ANIMA Working Group K. Watsen
Internet-Draft Juniper Networks
Intended status: Standards Track M. Richardson
Expires: June 10, 2017 SSW
M. Pritikin
T. Eckert
Cisco Systems
December 7, 2016
Voucher and Voucher Revocation Profiles for Bootstrapping Protocols
draft-kwatsen-anima-voucher-00
Abstract
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.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at 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."
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This Internet-Draft will expire on June 10, 2017.
Copyright Notice
Copyright (c) 2016 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.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Requirements Language . . . . . . . . . . . . . . . . . . . . 3
3. Tree Diagram Notation . . . . . . . . . . . . . . . . . . . . 3
4. Voucher . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
4.1. Tree Diagram . . . . . . . . . . . . . . . . . . . . . . 4
4.2. Examples . . . . . . . . . . . . . . . . . . . . . . . . 4
4.3. YANG Module . . . . . . . . . . . . . . . . . . . . . . . 5
5. Voucher Revocation . . . . . . . . . . . . . . . . . . . . . 9
5.1. Tree Diagram . . . . . . . . . . . . . . . . . . . . . . 9
5.2. Examples . . . . . . . . . . . . . . . . . . . . . . . . 10
5.3. YANG Module . . . . . . . . . . . . . . . . . . . . . . . 11
6. Security Considerations . . . . . . . . . . . . . . . . . . . 16
6.1. Clock Sensitivity . . . . . . . . . . . . . . . . . . . . 16
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 16
7.1. The IETF XML Registry . . . . . . . . . . . . . . . . . . 16
7.2. The YANG Module Names Registry . . . . . . . . . . . . . 17
8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 17
9. References . . . . . . . . . . . . . . . . . . . . . . . . . 17
9.1. Normative References . . . . . . . . . . . . . . . . . . 17
9.2. Informative References . . . . . . . . . . . . . . . . . 18
Appendix A. Change Log . . . . . . . . . . . . . . . . . . . . . 19
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 19
1. Introduction
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.
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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.
2. Requirements Language
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].
3. Tree Diagram Notation
The meaning of the symbols in the above diagram is as follows:
o Brackets "[" and "]" enclose list keys.
o Braces "{" and "}" enclose feature names, and indicate that the
named feature must be present for the subtree to be present.
o Abbreviations before data node names: "rw" (read-write) represents
configuration data and "ro" (read-only) represents state data.
o Symbols after data node names: "?" means an optional node, "!"
means a presence container, and "*" denotes a list and leaf-list.
o Parentheses enclose choice and case nodes, and case nodes are also
marked with a colon (":").
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o Ellipsis ("...") stands for contents of subtrees that are not
shown.
4. Voucher
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.
4.1. Tree Diagram
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?
4.2. Examples
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"
}
}
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The following illustrates a long-lived voucher encoded in XML:
verified
base64-encoded X.509 DER
Example Inc.
example.com
AAA123456789
BBB123456789
CCC123456789
2016-10-07T19:31:42Z
4.3. YANG Module
file "ietf-voucher@2016-12-07.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:
WG List:
Author: Kent Watsen
Author: Max Pritikin
Author: Michael Richardson
";
description
"This module defines the format for a voucher, which is
produced by a device's manufacturer or delegate to securely
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assign one or more devices to an 'owner', so that the
devices may establish a secure connection to the owner's
network infrastructure.";
revision "2016-12-07" {
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,
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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,
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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...
}
}
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}
5. Voucher Revocation
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.
5.1. Tree Diagram
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.
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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?
5.2. Examples
The following illustrates an issuer-wide voucher revocation in XML:
issuer-wide
2016-10-31T23:59:59Z
2016-12-31T23:59:59Z
some fingerprint
some fingerprint
some fingerprint
The following illustrates a voucher-specific revocation in JSON:
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{
"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"
]
]
}
}
5.3. YANG Module
file "ietf-voucher-revocation@2016-12-07.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:
WG List:
Author: Kent Watsen
Author: Max Pritikin
Author: Michael Richardson
";
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 "2016-12-07" {
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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.";
}
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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
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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 {
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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 {
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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...
}
}
}
6. Security Considerations
6.1. Clock Sensitivity
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.
7. IANA Considerations
7.1. The IETF XML Registry
This document registers two URIs in the IETF XML registry [RFC3688].
Following the format in [RFC3688], the following registrations are
requested:
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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.
7.2. The YANG Module Names Registry
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
8. Acknowledgements
The authors would like to thank for following for lively discussions
on list and in the halls (ordered by last name):
9. References
9.1. Normative References
[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., Ed., "YANG - A Data Modeling Language for
the Network Configuration Protocol (NETCONF)", RFC 6020,
DOI 10.17487/RFC6020, October 2010,
.
[RFC7950] Bjorklund, M., Ed., "The YANG 1.1 Data Modeling Language",
RFC 7950, DOI 10.17487/RFC7950, August 2016,
.
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9.2. Informative References
[draft-ietf-anima-bootstrapping-keyinfra]
Pritikin, M., Richardson, M., Behringer, M., and S.
Bjarnason, "Bootstrapping Key Infrastructures", draft-
ietf-anima-bootstrapping-keyinfra (work in progress),
2016, .
[draft-ietf-netconf-zerotouch]
Watsen, K. and M. Abrahamsson, "Zero Touch Provisioning
for NETCONF or RESTCONF based Management", draft-ietf-
netconf-zerotouch (work in progress), 2016,
.
[RFC3688] Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688,
DOI 10.17487/RFC3688, January 2004,
.
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Appendix A. Change Log
Authors' Addresses
Kent Watsen
Juniper Networks
EMail: kwatsen@juniper.net
Michael C. Richardson
Sandelman Software Works
EMail: mcr+ietf@sandelman.ca
URI: http://www.sandelman.ca/
Max Pritikin
Cisco Systems
EMail: pritikin@cisco.com
Toerless Eckert
Cisco Systems
EMail: tte+anima@cs.fau.de
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