Network Working Group A. Lindem, Ed.
Internet-Draft Y. Qu
Intended status: Standards Track D. Yeung
Expires: June 4, 2015 Cisco Systems
I. Chen
Ericsson
J. Zhang
Juniper Networks
Y. Yang
Cisco Systems
December 1, 2014
Key Chain YANG Data Model
draft-acee-rtg-yang-key-chain-00.txt
Abstract
This document describes the key chain YANG data model. Industry
standard key chains are lists of keys, send lifetimes, accept
lifetimes, and algorithms. By properly overlapping the send and
accept lifetimes of multiple key chain entries, keys and algorithms
may be gracefully updated. By representing them in a YANG data
model, key distribution can be automated. Key chains are commonly
used for routing protocol authentication and other applications. In
some applications, the protocols do not directly use the key chain
entry keys, but rather a key derivation function is used to derive a
short-lived key from the key-chain key.
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
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This Internet-Draft will expire on June 4, 2015.
Copyright Notice
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Copyright (c) 2014 IETF Trust and the persons identified as the
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described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Requirements Notation . . . . . . . . . . . . . . . . . . 3
2. Problem Statement . . . . . . . . . . . . . . . . . . . . . . 4
2.1. Graceful Key Rollover using Key Chains . . . . . . . . . . 4
3. Design of the Key Chain Model . . . . . . . . . . . . . . . . 5
4. Key Chain YANG Model . . . . . . . . . . . . . . . . . . . . . 7
5. Security Considerations . . . . . . . . . . . . . . . . . . . 12
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 13
7. References . . . . . . . . . . . . . . . . . . . . . . . . . . 14
7.1. Normative References . . . . . . . . . . . . . . . . . . . 14
7.2. Informative References . . . . . . . . . . . . . . . . . . 14
Appendix A. Acknowledgments . . . . . . . . . . . . . . . . . . . 15
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 16
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1. Introduction
This document describes the key chain YANG data model. Industry
standard key chains are lists of keys, send lifetimes, accept
lifetimes, and algorithms. By properly overlapping the send and
accept lifetimes of multiple key chain entries, keys and algorithms
may be gracefully updated. By representing them in a YANG data
model, key distribution can be automated. Key chains are commonly
used for routing protocol authentication and other applications. In
some applications, the protocols do not directly use the key chain
entry keys, but rather a key derivation function is used to derive a
short-lived key from the key-chain key.
1.1. Requirements Notation
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC-KEYWORDS].
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2. Problem Statement
This document describes a YANG [YANG] data model for key chains. Key
chains have been implemented and deployed by a large percentage of
network equipment vendors. Providing a standard YANG model will
facilitate automated key distribution and non-disruptive key
rollover. This will aid in tightening the security the of the core
routing infrastructure as recommended in [IAB-REPORT].
A key-chain is a list of containing one or more keys, Key IDs, their
send/accept lifetimes, and the associated algorithm. A conceptual
representation of a crypto key table is described in
[CRYPTO-KEYTABLE]. The key chain model presented herein represents a
practical implementation of the crypto key table. However, the key
selection is left to the using applications which is more inline with
the current operational models.
2.1. Graceful Key Rollover using Key Chains
Key chains may be used to gracefully update key and/or algorithms.
This MAY be accomplished by accepting all the keys that have a valid
accept lifetime and sending the key with the most recent send life
time. One scenario for key rollover would be:
1. Distribute a key chain with a new key to all the routers or other
networking devices in the domain of that key chain. The new
key's accept lifetime should be such that it is accepted during
the key rollover period. The send lifetime should be a time in
the future when it can be assured that all the routers in the
domain of that key are upgraded. This will have no immediate
impact on the keys used for transmission.
2. Assure that all the network devices have been updated with the
updated key chain and that their system times are roughly
synchronized. The system times of devices within an
administrative domain are commonly synchronized using Network
Time Protocol [NTP-PROTO]. This also may be automated.
3. When the send lifetime of the new key becomes valid, the network
devices within the domain of the key chain will start sending the
new key.
4. At some point in the future, a new key chain with the old key
removed may be distributed to the the network devices within the
domain of the key chain. However, this may be deferred until the
next key rollover. If this is done, the key chain will include
two keys; either the current and future key during rollover
periods or the current and previous keys the rest of the time.
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3. Design of the Key Chain Model
The ietf-keychain module contains a list of one or more keys indexed
by a Key ID. For some applications (e.g., OSPFv3 [OSPFV3-AUTH]), the
Key-Id is used to identify the key-chain entry to be used. In
addition to the Key-ID, each key-chain entry includes a key-string.
Optionally, the keys send/accept lifetimes and a cryptographic
algorithm. If the send/accept lifetime is unspecified, the key is
always considered valid.
Note that asymmetric keys, i.e., a different key value used for
transmission versus acceptance, may be supported with multiple key-
chain entries where the accept-lifetime or send-lifetime is not valid
(e.g., has an end-time equal to the start-time).
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+--rw key-chain
+--rw key-chain* [name]
+--rw name string
+--rw accept-tolerance {accept-tolerance}?
| +--rw (limit)?
| +--:(infinite)
| | +--rw infinite? empty
| +--:(duration)
| +--rw duration? yang:timeticks
+--rw key* [key-id]
+--rw key-id uint64
+--rw key-string
| +--rw (key-string-style)?
| +--:(keystring)
| | +--rw keystring? string
| +--:(hexadecimal) {hex-key-string}?
| +--rw hexadecimal-string? yang:hex-string
+--rw accept-lifetime
| +--rw (lifetime)?
| +--:(always)
| | +--rw always? empty
| +--:(start-end-time)
| +--rw start-date-time? yang:date-and-time
| +--rw (end-time)?
| +--:(infinite)
| | +--rw no-end-time? empty
| +--:(duration)
| | +--rw duration? uint32
| +--:(end-date-time)
| +--rw end-date-time? yang:date-and-time
+--rw send-lifetime
| +--rw (lifetime)?
| +--:(always)
| | +--rw always? empty
| +--:(start-end-time)
| +--rw start-date-time? yang:date-and-time
| +--rw (end-time)?
| +--:(infinite)
| | +--rw no-end-time? empty
| +--:(duration)
| | +--rw duration? uint32
| +--:(end-date-time)
| +--rw end-date-time? yang:date-and-time
+--rw crypto-algorithm? enumeration {cryptographic-algorithm}?
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4. Key Chain YANG Model
module ietf-key-chain {
namespace "urn:ietf:params:xml:ns:yang:ietf-key-chain";
// replace with IANA namespace when assigned
prefix key-chain;
import ietf-yang-types {
prefix "yang";
}
import ietf-routing {
prefix "rt";
}
organization
"Cisco Systems
170 West Tasman Drive
San Jose, CA 95134-1706
USA";
contact
"Derek Yeung myeung@cisco.com";
description
"This YANG module defines the generic configuration
data for key-chain. It is intended that the module
will be extended by vendors to define vendor-specific
key-chain configuration parameters.
";
revision 2014-11-22 {
description
"Initial revision.";
reference
"RFC XXXX: A YANG Data Model for key-chain";
}
feature cryptographic-algorithm {
description
"Support cryptographic algorithm.";
}
feature hex-key-string {
description
"Support hesadecimal key string.";
}
feature accept-tolerance {
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description
"To specify the tolerance or acceptance limit.";
}
grouping lifetime {
description
"Key lifetime specification.";
choice lifetime {
default always;
case always {
leaf always {
type empty;
}
description
"Key is always valid.";
}
case start-end-time {
leaf start-date-time {
type yang:date-and-time;
description "Start time.";
}
choice end-time {
default infinite;
description
"End-time setting.";
case infinite {
leaf no-end-time {
type empty;
}
description
"Never expires.";
}
case duration {
leaf duration {
type uint32 {
range "1..2147483646";
}
description "Key lifetime duration, in seconds";
}
}
case end-date-time {
leaf end-date-time {
type yang:date-and-time;
description "End time.";
}
}
}
}
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}
}
container key-chain {
description
"Container for key chains.";
list key-chain {
key "name";
description
"A key-chain is a sequence of keys that are collectively
managed for authentication.";
leaf name {
type string;
description "Name of the key-chain.";
}
container accept-tolerance {
if-feature accept-tolerance;
choice limit {
case infinite {
leaf infinite {
type empty;
description
"The accept key never expires.";
}
}
case duration {
leaf duration {
type yang:timeticks;
description
"Tolerance range, in seconds.";
}
}
}
}
list key {
key "key-id";
description "One key.";
leaf key-id {
type uint64;
description "Key id.";
}
container key-string {
description "The key string.";
choice key-string-style {
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description
"Key string styles";
case keystring {
leaf keystring {
type string;
description
"A string.";
}
}
case hexadecimal {
if-feature hex-key-string;
leaf hexadecimal-string {
type yang:hex-string;
description
"Hexadecimal string.";
}
}
}
}
container accept-lifetime {
description "Specify accept lifetime.";
uses lifetime;
}
container send-lifetime {
description "Specify send lifetime.";
uses lifetime;
}
leaf crypto-algorithm {
if-feature cryptographic-algorithm;
type enumeration {
enum hmac-md5 {
description "The hmac-md5 algorithm.";
}
enum hmac-sha1-12 {
description "The hmac-sha1-12 algorithm.";
}
enum hmac-sha1-20 {
description "The hmac-sha1-20 algorithm.";
}
enum md5 {
description "The md5 algorithm.";
}
enum sha-1 {
description "The sha-1 algorithm.";
}
enum hmac-sha-1 {
description "HMAC-SHA-1 authentication algorithm.";
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}
enum hmac-sha-256 {
description "HMAC-SHA-256 authentication algorithm.";
}
enum hmac-sha-384 {
description "HMAC-SHA-384 authentication algorithm.";
}
enum hmac-sha-512 {
description "HMAC-SHA-512 authentication algorithm.";
}
}
description "The crypto algorithm used.";
}
}
}
}
}
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5. Security Considerations
This document enable the automated distribution of industry standard
key chains using the NETCONF [NETCONF] protocol. As such, the
security considerations for the NETCONF protocol are applicable.
Given that the key chains themselves are sensitive data, it is
RECOMMENDED that the NETCONF communication channel be encrypted. One
way to do accomplish this would be to invoke and run NETCONF over SSH
as described in [NETCONF-SSH].
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6. IANA Considerations
This document registers a URI in the IETF XML registry
[XML-REGISTRY]. Following the format in RFC 3688, the following
registration is requested to be made:
URI: urn:ietf:params:xml:ns:yang:ietf-key-chain
Registrant Contact: The IESG.
XML: N/A, the requested URI is an XML namespace.
This document registers a YANG module in the YANG Module Names
registry [YANG].
name: ietf-acl namespace:
urn:ietf:params:xml:ns:yang:ietf-key-chain prefix: ietf-key-chain
reference: RFC XXXX
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7. References
7.1. Normative References
[NETCONF] Enns, R., Bjorklund, M., Schoenwaelder, J., and A.
Bierman, "Network Configuration Protocol (NETCONF)",
RFC 6241, June 2011.
[NETCONF-SSH]
Wasserman, M., "Using NETCONF Protocol over Secure Shell
(SSH)", RFC 6242, June 2011.
[RFC-KEYWORDS]
Bradner, S., "Key words for use in RFC's to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[XML-REGISTRY]
Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688,
January 2004.
[YANG] Bjorklund, M., "YANG - A Data Modeling Language for the
Network Configuration Protocol (NETCONF)", RFC 6020,
October 2010.
7.2. Informative References
[CRYPTO-KEYTABLE]
Housley, R., Polk, T., Hartman, S., and D. Zhang, "Table
of Cryptographic Keys", RFC 7210, April 2014.
[IAB-REPORT]
Andersson, L., Davies, E., and L. Zhang, "Report from the
IAB workshop on Unwanted Traffic March 9-10, 2006",
RFC 4948, August 2007.
[NTP-PROTO]
Mills, D., Martin, J., Burbank, J., and W. Kasch, "Network
Time Protocol Version 4: Protocol and Algorithms
Specification", RFC 5905, June 2010.
[OSPFV3-AUTH]
Bhatia, M., Manral, V., and A. Lindem, "Supporting
Authentication Trailer for OSPFv3", RFC 7166, March 2014.
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Appendix A. Acknowledgments
The RFC text was produced using Marshall Rose's xml2rfc tool.
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Authors' Addresses
Acee Lindem (editor)
Cisco Systems
301 Midenhall Way
Cary, NC 27513
USA
Email: acee@cisco.com
Yingzhen Qu
Cisco Systems
170 West Tasman Drive
San Jose, CA 95134
USA
Email: yiqu@cisco.com
Derek Yeung
Cisco Systems
170 West Tasman Drive
San Jose, CA 95134
USA
Email: myeung@cisco.com
Ing-Wher Chen
Ericsson
Email: ing-wher.chen@ericsson.com
Jeffrey Zhang
Juniper Networks
10 Technology Park Drive
Westford, MA 01886
USA
Email: zzhang@juniper.net
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Yi Yang
Cisco Systems
7025 Kit Creek Road
Research Triangle Park, NC 27709
USA
Email: yiya@cisco.com
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