| ANIMA Working Group | K. Watsen |
| Internet-Draft | Juniper Networks |
| Intended status: Standards Track | M. Richardson |
| Expires: July 8, 2017 | SSW |
| M. Pritikin | |
| Cisco Systems | |
| T. Eckert | |
| January 4, 2017 |
Voucher and Voucher Revocation Profiles for Bootstrapping Protocols
draft-ietf-anima-voucher-00
This memo defines the two artifacts "voucher" and "voucher-revocation", which are YANG-defined structures that have been signed by a TBD algorithm.
The voucher artifact is generated by the device's manufacture or delegate. The voucher's purpose is to securely assign one or more devices to an owner. The voucher informs each device which entity it should consider to be its owner.
The voucher revocation artifact is used by the manufacturer or delegate (i.e. the issuer of the voucher) to revoke vouchers, if ever necessary. The voucher revocation format defined herein supports both issuer-wide and voucher-specific constructs, enabling usage flexibility.
For both artifacts, this memo only defines the artifact, leaving it to future work to describe specialized protocols for accessing them.
This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet-Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress."
This Internet-Draft will expire on July 8, 2017.
Copyright (c) 2017 IETF Trust and the persons identified as the document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (http://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License.
This document defines a strategy to securely assign devices to an owner, using an artifact signed, directly or indirectly, by the device's manufacturer. This artifact is known as the voucher.
A voucher may be useful in several contexts, but the driving motivation herein is to support secure bootstrapping mechanisms, such as are defined in [draft-ietf-netconf-zerotouch] and [draft-ietf-anima-bootstrapping-keyinfra]. Assigning ownership is important to bootstrapping mechanisms so that the booting device can authenticate the network that's trying to take control of it.
The lifetimes of vouchers may vary. In some bootstrapping protocols the vouchers may be ephemeral, whereas in others the vouchers may be potentially long-lived. In order to support the second category of vouchers, this document also defines a voucher revocation artifact, enabling the manufacturer or delegate to communicate the validity of its vouchers.
For both artifacts, this memo only defines the artifact, leaving it to future work to describe specialized protocols for accessing them.
This document uses YANG [RFC7950] to define the voucher and voucher revocation formats. YANG is a data modeling language with established mappings to XML and JSON, with mappings to other encodings in progress. Which encodings a particular solution uses is outside the scope of this document.
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in the sections below are to be interpreted as described in RFC 2119 [RFC2119].
The meaning of the symbols in the above diagram is as follows:
The voucher is generated by the device's manufacture or delegate. The voucher's purpose is to securely assign one or more devices to an owner. The voucher informs each device which entity it should consider to be its owner.
The voucher is signed by the device's manufacturer or delegate. NOTE: AT THIS TIME, THE SIGNING STRATEGY HAS NOT BEEN SELECTED.
Following is the tree diagram for the YANG module specified in Section 4.3. Details regarding each node in the tree diagram are provided in the YANG module. Please see Section 3 for information on tree diagram notation.
module: ietf-voucher
+--ro voucher
+--ro assertion enumeration
+--ro trusted-ca-certificate? binary
+--ro certificate-id
| +--ro cn-id? string
| +--ro dns-id? string
+--ro unique-id* string
+--ro nonce? string
+--ro created-on? yang:date-and-time
+--ro expires-on? yang:date-and-time
+--ro revocation-location? inet:uri
+--ro additional-data?
The following illustrates an ephemeral voucher encoded in JSON:
{
"ietf-voucher:voucher": {
"assertion": "logged",
"trusted-ca-certificate": "base64-encoded X.509 DER",
"owner-id": "Registrar3245",
"unique-id": "JADA123456789",
"created-on": "2016-10-07T19:31:42Z",
"nonce": "987987623489567"
}
}
The following illustrates a long-lived voucher encoded in XML:
<voucher
xmlns="urn:ietf:params:xml:ns:yang:ietf-voucher">
<assertion>verified</assertion>
<trusted-ca-certificate>
base64-encoded X.509 DER
</trusted-ca-certificate>
<certificate-id>
<cn-id>Example Inc.</cn-id> <!-- maybe this should be a DN? -->
<dns-id>example.com</dns-id>
</certificate-id>
<unique-id>AAA123456789</unique-id>
<unique-id>BBB123456789</unique-id>
<unique-id>CCC123456789</unique-id>
<created-on>2016-10-07T19:31:42Z</created-on>
</voucher>
<CODE BEGINS> file "ietf-voucher@2017-01-04.yang"
module ietf-voucher {
yang-version 1.1;
namespace
"urn:ietf:params:xml:ns:yang:ietf-voucher";
prefix "vch";
import ietf-yang-types { prefix yang; }
import ietf-inet-types { prefix inet; }
organization
"IETF ANIMA Working Group";
contact
"WG Web: <http://tools.ietf.org/wg/anima/>
WG List: <mailto:anima@ietf.org>
Author: Kent Watsen
<mailto:kwatsen@juniper.net>
Author: Max Pritikin
<mailto:pritikin@cisco.com>
Author: Michael Richardson
<mailto:mcr+ietf@sandelman.ca>";
description
"This module defines the format for a voucher, which is
produced by a device's manufacturer or delegate to securely
assign one or more devices to an 'owner', so that the
devices may establish a secure connection to the owner's
network infrastructure.";
revision "2017-01-04" {
description
"Initial version";
reference
"RFC XXXX: Voucher and Voucher Revocation Profiles
for Bootstrapping Protocols";
}
// top-level container
container voucher {
config false;
description
"A voucher that can be used to assign one or more devices to
an owner.";
leaf assertion {
type enumeration {
enum verified {
description
"Indicates that the ownership has been positively
verified by the device's manufacturer or delegate
(e.g., through sales channel integration).";
}
enum logged {
description
"Indicates that this ownership assignment has been
logged into a database maintained by the device's
manufacturer or delegate (voucher transparency).";
}
}
mandatory true;
description
"The assertion is a statement from the manufacturer or
delegate regarding the nature of this voucher. This
allows the device to know what assurance the manufacturer
provides, which supports more detailed policy checks
such as 'I only want to allow verified devices, not
just logged devices'.";
}
leaf trusted-ca-certificate {
type binary;
description
"An X.509 v3 certificate structure as specified by RFC 5280,
Section 4 encoded using the ASN.1 distinguished encoding
rules (DER), as specified in ITU-T X.690.
This certificate is used by a bootstrapping device to
trust another public key infrastructure, in order to
verify another certificate supplied to the device
separately by the bootstrapping protocol, the other
certificate must have this certificate somewhere in
its chain of certificates.";
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).";
}
container certificate-id {
description
"When provided, the device MUST also perform RFC 6125
style validation of another certificate supplied to
the device separately by the bootstrapping protocol
against all the provided ids.";
leaf cn-id {
type string;
description
"The common name field in the cetificate must match
this value.";
}
leaf dns-id {
type string;
description
"A subjectAltName entry of type dNSName in the
certificate must match this value.";
}
}
leaf-list unique-id {
type string;
min-elements 1;
description
"A regular expression identifying one more more device
unique identifiers (e.g., serial numbers). For instance,
the expression could match just a single serial number,
or it might match a range of serial numbers. Devices
use this value to determine if the voucher applies to
them.";
// Ed. both the zerotouch and brwski solutions are devid
// oriented, and so renaming this field to 'serial-number'
// wouldn't be crazy. But devid/serial-number (typically)
// assumes physical chassis, is it worth using this
// term which might extend to e.g. virtual appliances?
}
leaf nonce {
type string; // unit64?
description
"what can be said about this that's ANIMA-neutral?";
}
leaf created-on {
type yang:date-and-time;
description
"The date this voucher was created";
}
leaf expires-on {
type yang:date-and-time;
description
"An optional date value for when this voucher expires.";
}
leaf revocation-location {
type inet:uri;
description
"A URI indicating where revocation information may be
obtained.";
}
anydata additional-data {
description
"Additional data signed by the manufacturer. The manufacturer
might put additional data into its vouchers, for human or
device consumption.";
// Ed. is the additional data normative? - if so, should we
// remove this free-form field, and assume it will be formally
// extended later? Note: the zerotouch draft doesn't need this
// field...
}
}
}
<CODE ENDS>
The vouchers revocation artifact is used to verify the revocation status of vouchers. Voucher revocations are signed by the manufacturer or delegate (i.e. the issuer of the voucher). Vouchers revocation statements MAY be verified by devices during the bootstrapping process, or at any time before or after by any entity (e.g., registrar or equivalent) as needed. Registrars or equivalent SHOULD verify voucher revocation statements and make policy decisions in case devices are not doing so themselves.
Revocations are generally needed when it is critical for devices to know that assurances implied at the time the voucher was signed are still valid at the time the voucher is being processed.
As mentioned in Section 1, the lifetimes of vouchers may vary. In some bootstrapping protocols the vouchers may be ephemeral, whereas in others the vouchers may be potentially long-lived. For bootstrapping protocols that support ephemeral vouchers, there is no need to support revocations. For bootstrapping protocols that support long-lived vouchers, the need to support revoking vouchers is a decision for each manufacturer.
If revocations are not supported then voucher assignments are essentially forever, which may be acceptable for various kinds of devices. If revocations are supported, then it becomes possible to support various scenarios such as handling a key compromise or change in ownership.
The voucher revocation format defined herein supports both issuer-wide (similar to a CRL) or voucher-specific (similar to an OCSP response) constructs, enabling usage flexibility.
NOTE: AT THIS TIME, THE SIGNING STRATEGY HAS NOT BEEN SELECTED.
Following is the tree diagram for the YANG module specified in Section 5.3. Details regarding each node in the tree diagram are provided in the YANG module. Please see Section 3 for information on tree diagram notation.
module: ietf-voucher-revocation
+--ro voucher-revocation
+--ro revocation-type enumeration
+--ro created-on yang:date-and-time
+--ro expires-on? yang:date-and-time
+--ro (voucher-revocation-type)?
| +--:(issuer-wide)
| | +--ro issuer-wide
| | +--ro (list-type)?
| | +--:(whitelist)
| | | +--ro whitelist
| | | +--ro voucher-identifier* string
| | +--:(blacklist)
| | +--ro blacklist
| | +--ro voucher-identifier* string
| +--:(voucher-specific)
| +--ro voucher-specific
| +--ro voucher-identifier string
| +--ro voucher-status enumeration
| +--ro revocation-information
| +--ro revoked-on yang:date-and-time
| +--ro revocation-reason enumeration
+--ro additional-data?
The following illustrates an issuer-wide voucher revocation in XML:
<voucher-revocation
xmlns="urn:ietf:params:xml:ns:yang:ietf-voucher-revocation">
<revocation-type>issuer-wide</revocation-type>
<created-on>2016-10-31T23:59:59Z</created-on>
<expires-on>2016-12-31T23:59:59Z</expires-on>
<issuer-wide>
<blacklist>
<voucher-identifier>some fingerprint</voucher-identifier>
<voucher-identifier>some fingerprint</voucher-identifier>
<voucher-identifier>some fingerprint</voucher-identifier>
</blacklist>
</issuer-wide>
</voucher>
The following illustrates a voucher-specific revocation in JSON:
{
"ietf-voucher-revocation:voucher-revocation": {
"revocation-type": "voucher-specific",
"created-on": "2016-10-31T23:59:59Z"
"expires-on": "2016-12-31T23:59:59Z"
"voucher-specific": [
"voucher-identifier": "some fingerprint",
"voucher-status": "revoked",
"revocation-information": [
"revoked-on": "2016-11-31T23:59:59Z",
"revocation-reason": "key-compromise"
]
]
}
}
<CODE BEGINS> file "ietf-voucher-revocation@2017-01-04.yang"
module ietf-voucher-revocation {
yang-version 1.1;
namespace
"urn:ietf:params:xml:ns:yang:ietf-voucher-revocation";
prefix "vr";
import ietf-yang-types { prefix yang; }
organization
"IETF ANIMA Working Group";
contact
"WG Web: <http://tools.ietf.org/wg/anima/>
WG List: <mailto:anima@ietf.org>
Author: Kent Watsen
<mailto:kwatsen@juniper.net>
Author: Max Pritikin
<mailto:pritikin@cisco.com>
Author: Michael Richardson
<mailto:mcr+ietf@sandelman.ca>";
description
"This module defines the format for a voucher revocation,
which is produced by a manufacturer or delegate to indicate
the revocation status of vouchers.";
revision "2017-01-04" {
description
"Initial version";
reference
"RFC XXXX: Voucher and Voucher Revocation Profiles
for Bootstrapping Protocols";
}
// top-level container
container voucher-revocation {
config false;
description
"A voucher revocation that can provide revocation status
information for one or more devices.";
leaf revocation-type {
type enumeration {
enum issuer-wide {
description
"Indicates that this revocation spans all
the vouchers the issuer has issued to date";
}
enum voucher-specific {
description
"Indicated that this revocation only regards
a single voucher.";
}
}
mandatory true;
description
"The revocation-type indicates if the revocation
is issuer-wide or voucher-specific. Both variations
exist to enable implementations to choose between the
number of revocation artifacts generated versus
individual artifact size.";
}
leaf created-on {
type yang:date-and-time;
mandatory true;
description
"The date this voucher was created";
}
leaf expires-on {
type yang:date-and-time;
description
"An optional date value for when this voucher expires.";
}
choice voucher-revocation-type {
description
"Identifies the revocation type as being either issuer-wide
or voucher-specific.";
container issuer-wide {
description
"This revocation provides issuer-wide revocation status
(similar to a CRL).";
choice list-type {
description
"Indentifies if this issuer-wide revocation is provided
in the form of a whitelist or a blacklist";
container whitelist {
leaf-list voucher-identifier {
type string;
description
"A fingerprint over the voucher artifact.";
}
description
"Indicates that the listed of vouchers are known
to be good. If a voucher is not listed, then
it is considered revoked.";
}
container blacklist {
leaf-list voucher-identifier {
type string;
description
"A fingerprint over the voucher artifact.
Missing if list is empty.";
}
description
"Indicates that the list of vouchers have been
revoked. If a voucher is not listed, then it
is considered good.";
}
} // end list-type
} // end issuer-wide
container voucher-specific {
description
"This revocation provides voucher-specific revocation
status (similar to an OCSP response).";
leaf voucher-identifier {
type string;
mandatory true;
description
"A fingerprint over the voucher artifact.";
}
leaf voucher-status {
type enumeration {
enum good {
description
"Indicates that this voucher is valid";
}
enum revoked {
description
"Indicates that this voucher is invalid";
}
enum unknown {
description
"Indicates that the voucher's status is unknown";
}
}
mandatory true;
description
"Indicates if the revocation status for the specified
voucher.";
}
container revocation-information {
must "../voucher-status = 'revoked'";
leaf revoked-on {
type yang:date-and-time;
mandatory true;
description
"The date this voucher was revoked";
}
leaf revocation-reason {
type enumeration {
enum unspecified {
description
"Indicates that the reason the voucher
was revoked is unspecified.";
}
enum key-compromise {
description
"Indicates that the reason the voucher
was revoked is because its key was
compromised.";
}
enum issuer-compromise {
description
"Indicates that the reason the voucher
was revoked is because its issuer was
compromised.";
}
enum affiliation-changed {
description
"Indicates that the reason the voucher
was revoked is because its affiliation
changed (e.g., device assigned to a
new owner.";
}
enum superseded {
description
"Indicates that the reason the voucher
was revoked is because it has been
superseded (e.g., the previous voucher
expired.";
}
enum cessation-of-operation {
description
"Indicates that the reason the voucher
was revoked is because its issuer has
ceased operations.";
}
} // end enumeration
mandatory true;
description
"modeled after 'CRLReason' in RFC 5280.";
} // end revocation reason
description
"Provides details regarding why a voucher's revocation.
Modeled after 'ResponseData' in RFC6960.";
} // end revocation-information
} // end voucher-specific
}
anydata additional-data {
description
"Additional data signed by the manufacturer. The manufacturer
might put additional data into its voucher revocations, for
human or device consumption.";
// Ed. is the additional data normative? - if so, should we
// remove this free-form field, and assume it will be formally
// extended later? Note: the zerotouch draft doesn't need this
// field...
}
}
}
<CODE ENDS>
This document defines artifacts containing time values for voucher expirations and revocations, which require an accurate clock in order to be processed correctly. Implementations MUST ensure 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, it is RECOMMENDED that implementations disable the aspects of the solution having clock sensitivity. In particular, such implementations should assume that vouchers neither ever expire or are revokable.
It is important to note that implementations SHOULD NOT rely on NTP for time, as it is not a secure protocol.
This document registers two URIs in the IETF XML registry [RFC3688]. Following the format in [RFC3688], the following registrations are requested:
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. URI: urn:ietf:params:xml:ns:yang:ietf-voucher-revocation Registrant Contact: The ANIMA WG of the IETF. XML: N/A, the requested URI is an XML namespace.
This document registers two YANG modules in the YANG Module Names registry [RFC6020]. Following the format defined in [RFC6020], the the following registrations are requested:
name: ietf-voucher namespace: urn:ietf:params:xml:ns:yang:ietf-voucher prefix: vch reference: RFC XXXX name: ietf-voucher-revocation namespace: urn:ietf:params:xml:ns:yang:ietf-voucher-revocation prefix: vchr reference: RFC XXXX
The authors would like to thank for following for lively discussions on list and in the halls (ordered by last name):
| [RFC2119] | Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997. |
| [RFC6020] | Bjorklund, M., "YANG - A Data Modeling Language for the Network Configuration Protocol (NETCONF)", RFC 6020, DOI 10.17487/RFC6020, October 2010. |
| [RFC7950] | Bjorklund, M., "The YANG 1.1 Data Modeling Language", RFC 7950, DOI 10.17487/RFC7950, August 2016. |
| [draft-ietf-anima-bootstrapping-keyinfra] | Pritikin, M., Richardson, M., Behringer, M. and S. Bjarnason, "Bootstrapping Key Infrastructures", Internet-Draft draft-ietf-anima-bootstrapping-keyinfra, 2016. |
| [draft-ietf-netconf-zerotouch] | Watsen, K. and M. Abrahamsson, "Zero Touch Provisioning for NETCONF or RESTCONF based Management", Internet-Draft draft-ietf-netconf-zerotouch, 2016. |
| [RFC3688] | Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688, DOI 10.17487/RFC3688, January 2004. |