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NETCONF Working Group                                          K. Watsen
Internet-Draft                                          Juniper Networks
Intended status: Standards Track                                   G. Wu
Expires: April 21, 2018                                    Cisco Systems
                                                        October 18, 2017


             YANG Groupings for TLS Clients and TLS Servers
                draft-ietf-netconf-tls-client-server-04

Abstract

   This document defines three YANG modules: the first defines groupings
   for a generic TLS client, the second defines groupings for a generic
   TLS server, and the third defines common identities and groupings
   used by both the client and the server.  It is intended that these
   groupings will be used by applications using the TLS protocol.

Editorial Note (To be removed by RFC Editor)

   This draft contains many placeholder values that need to be replaced
   with finalized values at the time of publication.  This note
   summarizes all of the substitutions that are needed.  No other RFC
   Editor instructions are specified elsewhere in this document.

   This document contains references to other drafts in progress, both
   in the Normative References section, as well as in body text
   throughout.  Please update the following references to reflect their
   final RFC assignments:

   o  I-D.ietf-netconf-keystore

   Artwork in this document contains shorthand references to drafts in
   progress.  Please apply the following replacements:

   o  "XXXX" --> the assigned RFC value for this draft

   o  "YYYY" --> the assigned RFC value for I-D.ietf-netconf-keystore

   Artwork in this document contains placeholder values for the date of
   publication of this draft.  Please apply the following replacement:

   o  "2017-10-19" --> the publication date of this draft

   The following Appendix section is to be removed prior to publication:

   o  Appendix A.  Change Log




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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 https://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 April 21, 2018.

Copyright Notice

   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
   (https://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.  Terminology . . . . . . . . . . . . . . . . . . . . . . .   3
     1.2.  Tree Diagrams . . . . . . . . . . . . . . . . . . . . . .   4
   2.  The TLS Client Model  . . . . . . . . . . . . . . . . . . . .   4
     2.1.  Tree Diagram  . . . . . . . . . . . . . . . . . . . . . .   4
     2.2.  Example Usage . . . . . . . . . . . . . . . . . . . . . .   5
     2.3.  YANG Model  . . . . . . . . . . . . . . . . . . . . . . .   5
   3.  The TLS Server Model  . . . . . . . . . . . . . . . . . . . .   8
     3.1.  Tree Diagram  . . . . . . . . . . . . . . . . . . . . . .   8
     3.2.  Example Usage . . . . . . . . . . . . . . . . . . . . . .   9
     3.3.  YANG Model  . . . . . . . . . . . . . . . . . . . . . . .   9
   4.  The TLS Common Model  . . . . . . . . . . . . . . . . . . . .  12
     4.1.  Tree Diagram  . . . . . . . . . . . . . . . . . . . . . .  13
     4.2.  Example Usage . . . . . . . . . . . . . . . . . . . . . .  13



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     4.3.  YANG Model  . . . . . . . . . . . . . . . . . . . . . . .  13
   5.  Security Considerations . . . . . . . . . . . . . . . . . . .  22
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  23
     6.1.  The IETF XML Registry . . . . . . . . . . . . . . . . . .  23
     6.2.  The YANG Module Names Registry  . . . . . . . . . . . . .  23
   7.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .  24
   8.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  24
     8.1.  Normative References  . . . . . . . . . . . . . . . . . .  24
     8.2.  Informative References  . . . . . . . . . . . . . . . . .  25
   Appendix A.  Change Log . . . . . . . . . . . . . . . . . . . . .  27
     A.1.  server-model-09 to 00 . . . . . . . . . . . . . . . . . .  27
     A.2.  00 to 01  . . . . . . . . . . . . . . . . . . . . . . . .  27
     A.3.  01 to 02  . . . . . . . . . . . . . . . . . . . . . . . .  27
     A.4.  02 to 03  . . . . . . . . . . . . . . . . . . . . . . . .  27
     A.5.  03 to 04  . . . . . . . . . . . . . . . . . . . . . . . .  27
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  27

1.  Introduction

   This document defines three YANG [RFC7950] modules: the first defines
   a grouping for a generic TLS client, the second defines a grouping
   for a generic TLS server, and the third defines identities and
   groupings common to both the client and the server (TLS is defined in
   [RFC5246]).  It is intended that these groupings will be used by
   applications using the TLS protocol.  For instance, these groupings
   could be used to help define the data model for an HTTPS [RFC2818]
   server or a NETCONF over TLS [RFC7589] based server.

   The client and server YANG modules in this document each define one
   grouping, which is focused on just TLS-specific configuration, and
   specifically avoids any transport-level configuration, such as what
   ports to listen-on or connect-to.  This enables applications the
   opportunity to define their own strategy for how the underlying TCP
   connection is established.  For instance, applications supporting
   NETCONF Call Home [RFC8071] could use the grouping for the TLS parts
   it provides, while adding data nodes for the TCP-level call-home
   configuration.

1.1.  Terminology

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
   "OPTIONAL" in this document are to be interpreted as described in BCP
   14 [RFC2119] [RFC8174] when, and only when, they appear in all
   capitals, as shown here.






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1.2.  Tree Diagrams

   A simplified graphical representation of the data models is used in
   this document.  The meaning of the symbols in these diagrams 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" means configuration
      (read-write) and "ro" state data (read-only).

   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 (":").

   o  Ellipsis ("...") stands for contents of subtrees that are not
      shown.

2.  The TLS Client Model

   The TLS client model presented in this section contains one YANG
   grouping, to just configure the TLS client, omitting, for instance,
   any configuration for which IP address or port the client should
   connect to.

   This grouping references data nodes defined by the keystore model
   [I-D.ietf-netconf-keystore].  For instance, a reference to the
   keystore model is made to indicate which trusted CA certificate a
   client should use to authenticate the server's certificate.

2.1.  Tree Diagram

   The following tree diagram presents the data model for the grouping
   defined in the ietf-tls-client module.  Please see Section 1.2 for
   tree diagram notation.











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   module: ietf-tls-client

     grouping tls-client-grouping
       +---- client-auth
       |  +---- (auth-type)?
       |     +--:(certificate)
       |        +---- certificate?   leafref
       +---- server-auth
       |  +---- pinned-ca-certs?
       |  |       -> /ks:keystore/pinned-certificates/name
       |  +---- pinned-server-certs?
       |          -> /ks:keystore/pinned-certificates/name
       +---- hello-params {tls-client-hello-params-config}?
          +---- tls-versions
          |  +---- tls-version*   identityref
          +---- cipher-suites
             +---- cipher-suite*   identityref

2.2.  Example Usage

   This section shows how it would appear if the tls-client-grouping
   were populated with some data.  This example is consistent with the
   examples presented in Section 2.2 of [I-D.ietf-netconf-keystore].

<!-- hypothetical example, as groupings don't have instance data -->
<tls-client xmlns="urn:ietf:params:xml:ns:yang:ietf-tls-client">

  <!-- how this client will authenticate itself to the server -->
  <client-auth>
    <certificate>builtin-idevid-cert</certificate>
  </client-auth>

  <!-- which certificates will this client trust -->
  <server-auth>
    <pinned-ca-certs>deployment-specific-ca-certs</pinned-ca-certs>
    <pinned-server-certs>explicitly-trusted-client-certs</pinned-server-certs>
  </server-auth>

</tls-client>

2.3.  YANG Model

   This YANG module has a normative references to [RFC6991] and
   [I-D.ietf-netconf-keystore].

   <CODE BEGINS> file "ietf-tls-client@2017-10-19.yang"
   module ietf-tls-client {
     yang-version 1.1;



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     namespace "urn:ietf:params:xml:ns:yang:ietf-tls-client";
     prefix "tlsc";

     import ietf-tls-common {
       prefix tlscmn;
       revision-date 2017-10-19; // stable grouping definitions
       reference
         "RFC XXXX: YANG Groupings for TLS Clients and TLS Servers";
     }

     import ietf-keystore {
       prefix ks;
       reference
         "RFC YYYY: Keystore Model";
     }

     organization
      "IETF NETCONF (Network Configuration) Working Group";

     contact
      "WG Web:   <http://tools.ietf.org/wg/netconf/>
       WG List:  <mailto:netconf@ietf.org>

       Author:   Kent Watsen
                 <mailto:kwatsen@juniper.net>

       Author:   Gary Wu
                 <mailto:garywu@cisco.com>";


     description
      "This module defines a reusable grouping for a TLS client that
       can be used as a basis for specific TLS client instances.

       Copyright (c) 2017 IETF Trust and the persons identified as
       authors of the code. All rights reserved.

       Redistribution and use in source and binary forms, with or
       without modification, is permitted pursuant to, and subject
       to the license terms contained in, the Simplified BSD
       License set forth in Section 4.c of the IETF Trust's
       Legal Provisions Relating to IETF Documents
       (http://trustee.ietf.org/license-info).

       This version of this YANG module is part of RFC XXXX; see
       the RFC itself for full legal notices.";

     revision "2017-10-19" {



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       description
        "Initial version";
       reference
        "RFC XXXX: YANG Groupings for TLS Clients and TLS Servers";
     }

     feature tls-client-hello-params-config {
       description
         "TLS hello message parameters are configurable on a TLS
          client.";
     }

     grouping tls-client-grouping {
       description
         "A reusable grouping for configuring a TLS client without
          any consideration for how an underlying TCP session is
          established.";

       container client-auth {
         description
           "The credentials used by the client to authenticate to
            the TLS server.";

         choice auth-type {
           description
             "The authentication type.";
           leaf certificate {
             type leafref {
               path "/ks:keystore/ks:keys/ks:key/ks:certificates"
                    + "/ks:certificate/ks:name";
             }
             description
               "A certificates to be used for user authentication.";
           }
         }
       }

       container server-auth {
         must 'pinned-ca-certs or pinned-server-certs';
         description
           "Trusted server identities.";
         leaf pinned-ca-certs {
           type leafref {
             path "/ks:keystore/ks:pinned-certificates/ks:name";
           }
           description
             "A reference to a list of certificate authority (CA)
              certificates used by the TLS client to authenticate



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              TLS server certificates.  A server certificate is
              authenticated if it has a valid chain of trust to
              a configured pinned CA certificate.";
         }

         leaf pinned-server-certs {
           type leafref {
             path "/ks:keystore/ks:pinned-certificates/ks:name";
           }
           description
             "A reference to a list of server certificates used by
              the TLS client to authenticate TLS server certificates.
              A server certificate is authenticated if it is an
              exact match to a configured pinned server certificate.";
         }
       }

       container hello-params {
         if-feature tls-client-hello-params-config;
         uses tlscmn:hello-params-grouping;
         description
           "Configurable parameters for the TLS hello message.";
       }

     } // end tls-client-grouping

   }
   <CODE ENDS>

3.  The TLS Server Model

   The TLS server model presented in this section contains one YANG
   grouping, for just the TLS-level configuration, omitting, for
   instance, configuration for which ports to open to listen for
   connections on.

   This grouping references data nodes defined by the keystore model
   [I-D.ietf-netconf-keystore].  For instance, a reference to the
   keystore model is made to indicate which certificate a server should
   present.

3.1.  Tree Diagram

   The following tree diagram presents the data model for the grouping
   defined in the ietf-tls-server module.  Please see Section 1.2 for
   tree diagram notation.





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   module: ietf-tls-server

     grouping tls-server-grouping
       +---- certificates
       |  +---- certificate* [name]
       |     +---- name?   leafref
       +---- client-auth
       |  +---- pinned-ca-certs?
       |  |       -> /ks:keystore/pinned-certificates/name
       |  +---- pinned-client-certs?
       |          -> /ks:keystore/pinned-certificates/name
       +---- hello-params {tls-server-hello-params-config}?
          +---- tls-versions
          |  +---- tls-version*   identityref
          +---- cipher-suites
             +---- cipher-suite*   identityref

3.2.  Example Usage

   This section shows how it would appear if the tls-server-grouping
   were populated with some data.  This example is consistent with the
   examples presented in Section 2.2 of [I-D.ietf-netconf-keystore].

<tls-server xmlns="urn:ietf:params:xml:ns:yang:ietf-tls-server">

  <!-- how this server will authenticate itself to the client -->
  <certificates>
    <certificate>
      <name>tls-ec-cert</name>
    </certificate>
  </certificates>

  <!-- which certificates will this server trust -->
  <client-auth>
    <pinned-ca-certs>deployment-specific-ca-certs</pinned-ca-certs>
    <pinned-client-certs>explicitly-trusted-client-certs</pinned-client-certs>
  </client-auth>

</tls-server>

3.3.  YANG Model

   This YANG module has a normative references to [RFC6991], and
   [I-D.ietf-netconf-keystore].

   <CODE BEGINS> file "ietf-tls-server@2017-10-19.yang"
   module ietf-tls-server {
     yang-version 1.1;



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     namespace "urn:ietf:params:xml:ns:yang:ietf-tls-server";
     prefix "tlss";

     import ietf-tls-common {
       prefix tlscmn;
       revision-date 2017-10-19; // stable grouping definitions
       reference
         "RFC XXXX: YANG Groupings for TLS Clients and TLS Servers";
     }

     import ietf-keystore {
       prefix ks;
       reference
         "RFC YYYY: Keystore Model";
     }

     organization
      "IETF NETCONF (Network Configuration) Working Group";

     contact
      "WG Web:   <http://tools.ietf.org/wg/netconf/>
       WG List:  <mailto:netconf@ietf.org>

       Author:   Kent Watsen
                 <mailto:kwatsen@juniper.net>

       Author:   Gary Wu
                 <mailto:garywu@cisco.com>";


     description
      "This module defines a reusable grouping for a TLS server that
       can be used as a basis for specific TLS server instances.

       Copyright (c) 2017 IETF Trust and the persons identified as
       authors of the code. All rights reserved.

       Redistribution and use in source and binary forms, with or
       without modification, is permitted pursuant to, and subject
       to the license terms contained in, the Simplified BSD
       License set forth in Section 4.c of the IETF Trust's
       Legal Provisions Relating to IETF Documents
       (http://trustee.ietf.org/license-info).

       This version of this YANG module is part of RFC XXXX; see
       the RFC itself for full legal notices.";

     revision "2017-10-19" {



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       description
        "Initial version";
       reference
        "RFC XXXX: YANG Groupings for TLS Clients and TLS Servers";
     }

     feature tls-server-hello-params-config {
       description
         "TLS hello message parameters are configurable on a TLS
          server.";
     }


     // groupings

     grouping tls-server-grouping {
       description
         "A reusable grouping for configuring a TLS server without
          any consideration for how underlying TCP sessions are
          established.";

       container certificates {
         description
           "The list of certificates the TLS server will present when
            establishing a TLS connection in its Certificate message,
            as defined in Section 7.4.2 in RFC 5246.";
         reference
           "RFC 5246:
              The Transport Layer Security (TLS) Protocol Version 1.2";
         list certificate {
           key name;
           min-elements 1;
           description
             "An unordered list of certificates the TLS server can pick
              from when sending its Server Certificate message.";
           reference
             "RFC 5246: The TLS Protocol, Section 7.4.2";
           leaf name {
             type leafref {
               path "/ks:keystore/ks:keys/ks:key/ks:certificates/"
                    + "ks:certificate/ks:name";
             }
             description
               "The name of the certificate in the keystore.";
           }
         }
       }




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       container client-auth {
         description
           "A reference to a list of pinned certificate authority (CA)
            certificates and a reference to a list of pinned client
            certificates.";
         leaf pinned-ca-certs {
           type leafref {
             path "/ks:keystore/ks:pinned-certificates/ks:name";
           }
           description
             "A reference to a list of certificate authority (CA)
              certificates used by the TLS server to authenticate
              TLS client certificates.  A client certificate is
              authenticated if it has a valid chain of trust to
              a configured pinned CA certificate.";
         }
         leaf pinned-client-certs {
           type leafref {
             path "/ks:keystore/ks:pinned-certificates/ks:name";
           }
           description
             "A reference to a list of client certificates used by
              the TLS server to authenticate TLS client certificates.
              A clients certificate is authenticated if it is an
              exact match to a configured pinned client certificate.";
         }
       }

       container hello-params {
         if-feature tls-server-hello-params-config;
         uses tlscmn:hello-params-grouping;
         description
           "Configurable parameters for the TLS hello message.";
       }

     } // end tls-server-grouping

   }
   <CODE ENDS>

4.  The TLS Common Model

   The TLS common model presented in this section contains identities
   and groupings common to both TLS clients and TLS servers.  The hello-
   params-grouping can be used to configure the list of TLS algorithms
   permitted by the TLS client or TLS server.  The lists of algorithms
   are ordered such that, if multiple algorithms are permitted by the
   client, the algorithm that appears first in its list that is also



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   permitted by the server is used for the TLS transport layer
   connection.  The ability to restrict the the algorithms allowed is
   provided in this grouping for TLS clients and TLS servers that are
   capable of doing so and may serve to make TLS clients and TLS servers
   compliant with security policies.

   Features are defined for algorithms that are OPTIONAL or are not
   widely supported by popular implementations.  Note that the list of
   algorithms is not exhaustive.

4.1.  Tree Diagram

   The following tree diagram presents the data model for the grouping
   defined in the ietf-tls-common module.  Please see Section 1.2 for
   tree diagram notation.

   module: ietf-tls-common

     grouping hello-params-grouping
       +---- tls-versions
       |  +---- tls-version*   identityref
       +---- cipher-suites
          +---- cipher-suite*   identityref

4.2.  Example Usage

   This section shows how it would appear if the transport-params-
   grouping were populated with some data.

   <!-- hypothetical example, as groupings don't have instance data -->
   <hello-params
      xmlns:tlscmn="urn:ietf:params:xml:ns:yang:ietf-tls-common">
     <tls-versions>
       <tls-version>tlscmn:tls-1.1</tls-version>
       <tls-version>tlscmn:tls-1.2</tls-version>
     </tls-versions>
     <cipher-suites>
       <cipher-suite>tlscmn:dhe-rsa-with-aes-128-cbc-sha</cipher-suite>
       <cipher-suite>tlscmn:rsa-with-aes-128-cbc-sha</cipher-suite>
       <cipher-suite>tlscmn:rsa-with-3des-ede-cbc-sha</cipher-suite>
     </cipher-suites>
   </hello-params>

4.3.  YANG Model

   This YANG module has a normative references to [RFC2246], [RFC4346],
   [RFC4492], [RFC5246], [RFC5288], and [RFC5289].




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   <CODE BEGINS> file "ietf-tls-common@2017-10-19.yang"
   module ietf-tls-common {
     yang-version 1.1;

     namespace "urn:ietf:params:xml:ns:yang:ietf-tls-common";
     prefix "tlscmn";

     organization
      "IETF NETCONF (Network Configuration) Working Group";

     contact
      "WG Web:   <http://tools.ietf.org/wg/netconf/>
       WG List:  <mailto:netconf@ietf.org>

       Author:   Kent Watsen
                 <mailto:kwatsen@juniper.net>

       Author:   Gary Wu
                 <mailto:garywu@cisco.com>";


     description
      "This module defines a common features, identities, and groupings
       for Transport Layer Security (TLS).

       Copyright (c) 2017 IETF Trust and the persons identified as
       authors of the code. All rights reserved.

       Redistribution and use in source and binary forms, with or
       without modification, is permitted pursuant to, and subject
       to the license terms contained in, the Simplified BSD
       License set forth in Section 4.c of the IETF Trust's
       Legal Provisions Relating to IETF Documents
       (http://trustee.ietf.org/license-info).

       This version of this YANG module is part of RFC XXXX; see
       the RFC itself for full legal notices.";

     revision "2017-10-19" {
       description
        "Initial version";
       reference
        "RFC XXXX: YANG Groupings for TLS Clients and TLS Servers";
     }

     // features
     feature tls-1_0 {
       description



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         "TLS Protocol Version 1.0 is supported.";
       reference
         "RFC 2246: The TLS Protocol Version 1.0";
     }

     feature tls-1_1 {
       description
         "TLS Protocol Version 1.1 is supported.";
       reference
         "RFC 4346: The Transport Layer Security (TLS) Protocol
                    Version 1.1";
     }

     feature tls-1_2 {
       description
         "TLS Protocol Version 1.2 is supported.";
       reference
         "RFC 5246: The Transport Layer Security (TLS) Protocol
                    Version 1.2";
     }

     feature tls-ecc {
       description
         "Elliptic Curve Cryptography (ECC) is supported for TLS.";
       reference
         "RFC 4492: Elliptic Curve Cryptography (ECC) Cipher Suites
                    for Transport Layer Security (TLS)";
     }

     feature tls-dhe {
       description
         "Ephemeral Diffie-Hellman key exchange is supported for TLS.";
       reference
         "RFC 5246: The Transport Layer Security (TLS) Protocol
                    Version 1.2";
     }

     feature tls-3des {
       description
         "The Triple-DES block cipher is supported for TLS.";
       reference
         "RFC 5246: The Transport Layer Security (TLS) Protocol
                    Version 1.2";
     }

     feature tls-gcm {
       description
         "The Galois/Counter Mode authenticated encryption mode is



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          supported for TLS.";
       reference
         "RFC 5288: AES Galois Counter Mode (GCM) Cipher Suites for
                    TLS";
     }

     feature tls-sha2 {
       description
         "The SHA2 family of cryptographic hash functions is supported
          for TLS.";
       reference
         "FIPS PUB 180-4: Secure Hash Standard (SHS)";
     }

     // identities
     identity tls-version-base {
       description
         "Base identity used to identify TLS protocol versions.";
     }

     identity tls-1.0 {
       base tls-version-base;
       if-feature tls-1_0;
       description
         "TLS Protocol Version 1.0.";
       reference
         "RFC 2246: The TLS Protocol Version 1.0";
     }

     identity tls-1.1 {
       base tls-version-base;
       if-feature tls-1_1;
       description
         "TLS Protocol Version 1.1.";
       reference
         "RFC 4346: The Transport Layer Security (TLS) Protocol
                    Version 1.1";
     }

     identity tls-1.2 {
       base tls-version-base;
       if-feature tls-1_2;
       description
         "TLS Protocol Version 1.2.";
       reference
         "RFC 5246: The Transport Layer Security (TLS) Protocol
                    Version 1.2";
     }



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     identity cipher-suite-base {
       description
         "Base identity used to identify TLS cipher suites.";
     }

     identity rsa-with-aes-128-cbc-sha {
       base cipher-suite-base;
       description
         "Cipher suite TLS_RSA_WITH_AES_128_CBC_SHA.";
       reference
         "RFC 5246: The Transport Layer Security (TLS) Protocol
                    Version 1.2";
     }

     identity rsa-with-aes-256-cbc-sha {
       base cipher-suite-base;
       description
         "Cipher suite TLS_RSA_WITH_AES_256_CBC_SHA.";
       reference
         "RFC 5246: The Transport Layer Security (TLS) Protocol
                    Version 1.2";
     }

     identity rsa-with-aes-128-cbc-sha256 {
       base cipher-suite-base;
       if-feature tls-sha2;
       description
         "Cipher suite TLS_RSA_WITH_AES_128_CBC_SHA256.";
       reference
         "RFC 5246: The Transport Layer Security (TLS) Protocol
                    Version 1.2";
     }

     identity rsa-with-aes-256-cbc-sha256 {
       base cipher-suite-base;
       if-feature tls-sha2;
       description
         "Cipher suite TLS_RSA_WITH_AES_256_CBC_SHA256.";
       reference
         "RFC 5246: The Transport Layer Security (TLS) Protocol
                    Version 1.2";
     }

     identity dhe-rsa-with-aes-128-cbc-sha {
       base cipher-suite-base;
       if-feature tls-dhe;
       description
         "Cipher suite TLS_DHE_RSA_WITH_AES_128_CBC_SHA.";



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       reference
         "RFC 5246: The Transport Layer Security (TLS) Protocol
                    Version 1.2";
     }

     identity dhe-rsa-with-aes-256-cbc-sha {
       base cipher-suite-base;
       if-feature tls-dhe;
       description
         "Cipher suite TLS_DHE_RSA_WITH_AES_256_CBC_SHA.";
       reference
         "RFC 5246: The Transport Layer Security (TLS) Protocol
                    Version 1.2";
     }

     identity dhe-rsa-with-aes-128-cbc-sha256 {
       base cipher-suite-base;
       if-feature "tls-dhe and tls-sha2";
       description
         "Cipher suite TLS_DHE_RSA_WITH_AES_128_CBC_SHA256.";
       reference
         "RFC 5246: The Transport Layer Security (TLS) Protocol
                    Version 1.2";
     }

     identity dhe-rsa-with-aes-256-cbc-sha256 {
       base cipher-suite-base;
       if-feature "tls-dhe and tls-sha2";
       description
         "Cipher suite TLS_DHE_RSA_WITH_AES_256_CBC_SHA256.";
       reference
         "RFC 5246: The Transport Layer Security (TLS) Protocol
                    Version 1.2";
     }

     identity ecdhe-ecdsa-with-aes-128-cbc-sha256 {
       base cipher-suite-base;
       if-feature "tls-ecc and tls-sha2";
       description
         "Cipher suite TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA256.";
       reference
         "RFC 5289: TLS Elliptic Curve Cipher Suites with
                    SHA-256/384 and AES Galois Counter Mode (GCM)";
     }

     identity ecdhe-ecdsa-with-aes-256-cbc-sha384 {
       base cipher-suite-base;
       if-feature "tls-ecc and tls-sha2";



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       description
         "Cipher suite TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA384.";
       reference
         "RFC 5289: TLS Elliptic Curve Cipher Suites with
                    SHA-256/384 and AES Galois Counter Mode (GCM)";
     }

     identity ecdhe-rsa-with-aes-128-cbc-sha256 {
       base cipher-suite-base;
       if-feature "tls-ecc and tls-sha2";
       description
         "Cipher suite TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256.";
       reference
         "RFC 5289: TLS Elliptic Curve Cipher Suites with
                    SHA-256/384 and AES Galois Counter Mode (GCM)";
     }

     identity ecdhe-rsa-with-aes-256-cbc-sha384 {
       base cipher-suite-base;
       if-feature "tls-ecc and tls-sha2";
       description
         "Cipher suite TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384.";
       reference
         "RFC 5289: TLS Elliptic Curve Cipher Suites with
                    SHA-256/384 and AES Galois Counter Mode (GCM)";
     }

     identity ecdhe-ecdsa-with-aes-128-gcm-sha256 {
       base cipher-suite-base;
       if-feature "tls-ecc and tls-gcm and tls-sha2";
       description
         "Cipher suite TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256.";
       reference
         "RFC 5289: TLS Elliptic Curve Cipher Suites with
                    SHA-256/384 and AES Galois Counter Mode (GCM)";
     }

     identity ecdhe-ecdsa-with-aes-256-gcm-sha384 {
       base cipher-suite-base;
       if-feature "tls-ecc and tls-gcm and tls-sha2";
       description
         "Cipher suite TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384.";
       reference
         "RFC 5289: TLS Elliptic Curve Cipher Suites with
                    SHA-256/384 and AES Galois Counter Mode (GCM)";
     }

     identity ecdhe-rsa-with-aes-128-gcm-sha256 {



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       base cipher-suite-base;
       if-feature "tls-ecc and tls-gcm and tls-sha2";
       description
         "Cipher suite TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256.";
       reference
         "RFC 5289: TLS Elliptic Curve Cipher Suites with
                    SHA-256/384 and AES Galois Counter Mode (GCM)";
     }

     identity ecdhe-rsa-with-aes-256-gcm-sha384 {
       base cipher-suite-base;
       if-feature "tls-ecc and tls-gcm and tls-sha2";
       description
         "Cipher suite TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384.";
       reference
         "RFC 5289: TLS Elliptic Curve Cipher Suites with
                    SHA-256/384 and AES Galois Counter Mode (GCM)";
     }

     identity rsa-with-3des-ede-cbc-sha {
       base cipher-suite-base;
       if-feature tls-3des;
       description
         "Cipher suite TLS_RSA_WITH_3DES_EDE_CBC_SHA.";
       reference
         "RFC 5246: The Transport Layer Security (TLS) Protocol
                    Version 1.2";
     }

     identity ecdhe-rsa-with-3des-ede-cbc-sha {
       base cipher-suite-base;
       if-feature "tls-ecc and tls-3des";
       description
         "Cipher suite TLS_ECDHE_RSA_WITH_3DES_EDE_CBC_SHA.";
       reference
         "RFC 4492: Elliptic Curve Cryptography (ECC) Cipher Suites
                    for Transport Layer Security (TLS)";
     }

     identity ecdhe-rsa-with-aes-128-cbc-sha {
       base cipher-suite-base;
       if-feature "tls-ecc";
       description
         "Cipher suite TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA.";
       reference
         "RFC 4492: Elliptic Curve Cryptography (ECC) Cipher Suites
                    for Transport Layer Security (TLS)";
     }



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     identity ecdhe-rsa-with-aes-256-cbc-sha {
       base cipher-suite-base;
       if-feature "tls-ecc";
       description
         "Cipher suite TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA.";
       reference
         "RFC 4492: Elliptic Curve Cryptography (ECC) Cipher Suites
                    for Transport Layer Security (TLS)";
     }

     // groupings

     grouping hello-params-grouping {
       description
         "A reusable grouping for TLS hello message parameters.";
       reference
         "RFC 5246: The Transport Layer Security (TLS) Protocol
                    Version 1.2";

       container tls-versions {
         description
           "Parameters regarding TLS versions.";
         leaf-list tls-version {
           type identityref {
             base tls-version-base;
           }
           description
             "Acceptable TLS protocol versions.

              If this leaf-list is not configured (has zero elements)
              the acceptable TLS protocol versions are implementation-
              defined.";
         }
       }
       container cipher-suites {
         description
           "Parameters regarding cipher suites.";
         leaf-list cipher-suite {
           type identityref {
             base cipher-suite-base;
           }
           ordered-by user;
           description
             "Acceptable cipher suites in order of descending
              preference.

              If this leaf-list is not configured (has zero elements)
              the acceptable cipher suites are implementation-



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              defined.";
         }
       }

     } // end hello-params-grouping

   }
   <CODE ENDS>

5.  Security Considerations

   The YANG modules defined in this document are designed to be accessed
   via YANG based management protocols, such as NETCONF [RFC6241] and
   RESTCONF [RFC8040].  Both of these protocols have mandatory-to-
   implement secure transport layers (e.g., SSH, TLS) with mutual
   authentication.

   The NETCONF access control model (NACM) [RFC6536] provides the means
   to restrict access for particular users to a pre-configured subset of
   all available protocol operations and content.

   Since the modules defined in this document only define groupings,
   these considerations are primarily for the designers of other modules
   that use these groupings.

   There are a number of data nodes defined in the YANG modules that are
   writable/creatable/deletable (i.e., config true, which is the
   default).  These data nodes may be considered sensitive or vulnerable
   in some network environments.  Write operations (e.g., edit-config)
   to these data nodes without proper protection can have a negative
   effect on network operations.  These are the subtrees and data nodes
   and their sensitivity/vulnerability:

      /: The entire data tree of all the groupings defined in this draft
         is sensitive to write operations.  For instance, the addition
         or removal of references to keys, certificates, trusted
         anchors, etc., can dramatically alter the implemented security
         policy.  However, no NACM annotations are applied as the data
         SHOULD be editable by users other than a designated 'recovery
         session'.

   Some of the readable data nodes in the YANG modules may be considered
   sensitive or vulnerable in some network environments.  It is thus
   important to control read access (e.g., via get, get-config, or
   notification) to these data nodes.  These are the subtrees and data
   nodes and their sensitivity/vulnerability:

      NONE



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   Some of the RPC operations in this YANG module may be considered
   sensitive or vulnerable in some network environments.  It is thus
   important to control access to these operations.  These are the
   operations and their sensitivity/vulnerability:

      NONE

6.  IANA Considerations

6.1.  The IETF XML Registry

   This document registers three 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-tls-client
      Registrant Contact: The NETCONF WG of the IETF.
      XML: N/A, the requested URI is an XML namespace.

      URI: urn:ietf:params:xml:ns:yang:ietf-tls-server
      Registrant Contact: The NETCONF WG of the IETF.
      XML: N/A, the requested URI is an XML namespace.

      URI: urn:ietf:params:xml:ns:yang:ietf-tls-common
      Registrant Contact: The NETCONF WG of the IETF.
      XML: N/A, the requested URI is an XML namespace.

6.2.  The YANG Module Names Registry

   This document registers three YANG modules in the YANG Module Names
   registry [RFC7950].  Following the format in [RFC7950], the the
   following registrations are requested:

      name:         ietf-tls-client
      namespace:    urn:ietf:params:xml:ns:yang:ietf-tls-client
      prefix:       tlsc
      reference:    RFC XXXX

      name:         ietf-tls-server
      namespace:    urn:ietf:params:xml:ns:yang:ietf-tls-server
      prefix:       tlss
      reference:    RFC XXXX

      name:         ietf-tls-common
      namespace:    urn:ietf:params:xml:ns:yang:ietf-tls-common
      prefix:       tlscmn
      reference:    RFC XXXX




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7.  Acknowledgements

   The authors would like to thank for following for lively discussions
   on list and in the halls (ordered by last name): Andy Bierman, Martin
   Bjorklund, Benoit Claise, Mehmet Ersue, Balazs Kovacs, David
   Lamparter, Alan Luchuk, Ladislav Lhotka, Radek Krejci, Tom Petch,
   Juergen Schoenwaelder, Phil Shafer, Sean Turner, and Bert Wijnen.

8.  References

8.1.  Normative References

   [I-D.ietf-netconf-keystore]
              Watsen, K., "Keystore Model", draft-ietf-netconf-
              keystore-02 (work in progress), June 2017.

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,
              <https://www.rfc-editor.org/info/rfc2119>.

   [RFC2246]  Dierks, T. and C. Allen, "The TLS Protocol Version 1.0",
              RFC 2246, DOI 10.17487/RFC2246, January 1999,
              <https://www.rfc-editor.org/info/rfc2246>.

   [RFC4346]  Dierks, T. and E. Rescorla, "The Transport Layer Security
              (TLS) Protocol Version 1.1", RFC 4346,
              DOI 10.17487/RFC4346, April 2006,
              <https://www.rfc-editor.org/info/rfc4346>.

   [RFC4492]  Blake-Wilson, S., Bolyard, N., Gupta, V., Hawk, C., and B.
              Moeller, "Elliptic Curve Cryptography (ECC) Cipher Suites
              for Transport Layer Security (TLS)", RFC 4492,
              DOI 10.17487/RFC4492, May 2006,
              <https://www.rfc-editor.org/info/rfc4492>.

   [RFC5246]  Dierks, T. and E. Rescorla, "The Transport Layer Security
              (TLS) Protocol Version 1.2", RFC 5246,
              DOI 10.17487/RFC5246, August 2008,
              <https://www.rfc-editor.org/info/rfc5246>.

   [RFC5288]  Salowey, J., Choudhury, A., and D. McGrew, "AES Galois
              Counter Mode (GCM) Cipher Suites for TLS", RFC 5288,
              DOI 10.17487/RFC5288, August 2008,
              <https://www.rfc-editor.org/info/rfc5288>.






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   [RFC5289]  Rescorla, E., "TLS Elliptic Curve Cipher Suites with SHA-
              256/384 and AES Galois Counter Mode (GCM)", RFC 5289,
              DOI 10.17487/RFC5289, August 2008,
              <https://www.rfc-editor.org/info/rfc5289>.

   [RFC6536]  Bierman, A. and M. Bjorklund, "Network Configuration
              Protocol (NETCONF) Access Control Model", RFC 6536,
              DOI 10.17487/RFC6536, March 2012,
              <https://www.rfc-editor.org/info/rfc6536>.

   [RFC6991]  Schoenwaelder, J., Ed., "Common YANG Data Types",
              RFC 6991, DOI 10.17487/RFC6991, July 2013,
              <https://www.rfc-editor.org/info/rfc6991>.

   [RFC7589]  Badra, M., Luchuk, A., and J. Schoenwaelder, "Using the
              NETCONF Protocol over Transport Layer Security (TLS) with
              Mutual X.509 Authentication", RFC 7589,
              DOI 10.17487/RFC7589, June 2015,
              <https://www.rfc-editor.org/info/rfc7589>.

   [RFC7950]  Bjorklund, M., Ed., "The YANG 1.1 Data Modeling Language",
              RFC 7950, DOI 10.17487/RFC7950, August 2016,
              <https://www.rfc-editor.org/info/rfc7950>.

   [RFC8174]  Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
              2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
              May 2017, <https://www.rfc-editor.org/info/rfc8174>.

8.2.  Informative References

   [RFC2818]  Rescorla, E., "HTTP Over TLS", RFC 2818,
              DOI 10.17487/RFC2818, May 2000,
              <https://www.rfc-editor.org/info/rfc2818>.

   [RFC3688]  Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688,
              DOI 10.17487/RFC3688, January 2004,
              <https://www.rfc-editor.org/info/rfc3688>.

   [RFC6241]  Enns, R., Ed., Bjorklund, M., Ed., Schoenwaelder, J., Ed.,
              and A. Bierman, Ed., "Network Configuration Protocol
              (NETCONF)", RFC 6241, DOI 10.17487/RFC6241, June 2011,
              <https://www.rfc-editor.org/info/rfc6241>.

   [RFC8040]  Bierman, A., Bjorklund, M., and K. Watsen, "RESTCONF
              Protocol", RFC 8040, DOI 10.17487/RFC8040, January 2017,
              <https://www.rfc-editor.org/info/rfc8040>.





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   [RFC8071]  Watsen, K., "NETCONF Call Home and RESTCONF Call Home",
              RFC 8071, DOI 10.17487/RFC8071, February 2017,
              <https://www.rfc-editor.org/info/rfc8071>.
















































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Appendix A.  Change Log

A.1.  server-model-09 to 00

   o  This draft was split out from draft-ietf-netconf-server-model-09.

   o  Noted that '0.0.0.0' and '::' might have special meanings.

A.2.  00 to 01

   o  Renamed "keychain" to "keystore".

A.3.  01 to 02

   o  Removed the groupings containing transport-level configuration.
      Now modules contain only the transport-independent groupings.

   o  Filled in previously incomplete 'ietf-tls-client' module.

   o  Added cipher suites for various algorithms into new 'ietf-tls-
      common' module.

A.4.  02 to 03

   o  Added a 'must' statement to container 'server-auth' asserting that
      at least one of the various auth mechanisms must be specified.

   o  Fixed description statement for leaf 'trusted-ca-certs'.

A.5.  03 to 04

   o  Updated title to "YANG Groupings for TLS Clients and TLS Servers"

   o  Updated leafref paths to point to new keystore path

   o  Changed the YANG prefix for ietf-tls-common from 'tlscom' to
      'tlscmn'.

   o  Added TLS protocol verions 1.0 and 1.1.

   o  Made author lists consistent

Authors' Addresses

   Kent Watsen
   Juniper Networks

   EMail: kwatsen@juniper.net



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   Gary Wu
   Cisco Systems

   EMail: garywu@cisco.com















































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