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Versions: (draft-ietf-netconf-system-keychain) 00 01 02 03 04 05 06 07 08 09 10 11

NETCONF Working Group                                          K. Watsen
Internet-Draft                                          Juniper Networks
Intended status: Standards Track                        October 30, 2017
Expires: May 3, 2018


               YANG Data Model for a "Keystore" Mechanism
                     draft-ietf-netconf-keystore-04

Abstract

   This document defines a YANG module called a "keystore", containing
   pinned certificates and pinned SSH host-keys.  The module also
   defines a grouping for configuring public key pairs and a grouping
   for configuring certificates.  The module also defines a notification
   that a system can use when one of its configured certificates is
   about to expire.

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.

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

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

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

   o  "2017-10-30" --> the publication date of this draft

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

   o  Appendix A.  Change Log

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/.



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   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 May 3, 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.  Requirements Language . . . . . . . . . . . . . . . . . .   3
   2.  Tree Diagram  . . . . . . . . . . . . . . . . . . . . . . . .   4
   3.  Example Usage . . . . . . . . . . . . . . . . . . . . . . . .   5
   4.  YANG Module . . . . . . . . . . . . . . . . . . . . . . . . .  10
   5.  Security Considerations . . . . . . . . . . . . . . . . . . .  21
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  22
     6.1.  The IETF XML Registry . . . . . . . . . . . . . . . . . .  22
     6.2.  The YANG Module Names Registry  . . . . . . . . . . . . .  22
   7.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .  23
   8.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  23
     8.1.  Normative References  . . . . . . . . . . . . . . . . . .  23
     8.2.  Informative References  . . . . . . . . . . . . . . . . .  24
   Appendix A.  Change Log . . . . . . . . . . . . . . . . . . . . .  26
     A.1.  00 to 01  . . . . . . . . . . . . . . . . . . . . . . . .  26
     A.2.  01 to 02  . . . . . . . . . . . . . . . . . . . . . . . .  26
     A.3.  02 to 03  . . . . . . . . . . . . . . . . . . . . . . . .  26
     A.4.  03 to 04  . . . . . . . . . . . . . . . . . . . . . . . .  26
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .  27








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1.  Introduction

   This document defines a YANG [RFC7950] module for a system-level
   mechanism, herein called a "keystore".  The keystore provides a
   centralized location for security sensitive data, as described below.

   This module has the following characteristics:

   o  A 'grouping' for a public/private key pair, and an 'action' for
      requesting the system to generate a new private key.

   o  A 'grouping' for a list of certificates that might be associated
      with a public/private key pair, and an 'action' the requesting a
      system to generate a certificate signing request.

   o  An unordered list of pinned certificate sets, where each pinned
      certificate set contains an unordered list of pinned certificates.
      This structure enables a server to use specific sets of pinned
      certificates on a case-by-case basis.  For instance, one set of
      pinned certificates might be used by an HTTPS-client when
      connecting to particular HTTPS servers, while another set of
      pinned certificates might be used by a server when authenticating
      client connections (e.g., certificate-based client
      authentication).

   o  An unordered list of pinned SSH host key sets, where each pinned
      SSH host key set contains an unordered list of pinned SSH host
      keys.  This structure enables a server to use specific sets of
      pinned SSH host-keys on a case-by-case basis.  For instance, SSH
      clients can be configured to use different sets of pinned SSH host
      keys when connecting to different SSH servers.

   o  A notification to indicate when a certificate is about to expire.

   Special consideration has been given for systems that have Trusted
   Protection Modules (TPMs).  These systems are unique in that the TPM
   must be directed to generate new keys (it is not possible to load a
   key into a TPM) and it is not possible to backup/restore the TPM's
   private keys as configuration.

   It is not required that a system has an operating system level
   keystore utility to implement this module.

1.1.  Requirements Language

   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



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   14 [RFC2119] [RFC8174] when, and only when, they appear in all
   capitals, as shown here.

2.  Tree Diagram

   The following tree diagram [I-D.ietf-netmod-yang-tree-diagrams]
   provides an overview of the data model for the "ietf-keystore"
   module.

   module: ietf-keystore
       +--rw keystore
          +--rw pinned-certificates* [name]
          |  +--rw name                  string
          |  +--rw description?          string
          |  +--rw pinned-certificate* [name]
          |     +--rw name    string
          |     +--rw data    binary
          +--rw pinned-host-keys* [name]
             +--rw name               string
             +--rw description?       string
             +--rw pinned-host-key* [name]
                +--rw name    string
                +--rw data    binary

     notifications:
       +---n certificate-expiration
          +--ro certificate        instance-identifier
          +--ro expiration-date    yang:date-and-time

     grouping certificate-grouping
       +---- certificates
       |  +---- certificate* [name]
       |     +---- name?    string
       |     +---- value?   binary
       +---x generate-certificate-signing-request
          +---w input
          |  +---w subject       binary
          |  +---w attributes?   binary
          +--ro output
             +--ro certificate-signing-request    binary
     grouping private-key-grouping
       +---- algorithm?              identityref
       +---- private-key?            union
       +---- public-key?             binary
       +---x generate-private-key
          +---w input
             +---w algorithm    identityref




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3.  Example Usage

   The following example illustrates what a configured keystore might
   look like.

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

     <!-- Manufacturer's trust root CA certs -->
     <pinned-certificates>
       <name>manufacturers-root-ca-certs</name>
       <description>
         Certificates built into the device for authenticating
         manufacturer-signed objects, such as TLS server certificates,
         vouchers, etc..  Note, though listed here, these are not
         configurable; any attempt to do so will be denied.
       </description>
       <pinned-certificate>
         <name>Manufacturer Root CA cert 1</name>
         <data>base64encodedvalue==</data>
       </pinned-certificate>
       <pinned-certificate>
         <name>Manufacturer Root CA cert 2</name>
         <data>base64encodedvalue==</data>
       </pinned-certificate>
     </pinned-certificates>

     <!-- pinned netconf/restconf client certificates -->
     <pinned-certificates>
       <name>explicitly-trusted-client-certs</name>
       <description>
         Specific client authentication certificates for explicitly
         trusted clients.  These are needed for client certificates
         that are not signed by a pinned CA.
       </description>
       <pinned-certificate>
         <name>George Jetson</name>
         <data>base64encodedvalue==</data>
       </pinned-certificate>
     </pinned-certificates>

     <!-- pinned netconf/restconf server certificates -->
     <pinned-certificates>
       <name>explicitly-trusted-server-certs</name>
       <description>
         Specific server authentication certificates for explicitly
         trusted servers.  These are needed for server certificates
         that are not signed by a pinned CA.
       </description>



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       <pinned-certificate>
         <name>Fred Flintstone</name>
         <data>base64encodedvalue==</data>
       </pinned-certificate>
     </pinned-certificates>

     <!-- trust anchors (CA certs) for authenticating clients -->
     <pinned-certificates>
       <name>deployment-specific-ca-certs</name>
       <description>
         Trust anchors (i.e. CA certs) that are used to authenticate
         client connections.  Clients are authenticated if their
         certificate has a chain of trust to one of these configured
         CA certificates.
       </description>
       <pinned-certificate>
         <name>ca.example.com</name>
         <data>base64encodedvalue==</data>
       </pinned-certificate>
     </pinned-certificates>

     <!-- trust anchors for random HTTPS servers on Internet -->
     <pinned-certificates>
       <name>common-ca-certs</name>
       <description>
         Trusted certificates to authenticate common HTTPS servers.
         These certificates are similar to those that might be
         shipped with a web browser.
       </description>
       <pinned-certificate>
         <name>ex-certificate-authority</name>
         <data>base64encodedvalue==</data>
       </pinned-certificate>
     </pinned-certificates>

     <!-- pinned SSH host keys -->
     <pinned-host-keys>
       <name>explicitly-trusted-ssh-host-keys</name>
       <description>
         Trusted SSH host keys used to authenticate SSH servers.
         These host keys would be analogous to those stored in
         a known_hosts file in OpenSSH.
       </description>
       <pinned-host-key>
         <name>corp-fw1</name>
         <data>base64encodedvalue==</data>
       </pinned-host-key>
     </pinned-host-keys>



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   </keystore>

   The following example illustrates the "certificate-expiration"
   notification in use with the NETCONF protocol.

   [ note: '\' line wrapping for formatting only]

   <notification
     xmlns="urn:ietf:params:xml:ns:netconf:notification:1.0">
     <eventTime>2016-07-08T00:01:00Z</eventTime>
     <certificate-expiration
       xmlns="urn:ietf:params:xml:ns:yang:ietf-keystore">
       <certificate xmlns:ks="urn:ietf:params:xml:ns:yang:ietf-keystore\
   ">
         /ks:keystore/ks:keys/ks:key[ks:name='ex-rsa-key']/ks:certifica\
   tes/ks:certificate[ks:name='ex-rsa-cert']
       </certificate>
       <expiration-date>2016-08-08T14:18:53-05:00</expiration-date>
     </certificate-expiration>
   </notification>


   The following example module has been constructed to illustrate the
   groupings defined in the "ietf-keystore" module.



























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   module ex-keystore-usage {
     yang-version 1.1;

     namespace "http://example.com/ns/example-keystore-usage";
     prefix "eku";

     import ietf-keystore {
       prefix ks;
       reference
         "RFC VVVV: YANG Data Model for a 'Keystore' Mechanism";
     }

     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>";

     description
      "This module uses the groupings defines the keystore draft
       for illustration.";

     revision "YYYY-MM-DD" {
       description
        "Initial version";
     }

     container key {
       uses ks:private-key-grouping;
       uses ks:certificate-grouping;
       description
         "A container of certificates, and an action to generate
          a certificate signing request.";
     }
   }

   The following example illustrates what a configured key might look
   like.  This example uses the "ex-keystore-usage" module above.











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  [ note: '\' line wrapping for formatting only]

  <key xmlns="http://example.com/ns/example-keystore-usage">
    <algorithm xmlns:ks="urn:ietf:params:xml:ns:yang:ietf-keystore">ks:\
  secp521r1</algorithm>
    <private-key>base64encodedvalue==</private-key>
    <public-key>base64encodedvalue==</public-key>
    <certificates>
      <certificate>
        <name>domain certificate</name>
        <value>base64encodedvalue==</value>
      </certificate>
    </certificates>
   </key>

   The following example illustrates the "generate-certificate-signing-
   request" action in use with the NETCONF protocol.  This example uses
   the "ex-keystore-usage" module above.

  REQUEST
  -------
  <rpc message-id="101" xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
    <action xmlns="urn:ietf:params:xml:ns:yang:1">
      <key xmlns="http://example.com/ns/example-keystore-usage">
        <generate-certificate-signing-request>
          <subject>base64encodedvalue==</subject>
          <attributes>base64encodedvalue==</attributes>
        </generate-certificate-signing-request>
      </key>
    </action>
  </rpc>

  RESPONSE
  --------
  <rpc-reply message-id="101"
     xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
     <certificate-signing-request
       xmlns="http://example.com/ns/example-keystore-usage">
       base64encodedvalue==
     </certificate-signing-request>
  </rpc-reply>


   The following example illustrates the "generate-private-key" action
   in use with the NETCONF protocol.  This example uses the "ex-
   keystore-usage" module above.





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   REQUEST
   -------
   [ note: '\' line wrapping for formatting only]

   <rpc message-id="101" xmlns="urn:ietf:params:xml:ns:netconf:base:1.0\
   ">
     <action xmlns="urn:ietf:params:xml:ns:yang:1">
       <key xmlns="http://example.com/ns/example-keystore-usage">
         <generate-private-key>
           <algorithm xmlns:ks="urn:ietf:params:xml:ns:yang:ietf-keysto\
   re">ks:secp521r1</algorithm>
         </generate-private-key>
       </key>
     </action>
   </rpc>

   RESPONSE
   --------
   <rpc-reply message-id="101"
      xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
     <ok/>
   </rpc-reply>

4.  YANG Module

   This YANG module imports modules defined in [RFC6536] and [RFC6991].
   This module uses data types defined in [RFC2315], [RFC2986],
   [RFC3447], [RFC4253], [RFC5280], [RFC5915], and [ITU.X690.1994].
   This module uses algorithms defined in [RFC3447] and [RFC5480].

  <CODE BEGINS> file "ietf-keystore@2017-10-30.yang"
  module ietf-keystore {
    yang-version 1.1;

    namespace "urn:ietf:params:xml:ns:yang:ietf-keystore";
    prefix "ks";

    import ietf-yang-types {
      prefix yang;
      reference
        "RFC 6991: Common YANG Data Types";
    }

    import ietf-netconf-acm {
      prefix nacm;
      reference
        "RFC 6536: Network Configuration Protocol (NETCONF) Access
         Control Model";



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    }

    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>";


    description
     "This module defines a keystore to centralize management
      of security credentials.

      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 VVVV; see
      the RFC itself for full legal notices.";

    revision "2017-10-30" {
      description
       "Initial version";
      reference
       "RFC VVVV: YANG Data Model for a 'Keystore' Mechanism";
    }

    // Identities

    identity key-algorithm {
      description
        "Base identity from which all key-algorithms are derived.";
    }

    identity rsa1024 {
      base key-algorithm;
      description
        "The RSA algorithm using a 1024-bit key.";



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      reference
        "RFC3447: Public-Key Cryptography Standards (PKCS) #1:
                  RSA Cryptography Specifications Version 2.1.";
    }

    identity rsa2048 {
      base key-algorithm;
      description
        "The RSA algorithm using a 2048-bit key.";
      reference
        "RFC3447: Public-Key Cryptography Standards (PKCS) #1:
                  RSA Cryptography Specifications Version 2.1.";
    }

    identity rsa3072 {
      base key-algorithm;
      description
        "The RSA algorithm using a 3072-bit key.";
      reference
        "RFC3447: Public-Key Cryptography Standards (PKCS) #1:
                  RSA Cryptography Specifications Version 2.1.";
    }

    identity rsa4096 {
      base key-algorithm;
      description
        "The RSA algorithm using a 4096-bit key.";
      reference
        "RFC3447: Public-Key Cryptography Standards (PKCS) #1:
                  RSA Cryptography Specifications Version 2.1.";
    }

    identity rsa7680 {
      base key-algorithm;
      description
        "The RSA algorithm using a 7680-bit key.";
      reference
        "RFC3447: Public-Key Cryptography Standards (PKCS) #1:
                  RSA Cryptography Specifications Version 2.1.";
    }

    identity rsa15360 {
      base key-algorithm;
      description
        "The RSA algorithm using a 15360-bit key.";
      reference
        "RFC3447: Public-Key Cryptography Standards (PKCS) #1:
                  RSA Cryptography Specifications Version 2.1.";



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    }

    identity secp192r1 {
      base key-algorithm;
      description
        "The secp192r1 algorithm.";
      reference
        "RFC5480:
           Elliptic Curve Cryptography Subject Public Key Information.";
    }

    identity secp256r1 {
      base key-algorithm;
      description
        "The secp256r1 algorithm.";
      reference
        "RFC5480:
           Elliptic Curve Cryptography Subject Public Key Information.";
    }

    identity secp384r1 {
      base key-algorithm;
      description
        "The secp384r1 algorithm.";
      reference
        "RFC5480:
           Elliptic Curve Cryptography Subject Public Key Information.";
    }

    identity secp521r1 {
      base key-algorithm;
      description
        "The secp521r1 algorithm.";
      reference
        "RFC5480:
           Elliptic Curve Cryptography Subject Public Key Information.";
    }


    // typedefs

    typedef pinned-certificates {
      type leafref {
        path "/ks:keystore/ks:pinned-certificates/ks:name";
      }
      description
        "This typedef enables importing modules to easily define a
         reference to pinned-certificates.  Use of this type also



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         impacts the YANG tree diagram output.";
      reference
        "I-D.ietf-netmod-yang-tree-diagrams: YANG Tree Diagrams";
    }

    typedef pinned-host-keys {
      type leafref {
        path "/ks:keystore/ks:pinned-host-keys/ks:name";
      }
      description
        "This typedef enables importing modules to easily define a
         reference to pinned-host-keys.  Use of this type also
         impacts the YANG tree diagram output.";
      reference
        "I-D.ietf-netmod-yang-tree-diagrams: YANG Tree Diagrams";
    }


    // groupings

    grouping private-key-grouping {
      description
        "A private/public key pair, and an action to request the
         system to generate a private key.";
      leaf algorithm {
        type identityref {
          base "key-algorithm";
        }
        description
          "Identifies the key's algorithm.  More specifically, this
           leaf specifies how the 'private-key' and 'public-key'
           binary leafs are encoded.";
      }
      leaf private-key {
        nacm:default-deny-all;
        type union {
          type binary;
          type enumeration {
            enum "hardware-protected" {
              description
               "The private key is inaccessible due to being
                protected by a cryptographic hardware module
                (e.g., a TPM).";
            }
          }
        }
        must "../algorithm";
        description



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          "A binary that contains the value of the private key.  The
           interpretation of the content is defined by the key
           algorithm.  For example, a DSA key is an integer, an RSA
           key is represented as RSAPrivateKey as defined in
           [RFC3447], and an Elliptic Curve Cryptography (ECC) key
           is represented as ECPrivateKey as defined in [RFC5915]";
        reference
          "RFC 3447: Public-Key Cryptography Standards (PKCS) #1:
                     RSA Cryptography Specifications Version 2.1.
           RFC 5915: Elliptic Curve Private Key Structure.";
      }
      leaf public-key {
        type binary;
        must "../algorithm";
        must "../private-key";
        description
          "A binary that contains the value of the public key.  The
           interpretation of the content is defined by the key
           algorithm.  For example, a DSA key is an integer, an RSA
           key is represented as RSAPublicKey as defined in
           [RFC3447], and an Elliptic Curve Cryptography (ECC) key
           is represented using the 'publicKey' described in
           [RFC5915]";
        reference
          "RFC 3447: Public-Key Cryptography Standards (PKCS) #1:
                     RSA Cryptography Specifications Version 2.1.
           RFC 5915: Elliptic Curve Private Key Structure.";
      }
      action generate-private-key {
        description
          "Requests the device to generate a private key using the
           specified key algorithm.  This action is primarily to
           support cryptographic processors that must generate
           the private key themselves.  The resulting key is
           considered operational state and hence only present
           in the <operational>.";
        input {
          leaf algorithm {
            type identityref {
              base "key-algorithm";
            }
            mandatory true;
            description
              "The algorithm to be used when generating the key.";
          }
        }
      } // end generate-private-key
    }



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    grouping certificate-grouping {
      description
        "A container of certificates, and an action to generate
         a certificate signing request.";
      container certificates {
        description
          "Certificates associated with this key.  More than one
           certificate supports, for instance, a TPM-protected
           key that has both IDevID and LDevID certificates
           associated.";
        list certificate {
          key name;
          description
            "A certificate for this private key.";
          leaf name {
            type string;
            description
              "An arbitrary name for the certificate.";
          }
          leaf value {
            type binary;
            description
             "A PKCS #7 SignedData structure, as specified by
              Section 9.1 in RFC 2315, containing just certificates
              (no content, signatures, or CRLs), encoded using ASN.1
              distinguished encoding rules (DER), as specified in
              ITU-T X.690.

              This structure contains the certificate itself as well
              as any intermediate certificates leading up to a trust
              anchor certificate.  The trust anchor certificate MAY
              be included as well.";
            reference
              "RFC 2315:
                 PKCS #7: Cryptographic Message Syntax Version 1.5.
               ITU-T X.690:
                 Information technology - ASN.1 encoding rules:
                 Specification of Basic Encoding Rules (BER),
                 Canonical Encoding Rules (CER) and Distinguished
                 Encoding Rules (DER).";
          }
        }
      }
      action generate-certificate-signing-request {
        description
          "Generates a certificate signing request structure for
           the associated private key using the passed subject and
           attribute values.  The specified assertions need to be



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           appropriate for the certificate's use.  For example,
           an entity certificate for a TLS server SHOULD have
           values that enable clients to satisfy RFC 6125
           processing.";
        input {
          leaf subject {
            type binary;
            mandatory true;
            description
              "The 'subject' field from the CertificationRequestInfo
               structure as specified by RFC 2986, Section 4.1 encoded
               using the ASN.1 distinguished encoding rules (DER), as
               specified in ITU-T X.690.";
            reference
              "RFC 2986:
                 PKCS #10: Certification Request Syntax Specification
                 Version 1.7.
               ITU-T X.690:
                  Information technology - ASN.1 encoding rules:
                  Specification of Basic Encoding Rules (BER),
                  Canonical Encoding Rules (CER) and Distinguished
                  Encoding Rules (DER).";
          }
          leaf attributes {
            type binary;
            description
             "The 'attributes' field from the CertificationRequestInfo
              structure as specified by RFC 2986, Section 4.1 encoded
              using the ASN.1 distinguished encoding rules (DER), as
              specified in ITU-T X.690.";
            reference
              "RFC 2986:
                 PKCS #10: Certification Request Syntax Specification
                 Version 1.7.
               ITU-T X.690:
                  Information technology - ASN.1 encoding rules:
                  Specification of Basic Encoding Rules (BER),
                  Canonical Encoding Rules (CER) and Distinguished
                  Encoding Rules (DER).";
          }
        }
        output {
          leaf certificate-signing-request {
            type binary;
            mandatory true;
            description
              "A CertificationRequest structure as specified by RFC
               2986, Section 4.1 encoded using the ASN.1 distinguished



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               encoding rules (DER), as specified in ITU-T X.690.";
            reference
              "RFC 2986:
                 PKCS #10: Certification Request Syntax Specification
                 Version 1.7.
               ITU-T X.690:
                  Information technology - ASN.1 encoding rules:
                  Specification of Basic Encoding Rules (BER),
                  Canonical Encoding Rules (CER) and Distinguished
                  Encoding Rules (DER).";

          }
        }
      }
    }


    // protocol accessible nodes

    container keystore {
      nacm:default-deny-write;
      description
        "The keystore contains X.509 certificates and SSH host keys.";

      list pinned-certificates {
        key name;
        description
          "A list of pinned certificates.  These certificates can be
           used by a server to authenticate clients, or by clients to
           authenticate servers.   Each list of pinned certificates
           SHOULD be specific to a purpose, as the list as a whole
           may be referenced by other modules.  For instance, a
           NETCONF server's configuration might use a specific list
           of pinned certificates for when authenticating NETCONF
           client connections.";
        leaf name {
          type string;
          description
            "An arbitrary name for this list of pinned certificates.";
        }
        leaf description {
          type string;
          description
            "An arbitrary description for this list of pinned
             certificates.";
        }
        list pinned-certificate {
          key name;



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          description
            "A pinned certificate.";
          leaf name {
            type string;
            description
              "An arbitrary name for this pinned certificate. The
               name must be unique across all lists of pinned
               certificates (not just this list) so that leafrefs
               from another module can resolve to unique values.";
          }
          leaf data {
            type binary;
            mandatory true;
            description
              "An X.509 v3 certificate structure as specified by RFC
               5280, Section 4 encoded using the ASN.1 distinguished
               encoding rules (DER), as specified in ITU-T X.690.";
            reference
              "RFC 5280:
                 Internet X.509 Public Key Infrastructure Certificate
                 and Certificate Revocation List (CRL) Profile.
               ITU-T X.690:
                  Information technology - ASN.1 encoding rules:
                  Specification of Basic Encoding Rules (BER),
                  Canonical Encoding Rules (CER) and Distinguished
                  Encoding Rules (DER).";
          }
        }
      }

      list pinned-host-keys {
        key name;
        description
          "A list of pinned host keys.  These pinned host-keys can
           be used by clients to authenticate SSH servers.  Each
           list of pinned host keys SHOULD be specific to a purpose,
           so the list as a whole may be referenced by other modules.
           For instance, a NETCONF client's configuration might
           point to a specific list of pinned host keys for when
           authenticating specific SSH servers.";
        leaf name {
          type string;
          description
            "An arbitrary name for this list of pinned SSH host keys.";
        }
        leaf description {
          type string;
          description



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            "An arbitrary description for this list of pinned SSH host
             keys.";
        }
        list pinned-host-key {
          key name;
          description
            "A pinned host key.";
          leaf name {
            type string;
            description
              "An arbitrary name for this pinned host-key. Must be
               unique across all lists of pinned host-keys (not just
               this list) so that a leafref to it from another module
               can resolve to unique values.";
          }
          leaf data {
            type binary;
            mandatory true;
            description
              "The binary public key data for this SSH key, as
               specified by RFC 4253, Section 6.6, i.e.:

                 string    certificate or public key format
                           identifier
                 byte[n]   key/certificate data.";
            reference
              "RFC 4253: The Secure Shell (SSH) Transport Layer
                         Protocol";
          }
        }
      }
    }

    notification certificate-expiration {
      description
        "A notification indicating that a configured certificate is
         either about to expire or has already expired.  When to send
         notifications is an implementation specific decision, but
         it is RECOMMENDED that a notification be sent once a month
         for 3 months, then once a week for four weeks, and then once
         a day thereafter.";
      leaf certificate {
        type instance-identifier;
        mandatory true;
        description
          "Identifies which certificate is expiring or is expired.";
      }
      leaf expiration-date {



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        type yang:date-and-time;
        mandatory true;
        description
          "Identifies the expiration date on the certificate.";
      }
    }

  }
  <CODE ENDS>

5.  Security Considerations

   The YANG module defined in this document is 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.

   There are a number of data nodes defined in this YANG module 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 defined by this module is sensitive to
         write operations.  For instance, the addition or removal of
         keys, certificates, trusted anchors, etc., can dramatically
         alter the implemented security policy.  This being the case,
         the top-level node in this module is marked with the NACM value
         'default-deny-write'.

      /keystore/keys/key/private-key:  When writing this node,
         implementations MUST ensure that the strength of the key being
         configured is not greater than the strength of the underlying
         secure transport connection over which it is communicated.
         Implementations SHOULD fail the write-request if ever the
         strength of the private key is greater then the strength of the
         underlying transport, and alert the client that the strength of
         the key may have been compromised.  Additionally, when deleting
         this node, implementations SHOULD automatically (without
         explicit request) zeroize these keys in the most secure manner




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         available, so as to prevent the remnants of their persisted
         storage locations from being analyzed in any meaningful way.

   Some of the readable data nodes in this YANG module 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:

      /keystore/keys/key/private-key:  This node is additionally
         sensitive to read operations such that, in normal use cases, it
         should never be returned to a client.  The best reason for
         returning this node is to support backup/restore type
         workflows.  This being the case, this node is marked with the
         NACM value 'default-deny-all'.

   Some of the 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:

      generate-certificate-signing-request:  For this action, it is
         RECOMMENDED that implementations assert channel binding
         [RFC5056], so as to ensure that the application layer that sent
         the request is the same as the device authenticated when the
         secure transport layer was established.

6.  IANA Considerations

6.1.  The IETF XML Registry

   This document registers one URI in the IETF XML registry [RFC3688].
   Following the format in [RFC3688], the following registration is
   requested:

      URI: urn:ietf:params:xml:ns:yang:ietf-keystore
      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 one YANG module in the YANG Module Names
   registry [RFC6020].  Following the format in [RFC6020], the the
   following registration is requested:







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      name:         ietf-keystore
      namespace:    urn:ietf:params:xml:ns:yang:ietf-keystore
      prefix:       ks
      reference:    RFC VVVV


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

   [ITU.X690.1994]
              International Telecommunications Union, "Information
              Technology - ASN.1 encoding rules: Specification of Basic
              Encoding Rules (BER), Canonical Encoding Rules (CER) and
              Distinguished Encoding Rules (DER)", ITU-T Recommendation
              X.690, 1994.

   [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>.

   [RFC2315]  Kaliski, B., "PKCS #7: Cryptographic Message Syntax
              Version 1.5", RFC 2315, DOI 10.17487/RFC2315, March 1998,
              <https://www.rfc-editor.org/info/rfc2315>.

   [RFC2986]  Nystrom, M. and B. Kaliski, "PKCS #10: Certification
              Request Syntax Specification Version 1.7", RFC 2986,
              DOI 10.17487/RFC2986, November 2000,
              <https://www.rfc-editor.org/info/rfc2986>.

   [RFC3447]  Jonsson, J. and B. Kaliski, "Public-Key Cryptography
              Standards (PKCS) #1: RSA Cryptography Specifications
              Version 2.1", RFC 3447, DOI 10.17487/RFC3447, February
              2003, <https://www.rfc-editor.org/info/rfc3447>.

   [RFC4253]  Ylonen, T. and C. Lonvick, Ed., "The Secure Shell (SSH)
              Transport Layer Protocol", RFC 4253, DOI 10.17487/RFC4253,
              January 2006, <https://www.rfc-editor.org/info/rfc4253>.




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   [RFC5280]  Cooper, D., Santesson, S., Farrell, S., Boeyen, S.,
              Housley, R., and W. Polk, "Internet X.509 Public Key
              Infrastructure Certificate and Certificate Revocation List
              (CRL) Profile", RFC 5280, DOI 10.17487/RFC5280, May 2008,
              <https://www.rfc-editor.org/info/rfc5280>.

   [RFC5480]  Turner, S., Brown, D., Yiu, K., Housley, R., and T. Polk,
              "Elliptic Curve Cryptography Subject Public Key
              Information", RFC 5480, DOI 10.17487/RFC5480, March 2009,
              <https://www.rfc-editor.org/info/rfc5480>.

   [RFC5915]  Turner, S. and D. Brown, "Elliptic Curve Private Key
              Structure", RFC 5915, DOI 10.17487/RFC5915, June 2010,
              <https://www.rfc-editor.org/info/rfc5915>.

   [RFC6020]  Bjorklund, M., Ed., "YANG - A Data Modeling Language for
              the Network Configuration Protocol (NETCONF)", RFC 6020,
              DOI 10.17487/RFC6020, October 2010,
              <https://www.rfc-editor.org/info/rfc6020>.

   [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>.

   [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>.

8.2.  Informative References

   [I-D.ietf-netmod-yang-tree-diagrams]
              Bjorklund, M. and L. Berger, "YANG Tree Diagrams", draft-
              ietf-netmod-yang-tree-diagrams-02 (work in progress),
              October 2017.

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

   [RFC4211]  Schaad, J., "Internet X.509 Public Key Infrastructure
              Certificate Request Message Format (CRMF)", RFC 4211,
              DOI 10.17487/RFC4211, September 2005,
              <https://www.rfc-editor.org/info/rfc4211>.



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   [RFC5056]  Williams, N., "On the Use of Channel Bindings to Secure
              Channels", RFC 5056, DOI 10.17487/RFC5056, November 2007,
              <https://www.rfc-editor.org/info/rfc5056>.

   [RFC5914]  Housley, R., Ashmore, S., and C. Wallace, "Trust Anchor
              Format", RFC 5914, DOI 10.17487/RFC5914, June 2010,
              <https://www.rfc-editor.org/info/rfc5914>.

   [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>.

   [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>.

   [Std-802.1AR-2009]
              IEEE SA-Standards Board, "IEEE Standard for Local and
              metropolitan area networks - Secure Device Identity",
              December 2009, <http://standards.ieee.org/findstds/
              standard/802.1AR-2009.html>.

























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Appendix A.  Change Log

A.1.  00 to 01

   o  Replaced the 'certificate-chain' structures with PKCS#7
      structures.  (Issue #1)

   o  Added 'private-key' as a configurable data node, and removed the
      'generate-private-key' and 'load-private-key' actions.  (Issue #2)

   o  Moved 'user-auth-credentials' to the ietf-ssh-client module.
      (Issues #4 and #5)

A.2.  01 to 02

   o  Added back 'generate-private-key' action.

   o  Removed 'RESTRICTED' enum from the 'private-key' leaf type.

   o  Fixed up a few description statements.

A.3.  02 to 03

   o  Changed draft's title.

   o  Added missing references.

   o  Collapsed sections and levels.

   o  Added RFC 8174 to Requirements Language Section.

   o  Renamed 'trusted-certificates' to 'pinned-certificates'.

   o  Changed 'public-key' from config false to config true.

   o  Switched 'host-key' from OneAsymmetricKey to definition from RFC
      4253.

A.4.  03 to 04

   o  Added typedefs around leafrefs to common keystore paths

   o  Now tree diagrams reference ietf-netmod-yang-tree-diagrams

   o  Removed Design Considerations section

   o  Moved key and certificate definitions from data tree to groupings




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Author's Address

   Kent Watsen
   Juniper Networks

   EMail: kwatsen@juniper.net













































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