outstanding vouchers
for that domain could be used by the attacker. The domain for that domain could be used by the attacker. The domain
administrator is clearly expected to initiate revocation of any administrator is clearly expected to initiate revocation of any
domain identity certificates (as is normal in PKI solutions). domain identity certificates (as is normal in PKI solutions).
Similarly they are expected to contact the MASA to indicate that an Similarly,they are expected to contact the MASA to indicate that an
outstanding (presumably short lifetime) voucher should be blocked outstanding (presumably short lifetime) voucher should be blocked
from automated renewal. Protocols for voucher distribution are from automated renewal. Protocols for voucher distribution are
RECOMMENDED to check for revocation of any domain identity RECOMMENDED to check for revocation of domain identity certificates
certificates before automated renewal of vouchers. before the signing of vouchers.
7.4. YANG Module Security Considerations
The YANG module specified in this document defines the schema for
data that is subsequently encapsulated by a CMS signed-data content
type, as described in Section 5 of [RFC5652]. 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
[RFC5246]) or by encapsulating the signed-data content type with an
enveloped-data content type (Section 6 of [RFC5652]), though details
for how to do this are outside the scope of this document.
The use of YANG to define data structures, via the 'yang-data'
statement, is relatively new and distinct from the traditional use of
YANG to define an API accessed by network management protocols such
as NETCONF [RFC6241] and RESTCONF [RFC8040]. For this reason, these
guidelines do not follow template described by Section 3.7 of
[YANG-GUIDE].
8. IANA Considerations 8. IANA Considerations
8.1. The IETF XML Registry 8.1. The IETF XML Registry
This document registers a URIs in the IETF XML registry [RFC3688]. This document registers a URI in the "IETF XML Registry" [RFC3688].
Following the format in [RFC3688], the following registration is IANA has registered the following:
requested:
URI: urn:ietf:params:xml:ns:yang:ietf-voucher URI: urn:ietf:params:xml:ns:yang:ietf-voucher
Registrant Contact: The ANIMA WG of the IETF. Registrant Contact: The ANIMA WG of the IETF.
XML: N/A, the requested URI is an XML namespace. XML: N/A, the requested URI is an XML namespace.
8.2. The YANG Module Names Registry 8.2. The YANG Module Names Registry
This document registers a YANG module in the YANG Module Names This document registers a YANG module in the "YANG Module Names"
registry [RFC6020]. Following the format defined in [RFC6020], the registry [RFC6020]. IANA has registered the following:
the following registration is requested:
name: ietf-voucher name: ietf-voucher
namespace: urn:ietf:params:xml:ns:yang:ietf-voucher namespace: urn:ietf:params:xml:ns:yang:ietf-voucher
prefix: vch prefix: vch
reference: RFC XXXX reference: RFC 8366
8.3. The IETF MIME Registry 8.3. The Media Types Registry
This document registers a URIs in the IETF XML registry [RFC3688]. This document registers a new media type in the "Media Types"
Following the format in [RFC3688], the following registration is registry [RFC6838]. IANA has registered the following:
requested:
Type name: application Type name: application
Subtype name: voucher-cms+json Subtype name: voucher-cms+json
Required parameters: none Required parameters: none
Optional parameters: none Optional parameters: none
Encoding considerations: CMS-signed JSON vouchers are ASN.1/DER Encoding considerations: CMS-signed JSON vouchers are ASN.1/DER
encoded. encoded.
Security considerations: See Security Considerations, Section 7 Security considerations: See Section 7
Interoperability considerations: The format is designed to be Interoperability considerations: The format is designed to be
broadly interoperable. broadly interoperable.
Published specification: THIS RFC. Published specification: RFC 8366
Applications that use this media type: ANIMA, 6tisch and NETCONF Applications that use this media type: ANIMA, 6tisch, and NETCONF
zero-touch imprinting systems zero-touch imprinting systems.
Fragment identifier considerations: none
Additional information: Additional information:
Deprecated alias names for this type: none
Magic number(s): None Magic number(s): None
File extension(s): .vcj File extension(s): .vcj
Macintosh file type code(s): none Macintosh file type code(s): none
Person & email address to contact for further information: IETF Person and email address to contact for further information:
ANIMA WG IETF ANIMA WG
Intended usage: LIMITED Intended usage: LIMITED
Restrictions on usage: NONE Restrictions on usage: NONE
Author: ANIMA WG Author: ANIMA WG
Change controller: IETF Change controller: IETF
Provisional registration? (standards tree only): NO Provisional registration? (standards tree only): NO
8.4. The SMI Security for S/MIME CMS Content Type Registry 8.4. The SMI Security for S/MIME CMS Content Type Registry
This document registers an OID in the "SMI Security for S/MIME CMS IANA has registered the following OID in the "SMI Security for S/MIME
Content Type" registry (1.2.840.113549.1.9.16.1), with the value: CMS Content Type (1.2.840.113549.1.9.16.1)" registry:
Decimal Description References Decimal Description References
------- -------------------------------------- ---------- ------- -------------------------------------- ----------
TBD1 id-ct-animaJSONVoucher [ThisRFC] 40 id-ct-animaJSONVoucher RFC 8366
9. References 9. References
9.1. Normative References 9.1. Normative References
[ITU.X690.1994] [ITU.X690.2015]
International Telecommunications Union, "Information International Telecommunication Union, "Information
Technology - ASN.1 encoding rules: Specification of Basic Technology - ASN.1 encoding rules: Specification of
Encoding Rules (BER), Canonical Encoding Rules (CER) and Basic Encoding Rules (BER), Canonical Encoding Rules
Distinguished Encoding Rules (DER)", ITU-T Recommendation (CER) and Distinguished Encoding Rules (DER)", ITU-T
X.690, 1994. Recommendation X.690, ISO/IEC 8825-1, August 2015,
<https://www.itu.int/rec/T-REC-X.690/>.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997, DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>. <https://www.rfc-editor.org/info/rfc2119>.
[RFC5652] Housley, R., "Cryptographic Message Syntax (CMS)", STD 70, [RFC5652] Housley, R., "Cryptographic Message Syntax (CMS)",
RFC 5652, DOI 10.17487/RFC5652, September 2009, STD 70, RFC 5652, DOI 10.17487/RFC5652, September 2009,
<https://www.rfc-editor.org/info/rfc5652>. <https://www.rfc-editor.org/info/rfc5652>.
[RFC6020] Bjorklund, M., Ed., "YANG - A Data Modeling Language for [RFC6020] Bjorklund, M., Ed., "YANG - A Data Modeling Language for
the Network Configuration Protocol (NETCONF)", RFC 6020, the Network Configuration Protocol (NETCONF)", RFC 6020,
DOI 10.17487/RFC6020, October 2010, DOI 10.17487/RFC6020, October 2010,
<https://www.rfc-editor.org/info/rfc6020>. <https://www.rfc-editor.org/info/rfc6020>.
[RFC7159] Bray, T., Ed., "The JavaScript Object Notation (JSON) Data [RFC7950] Bjorklund, M., Ed., "The YANG 1.1 Data Modeling
Interchange Format", RFC 7159, DOI 10.17487/RFC7159, March Language", RFC 7950, DOI 10.17487/RFC7950, August 2016,
2014, <https://www.rfc-editor.org/info/rfc7159>. <https://www.rfc-editor.org/info/rfc7950>.
[RFC7950] Bjorklund, M., Ed., "The YANG 1.1 Data Modeling Language", [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
RFC 7950, DOI 10.17487/RFC7950, August 2016, 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
<https://www.rfc-editor.org/info/rfc7950>. May 2017, <https://www.rfc-editor.org/info/rfc8174>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC [RFC8259] Bray, T., Ed., "The JavaScript Object Notation (JSON)
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, Data Interchange Format", STD 90, RFC 8259,
May 2017, <https://www.rfc-editor.org/info/rfc8174>. DOI 10.17487/RFC8259, December 2017,
<https://www.rfc-editor.org/info/rfc8259>.
9.2. Informative References 9.2. Informative References
[I-D.ietf-6tisch-dtsecurity-secure-join] [imprinting] Wikipedia, "Wikipedia article: Imprinting", February
Richardson, M., "6tisch Secure Join protocol", draft-ietf- 2018, <https://en.wikipedia.org/w/index.php?title=
6tisch-dtsecurity-secure-join-01 (work in progress), Imprinting_(psychology)&oldid=825757556>.
February 2017.
[I-D.ietf-anima-bootstrapping-keyinfra] [KEYINFRA] Pritikin, M., Richardson, M., Behringer, M., Bjarnason,
Pritikin, M., Richardson, M., Behringer, M., Bjarnason, S., and K. Watsen, "Bootstrapping Remote Secure Key
S., and K. Watsen, "Bootstrapping Remote Secure Key Infrastructures (BRSKI)", Work in Progress,
Infrastructures (BRSKI)", draft-ietf-anima-bootstrapping- draft-ietf-anima-bootstrapping-keyinfra-12, March 2018.
keyinfra-09 (work in progress), October 2017.
[I-D.ietf-netconf-zerotouch] [RFC3688] Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688,
Watsen, K., Abrahamsson, M., and I. Farrer, "Zero Touch DOI 10.17487/RFC3688, January 2004,
Provisioning for NETCONF or RESTCONF based Management", <https://www.rfc-editor.org/info/rfc3688>.
draft-ietf-netconf-zerotouch-19 (work in progress),
October 2017.
[I-D.ietf-netmod-yang-tree-diagrams] [RFC5246] Dierks, T. and E. Rescorla, "The Transport Layer
Bjorklund, M. and L. Berger, "YANG Tree Diagrams", draft- Security (TLS) Protocol Version 1.2", RFC 5246,
ietf-netmod-yang-tree-diagrams-04 (work in progress), DOI 10.17487/RFC5246, August 2008,
December 2017. <https://www.rfc-editor.org/info/rfc5246>.
[imprinting] [RFC6125] Saint-Andre, P. and J. Hodges, "Representation and
Wikipedia, "Wikipedia article: Imprinting", July 2015, Verification of Domain-Based Application Service
<https://en.wikipedia.org/wiki/Imprinting_(psychology)>. Identity within Internet Public Key Infrastructure Using
X.509 (PKIX) Certificates in the Context of Transport
Layer Security (TLS)", RFC 6125, DOI 10.17487/RFC6125,
March 2011, <https://www.rfc-editor.org/info/rfc6125>.
[RFC3688] Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688, [RFC6241] Enns, R., Ed., Bjorklund, M., Ed., Schoenwaelder, J.,
DOI 10.17487/RFC3688, January 2004, Ed., and A. Bierman, Ed., "Network Configuration
<https://www.rfc-editor.org/info/rfc3688>. Protocol (NETCONF)", RFC 6241, DOI 10.17487/RFC6241,
June 2011, <https://www.rfc-editor.org/info/rfc6241>.
[RFC6125] Saint-Andre, P. and J. Hodges, "Representation and [RFC6838] Freed, N., Klensin, J., and T. Hansen, "Media Type
Verification of Domain-Based Application Service Identity Specifications and Registration Procedures", BCP 13,
within Internet Public Key Infrastructure Using X.509 RFC 6838, DOI 10.17487/RFC6838, January 2013,
(PKIX) Certificates in the Context of Transport Layer <https://www.rfc-editor.org/info/rfc6838>.
Security (TLS)", RFC 6125, DOI 10.17487/RFC6125, March
2011, <https://www.rfc-editor.org/info/rfc6125>.
[RFC7435] Dukhovni, V., "Opportunistic Security: Some Protection [RFC7435] Dukhovni, V., "Opportunistic Security: Some Protection
Most of the Time", RFC 7435, DOI 10.17487/RFC7435, Most of the Time", RFC 7435, DOI 10.17487/RFC7435,
December 2014, <https://www.rfc-editor.org/info/rfc7435>. December 2014,
<https://www.rfc-editor.org/info/rfc7435>.
[RFC8040] Bierman, A., Bjorklund, M., and K. Watsen, "RESTCONF
Protocol", RFC 8040, DOI 10.17487/RFC8040, January 2017,
<https://www.rfc-editor.org/info/rfc8040>.
[RFC8340] Bjorklund, M. and L. Berger, Ed., "YANG Tree Diagrams",
BCP 215, RFC 8340, DOI 10.17487/RFC8340, March 2018,
<https://www.rfc-editor.org/info/rfc8340>.
[SECUREJOIN] Richardson, M., "6tisch Secure Join protocol", Work in
Progress, draft-ietf-6tisch-dtsecurity-secure-join-01,
February 2017.
[Stajano99theresurrecting] [Stajano99theresurrecting]
Stajano, F. and R. Anderson, "The resurrecting duckling: Stajano, F. and R. Anderson, "The Resurrecting Duckling:
security issues for ad-hoc wireless networks", 1999, Security Issues for Ad-Hoc Wireless Networks", 1999,
<https://www.cl.cam.ac.uk/~fms27/ <https://www.cl.cam.ac.uk/research/dtg/www/files/
papers/1999-StajanoAnd-duckling.pdf>. publications/public/files/tr.1999.2.pdf>.
Appendix A. Acknowledgements [YANG-GUIDE] Bierman, A., "Guidelines for Authors and Reviewers of
YANG Data Model Documents", Work in Progress,
draft-ietf-netmod-rfc6087bis-20, March 2018.
[ZERO-TOUCH] Watsen, K., Abrahamsson, M., and I. Farrer, "Zero Touch
Provisioning for Networking Devices", Work in Progress,
draft-ietf-netconf-zerotouch-21, March 2018.
Acknowledgements
The authors would like to thank for following for lively discussions The authors would like to thank for following for lively discussions
on list and in the halls (ordered by last name): William Atwood, on list and in the halls (ordered by last name): William Atwood,
Toerless Eckert, Sheng Jiang. Toerless Eckert, and Sheng Jiang.
Russ Housley provided the upgrade from PKCS7 to CMS(RFC5652), along Russ Housley provided the upgrade from PKCS7 to CMS (RFC 5652) along
with the detailed CMS structure diagram. with the detailed CMS structure diagram.
Authors' Addresses Authors' Addresses
Kent Watsen Kent Watsen
Juniper Networks Juniper Networks
EMail: kwatsen@juniper.net Email: kwatsen@juniper.net
Michael C. Richardson Michael C. Richardson
Sandelman Software Sandelman Software
EMail: mcr+ietf@sandelman.ca Email: mcr+ietf@sandelman.ca
URI: http://www.sandelman.ca/ URI: http://www.sandelman.ca/
Max Pritikin Max Pritikin
Cisco Systems Cisco Systems
EMail: pritikin@cisco.com Email: pritikin@cisco.com
Toerless Eckert Toerless Eckert
Futurewei Technologies Inc. Huawei USA - Futurewei Technologies Inc.
2330 Central Expy 2330 Central Expy
Santa Clara 95050 Santa Clara 95050
USA United States of America
EMail: tte+ietf@cs.fau.de Email: tte+ietf@cs.fau.de, toerless.eckert@huawei.com
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