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Network Working Group                                     A. Lindem, Ed.
Internet-Draft                                                     Y. Qu
Intended status: Standards Track                                D. Yeung
Expires: August 31, 2015                                   Cisco Systems
                                                                 I. Chen
                                                                Ericsson
                                                                J. Zhang
                                                        Juniper Networks
                                                                 Y. Yang
                                                           Cisco Systems
                                                       February 27, 2015


                       Key Chain YANG Data Model
                  draft-acee-rtg-yang-key-chain-01.txt

Abstract

   This document describes the key chain YANG data model.  A key chain
   is a list of elements each containing a key, send lifetime, accept
   lifetime, and algorithm.  By properly overlapping the send and accept
   lifetimes of multiple key chain elements, 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 use the key chain element key
   directly, but rather a key derivation function is used to derive a
   short-lived key from the key chain element 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 August 31, 2015.






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Copyright Notice

   Copyright (c) 2015 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
     1.1.  Requirements Notation . . . . . . . . . . . . . . . . . .   3
   2.  Problem Statement . . . . . . . . . . . . . . . . . . . . . .   3
     2.1.  Graceful Key Rollover using Key Chains  . . . . . . . . .   3
   3.  Design of the Key Chain Model . . . . . . . . . . . . . . . .   4
   4.  Key Chain YANG Model  . . . . . . . . . . . . . . . . . . . .   6
   5.  Security Considerations . . . . . . . . . . . . . . . . . . .  11
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  11
   7.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  11
     7.1.  Normative References  . . . . . . . . . . . . . . . . . .  11
     7.2.  Informative References  . . . . . . . . . . . . . . . . .  12
   Appendix A.  Acknowledgments  . . . . . . . . . . . . . . . . . .  12
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  12

1.  Introduction

   This document describes the key chain YANG data model.  A key chain
   is a list of elements each containing a key, send lifetime, accept
   lifetime, and algorithm.  By properly overlapping the send and accept
   lifetimes of multiple key chain elements, 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 use the key chain element key
   directly, but rather a key derivation function is used to derive a
   short-lived key from the key chain element key.








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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].

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 of the core
   routing infrastructure as recommended in [IAB-REPORT].

   A key chain is a list of containing one or more elements containing a
   Key ID, key, send/accept lifetimes, and the associated authentication
   or encryption 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 applications
   requiring authentication or encryption.  This is more inline with the
   current operational model.

2.1.  Graceful Key Rollover using Key Chains

   Key chains may be used to gracefully update the key and/or algorithm
   used by an application for authentication or encryption.  This MAY be
   accomplished by accepting all the keys that have a valid accept
   lifetime and sending the key with the most recent send lifetime.  One
   scenario for facilitating key rollover is to:

   1.  Distribute a key chain with a new key to all the routers or other
       network 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 (e.g., using
       Network Time Protocol (NTP) [NTP-PROTO]).  This also may be
       automated.





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   3.  When the send lifetime of the new key becomes valid, the network
       devices within the domain of 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 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 always
       include two keys; either the current and future key (during key
       rollovers) or the current and previous keys (between key
       rollovers).

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 element to be used.  In
   addition to the Key-ID, each key chain element includes a key-string.
   Optionally, the key chain entries include 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 elements where the accept-lifetime or send-lifetime is not
   valid (e.g., has an end-time equal to the start-time).

   Due to the differences in key chain implementations across various
   vendors, some of the data elements are optional.  Additionally, the
   key-chain is made a grouping so that an implementation could support
   scoping other than at the global level.

+--rw key-chains* [name]
   +--rw name                string
   +--rw accept-tolerance {accept-tolerance}?
   |  +--rw duration?   uint32
   +--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 lifetime
      |  +--rw (lifetime)?
      |     +--:(send-and-accept-lifetime)
      |     |  +--rw send-accept-lifetime



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      |     |     +--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
      |     +--:(independent-send-accept-lifetime)
      |        |                  {independent-send-accept-lifetime}?
      |        +--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 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 crypto-algorithm {cryptographic-algorithm}?
         +--rw (algorithm)?
            +--:(hmac-sha1-12)
            |  +--rw hmac-sha1-12?   empty
            +--:(hmac-sha1-20)
            |  +--rw hmac-sha1-20?   empty
            +--:(md5)
            |  +--rw md5?            empty



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            +--:(sha-1)
            |  +--rw sha-1?          empty
            +--:(hmac-sha-1)
            |  +--rw hmac-sha-1?     empty
            +--:(hmac-sha-256)
            |  +--rw hmac-sha-256?   empty
            +--:(hmac-sha-384)
            |  +--rw hmac-sha-384?   empty
            +--:(hmac-sha-512)
               +--rw hmac-sha-512?   empty


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";
     }

     organization
       "Cisco Systems
        170 West Tasman Drive
        San Jose, CA 95134-1706
        USA";
     contact
       "Acee Lindem - acee@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 2015-02-24 {
       description
         "Initial revision.";
       reference
         "RFC XXXX: A YANG Data Model for key-chain";
     }

     feature cryptographic-algorithm {
       description
         "Support cryptographic algorithm.";



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     }

     feature hex-key-string {
       description
         "Support hexadecimal key string.";
     }

     feature accept-tolerance {
       description
         "To specify the tolerance or acceptance limit.";
     }

     feature independent-send-accept-lifetime {
       description
         "Support for independent send and accept key lifetimes.";
     }

     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 {



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                   range "1..2147483646";
                 }
                 units seconds;
                 description "Key lifetime duration, in seconds";
               }
             }
             case end-date-time {
               leaf end-date-time {
                 type yang:date-and-time;
                 description "End time.";
               }
             }
           }
         }
       }
     }

     grouping key-chain {
       description
         "Grouping for one key-chain.";

       leaf name {
         type string;
         description "Name of the key-chain.";
       }

       container accept-tolerance {
         if-feature accept-tolerance;
         leaf duration {
           type uint32;
           units seconds;
           default "0";
           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 {
              description



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                "Key string styles";
              case keystring {
                leaf keystring {
                  type string;
                }
              }
              case hexadecimal {
                if-feature hex-key-string;
                leaf hexadecimal-string {
                  type yang:hex-string;
                  description
                    "Hexadecimal string.";
                }
              }
            }
         }
         container lifetime {
           description "Specify a key's lifetime.";
           choice lifetime {
             case send-and-accept-lifetime {
               description
                 "Send and accept key have the same lifetime.";
               container send-accept-lifetime {
                 uses lifetime;
               }
             }
             case independent-send-accept-lifetime {
               if-feature independent-send-accept-lifetime;
               description
                 "Independent send and accept key lifetimes.";
               container send-lifetime {
                 uses lifetime;
               }
               container accept-lifetime {
                 uses lifetime;
               }
             }
           }
         }

         container crypto-algorithm {
           if-feature cryptographic-algorithm;
           choice algorithm {
             case hmac-sha1-12 {
               leaf hmac-sha1-12 {
                 type empty;
                 description "The HMAC-SHA1-12 algorithm.";
               }



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             }
             case hmac-sha1-20 {
               leaf hmac-sha1-20 {
                 type empty;
                 description "The HMAC-SHA1-20 algorithm.";
               }
             }
             case md5 {
               leaf md5 {
                 type empty;
                 description "The MD5 algorithm.";
               }
             }
             case sha-1 {
               leaf sha-1 {
                 type empty;
                 description "The SHA-1 algorithm.";
               }
             }
             case hmac-sha-1 {
               leaf hmac-sha-1 {
                 type empty;
                 description "HMAC-SHA-1 authentication algorithm.";
               }
             }
             case hmac-sha-256 {
               leaf hmac-sha-256 {
                 type empty;
                 description "HMAC-SHA-256 authentication algorithm.";
               }
             }
             case hmac-sha-384 {
               leaf hmac-sha-384 {
                 type empty;
                 description "HMAC-SHA-384 authentication algorithm.";
               }
             }
             case hmac-sha-512 {
               leaf hmac-sha-512 {
                 type empty;
                 description "HMAC-SHA-512 authentication algorithm.";
               }
             }
           }
           description "The crypto algorithm used.";
         }
       }
     }



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     list key-chains {
       key "name";
       description
         "A key-chain is a sequence of keys that are collectively
         managed for authentication.";
       uses key-chain;
     }
   }


5.  Security Considerations

   This document enables 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].

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

7.  References

7.1.  Normative References

   [NETCONF]  Enns, R., Bjorklund, M., Schoenwaelder, J., and A.
              Bierman, "Network Configuration Protocol (NETCONF)", RFC
              6241, June 2011.






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   [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.

Appendix A.  Acknowledgments

   The RFC text was produced using Marshall Rose's xml2rfc tool.

Authors' Addresses










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   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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