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Versions: (draft-ietf-netconf-system-keychain) 00 01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16 18

NETCONF Working Group                                          K. Watsen
Internet-Draft                                           Watsen Networks
Intended status: Standards Track                             8 July 2020
Expires: 9 January 2021


                    A YANG Data Model for a Keystore
                     draft-ietf-netconf-keystore-18

Abstract

   This document defines a YANG 1.1 module called "ietf-keystore" that
   enables centralized configuration of both symmetric and asymmetric
   keys.  The secret value for both key types may be encrypted.
   Asymmetric keys may be associated with certificates.  Notifications
   are sent when certificates are about to expire.

Editorial Note (To be removed by RFC Editor)

   This draft contains 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:

   *  "AAAA" --> the assigned RFC value for draft-ietf-netconf-crypto-
      types

   *  "CCCC" --> 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:

   *  "2020-07-08" --> the publication date of this draft

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

   *  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.






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   This Internet-Draft will expire on 9 January 2021.

Copyright Notice

   Copyright (c) 2020 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/
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   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.  Relation to other RFCs  . . . . . . . . . . . . . . . . .   4
     1.2.  Specification Language  . . . . . . . . . . . . . . . . .   5
     1.3.  Adherence to the NMDA . . . . . . . . . . . . . . . . . .   5
   2.  The "ietf-keystore" Module  . . . . . . . . . . . . . . . . .   5
     2.1.  Data Model Overview . . . . . . . . . . . . . . . . . . .   5
     2.2.  Example Usage . . . . . . . . . . . . . . . . . . . . . .  12
     2.3.  YANG Module . . . . . . . . . . . . . . . . . . . . . . .  23
   3.  Support for Built-in Keys . . . . . . . . . . . . . . . . . .  31
   4.  Encrypting Keys in Configuration  . . . . . . . . . . . . . .  34
   5.  Security Considerations . . . . . . . . . . . . . . . . . . .  38
     5.1.  Data at Rest  . . . . . . . . . . . . . . . . . . . . . .  38
     5.2.  The "ietf-keystore" YANG Module . . . . . . . . . . . . .  38
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  39
     6.1.  The IETF XML Registry . . . . . . . . . . . . . . . . . .  39
     6.2.  The YANG Module Names Registry  . . . . . . . . . . . . .  39
   7.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  39
     7.1.  Normative References  . . . . . . . . . . . . . . . . . .  39
     7.2.  Informative References  . . . . . . . . . . . . . . . . .  40
   Appendix A.  Change Log . . . . . . . . . . . . . . . . . . . . .  42



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     A.1.  00 to 01  . . . . . . . . . . . . . . . . . . . . . . . .  42
     A.2.  01 to 02  . . . . . . . . . . . . . . . . . . . . . . . .  42
     A.3.  02 to 03  . . . . . . . . . . . . . . . . . . . . . . . .  42
     A.4.  03 to 04  . . . . . . . . . . . . . . . . . . . . . . . .  42
     A.5.  04 to 05  . . . . . . . . . . . . . . . . . . . . . . . .  43
     A.6.  05 to 06  . . . . . . . . . . . . . . . . . . . . . . . .  43
     A.7.  06 to 07  . . . . . . . . . . . . . . . . . . . . . . . .  43
     A.8.  07 to 08  . . . . . . . . . . . . . . . . . . . . . . . .  43
     A.9.  08 to 09  . . . . . . . . . . . . . . . . . . . . . . . .  43
     A.10. 09 to 10  . . . . . . . . . . . . . . . . . . . . . . . .  44
     A.11. 10 to 11  . . . . . . . . . . . . . . . . . . . . . . . .  44
     A.12. 11 to 12  . . . . . . . . . . . . . . . . . . . . . . . .  44
     A.13. 12 to 13  . . . . . . . . . . . . . . . . . . . . . . . .  45
     A.14. 13 to 14  . . . . . . . . . . . . . . . . . . . . . . . .  45
     A.15. 14 to 15  . . . . . . . . . . . . . . . . . . . . . . . .  45
     A.16. 15 to 16  . . . . . . . . . . . . . . . . . . . . . . . .  45
     A.17. 16 to 17  . . . . . . . . . . . . . . . . . . . . . . . .  45
     A.18. 17 to 18  . . . . . . . . . . . . . . . . . . . . . . . .  46
   Acknowledgements  . . . . . . . . . . . . . . . . . . . . . . . .  46
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .  46

1.  Introduction

   This document defines a YANG 1.1 [RFC7950] module called "ietf-
   keystore" that enables centralized configuration of both symmetric
   and asymmetric keys.  The secret value for both key types may be
   encrypted.  Asymmetric keys may be associated with certificates.
   Notifications are sent when certificates are about to expire.

   The "ietf-keystore" module defines many "grouping" statements
   intended for use by other modules that may import it.  For instance,
   there are groupings that defined enabling a key to be either
   configured locally (within the defining data model) or be a reference
   to a key in the Keystore.

   Special consideration has been given for systems that have
   cryptographic hardware, such as a Trusted Protection Module (TPM).
   These systems are unique in that the cryptographic hardware hides the
   secret key values.  To support such hardware, symmetric keys may have
   the value "hidden-key" and asymmetric keys may have the value
   "hidden-private-key".  While how such keys are created or destroyed
   is outside the scope of this document, the Keystore can contain
   entries for such keys, enabling them to be referenced by other
   configuration elements.







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   It is not required that a system has an operating system level
   keystore utility, with or without HSM backing, to implement this
   module.  It is also possible that a system implementing the module to
   possess a multiplicity of operating system level keystore utilities
   and/or a multiplicity of HSMs.

1.1.  Relation to other RFCs

   This document presents one or more YANG modules [RFC7950] that are
   part of a collection of RFCs that work together to define
   configuration modules for clients and servers of both the NETCONF
   [RFC6241] and RESTCONF [RFC8040] protocols.

   The modules have been defined in a modular fashion to enable their
   use by other efforts, some of which are known to be in progress at
   the time of this writing, with many more expected to be defined in
   time.

   The relationship between the various RFCs in the collection is
   presented in the below diagram.  The labels in the diagram represent
   the primary purpose provided by each RFC.  Links the each RFC are
   provided below the diagram.

                                  crypto-types
                                    ^      ^
                                   /        \
                                  /          \
                         truststore         keystore
                          ^     ^             ^  ^
                          |     +---------+   |  |
                          |               |   |  |
                          |      +------------+  |
   tcp-client-server      |     /         |      |
      ^    ^        ssh-client-server     |      |
      |    |           ^            tls-client-server
      |    |           |              ^     ^        http-client-server
      |    |           |              |     |                 ^
      |    |           |        +-----+     +---------+       |
      |    |           |        |                     |       |
      |    +-----------|--------|--------------+      |       |
      |                |        |              |      |       |
      +-----------+    |        |              |      |       |
                  |    |        |              |      |       |
                  |    |        |              |      |       |
               netconf-client-server       restconf-client-server






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   +=======================+===========================================+
   | Label in Diagram      | Originating RFC                           |
   +=======================+===========================================+
   | crypto-types          | [I-D.ietf-netconf-crypto-types]           |
   +-----------------------+-------------------------------------------+
   | truststore            | [I-D.ietf-netconf-trust-anchors]          |
   +-----------------------+-------------------------------------------+
   | keystore              | [I-D.ietf-netconf-keystore]               |
   +-----------------------+-------------------------------------------+
   | tcp-client-server     | [I-D.ietf-netconf-tcp-client-server]      |
   +-----------------------+-------------------------------------------+
   | ssh-client-server     | [I-D.ietf-netconf-ssh-client-server]      |
   +-----------------------+-------------------------------------------+
   | tls-client-server     | [I-D.ietf-netconf-tls-client-server]      |
   +-----------------------+-------------------------------------------+
   | http-client-server    | [I-D.ietf-netconf-http-client-server]     |
   +-----------------------+-------------------------------------------+
   | netconf-client-server | [I-D.ietf-netconf-netconf-client-server]  |
   +-----------------------+-------------------------------------------+
   |restconf-client-server | [I-D.ietf-netconf-restconf-client-server] |
   +-----------------------+-------------------------------------------+

                       Table 1: Label to RFC Mapping

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

1.3.  Adherence to the NMDA

   This document in compliant with Network Management Datastore
   Architecture (NMDA) [RFC8342].  For instance, keys and associated
   certificates installed during manufacturing (e.g., for an IDevID
   [Std-802.1AR-2009] certificate) are expected to appear in
   <operational> (see Section 3).

2.  The "ietf-keystore" Module

   This section defines a YANG 1.1 [RFC7950] module that defines a
   "keystore" and groupings supporting downstream modules to reference
   the keystore or have locally-defined definitions.

2.1.  Data Model Overview




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2.1.1.  Features

   The following diagram lists all the "feature" statements defined in
   the "ietf-keystore" module:

   Features:
     +-- keystore-supported
     +-- local-definitions-supported

2.1.2.  Typedefs

   The following diagram lists the "typedef" statements defined in the
   "ietf-keystore" module:

   Typedefs:
     leafref
       +-- symmetric-key-ref
       +-- asymmetric-key-ref

   Comments:

   *  All of the typedefs defined in the "ietf-keystore" module extend
      the base "leafref" type defined in [RFC7950].

   *  The leafrefs refer to symmetric and asymmetric keys in the
      keystore.  These typedefs are provided primarily as an aid to
      downstream modules that import the "ietf-keystore" module.

2.1.3.  Groupings

   The following diagram lists all the "grouping" statements defined in
   the "ietf-keystore" module:

   Groupings:
     +-- encrypted-by-choice-grouping
     +-- asymmetric-key-certificate-ref-grouping
     +-- local-or-keystore-symmetric-key-grouping
     +-- local-or-keystore-asymmetric-key-grouping
     +-- local-or-keystore-asymmetric-key-with-certs-grouping
     +-- local-or-keystore-end-entity-cert-with-key-grouping
     +-- keystore-grouping

   Each of these groupings are presented in the following subsections.

2.1.3.1.  The "encrypted-by-choice-grouping" Grouping

   The following tree diagram [RFC8340] illustrates the "encrypted-by-
   choice-grouping" grouping:



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      |  The grouping's name is intended to be parsed "(encrypted-by)-
      |  (choice-grouping)", not as "(encrypted)-(by-
      |  choice)-(grouping)".

     grouping encrypted-by-choice-grouping
       +-- (encrypted-by-choice)
          +--:(symmetric-key-ref)
          |  +-- symmetric-key-ref?
          |          -> /keystore/symmetric-keys/symmetric-key/name
          +--:(asymmetric-key-ref)
             +-- asymmetric-key-ref?
                     -> /keystore/asymmetric-keys/asymmetric-key/name

   Comments:

   *  This grouping defines a "choice" statement with options to
      reference either a symmetric or an asymmetric key configured in
      the keystore.

2.1.3.2.  The "asymmetric-key-certificate-ref-grouping" Grouping

   The following tree diagram [RFC8340] illustrates the "asymmetric-key-
   certificate-ref-grouping" grouping:

     grouping asymmetric-key-certificate-ref-grouping
       +-- asymmetric-key?   ks:asymmetric-key-ref
       +-- certificate?      leafref

   Comments:

   *  This grouping defines a reference to a certificate in two parts:
      the first being the name of the asymmetric key the certificate is
      associated with, and the second being the name of the certificate
      itself.

2.1.3.3.  The "local-or-keystore-symmetric-key-grouping" Grouping

   The following tree diagram [RFC8340] illustrates the "local-or-
   keystore-symmetric-key-grouping" grouping:

     grouping local-or-keystore-symmetric-key-grouping
       +-- (local-or-keystore)
          +--:(local) {local-definitions-supported}?
          |  +-- local-definition
          |     +---u ct:symmetric-key-grouping
          +--:(keystore) {keystore-supported}?
             +-- keystore-reference?   ks:symmetric-key-ref




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   Comments:

   *  The "local-or-keystore-symmetric-key-grouping" grouping is
      provided soley as convenience to downstream modules that wish to
      offer an option as to if an symmetric key is defined locally or as
      a reference to a symmetric key in the keystore.

   *  A "choice" statement is used to expose the various options.  Each
      option is enabled by a "feature" statement.  Additional "case"
      statements MAY be augmented in if, e.g., there is a need to
      reference a symmetric key in an alternate location.

   *  For the "local-definition" option, the defintion uses the
      "symmetric-key-grouping" grouping discussed in Section 2.1.3.2 of
      [I-D.ietf-netconf-crypto-types].

   *  For the "keystore" option, the "keystore-reference" is an instance
      of the "symmetric-key-ref" discussed in Section 2.1.2.

2.1.3.4.  The "local-or-keystore-asymmetric-key-grouping" Grouping

   The following tree diagram [RFC8340] illustrates the "local-or-
   keystore-asymmetric-key-grouping" grouping:

     grouping local-or-keystore-asymmetric-key-grouping
       +-- (local-or-keystore)
          +--:(local) {local-definitions-supported}?
          |  +-- local-definition
          |     +---u ct:asymmetric-key-pair-grouping
          +--:(keystore) {keystore-supported}?
             +-- keystore-reference?   ks:asymmetric-key-ref

   Comments:

   *  The "local-or-keystore-asymmetric-key-grouping" grouping is
      provided soley as convenience to downstream modules that wish to
      offer an option as to if an asymmetric key is defined locally or
      as a reference to a asymmetric key in the keystore.

   *  A "choice" statement is used to expose the various options.  Each
      option is enabled by a "feature" statement.  Additional "case"
      statements MAY be augmented in if, e.g., there is a need to
      reference a asymmetric key in an alternate location.

   *  For the "local-definition" option, the defintion uses the
      "asymmetric-key-pair-grouping" grouping discussed in
      Section 2.1.3.4 of [I-D.ietf-netconf-crypto-types].




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   *  For the "keystore" option, the "keystore-reference" is an instance
      of the "asymmetric-key-ref" typedef discussed in Section 2.1.2.

2.1.3.5.  The "local-or-keystore-asymmetric-key-with-certs-grouping"
          Grouping

   The following tree diagram [RFC8340] illustrates the "local-or-
   keystore-asymmetric-key-with-certs-grouping" grouping:

     grouping local-or-keystore-asymmetric-key-with-certs-grouping
       +-- (local-or-keystore)
          +--:(local) {local-definitions-supported}?
          |  +-- local-definition
          |     +---u ct:asymmetric-key-pair-with-certs-grouping
          +--:(keystore) {keystore-supported}?
             +-- keystore-reference?   ks:asymmetric-key-ref

   Comments:

   *  The "local-or-keystore-asymmetric-key-with-certs-grouping"
      grouping is provided soley as convenience to downstream modules
      that wish to offer an option as to if an asymmetric key is defined
      locally or as a reference to a asymmetric key in the keystore.

   *  A "choice" statement is used to expose the various options.  Each
      option is enabled by a "feature" statement.  Additional "case"
      statements MAY be augmented in if, e.g., there is a need to
      reference a asymmetric key in an alternate location.

   *  For the "local-definition" option, the defintion uses the
      "asymmetric-key-pair-with-certs-grouping" grouping discussed in
      Section 2.1.3.10 of [I-D.ietf-netconf-crypto-types].

   *  For the "keystore" option, the "keystore-reference" is an instance
      of the "asymmetric-key-ref" typedef discussed in Section 2.1.2.

2.1.3.6.  The "local-or-keystore-end-entity-cert-with-key-grouping"
          Grouping

   The following tree diagram [RFC8340] illustrates the "local-or-
   keystore-end-entity-cert-with-key-grouping" grouping:










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     grouping local-or-keystore-end-entity-cert-with-key-grouping
       +-- (local-or-keystore)
          +--:(local) {local-definitions-supported}?
          |  +-- local-definition
          |     +---u ct:asymmetric-key-pair-with-cert-grouping
          +--:(keystore) {keystore-supported}?
             +-- keystore-reference
                +---u asymmetric-key-certificate-ref-grouping

   Comments:

   *  The "local-or-keystore-end-entity-cert-with-key-grouping" grouping
      is provided soley as convenience to downstream modules that wish
      to offer an option as to if an symmetric key is defined locally or
      as a reference to a symmetric key in the keystore.

   *  A "choice" statement is used to expose the various options.  Each
      option is enabled by a "feature" statement.  Additional "case"
      statements MAY be augmented in if, e.g., there is a need to
      reference a symmetric key in an alternate location.

   *  For the "local-definition" option, the defintion uses the
      "asymmetric-key-pair-with-certs-grouping" grouping discussed in
      Section 2.1.3.10 of [I-D.ietf-netconf-crypto-types].

   *  For the "keystore" option, the "keystore-reference" uses the
      "asymmetric-key-certificate-ref-grouping" grouping discussed in
      Section 2.1.3.2.

2.1.3.7.  The "keystore-grouping" Grouping

   The following tree diagram [RFC8340] illustrates the "keystore-
   grouping" grouping:

     grouping keystore-grouping
       +-- asymmetric-keys
       |  +-- asymmetric-key* [name]
       |     +-- name?                                         string
       |     +---u ct:asymmetric-key-pair-with-certs-grouping
       +-- symmetric-keys
          +-- symmetric-key* [name]
             +-- name?                        string
             +---u ct:symmetric-key-grouping

   Comments:






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   *  The "keystore-grouping" grouping is defines a keystore instance as
      being composed of symmetric and asymmetric keys.  The stucture for
      the symmetric and asymmetric keys is essentially the same, being a
      "list" inside a "container".

   *  For asymmetric keys, each "asymmetric-key" uses the "asymmetric-
      key-pair-with-certs-grouping" grouping discussed Section 2.1.3.10
      of [I-D.ietf-netconf-crypto-types].

   *  For symmetric keys, each "symmetric-key" uses the "symmetric-key-
      grouping" grouping discussed Section 2.1.3.2 of
      [I-D.ietf-netconf-crypto-types].

2.1.4.  Protocol-accessible Nodes

   The following diagram lists all the protocol-accessible nodes defined
   in the "ietf-keystore" module:

   module: ietf-keystore
     +--rw keystore
        +--rw asymmetric-keys
        |  +--rw asymmetric-key* [name]
        |     +--rw name                                    string
        |     +--rw public-key-format                       identityref
        |     +--rw public-key                              binary
        |     +--rw private-key-format?                     identityref
        |     +--rw (private-key-type)
        |     |  +--:(private-key)
        |     |  |  +--rw private-key?                      binary
        |     |  +--:(hidden-private-key)
        |     |  |  +--rw hidden-private-key?               empty
        |     |  +--:(encrypted-private-key)
        |     |     +--rw encrypted-private-key
        |     |        +--rw encrypted-by
        |     |        |  +--rw (encrypted-by-choice)
        |     |        |     +--:(symmetric-key-ref)
        |     |        |     |  +--rw symmetric-key-ref?    leafref
        |     |        |     +--:(asymmetric-key-ref)
        |     |        |        +--rw asymmetric-key-ref?   leafref
        |     |        +--rw encrypted-value    binary
        |     +--rw certificates
        |     |  +--rw certificate* [name]
        |     |     +--rw name                      string
        |     |     +--rw cert-data                 end-entity-cert-cms
        |     |     +---n certificate-expiration
        |     |        +-- expiration-date    yang:date-and-time
        |     +---x generate-certificate-signing-request
        |             {certificate-signing-request-generation}?



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        |        +---w input
        |        |  +---w csr-info    ct:csr-info
        |        +--ro output
        |           +--ro certificate-signing-request    ct:csr
        +--rw symmetric-keys
           +--rw symmetric-key* [name]
              +--rw name                   string
              +--rw key-format?            identityref
              +--rw (key-type)
                 +--:(key)
                 |  +--rw key?             binary
                 +--:(hidden-key)
                 |  +--rw hidden-key?      empty
                 +--:(encrypted-key)
                    +--rw encrypted-key
                       +--rw encrypted-by
                       |  +--rw (encrypted-by-choice)
                       |     +--:(symmetric-key-ref)
                       |     |  +--rw symmetric-key-ref?    leafref
                       |     +--:(asymmetric-key-ref)
                       |        +--rw asymmetric-key-ref?   leafref
                       +--rw encrypted-value    binary

   Comments:

   *  Protocol-accessible nodes are those nodes that are accessible when
      the module is "implemented", as described in Section 5.6.5 of
      [RFC7950].

   *  For the "ietf-keystore" module, the protcol-accessible nodes are
      an instance of the "keystore-grouping" discussed in
      Section 2.1.3.7 grouping.  Note that, in this diagram, all the
      used groupings have been expanded, enabling the keystore's full
      structure to be seen.

   *  The reason for why "keystore-grouping" exists separate from the
      protocol-accessible nodes definition is so as to enable instances
      of the keystore to be instantiated in other locations, as may be
      needed or desired by some modules.

2.2.  Example Usage

   The examples in this section are encoded using XML, such as might be
   the case when using the NETCONF protocol.  Other encodings MAY be
   used, such as JSON when using the RESTCONF protocol.






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2.2.1.  A Keystore Instance

   The following example illustrates keys in <running>.  Please see
   Section 3 for an example illustrating built-in values in
   <operational>.

   =============== NOTE: '\' line wrapping per RFC 8792 ================

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

      <symmetric-keys>
         <symmetric-key>
            <name>cleartext-symmetric-key</name>
            <key-format>ct:octet-string-key-format</key-format>
            <key>base64encodedvalue==</key>
         </symmetric-key>
         <symmetric-key>
            <name>hidden-symmetric-key</name>
            <hidden-key/>
         </symmetric-key>
         <symmetric-key>
            <name>encrypted-symmetric-key</name>
            <key-format>
               ct:encrypted-one-symmetric-key-format
            </key-format>
            <encrypted-key>
              <encrypted-by>
                <asymmetric-key-ref>hidden-asymmetric-key</asymmetric-k\
   ey-ref>
              </encrypted-by>
              <encrypted-value>base64encodedvalue==</encrypted-value>
            </encrypted-key>
         </symmetric-key>
      </symmetric-keys>

      <asymmetric-keys>
         <asymmetric-key>
            <name>ssh-rsa-key</name>
            <public-key-format>
               ct:ssh-public-key-format
            </public-key-format>
            <public-key>base64encodedvalue==</public-key>
            <private-key-format>
               ct:rsa-private-key-format
            </private-key-format>
            <private-key>base64encodedvalue==</private-key>
         </asymmetric-key>



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         <asymmetric-key>
            <name>ssh-rsa-key-with-cert</name>
            <public-key-format>
               ct:subject-public-key-info-format
            </public-key-format>
            <public-key>base64encodedvalue==</public-key>
            <private-key-format>
               ct:rsa-private-key-format
            </private-key-format>
            <private-key>base64encodedvalue==</private-key>
            <certificates>
               <certificate>
                  <name>ex-rsa-cert2</name>
                  <cert-data>base64encodedvalue==</cert-data>
               </certificate>
            </certificates>
         </asymmetric-key>
         <asymmetric-key>
            <name>raw-private-key</name>
            <public-key-format>
               ct:subject-public-key-info-format
            </public-key-format>
            <public-key>base64encodedvalue==</public-key>
            <private-key-format>
               ct:rsa-private-key-format
            </private-key-format>
            <private-key>base64encodedvalue==</private-key>
         </asymmetric-key>
         <asymmetric-key>
            <name>rsa-asymmetric-key</name>
            <public-key-format>
               ct:subject-public-key-info-format
            </public-key-format>
            <public-key>base64encodedvalue==</public-key>
            <private-key-format>
               ct:rsa-private-key-format
            </private-key-format>
            <private-key>base64encodedvalue==</private-key>
            <certificates>
               <certificate>
                  <name>ex-rsa-cert</name>
                  <cert-data>base64encodedvalue==</cert-data>
               </certificate>
            </certificates>
         </asymmetric-key>
         <asymmetric-key>
            <name>ec-asymmetric-key</name>
            <public-key-format>



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               ct:subject-public-key-info-format
            </public-key-format>
            <public-key>base64encodedvalue==</public-key>
            <private-key-format>
               ct:ec-private-key-format
            </private-key-format>
            <private-key>base64encodedvalue==</private-key>
            <certificates>
               <certificate>
                  <name>ex-ec-cert</name>
                  <cert-data>base64encodedvalue==</cert-data>
               </certificate>
            </certificates>
         </asymmetric-key>
         <asymmetric-key>
            <name>hidden-asymmetric-key</name>
            <public-key-format>
               ct:subject-public-key-info-format
            </public-key-format>
            <public-key>base64encodedvalue==</public-key>
            <hidden-private-key/>
            <certificates>
               <certificate>
                  <name>builtin-idevid-cert</name>
                  <cert-data>base64encodedvalue==</cert-data>
               </certificate>
               <certificate>
                  <name>my-ldevid-cert</name>
                  <cert-data>base64encodedvalue==</cert-data>
               </certificate>
            </certificates>
         </asymmetric-key>
         <asymmetric-key>
            <name>encrypted-asymmetric-key</name>
            <public-key-format>
               ct:subject-public-key-info-format
            </public-key-format>
            <public-key>base64encodedvalue==</public-key>
            <private-key-format>
               ct:encrypted-one-asymmetric-key-format
            </private-key-format>
            <encrypted-private-key>
              <encrypted-by>
                <symmetric-key-ref>encrypted-symmetric-key</symmetric-k\
   ey-ref>
              </encrypted-by>
              <encrypted-value>base64encodedvalue==</encrypted-value>
            </encrypted-private-key>



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         </asymmetric-key>
      </asymmetric-keys>
   </keystore>

2.2.2.  A Certificate Expiration Notification

   The following example illustrates a "certificate-expiration"
   notification for a certificate associated with a key configured in
   the keystore.

   =============== NOTE: '\' line wrapping per RFC 8792 ================

   <notification
     xmlns="urn:ietf:params:xml:ns:netconf:notification:1.0">
     <eventTime>2018-05-25T00:01:00Z</eventTime>
     <keystore xmlns="urn:ietf:params:xml:ns:yang:ietf-keystore">
       <asymmetric-keys>
         <asymmetric-key>
           <name>hidden-asymmetric-key</name>
           <certificates>
             <certificate>
               <name>my-ldevid-cert</name>
               <certificate-expiration>
                 <expiration-date>2018-08-05T14:18:53-05:00</expiration\
   -date>
               </certificate-expiration>
             </certificate>
           </certificates>
         </asymmetric-key>
       </asymmetric-keys>
     </keystore>
   </notification>

2.2.3.  The "Local or Keystore" Groupings

   This section illustrates the various "local-or-keystore" groupings
   defined in the "ietf-keystore" module, specifically the "local-or-
   keystore-symmetric-key-grouping" (Section 2.1.3.3), "local-or-
   keystore-asymmetric-key-grouping" (Section 2.1.3.4), "local-or-
   keystore-asymmetric-key-with-certs-grouping" (Section 2.1.3.5), and
   "local-or-keystore-end-entity-cert-with-key-grouping"
   (Section 2.1.3.6) groupings.

   The following non-normative module is defined to illustrate these
   groupings:






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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 CCCC: A YANG Data Model for a Keystore";
     }

     organization
      "Example Corporation";

     contact
      "Author: YANG Designer <mailto:yang.designer@example.com>";

     description
      "This module illustrates notable groupings defined in
       the 'ietf-keystore' module.";

     revision "2020-07-08" {
       description
        "Initial version";
       reference
        "RFC CCCC: A YANG Data Model for a Keystore";
     }

     container keystore-usage {
       description
         "An illustration of the various keystore groupings.";

       list symmetric-key {
         key name;
         leaf name {
           type string;
           description
             "An arbitrary name for this key.";
         }
         uses ks:local-or-keystore-symmetric-key-grouping;
         description
           "An symmetric key that may be configured locally or be a
            reference to a symmetric key in the keystore.";
       }

       list asymmetric-key {
         key name;



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         leaf name {
           type string;
           description
             "An arbitrary name for this key.";
         }
         uses ks:local-or-keystore-asymmetric-key-grouping;
         description
           "An asymmetric key, with no certs, that may be configured
            locally or be a reference to an asymmetric key in the
            keystore.  The intent is to reference just the asymmetric
            key, not any certificates that may also be associated
            with the asymmetric key.";
       }

       list asymmetric-key-with-certs {
         key name;
         leaf name {
           type string;
           description
             "An arbitrary name for this key.";
         }
         uses ks:local-or-keystore-asymmetric-key-with-certs-grouping;
         description
           "An asymmetric key and its associated certs, that may be
            configured locally or be a reference to an asymmetric key
            (and its associated certs) in the keystore.";
       }

       list end-entity-cert-with-key {
         key name;
         leaf name {
           type string;
           description
             "An arbitrary name for this key.";
         }
         uses ks:local-or-keystore-end-entity-cert-with-key-grouping;
         description
           "An end-entity certificate, and its associated private key,
            that may be configured locally or be a reference to a
            specific certificate (and its associated private key) in
            the keystore.";
       }
     }

   }

   The tree diagram [RFC8340] for this example module follows:




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   module: ex-keystore-usage
     +--rw keystore-usage
        +--rw symmetric-key* [name]
        |  +--rw name                        string
        |  +--rw (local-or-keystore)
        |     +--:(local) {local-definitions-supported}?
        |     |  +--rw local-definition
        |     |     +--rw key-format?            identityref
        |     |     +--rw (key-type)
        |     |        +--:(key)
        |     |        |  +--rw key?             binary
        |     |        +--:(hidden-key)
        |     |        |  +--rw hidden-key?      empty
        |     |        +--:(encrypted-key)
        |     |           +--rw encrypted-key
        |     |              +--rw encrypted-by
        |     |              +--rw encrypted-value    binary
        |     +--:(keystore) {keystore-supported}?
        |        +--rw keystore-reference?   ks:symmetric-key-ref
        +--rw asymmetric-key* [name]
        |  +--rw name                        string
        |  +--rw (local-or-keystore)
        |     +--:(local) {local-definitions-supported}?
        |     |  +--rw local-definition
        |     |     +--rw public-key-format              identityref
        |     |     +--rw public-key                     binary
        |     |     +--rw private-key-format?            identityref
        |     |     +--rw (private-key-type)
        |     |        +--:(private-key)
        |     |        |  +--rw private-key?             binary
        |     |        +--:(hidden-private-key)
        |     |        |  +--rw hidden-private-key?      empty
        |     |        +--:(encrypted-private-key)
        |     |           +--rw encrypted-private-key
        |     |              +--rw encrypted-by
        |     |              +--rw encrypted-value    binary
        |     +--:(keystore) {keystore-supported}?
        |        +--rw keystore-reference?   ks:asymmetric-key-ref
        +--rw asymmetric-key-with-certs* [name]
        |  +--rw name                        string
        |  +--rw (local-or-keystore)
        |     +--:(local) {local-definitions-supported}?
        |     |  +--rw local-definition
        |     |     +--rw public-key-format
        |     |     |       identityref
        |     |     +--rw public-key                              binary
        |     |     +--rw private-key-format?
        |     |     |       identityref



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        |     |     +--rw (private-key-type)
        |     |     |  +--:(private-key)
        |     |     |  |  +--rw private-key?                      binary
        |     |     |  +--:(hidden-private-key)
        |     |     |  |  +--rw hidden-private-key?               empty
        |     |     |  +--:(encrypted-private-key)
        |     |     |     +--rw encrypted-private-key
        |     |     |        +--rw encrypted-by
        |     |     |        +--rw encrypted-value    binary
        |     |     +--rw certificates
        |     |     |  +--rw certificate* [name]
        |     |     |     +--rw name                      string
        |     |     |     +--rw cert-data
        |     |     |     |       end-entity-cert-cms
        |     |     |     +---n certificate-expiration
        |     |     |        +-- expiration-date    yang:date-and-time
        |     |     +---x generate-certificate-signing-request
        |     |             {certificate-signing-request-generation}?
        |     |        +---w input
        |     |        |  +---w csr-info    ct:csr-info
        |     |        +--ro output
        |     |           +--ro certificate-signing-request    ct:csr
        |     +--:(keystore) {keystore-supported}?
        |        +--rw keystore-reference?   ks:asymmetric-key-ref
        +--rw end-entity-cert-with-key* [name]
           +--rw name                        string
           +--rw (local-or-keystore)
              +--:(local) {local-definitions-supported}?
              |  +--rw local-definition
              |     +--rw public-key-format
              |     |       identityref
              |     +--rw public-key                              binary
              |     +--rw private-key-format?
              |     |       identityref
              |     +--rw (private-key-type)
              |     |  +--:(private-key)
              |     |  |  +--rw private-key?                      binary
              |     |  +--:(hidden-private-key)
              |     |  |  +--rw hidden-private-key?               empty
              |     |  +--:(encrypted-private-key)
              |     |     +--rw encrypted-private-key
              |     |        +--rw encrypted-by
              |     |        +--rw encrypted-value    binary
              |     +--rw cert-data?
              |     |       end-entity-cert-cms
              |     +---n certificate-expiration
              |     |  +-- expiration-date    yang:date-and-time
              |     +---x generate-certificate-signing-request



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              |             {certificate-signing-request-generation}?
              |        +---w input
              |        |  +---w csr-info    ct:csr-info
              |        +--ro output
              |           +--ro certificate-signing-request    ct:csr
              +--:(keystore) {keystore-supported}?
                 +--rw keystore-reference
                    +--rw asymmetric-key?   ks:asymmetric-key-ref
                    +--rw certificate?      leafref

   The following example provides two equivalent instances of each
   grouping, the first being a reference to a keystore and the second
   being locally-defined.  The instance having a reference to a keystore
   is consistent with the keystore defined in Section 2.2.1.  The two
   instances are equivalent, as the locally-defined instance example
   contains the same values defined by the keystore instance referenced
   by its sibling example.

   <keystore-usage
     xmlns="http://example.com/ns/example-keystore-usage"
     xmlns:ct="urn:ietf:params:xml:ns:yang:ietf-crypto-types">

     <!-- The following two equivalent examples illustrate the -->
     <!-- "local-or-keystore-symmetric-key-grouping" grouping: -->

     <symmetric-key>
       <name>example 1a</name>
       <keystore-reference>cleartext-symmetric-key</keystore-reference>
     </symmetric-key>

     <symmetric-key>
       <name>example 1b</name>
       <local-definition>
         <key-format>ct:octet-string-key-format</key-format>
         <key>base64encodedvalue==</key>
       </local-definition>
     </symmetric-key>


     <!-- The following two equivalent examples illustrate the  -->
     <!-- "local-or-keystore-asymmetric-key-grouping" grouping: -->

     <asymmetric-key>
       <name>example 2a</name>
       <keystore-reference>rsa-asymmetric-key</keystore-reference>
     </asymmetric-key>

     <asymmetric-key>



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       <name>example 2b</name>
       <local-definition>
         <public-key-format>
           ct:subject-public-key-info-format
         </public-key-format>
         <public-key>base64encodedvalue==</public-key>
         <private-key-format>
           ct:rsa-private-key-format
         </private-key-format>
         <private-key>base64encodedvalue==</private-key>
       </local-definition>
     </asymmetric-key>


     <!-- the following two equivalent examples illustrate        -->
     <!-- "local-or-keystore-asymmetric-key-with-certs-grouping": -->

     <asymmetric-key-with-certs>
       <name>example 3a</name>
       <keystore-reference>rsa-asymmetric-key</keystore-reference>
     </asymmetric-key-with-certs>

     <asymmetric-key-with-certs>
       <name>example 3b</name>
       <local-definition>
         <public-key-format>
             ct:subject-public-key-info-format
         </public-key-format>
         <public-key>base64encodedvalue==</public-key>
         <private-key-format>
           ct:rsa-private-key-format
         </private-key-format>
         <private-key>base64encodedvalue==</private-key>
         <certificates>
           <certificate>
             <name>a locally-defined cert</name>
             <cert-data>base64encodedvalue==</cert-data>
           </certificate>
         </certificates>
       </local-definition>
     </asymmetric-key-with-certs>


     <!-- The following two equivalent examples illustrate       -->
     <!-- "local-or-keystore-end-entity-cert-with-key-grouping": -->

     <end-entity-cert-with-key>
       <name>example 4a</name>



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       <keystore-reference>
         <asymmetric-key>rsa-asymmetric-key</asymmetric-key>
         <certificate>ex-rsa-cert</certificate>
       </keystore-reference>
     </end-entity-cert-with-key>

     <end-entity-cert-with-key>
       <name>example 4b</name>
       <local-definition>
         <public-key-format>
           ct:subject-public-key-info-format
         </public-key-format>
         <public-key>base64encodedvalue==</public-key>
         <private-key-format>
           ct:rsa-private-key-format
         </private-key-format>
         <private-key>base64encodedvalue==</private-key>
         <cert-data>base64encodedvalue==</cert-data>
       </local-definition>
     </end-entity-cert-with-key>

   </keystore-usage>

2.3.  YANG Module

   This YANG module has normative references to [RFC8341] and
   [I-D.ietf-netconf-crypto-types].

   <CODE BEGINS> file "ietf-keystore@2020-07-08.yang"

   module ietf-keystore {
     yang-version 1.1;
     namespace "urn:ietf:params:xml:ns:yang:ietf-keystore";
     prefix ks;

     import ietf-netconf-acm {
       prefix nacm;
       reference
         "RFC 8341: Network Configuration Access Control Model";
     }

     import ietf-crypto-types {
       prefix ct;
       reference
         "RFC AAAA: YANG Data Types and Groupings for Cryptography";
     }

     organization



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       "IETF NETCONF (Network Configuration) Working Group";

     contact
       "WG Web:   <http://datatracker.ietf.org/wg/netconf/>
        WG List:  <mailto:netconf@ietf.org>
        Author:   Kent Watsen <mailto:kent+ietf@watsen.net>";

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

        Copyright (c) 2020 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
        (https://trustee.ietf.org/license-info).

        This version of this YANG module is part of RFC CCCC
        (https://www.rfc-editor.org/info/rfcCCCC); see the RFC
        itself for full legal notices.

        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 (RFC 2119)
        (RFC 8174) when, and only when, they appear in all
        capitals, as shown here.";

     revision 2020-07-08 {
       description
         "Initial version";
       reference
         "RFC CCCC: A YANG Data Model for a Keystore";
     }

     /****************/
     /*   Features   */
     /****************/

     feature keystore-supported {
       description
         "The 'keystore-supported' feature indicates that the server
          supports the Keystore.";
     }



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     feature local-definitions-supported {
       description
         "The 'local-definitions-supported' feature indicates that the
          server supports locally-defined keys.";
     }

     /****************/
     /*   Typedefs   */
     /****************/

     typedef symmetric-key-ref {
       type leafref {
         path "/ks:keystore/ks:symmetric-keys/ks:symmetric-key"
            + "/ks:name";
       }
       description
         "This typedef enables modules to easily define a reference
          to a symmetric key stored in the Keystore.";
     }

     typedef asymmetric-key-ref {
       type leafref {
         path "/ks:keystore/ks:asymmetric-keys/ks:asymmetric-key"
            + "/ks:name";
       }
       description
         "This typedef enables modules to easily define a reference
          to an asymmetric key stored in the Keystore.";
     }

     /*****************/
     /*   Groupings   */
     /*****************/

     grouping encrypted-by-choice-grouping {
       description
         "A grouping that defines a choice enabling references
          to other keys.";
       choice encrypted-by-choice {
         nacm:default-deny-write;
         mandatory true;
         description
           "A choice amongst other symmetric or asymmetric keys.";
         case symmetric-key-ref {
           leaf symmetric-key-ref {
             type leafref {
               path "/ks:keystore/ks:symmetric-keys/"
                    + "ks:symmetric-key/ks:name";



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             }
             description
              "Identifies the symmetric key used to encrypt this key.";
           }
         }
         case asymmetric-key-ref {
           leaf asymmetric-key-ref {
             type leafref {
               path "/ks:keystore/ks:asymmetric-keys/"
                    + "ks:asymmetric-key/ks:name";
             }
             description
              "Identifies the asymmetric key used to encrypt this key.";
           }
         }
       }
     }

     grouping asymmetric-key-certificate-ref-grouping {
       description
         "This grouping defines a reference to a specific certificate
          associated with an asymmetric key stored in the Keystore.";
       leaf asymmetric-key {
         nacm:default-deny-write;
         type ks:asymmetric-key-ref;
         must '../certificate';
         description
           "A reference to an asymmetric key in the Keystore.";
       }
       leaf certificate {
         nacm:default-deny-write;
         type leafref {
           path "/ks:keystore/ks:asymmetric-keys/ks:asymmetric-key[ks:"
                + "name = current()/../asymmetric-key]/ks:certificates"
                + "/ks:certificate/ks:name";
         }
         must '../asymmetric-key';
         description
           "A reference to a specific certificate of the
            asymmetric key in the Keystore.";
       }
     }


     // local-or-keystore-* groupings

     grouping local-or-keystore-symmetric-key-grouping {
       description



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         "A grouping that expands to allow the symmetric key to be
          either stored locally, within the using data model, or be
          a reference to a symmetric key stored in the Keystore.";
       choice local-or-keystore {
         nacm:default-deny-write;
         mandatory true;
         description
           "A choice between an inlined definition and a definition
            that exists in the Keystore.";
         case local {
           if-feature "local-definitions-supported";
           container local-definition {
             description
               "Container to hold the local key definition.";
             uses ct:symmetric-key-grouping;
           }
         }
         case keystore {
           if-feature "keystore-supported";
           leaf keystore-reference {
             type ks:symmetric-key-ref;
             description
               "A reference to an symmetric key that exists in
                the Keystore.";
           }
         }
       }
     }

     grouping local-or-keystore-asymmetric-key-grouping {
       description
         "A grouping that expands to allow the asymmetric key to be
          either stored locally, within the using data model, or be
          a reference to an asymmetric key stored in the Keystore.";
       choice local-or-keystore {
         nacm:default-deny-write;
         mandatory true;
         case local {
           if-feature "local-definitions-supported";
           container local-definition {
             description
               "Container to hold the local key definition.";
             uses ct:asymmetric-key-pair-grouping;
           }
         }
         case keystore {
           if-feature "keystore-supported";
           leaf keystore-reference {



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             type ks:asymmetric-key-ref;
             description
               "A reference to an asymmetric key that exists in
                the Keystore.  The intent is to reference just the
                asymmetric key without any regard for any certificates
                that may be associated with it.";
           }
         }
         description
           "A choice between an inlined definition and a definition
            that exists in the Keystore.";
       }
     }

     grouping local-or-keystore-asymmetric-key-with-certs-grouping {
       description
         "A grouping that expands to allow an asymmetric key and its
          associated certificates to be either stored locally, within
          the using data model, or be a reference to an asymmetric key
          (and its associated certificates) stored in the Keystore.";
       choice local-or-keystore {
         nacm:default-deny-write;
         mandatory true;
         case local {
           if-feature "local-definitions-supported";
           container local-definition {
             description
               "Container to hold the local key definition.";
             uses ct:asymmetric-key-pair-with-certs-grouping;
           }
         }
         case keystore {
           if-feature "keystore-supported";
           leaf keystore-reference {
             type ks:asymmetric-key-ref;
             description
               "A reference to an asymmetric-key (and all of its
                associated certificates) in the Keystore.";
           }
         }
         description
           "A choice between an inlined definition and a definition
            that exists in the Keystore.";
       }
     }

     grouping local-or-keystore-end-entity-cert-with-key-grouping {
       description



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         "A grouping that expands to allow an end-entity certificate
          (and its associated private key) to be either stored locally,
          within the using data model, or be a reference to a specific
          certificate in the Keystore.";
       choice local-or-keystore {
         nacm:default-deny-write;
         mandatory true;
         case local {
           if-feature "local-definitions-supported";
           container local-definition {
             description
               "Container to hold the local key definition.";
             uses ct:asymmetric-key-pair-with-cert-grouping;
           }
         }
         case keystore {
           if-feature "keystore-supported";
           container keystore-reference {
             uses asymmetric-key-certificate-ref-grouping;
             description
               "A reference to a specific certificate (and its
                associated private key) in the Keystore.";
           }
         }
         description
           "A choice between an inlined definition and a definition
            that exists in the Keystore.";
       }
     }

     grouping keystore-grouping {
       description
         "Grouping definition enables use in other contexts.  If ever
          done, implementations SHOULD augment new 'case' statements
          into local-or-keystore 'choice' statements to supply leafrefs
          to the new location.";
       container asymmetric-keys {
         nacm:default-deny-write;
         description
           "A list of asymmetric keys.";
         list asymmetric-key {
           key "name";
           description
             "An asymmetric key.";
           leaf name {
             type string;
             description
               "An arbitrary name for the asymmetric key.";



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           }
           uses ct:asymmetric-key-pair-with-certs-grouping;
         }
       }
       container symmetric-keys {
         nacm:default-deny-write;
         description
           "A list of symmetric keys.";
         list symmetric-key {
           key "name";
           description
             "A symmetric key.";
           leaf name {
             type string;
             description
               "An arbitrary name for the symmetric key.";
           }
           uses ct:symmetric-key-grouping;
         }
       }
     } // grouping keystore-grouping



     /*********************************/
     /*   Protocol accessible nodes   */
     /*********************************/

     container keystore {
       description
         "The Keystore contains a list of symmetric keys and a list
          of asymmetric keys.";
       nacm:default-deny-write;
       uses keystore-grouping {
         augment "symmetric-keys/symmetric-key/key-type/encrypted-key/"
                 + "encrypted-key/encrypted-by" {
           description
             "Augments in a choice statement enabling the encrypting
              key to be any other symmetric or asymmetric key in the
              keystore.";
           uses encrypted-by-choice-grouping;
         }
         augment "asymmetric-keys/asymmetric-key/private-key-type/"
                 + "encrypted-private-key/encrypted-private-key/"
                 + "encrypted-by" {
           description
             "Augments in a choice statement enabling the encrypting
              key to be any other symmetric or asymmetric key in the



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              keystore.";
           uses encrypted-by-choice-grouping;
         }
       }
     }

   }

   <CODE ENDS>

3.  Support for Built-in Keys

   In some implementations, a server may support built-in keys.  Built-
   in built-in keys MAY be set during the manufacturing process or be
   dynamically generated the first time the server is booted or a
   particular service (e.g., SSH) is enabled.

   The key characteristic of the built-in keys is that they are provided
   by the system, as opposed to configuration.  As such, they are
   present in <operational>.  The example below illustrates what the
   keystore in <operational> might look like for a server in its factory
   default state.

   <keystore xmlns="urn:ietf:params:xml:ns:yang:ietf-keystore"
     xmlns:ct="urn:ietf:params:xml:ns:yang:ietf-crypto-types"
     xmlns:or="urn:ietf:params:xml:ns:yang:ietf-origin"
     or:origin="or:intended">
     <asymmetric-keys>
       <asymmetric-key or:origin="or:system">
         <name>Manufacturer-Generated Hidden Key</name>
         <public-key-format>
           ct:subject-public-key-info-format
         </public-key-format>
         <public-key>base64encodedvalue==</public-key>
         <hidden-private-key/>
         <certificates>
           <certificate>
             <name>Manufacturer-Generated IDevID Cert</name>
             <cert-data>base64encodedvalue==</cert-data>
           </certificate>
         </certificates>
       </asymmetric-key>
     </asymmetric-keys>
   </keystore>







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   In order for the built-in keys (and/or their associated built-in
   certificates) to be referenced by configuration, the referenced keys
   MUST first be copied into <running>.  The keys SHOULD be copied into
   <running> using the same "key" values, so that the server can bind
   the references to the built-in entries.

   Built-in "hidden" keys cannot be copied into other parts of the
   configuration because their private parts are hidden, and therefore
   impossible to replicate.  Built-in "encrypted" keys MAY be copied
   into other parts of the configuration so long as they maintain their
   reference to the other built-in key that encrypted them.

   Only the referenced keys need to be copied; that is, the keys in
   <running> MAY be a subset of the built-in keys define in
   <operational>.  No keys may be added or changed (with exception to
   associating additional certificates to a built-in key); that is, the
   keys in <running> MUST be a subset (which includes the whole of the
   set) of the built-in keys define in <operational>.

   A server MUST reject attempts to modify any aspect of built-in keys,
   with exception to associating additional certificates to a built-in
   key.  That these keys are "configured" in <running> is an illusion,
   as they are strictly a read-only subset of that which must already
   exist in <operational>.

   The following example illustrates how a single built-in key
   definition from the previous example has been propagated to
   <running>:























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   <keystore xmlns="urn:ietf:params:xml:ns:yang:ietf-keystore"
     xmlns:ct="urn:ietf:params:xml:ns:yang:ietf-crypto-types">
     <asymmetric-keys>
       <asymmetric-key>
         <name>Manufacturer-Generated Hidden Key</name>
         <public-key-format>
           ct:subject-public-key-info-format
         </public-key-format>
         <public-key>base64encodedvalue==</public-key>
         <hidden-private-key/>
         <certificates>
           <certificate>
             <name>Manufacturer-Generated IDevID Cert</name>
             <cert-data>base64encodedvalue==</cert-data>
           </certificate>
           <certificate>
             <name>Deployment-Specific LDevID Cert</name>
             <cert-data>base64encodedvalue==</cert-data>
           </certificate>
         </certificates>
       </asymmetric-key>
     </asymmetric-keys>
   </keystore>

   After the above configuration is applied, <operational> should appear
   as follows:

























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   <keystore xmlns="urn:ietf:params:xml:ns:yang:ietf-keystore"
     xmlns:ct="urn:ietf:params:xml:ns:yang:ietf-crypto-types"
     xmlns:or="urn:ietf:params:xml:ns:yang:ietf-origin"
     or:origin="or:intended">
     <asymmetric-keys>
       <asymmetric-key or:origin="or:system">
         <name>Manufacturer-Generated Hidden Key</name>
         <public-key-format>
           ct:subject-public-key-info-format
         </public-key-format>
         <public-key>base64encodedvalue==</public-key>
         <hidden-private-key/>
         <certificates>
           <certificate>
             <name>Manufacturer-Generated IDevID Cert</name>
             <cert-data>base64encodedvalue==</cert-data>
           </certificate>
           <certificate or:origin="or:intended">
             <name>Deployment-Specific LDevID Cert</name>
             <cert-data>base64encodedvalue==</cert-data>
           </certificate>
         </certificates>
       </asymmetric-key>
     </asymmetric-keys>
   </keystore>

4.  Encrypting Keys in Configuration

   This section describes an approach that enables all the private keys
   on a server to be encrypted, such that traditional backup/restore
   procedures can be used without concern for keys being compromised
   when in transit.

4.1.  Root Key

   The cornerstone to this solution is the existence of a "root" key
   that can be used to encrypt all the other keys.  The server MUST be
   able to use this key to decrypt the other keys in the configuration.

   The root key SHOULD be a hidden key, i.e., one whose private data has
   no presence in <running> or <operational> (see "hidden-key" and
   "hidden-private-key" in "ietf-crypto-types"
   [I-D.ietf-netconf-crypto-types]).  If the server implementation does
   not support hidden keys, then the private data part of key MUST be
   protected by access control with access granted only to an
   administrator with special access control rights (e.g., an
   organization's crypto officer).  Given the long lifetime of built-in
   keys (see Section 3), built-in keys MUST be hidden.



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   A hidden root key MAY be either a symmetric key or an asymmetric key.
   If the hidden root key is symmetric, then the server MUST provide
   APIs enabling other keys (ideally generated by the server) to be
   encrypted.  If the hidden root key is asymmetric, then the server
   SHOULD provide APIs enabling other keys to be both generated and
   encrypted by it, but MAY alternatively enable administrators with
   special access control rights to generate and encrypt the other keys
   themselves, using the hidden key's public part.  For practical
   reasons, an unhidden root key SHOULD be asymmetric, so that its
   public part can be accessed by other administrators without concern.

4.2.  Configuring Encrypting Keys

   Each time a new key is to be configured, it SHOULD be encrypted by
   the root key.

   In "ietf-crypto-types" [I-D.ietf-netconf-crypto-types], the format
   for an encrypted symmetric key is described by the "encrypted-one-
   symmetric-key-format" identity, while the format for an encrypted
   asymmetric key is described by the "encrypted-one-asymmetric-key-
   format" identity

   Ideally, the server implementation provides an API to generate a
   symmetric or asymmetric key, and encrypt the generated key using
   another key known to the system (e.g., the root key).  Thusly
   administrators can safely call this API to configure new keys.

   In case the server implementation does not provide such an API, then
   the generating and encrypting steps MAY be performed outside the
   server, e.g., by an administrator with special access control rights.

   In either case, the encrypted key can be configured into the Keystore
   using either the "encrypted-key" (for symmetric keys) or the
   "encrypted-private-key" (for asymmetric keys) nodes.  These two nodes
   contain both the encrypted value as well as a reference to the other
   key in the Keystore that it was encrypted by.

4.3.  Migrating Configuration to Another Server

   In the case a server's root key is used to encrypt other keys,
   migrating the configuration to another server may entail additional
   effort, assuming the second server has a different root key than the
   first server, in order for the second server to decrypt the other
   encrypted keys.







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   In some deployments, mechanisms outside the scope of this document
   may be used to migrate the root key from one server to another.  That
   said, beware that the ability to do so typically entails having
   access to the first server but, in many RMA scenarios, the first
   server may no longer be operational.

   Another option is to introduce a "shared root" key that acts as a
   portable intermediate root key.  This shared root key would only need
   to be known to an organization's crypto officer.  The shared root key
   SHOULD be encrypted offline by the crypto officer using each server's
   public key, which may be, e.g., in the server's IDevID certificate.
   The crypto officer can then safely handoff the encrypted shared key
   to other administrators responsible for server installations,
   including migrations.  In order to migrate configuration from a first
   server, an administrator would need to make just a single
   modification to the configuration before loading it onto a second
   server, which is to replace the shared key's Keystore entry from the
   first server (an encrypted key), with the shared key encrypted by the
   second server's root key.  The following diagram illustrates this
   idea:































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    +-------------+                                 +---------------+
    | shared key  |                                 |shared root key|
    |(unencrypted)|-------------------------------> |  (encrypted)  |
    +-------------+     encrypts offline using      +---------------+
           ^            each server's root key          |
           |                                            |
           |                                            |
           |  possesses    \o                           |
           +--------------  |\                          |
                           / \         shares with      |
                         crypto    +--------------------+
                         officer   |
                                   |
                                   |
   +----------------------+        |         +----------------------+
   |       server-1       |        |         |       server-2       |
   |    configuration     |        |         |    configuration     |
   |                      |        |         |                      |
   |                      |        |         |                      |
   |  +----------------+  |        |         |  +----------------+  |
   |  |   root key-1   |  |        |         |  |   root key-2   |  |
   |  |    (hidden)    |  |        |         |  |    (hidden)    |  |
   |  +----------------+  |        |         |  +----------------+  |
   |      ^               |        |         |      ^               |
   |      |               |        |         |      |               |
   |      |               |        |         |      |               |
   |      |  encrypted    |        |         |      |  encrypted    |
   |      |  by           |        |         |      |  by           |
   |      |               |        |         |      |               |
   |      |               |        |         |      |               |
   |  +----------------+  |        |         |  +----------------+  |
   |  |shared root key |  |        |         |  |shared root key |  |
   |  |  (encrypted)   |  |        v         |  |  (encrypted)   |  |
   |  +----------------+  |                  |  +----------------+  |
   |      ^               |     regular      |      ^               |
   |      |               |      admin       |      |               |
   |      |               |                  |      |               |
   |      |  encrypted    |       \o         |      |  encrypted    |
   |      |  by           |        |\        |      |  by           |
   |      |               |       / \        |      |               |
   |      |               |                  |      |               |
   |  +----------------+  |----------------->|  +----------------+  |
   |  | all other keys |  |     migrate      |  | all other keys |  |
   |  |  (encrypted)   |  |  configuration   |  |  (encrypted)   |  |
   |  +----------------+  |                  |  +----------------+  |
   |                      |                  |                      |
   +----------------------+                  +----------------------+




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5.  Security Considerations

5.1.  Data at Rest

   The YANG module defined in this document defines a mechanism called a
   "keystore" that, by its name, suggests that it will protect its
   contents from unauthorized disclosure and modification.

   Security controls for the API (i.e., data in motion) are discussed in
   Section 5.2, but controls for the data at rest cannot be specified by
   the YANG module.

   In order to satisfy the expectations of a "keystore", it is
   RECOMMENDED that implementations ensure that the keystore contents
   are encrypted when persisted to non-volatile memory.

5.2.  The "ietf-keystore" YANG Module

   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) [RFC8341] provides the means
   to restrict access for particular users to a pre-configured subset of
   all available protocol operations and content.

   None of the readable data nodes defined in this YANG module are
   considered sensitive or vulnerable in network environments.  The NACM
   "default-deny-all" extension has not been set for any data nodes
   defined in this module.

      |  Please be aware that this module uses the "key" and "private-
      |  key" nodes from the "ietf-crypto-types" module
      |  [I-D.ietf-netconf-crypto-types], where said nodes have the NACM
      |  extension "default-deny-all" set, thus preventing unrestricted
      |  read-access to the cleartext key values.

   All of the writable data nodes defined by this module, both in the
   "grouping" statements as well as the protocol-accessible "keystore"
   instance, may be considered sensitive or vulnerable in some network
   environments..  For instance, any modification to a key or reference
   to a key may dramatically alter the implemented security policy.  For
   this reason, the NACM extension "default-deny-write" has been set for
   all data nodes defined in this module.





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   This module does not define any RPCs, actions, or notifications, and
   thus the security consideration for such is not provided here.

6.  IANA Considerations

6.1.  The IETF XML Registry

   This document registers one URI in the "ns" subregistry of 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:

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

7.  References

7.1.  Normative References

   [I-D.ietf-netconf-crypto-types]
              Watsen, K., "Common YANG Data Types for Cryptography",
              Work in Progress, Internet-Draft, draft-ietf-netconf-
              crypto-types-15, 20 May 2020,
              <https://tools.ietf.org/html/draft-ietf-netconf-crypto-
              types-15>.

   [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>.

   [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>.





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   [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>.

   [RFC8341]  Bierman, A. and M. Bjorklund, "Network Configuration
              Access Control Model", STD 91, RFC 8341,
              DOI 10.17487/RFC8341, March 2018,
              <https://www.rfc-editor.org/info/rfc8341>.

7.2.  Informative References

   [I-D.ietf-netconf-http-client-server]
              Watsen, K., "YANG Groupings for HTTP Clients and HTTP
              Servers", Work in Progress, Internet-Draft, draft-ietf-
              netconf-http-client-server-03, 20 May 2020,
              <https://tools.ietf.org/html/draft-ietf-netconf-http-
              client-server-03>.

   [I-D.ietf-netconf-keystore]
              Watsen, K., "A YANG Data Model for a Keystore", Work in
              Progress, Internet-Draft, draft-ietf-netconf-keystore-17,
              20 May 2020, <https://tools.ietf.org/html/draft-ietf-
              netconf-keystore-17>.

   [I-D.ietf-netconf-netconf-client-server]
              Watsen, K., "NETCONF Client and Server Models", Work in
              Progress, Internet-Draft, draft-ietf-netconf-netconf-
              client-server-19, 20 May 2020,
              <https://tools.ietf.org/html/draft-ietf-netconf-netconf-
              client-server-19>.

   [I-D.ietf-netconf-restconf-client-server]
              Watsen, K., "RESTCONF Client and Server Models", Work in
              Progress, Internet-Draft, draft-ietf-netconf-restconf-
              client-server-19, 20 May 2020,
              <https://tools.ietf.org/html/draft-ietf-netconf-restconf-
              client-server-19>.

   [I-D.ietf-netconf-ssh-client-server]
              Watsen, K. and G. Wu, "YANG Groupings for SSH Clients and
              SSH Servers", Work in Progress, Internet-Draft, draft-
              ietf-netconf-ssh-client-server-19, 20 May 2020,
              <https://tools.ietf.org/html/draft-ietf-netconf-ssh-
              client-server-19>.

   [I-D.ietf-netconf-tcp-client-server]
              Watsen, K. and M. Scharf, "YANG Groupings for TCP Clients
              and TCP Servers", Work in Progress, Internet-Draft, draft-



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              ietf-netconf-tcp-client-server-06, 16 June 2020,
              <https://tools.ietf.org/html/draft-ietf-netconf-tcp-
              client-server-06>.

   [I-D.ietf-netconf-tls-client-server]
              Watsen, K. and G. Wu, "YANG Groupings for TLS Clients and
              TLS Servers", Work in Progress, Internet-Draft, draft-
              ietf-netconf-tls-client-server-19, 20 May 2020,
              <https://tools.ietf.org/html/draft-ietf-netconf-tls-
              client-server-19>.

   [I-D.ietf-netconf-trust-anchors]
              Watsen, K., "A YANG Data Model for a Truststore", Work in
              Progress, Internet-Draft, draft-ietf-netconf-trust-
              anchors-10, 20 May 2020, <https://tools.ietf.org/html/
              draft-ietf-netconf-trust-anchors-10>.

   [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>.

   [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>.

   [RFC8340]  Bjorklund, M. and L. Berger, Ed., "YANG Tree Diagrams",
              BCP 215, RFC 8340, DOI 10.17487/RFC8340, March 2018,
              <https://www.rfc-editor.org/info/rfc8340>.

   [RFC8342]  Bjorklund, M., Schoenwaelder, J., Shafer, P., Watsen, K.,
              and R. Wilton, "Network Management Datastore Architecture
              (NMDA)", RFC 8342, DOI 10.17487/RFC8342, March 2018,
              <https://www.rfc-editor.org/info/rfc8342>.

   [Std-802.1AR-2009]
              Group, W. -. H. L. L. P. W., "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

   This section is to be removed before publishing as an RFC.

A.1.  00 to 01

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

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

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

A.2.  01 to 02

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

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

   *  Fixed up a few description statements.

A.3.  02 to 03

   *  Changed draft's title.

   *  Added missing references.

   *  Collapsed sections and levels.

   *  Added RFC 8174 to Requirements Language Section.

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

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

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

A.4.  03 to 04

   *  Added typedefs around leafrefs to common keystore paths

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

   *  Removed Design Considerations section




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   *  Moved key and certificate definitions from data tree to groupings

A.5.  04 to 05

   *  Removed trust anchors (now in their own draft)

   *  Added back global keystore structure

   *  Added groupings enabling keys to either be locally defined or a
      reference to the keystore.

A.6.  05 to 06

   *  Added feature "local-keys-supported"

   *  Added nacm:default-deny-all and nacm:default-deny-write

   *  Renamed generate-asymmetric-key to generate-hidden-key

   *  Added an install-hidden-key action

   *  Moved actions inside fo the "asymmetric-key" container

   *  Moved some groupings to draft-ietf-netconf-crypto-types

A.7.  06 to 07

   *  Removed a "require-instance false"

   *  Clarified some description statements

   *  Improved the keystore-usage examples

A.8.  07 to 08

   *  Added "local-definition" containers to avoid posibility of the
      action/notification statements being under a "case" statement.

   *  Updated copyright date, boilerplate template, affiliation, folding
      algorithm, and reformatted the YANG module.

A.9.  08 to 09

   *  Added a 'description' statement to the 'must' in the /keystore/
      asymmetric-key node explaining that the descendent values may
      exist in <operational> only, and that implementation MUST assert
      that the values are either configured or that they exist in
      <operational>.



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   *  Copied above 'must' statement (and description) into the local-or-
      keystore-asymmetric-key-grouping, local-or-keystore-asymmetric-
      key-with-certs-grouping, and local-or-keystore-end-entity-cert-
      with-key-grouping statements.

A.10.  09 to 10

   *  Updated draft title to match new truststore draft title

   *  Moved everything under a top-level 'grouping' to enable use in
      other contexts.

   *  Renamed feature from 'local-keys-supported' to 'local-definitions-
      supported' (same name used in truststore)

   *  Removed the either-all-or-none 'must' expressions for the key's
      3-tuple values (since the values are now 'mandatory true' in
      crypto-types)

   *  Example updated to reflect 'mandatory true' change in crypto-types
      draft

A.11.  10 to 11

   *  Replaced typedef asymmetric-key-certificate-ref with grouping
      asymmetric-key-certificate-ref-grouping.

   *  Added feature feature 'key-generation'.

   *  Cloned groupings symmetric-key-grouping, asymmetric-key-pair-
      grouping, asymmetric-key-pair-with-cert-grouping, and asymmetric-
      key-pair-with-certs-grouping from crypto-keys, augmenting into
      each new case statements for values that have been encrypted by
      other keys in the keystore.  Refactored keystore model to use
      these groupings.

   *  Added new 'symmetric-keys' lists, as a sibling to the existing
      'asymmetric-keys' list.

   *  Added RPCs (not actions) 'generate-symmetric-key' and 'generate-
      asymmetric-key' to *return* a (potentially encrypted) key.

A.12.  11 to 12

   *  Updated to reflect crypto-type's draft using enumerations over
      identities.





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   *  Added examples for the 'generate-symmetric-key' and 'generate-
      asymmetric-key' RPCs.

   *  Updated the Introduction section.

A.13.  12 to 13

   *  Updated examples to incorporate new "key-format" identities.

   *  Made the two "generate-*-key" RPCs be "action" statements instead.

A.14.  13 to 14

   *  Updated YANG module and examples to incorporate the new
      iana-*-algorithm modules in the crypto-types draft..

A.15.  14 to 15

   *  Added new "Support for Built-in Keys" section.

   *  Added 'must' expressions asserting that the 'key-format' leaf
      whenever an encrypted key is specified.

   *  Added local-or-keystore-symmetric-key-grouping for PSK support.

A.16.  15 to 16

   *  Moved the generate key actions to ietf-crypt-types as RPCs, which
      are augmented by ietf-keystore to support encrypted keys.
      Examples updated accordingly.

   *  Added a SSH certificate-based key (RFC 6187) and a raw private key
      to the example instance document (partly so they could be
      referenced by examples in the SSH and TLS client/server drafts.

A.17.  16 to 17

   *  Removed augments to the "generate-symmetric-key" and "generate-
      asymmetric-key" groupings.

   *  Removed "generate-symmetric-key" and "generate-asymmetric-key"
      examples.

   *  Removed the "algorithm" nodes from remaining examples.

   *  Updated the "Support for Built-in Keys" section.

   *  Added new section "Encrypting Keys in Configuration".



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   *  Added a "Note to Reviewers" note to first page.

A.18.  17 to 18

   *  Removed dangling/unnecessary ref to RFC 8342.

   *  r/MUST/SHOULD/ wrt strength of keys being configured over
      transports.

   *  Added an example for the "certificate-expiration" notification.

   *  Clarified that OS MAY have a multiplicity of underlying keystores
      and/or HSMs.

   *  Clarified expected behavior for "built-in" keys in <operational>

   *  Clarified the "Migrating Configuration to Another Server" section.

   *  Expanded "Data Model Overview section(s) [remove "wall" of tree
      diagrams].

   *  Updated the Security Considerations section.

Acknowledgements

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

Author's Address

   Kent Watsen
   Watsen Networks

   Email: kent+ietf@watsen.net













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