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 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 June 4, 2015. Copyright Notice Lindem, et al. Expires June 4, 2015 [Page 1] Internet-Draft YANG Key Chain December 2014 Copyright (c) 2014 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 . . . . . . . . . . . . . . . . . . . . . . . . . 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 Lindem, et al. Expires June 4, 2015 [Page 2] Internet-Draft YANG Key Chain December 2014 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]. Lindem, et al. Expires June 4, 2015 [Page 3] Internet-Draft YANG Key Chain December 2014 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. Lindem, et al. Expires June 4, 2015 [Page 4] Internet-Draft YANG Key Chain December 2014 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). Lindem, et al. Expires June 4, 2015 [Page 5] Internet-Draft YANG Key Chain December 2014 +--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}? Lindem, et al. Expires June 4, 2015 [Page 6] Internet-Draft YANG Key Chain December 2014 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 { Lindem, et al. Expires June 4, 2015 [Page 7] Internet-Draft YANG Key Chain December 2014 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."; } } } } Lindem, et al. Expires June 4, 2015 [Page 8] Internet-Draft YANG Key Chain December 2014 } } 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 { Lindem, et al. Expires June 4, 2015 [Page 9] Internet-Draft YANG Key Chain December 2014 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."; Lindem, et al. Expires June 4, 2015 [Page 10] Internet-Draft YANG Key Chain December 2014 } 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."; } } } } } Lindem, et al. Expires June 4, 2015 [Page 11] Internet-Draft YANG Key Chain December 2014 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]. Lindem, et al. Expires June 4, 2015 [Page 12] Internet-Draft YANG Key Chain December 2014 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 Lindem, et al. Expires June 4, 2015 [Page 13] Internet-Draft YANG Key Chain December 2014 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. Lindem, et al. Expires June 4, 2015 [Page 14] Internet-Draft YANG Key Chain December 2014 Appendix A. Acknowledgments The RFC text was produced using Marshall Rose's xml2rfc tool. Lindem, et al. Expires June 4, 2015 [Page 15] Internet-Draft YANG Key Chain December 2014 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 Lindem, et al. Expires June 4, 2015 [Page 16] Internet-Draft YANG Key Chain December 2014 Yi Yang Cisco Systems 7025 Kit Creek Road Research Triangle Park, NC 27709 USA Email: yiya@cisco.com Lindem, et al. Expires June 4, 2015 [Page 17]