[Docs] [txt|pdf|xml|html] [Tracker] [WG] [Email] [Diff1] [Diff2] [Nits]

Versions: (draft-ietf-netconf-system-keychain) 00 01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16 20

NETCONF Working Group                                          K. Watsen
Internet-Draft                                           Watsen Networks
Intended status: Standards Track                          20 August 2020
Expires: 21 February 2021


                    A YANG Data Model for a Keystore
                     draft-ietf-netconf-keystore-20

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 or
   hidden.  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:

   *  "2020-08-20" --> 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.






Watsen                  Expires 21 February 2021                [Page 1]


Internet-Draft      A YANG Data Model for a Keystore         August 2020


   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at https://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on 21 February 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/
   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.  Relation to other RFCs  . . . . . . . . . . . . . . . . .   4
     1.2.  Specification Language  . . . . . . . . . . . . . . . . .   5
     1.3.  Terminology . . . . . . . . . . . . . . . . . . . . . . .   5
     1.4.  Adherence to the NMDA . . . . . . . . . . . . . . . . . .   6
   2.  The "ietf-keystore" Module  . . . . . . . . . . . . . . . . .   6
     2.1.  Data Model Overview . . . . . . . . . . . . . . . . . . .   6
     2.2.  Example Usage . . . . . . . . . . . . . . . . . . . . . .  17
     2.3.  YANG Module . . . . . . . . . . . . . . . . . . . . . . .  29
   3.  Support for Built-in Keys . . . . . . . . . . . . . . . . . .  37
   4.  Encrypting Keys in Configuration  . . . . . . . . . . . . . .  40
   5.  Security Considerations . . . . . . . . . . . . . . . . . . .  44
     5.1.  Data at Rest  . . . . . . . . . . . . . . . . . . . . . .  44
     5.2.  The "ietf-keystore" YANG Module . . . . . . . . . . . . .  44
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  45
     6.1.  The "IETF XML" Registry . . . . . . . . . . . . . . . . .  45
     6.2.  The "YANG Module Names" Registry  . . . . . . . . . . . .  45
   7.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  45
     7.1.  Normative References  . . . . . . . . . . . . . . . . . .  45
     7.2.  Informative References  . . . . . . . . . . . . . . . . .  46



Watsen                  Expires 21 February 2021                [Page 2]


Internet-Draft      A YANG Data Model for a Keystore         August 2020


   Appendix A.  Change Log . . . . . . . . . . . . . . . . . . . . .  48
     A.1.  00 to 01  . . . . . . . . . . . . . . . . . . . . . . . .  48
     A.2.  01 to 02  . . . . . . . . . . . . . . . . . . . . . . . .  48
     A.3.  02 to 03  . . . . . . . . . . . . . . . . . . . . . . . .  48
     A.4.  03 to 04  . . . . . . . . . . . . . . . . . . . . . . . .  48
     A.5.  04 to 05  . . . . . . . . . . . . . . . . . . . . . . . .  49
     A.6.  05 to 06  . . . . . . . . . . . . . . . . . . . . . . . .  49
     A.7.  06 to 07  . . . . . . . . . . . . . . . . . . . . . . . .  49
     A.8.  07 to 08  . . . . . . . . . . . . . . . . . . . . . . . .  49
     A.9.  08 to 09  . . . . . . . . . . . . . . . . . . . . . . . .  49
     A.10. 09 to 10  . . . . . . . . . . . . . . . . . . . . . . . .  50
     A.11. 10 to 11  . . . . . . . . . . . . . . . . . . . . . . . .  50
     A.12. 11 to 12  . . . . . . . . . . . . . . . . . . . . . . . .  50
     A.13. 12 to 13  . . . . . . . . . . . . . . . . . . . . . . . .  51
     A.14. 13 to 14  . . . . . . . . . . . . . . . . . . . . . . . .  51
     A.15. 14 to 15  . . . . . . . . . . . . . . . . . . . . . . . .  51
     A.16. 15 to 16  . . . . . . . . . . . . . . . . . . . . . . . .  51
     A.17. 16 to 17  . . . . . . . . . . . . . . . . . . . . . . . .  51
     A.18. 17 to 18  . . . . . . . . . . . . . . . . . . . . . . . .  52
     A.19. 18 to 19  . . . . . . . . . . . . . . . . . . . . . . . .  52
     A.20. 19 to 20  . . . . . . . . . . . . . . . . . . . . . . . .  52
   Acknowledgements  . . . . . . . . . . . . . . . . . . . . . . . .  52
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .  52

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 or hidden (see [I-D.ietf-netconf-crypto-types].  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 define 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 Platform Module (TPM).
   These systems are unique in that the cryptographic hardware hides the
   secret key values.  Additionally, such hardware is commonly
   initiailized when manufactured to protect a "built-in" asymmetric key
   for which the public half is conveyed in an identity certificate
   (e.g., an IDevID [Std-802.1AR-2009] certificate).  Please see
   Section 3 to see how built-in keys are supported.




Watsen                  Expires 21 February 2021                [Page 3]


Internet-Draft      A YANG Data Model for a Keystore         August 2020


   This document intends to support existing practices; it does not
   intend to define new behvior for systems to implement.  To simplify
   implementation, advanced key formats may be selectively implemented.

   Implementations may utilize zero or more operating system level
   keystore utilities and/or hardware security modules (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 normative dependency 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.
   Hyperlinks to 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





Watsen                  Expires 21 February 2021                [Page 4]


Internet-Draft      A YANG Data Model for a Keystore         August 2020


   +=======================+===========================================+
   | 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.  Terminology

   The terms "client" and "server" are defined in [RFC6241] and are not
   redefined here.

   The term "keystore" is defined in this draft as a mechanism that
   intends safeguard secrets placed into it for protection.

   The nomenclature "<running>" and "<operational>" are defined in
   [RFC8342].

   The sentence fragments "augmented" and "augmented in" are used herein
   as the past tense verbified form of the "augment" statement defined
   in Section 7.17 of [RFC7950].





Watsen                  Expires 21 February 2021                [Page 5]


Internet-Draft      A YANG Data Model for a Keystore         August 2020


1.4.  Adherence to the NMDA

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

2.  The "ietf-keystore" Module

   This section defines a YANG 1.1 [RFC7950] module called "ietf-
   keystore".  A high-level overview of the module is provided in
   Section 2.1.  Examples illustatrating the module's use are provided
   in Examples (Section 2.2).  The YANG module itself is defined in
   Section 2.3.

2.1.  Data Model Overview

   This section provides an overview of the "ietf-keystore" module in
   terms of its features, typedefs, groupings, and protocol-accessible
   nodes.

2.1.1.  Features

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

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

      |  The diagram above uses syntax that is similar to but not
      |  defined in [RFC8340].

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

      |  The diagram above uses syntax that is similar to but not
      |  defined in [RFC8340].

   Comments:




Watsen                  Expires 21 February 2021                [Page 6]


Internet-Draft      A YANG Data Model for a Keystore         August 2020


   *  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

      |  The diagram above uses syntax that is similar to but not
      |  defined in [RFC8340].

   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:

      |  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?    ks:symmetric-key-ref
          +--:(asymmetric-key-ref)
             +-- asymmetric-key-ref?   ks:asymmetric-key-ref

   Comments:

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




Watsen                  Expires 21 February 2021                [Page 7]


Internet-Draft      A YANG Data Model for a Keystore         August 2020


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

   Comments:

   *  The "local-or-keystore-symmetric-key-grouping" grouping is
      provided soley as convenience to downstream modules that wish to
      offer an option for whether a 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 2.1.4.3 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.




Watsen                  Expires 21 February 2021                [Page 8]


Internet-Draft      A YANG Data Model for a Keystore         August 2020


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 for whether an asymmetric key is defined locally
      or as a reference to an 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 an asymmetric key in an alternate location.

   *  For the "local-definition" option, the defintion uses the
      "asymmetric-key-pair-grouping" grouping discussed in
      Section 2.1.4.5 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.

2.1.3.5.  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:




Watsen                  Expires 21 February 2021                [Page 9]


Internet-Draft      A YANG Data Model for a Keystore         August 2020


   *  The "local-or-keystore-asymmetric-key-with-certs-grouping"
      grouping is provided soley as convenience to downstream modules
      that wish to offer an option for whether an asymmetric key is
      defined locally or as a reference to an 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 an 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 2.1.4.11 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:

     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 for whether a 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 2.1.4.11 of [I-D.ietf-netconf-crypto-types].



Watsen                  Expires 21 February 2021               [Page 10]


Internet-Draft      A YANG Data Model for a Keystore         August 2020


   *  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:

   *  The "keystore-grouping" grouping 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 in
      Section 2.1.4.11 of [I-D.ietf-netconf-crypto-types].

   *  For symmetric keys, each "symmetric-key" uses the "symmetric-key-
      grouping" grouping discussed in Section 2.1.4.3 of
      [I-D.ietf-netconf-crypto-types].

2.1.4.  Protocol-accessible Nodes

   The following tree diagram [RFC8340] lists all the protocol-
   accessible nodes defined in the "ietf-keystore" module, without
   expanding the "grouping" statements:

   module: ietf-keystore
     +--rw keystore
        +---u keystore-grouping

     grouping encrypted-by-choice-grouping
       +-- (encrypted-by-choice)
          +--:(symmetric-key-ref)
          |  +-- symmetric-key-ref?    ks:symmetric-key-ref



Watsen                  Expires 21 February 2021               [Page 11]


Internet-Draft      A YANG Data Model for a Keystore         August 2020


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

   The following tree diagram [RFC8340] lists all the protocol-
   accessible nodes defined in the "ietf-keystore" module, with all
   "grouping" statements expanded, enabling the keystore's full
   structure to be seen:



Watsen                  Expires 21 February 2021               [Page 12]


Internet-Draft      A YANG Data Model for a Keystore         August 2020


   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)
        |     |  +--:(cleartext-private-key)
        |     |  |  +--rw cleartext-private-key?            binary
        |     |  +--:(hidden-private-key)
        |     |  |  +--rw hidden-private-key?               empty
        |     |  +--:(encrypted-private-key) {private-key-encryption}?
        |     |     +--rw encrypted-private-key
        |     |        +--rw encrypted-by
        |     |        |  +--rw (encrypted-by-choice)
        |     |        |     +--:(symmetric-key-ref)
        |     |        |     |  +--rw symmetric-key-ref?
        |     |        |     |          ks:symmetric-key-ref
        |     |        |     +--:(asymmetric-key-ref)
        |     |        |        +--rw asymmetric-key-ref?
        |     |        |                ks:asymmetric-key-ref
        |     |        +--rw encrypted-value    binary
        |     +--rw certificates
        |     |  +--rw certificate* [name]
        |     |     +--rw name                      string
        |     |     +--rw cert-data                 end-entity-cert-cms
        |     |     +---n certificate-expiration
        |     |             {certificate-expiration-notification}?
        |     |        +-- 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
        +--rw symmetric-keys
           +--rw symmetric-key* [name]
              +--rw name                   string
              +--rw key-format?            identityref
              +--rw (key-type)
                 +--:(cleartext-key)
                 |  +--rw cleartext-key?   binary
                 +--:(hidden-key)
                 |  +--rw hidden-key?      empty
                 +--:(encrypted-key) {symmetric-key-encryption}?
                    +--rw encrypted-key



Watsen                  Expires 21 February 2021               [Page 13]


Internet-Draft      A YANG Data Model for a Keystore         August 2020


                       +--rw encrypted-by
                       |  +--rw (encrypted-by-choice)
                       |     +--:(symmetric-key-ref)
                       |     |  +--rw symmetric-key-ref?
                       |     |          ks:symmetric-key-ref
                       |     +--:(asymmetric-key-ref)
                       |        +--rw asymmetric-key-ref?
                       |                ks:asymmetric-key-ref
                       +--rw encrypted-value    binary

     grouping encrypted-by-choice-grouping
       +-- (encrypted-by-choice)
          +--:(symmetric-key-ref)
          |  +-- symmetric-key-ref?    ks:symmetric-key-ref
          +--:(asymmetric-key-ref)
             +-- asymmetric-key-ref?   ks:asymmetric-key-ref
     grouping asymmetric-key-certificate-ref-grouping
       +-- asymmetric-key?   ks:asymmetric-key-ref
       +-- certificate?      leafref
     grouping local-or-keystore-symmetric-key-grouping
       +-- (local-or-keystore)
          +--:(local) {local-definitions-supported}?
          |  +-- local-definition
          |     +-- key-format?            identityref
          |     +-- (key-type)
          |        +--:(cleartext-key)
          |        |  +-- cleartext-key?   binary
          |        +--:(hidden-key)
          |        |  +-- hidden-key?      empty
          |        +--:(encrypted-key) {symmetric-key-encryption}?
          |           +-- encrypted-key
          |              +-- encrypted-by
          |              +-- encrypted-value    binary
          +--:(keystore) {keystore-supported}?
             +-- keystore-reference?   ks:symmetric-key-ref
     grouping local-or-keystore-asymmetric-key-grouping
       +-- (local-or-keystore)
          +--:(local) {local-definitions-supported}?
          |  +-- local-definition
          |     +-- public-key-format              identityref
          |     +-- public-key                     binary
          |     +-- private-key-format?            identityref
          |     +-- (private-key-type)
          |        +--:(cleartext-private-key)
          |        |  +-- cleartext-private-key?   binary
          |        +--:(hidden-private-key)
          |        |  +-- hidden-private-key?      empty
          |        +--:(encrypted-private-key) {private-key-encryption}?



Watsen                  Expires 21 February 2021               [Page 14]


Internet-Draft      A YANG Data Model for a Keystore         August 2020


          |           +-- encrypted-private-key
          |              +-- encrypted-by
          |              +-- encrypted-value    binary
          +--:(keystore) {keystore-supported}?
             +-- keystore-reference?   ks:asymmetric-key-ref
     grouping local-or-keystore-asymmetric-key-with-certs-grouping
       +-- (local-or-keystore)
          +--:(local) {local-definitions-supported}?
          |  +-- local-definition
          |     +-- public-key-format                       identityref
          |     +-- public-key                              binary
          |     +-- private-key-format?                     identityref
          |     +-- (private-key-type)
          |     |  +--:(cleartext-private-key)
          |     |  |  +-- cleartext-private-key?            binary
          |     |  +--:(hidden-private-key)
          |     |  |  +-- hidden-private-key?               empty
          |     |  +--:(encrypted-private-key) {private-key-encryption}?
          |     |     +-- encrypted-private-key
          |     |        +-- encrypted-by
          |     |        +-- encrypted-value    binary
          |     +-- certificates
          |     |  +-- certificate* [name]
          |     |     +-- name?                     string
          |     |     +-- cert-data                 end-entity-cert-cms
          |     |     +---n certificate-expiration
          |     |             {certificate-expiration-notification}?
          |     |        +-- 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}?
             +-- keystore-reference?   ks:asymmetric-key-ref
     grouping local-or-keystore-end-entity-cert-with-key-grouping
       +-- (local-or-keystore)
          +--:(local) {local-definitions-supported}?
          |  +-- local-definition
          |     +-- public-key-format                       identityref
          |     +-- public-key                              binary
          |     +-- private-key-format?                     identityref
          |     +-- (private-key-type)
          |     |  +--:(cleartext-private-key)
          |     |  |  +-- cleartext-private-key?            binary
          |     |  +--:(hidden-private-key)
          |     |  |  +-- hidden-private-key?               empty



Watsen                  Expires 21 February 2021               [Page 15]


Internet-Draft      A YANG Data Model for a Keystore         August 2020


          |     |  +--:(encrypted-private-key) {private-key-encryption}?
          |     |     +-- encrypted-private-key
          |     |        +-- encrypted-by
          |     |        +-- encrypted-value    binary
          |     +-- cert-data?
          |     |       end-entity-cert-cms
          |     +---n certificate-expiration
          |     |       {certificate-expiration-notification}?
          |     |  +-- 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}?
             +-- keystore-reference
                +-- asymmetric-key?   ks:asymmetric-key-ref
                +-- certificate?      leafref
     grouping keystore-grouping
       +-- asymmetric-keys
       |  +-- asymmetric-key* [name]
       |     +-- name?                                   string
       |     +-- public-key-format                       identityref
       |     +-- public-key                              binary
       |     +-- private-key-format?                     identityref
       |     +-- (private-key-type)
       |     |  +--:(cleartext-private-key)
       |     |  |  +-- cleartext-private-key?            binary
       |     |  +--:(hidden-private-key)
       |     |  |  +-- hidden-private-key?               empty
       |     |  +--:(encrypted-private-key) {private-key-encryption}?
       |     |     +-- encrypted-private-key
       |     |        +-- encrypted-by
       |     |        +-- encrypted-value    binary
       |     +-- certificates
       |     |  +-- certificate* [name]
       |     |     +-- name?                     string
       |     |     +-- cert-data                 end-entity-cert-cms
       |     |     +---n certificate-expiration
       |     |             {certificate-expiration-notification}?
       |     |        +-- 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



Watsen                  Expires 21 February 2021               [Page 16]


Internet-Draft      A YANG Data Model for a Keystore         August 2020


       +-- symmetric-keys
          +-- symmetric-key* [name]
             +-- name?                  string
             +-- key-format?            identityref
             +-- (key-type)
                +--:(cleartext-key)
                |  +-- cleartext-key?   binary
                +--:(hidden-key)
                |  +-- hidden-key?      empty
                +--:(encrypted-key) {symmetric-key-encryption}?
                   +-- encrypted-key
                      +-- encrypted-by
                      +-- 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].

   *  The protcol-accessible nodes for the "ietf-keystore" module are an
      instance of the "keystore-grouping" grouping discussed in
      Section 2.1.3.7.

   *  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.

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>



Watsen                  Expires 21 February 2021               [Page 17]


Internet-Draft      A YANG Data Model for a Keystore         August 2020


            <name>cleartext-symmetric-key</name>
            <key-format>ct:octet-string-key-format</key-format>
            <cleartext-key>base64encodedvalue==</cleartext-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>
            <cleartext-private-key>base64encodedvalue==</cleartext-priv\
   ate-key>
         </asymmetric-key>
         <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>
            <cleartext-private-key>base64encodedvalue==</cleartext-priv\
   ate-key>
            <certificates>



Watsen                  Expires 21 February 2021               [Page 18]


Internet-Draft      A YANG Data Model for a Keystore         August 2020


               <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>
            <cleartext-private-key>base64encodedvalue==</cleartext-priv\
   ate-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>
            <cleartext-private-key>base64encodedvalue==</cleartext-priv\
   ate-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>
               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>
            <cleartext-private-key>base64encodedvalue==</cleartext-priv\
   ate-key>
            <certificates>



Watsen                  Expires 21 February 2021               [Page 19]


Internet-Draft      A YANG Data Model for a Keystore         August 2020


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








Watsen                  Expires 21 February 2021               [Page 20]


Internet-Draft      A YANG Data Model for a Keystore         August 2020


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.

   These examples assume the existence of an example module called "ex-
   keystore-usage" having the namespace "http://example.com/ns/example-
   keystore-usage".

   The ex-keystore-usage module is first presented using tree diagrams
   [RFC8340], followed by an instance example illustrating all the
   "local-or-keystore" groupings in use, followed by the YANG module
   itself.




Watsen                  Expires 21 February 2021               [Page 21]


Internet-Draft      A YANG Data Model for a Keystore         August 2020


   The following tree diagram illustrates "ex-keystore-usage" without
   expanding the "grouping" statements:

   module: ex-keystore-usage
     +--rw keystore-usage
        +--rw symmetric-key* [name]
        |  +--rw name                                           string
        |  +---u ks:local-or-keystore-symmetric-key-grouping
        +--rw asymmetric-key* [name]
        |  +--rw name                                            string
        |  +---u ks:local-or-keystore-asymmetric-key-grouping
        +--rw asymmetric-key-with-certs* [name]
        |  +--rw name
        |  |       string
        |  +---u ks:local-or-keystore-asymmetric-key-with-certs-grouping
        +--rw end-entity-cert-with-key* [name]
           +--rw name
           |       string
           +---u ks:local-or-keystore-end-entity-cert-with-key-grouping

   The following tree diagram illustrates the "ex-keystore-usage"
   module, with all "grouping" statements expanded, enabling the
   keystore's full structure to be seen:

   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)
        |     |        +--:(cleartext-key)
        |     |        |  +--rw cleartext-key?   binary
        |     |        +--:(hidden-key)
        |     |        |  +--rw hidden-key?      empty
        |     |        +--:(encrypted-key) {symmetric-key-encryption}?
        |     |           +--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



Watsen                  Expires 21 February 2021               [Page 22]


Internet-Draft      A YANG Data Model for a Keystore         August 2020


        |     |     +--rw public-key-format              identityref
        |     |     +--rw public-key                     binary
        |     |     +--rw private-key-format?            identityref
        |     |     +--rw (private-key-type)
        |     |        +--:(cleartext-private-key)
        |     |        |  +--rw cleartext-private-key?   binary
        |     |        +--:(hidden-private-key)
        |     |        |  +--rw hidden-private-key?      empty
        |     |        +--:(encrypted-private-key)
        |     |                 {private-key-encryption}?
        |     |           +--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
        |     |     +--rw (private-key-type)
        |     |     |  +--:(cleartext-private-key)
        |     |     |  |  +--rw cleartext-private-key?            binary
        |     |     |  +--:(hidden-private-key)
        |     |     |  |  +--rw hidden-private-key?               empty
        |     |     |  +--:(encrypted-private-key)
        |     |     |           {private-key-encryption}?
        |     |     |     +--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
        |     |     |             {certificate-expiration-notification}?
        |     |     |        +-- 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



Watsen                  Expires 21 February 2021               [Page 23]


Internet-Draft      A YANG Data Model for a Keystore         August 2020


        |     |           +--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)
              |     |  +--:(cleartext-private-key)
              |     |  |  +--rw cleartext-private-key?            binary
              |     |  +--:(hidden-private-key)
              |     |  |  +--rw hidden-private-key?               empty
              |     |  +--:(encrypted-private-key)
              |     |           {private-key-encryption}?
              |     |     +--rw encrypted-private-key
              |     |        +--rw encrypted-by
              |     |        +--rw encrypted-value    binary
              |     +--rw cert-data?
              |     |       end-entity-cert-cms
              |     +---n certificate-expiration
              |     |       {certificate-expiration-notification}?
              |     |  +-- 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
                    +--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.





Watsen                  Expires 21 February 2021               [Page 24]


Internet-Draft      A YANG Data Model for a Keystore         August 2020


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

   <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>
         <cleartext-key>base64encodedvalue==</cleartext-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>
       <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>
         <cleartext-private-key>base64encodedvalue==</cleartext-private\
   -key>
       </local-definition>
     </asymmetric-key>


     <!-- the following two equivalent examples illustrate        -->



Watsen                  Expires 21 February 2021               [Page 25]


Internet-Draft      A YANG Data Model for a Keystore         August 2020


     <!-- "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>
         <cleartext-private-key>base64encodedvalue==</cleartext-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>
       <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>



Watsen                  Expires 21 February 2021               [Page 26]


Internet-Draft      A YANG Data Model for a Keystore         August 2020


           ct:rsa-private-key-format
         </private-key-format>
         <cleartext-private-key>base64encodedvalue==</cleartext-private\
   -key>
         <cert-data>base64encodedvalue==</cert-data>
       </local-definition>
     </end-entity-cert-with-key>

   </keystore-usage>

   Following is the "ex-keystore-usage" module's YANG definition:

   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 "2020-08-20" {
       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 {



Watsen                  Expires 21 February 2021               [Page 27]


Internet-Draft      A YANG Data Model for a Keystore         August 2020


           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;
         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;



Watsen                  Expires 21 February 2021               [Page 28]


Internet-Draft      A YANG Data Model for a Keystore         August 2020


         description
           "An end-entity certificate and its associated asymmetric
            key, that may be configured locally or be a reference
            to another certificate (and its associated asymmetric
            key) in the keystore.";
       }
     }

   }

2.3.  YANG Module

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

   <CODE BEGINS> file "ietf-keystore@2020-08-20.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
       "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.



Watsen                  Expires 21 February 2021               [Page 29]


Internet-Draft      A YANG Data Model for a Keystore         August 2020


        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 2020-08-20 {
       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.";
     }

     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"



Watsen                  Expires 21 February 2021               [Page 30]


Internet-Draft      A YANG Data Model for a Keystore         August 2020


            + "/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 that can be augmented
          into the 'encrypted-by' node presented by the
          'symmetric-key-grouping' and 'asymmetric-key-pair-grouping'
          groupings defined in RFC AAAA.";
       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 ks:symmetric-key-ref;
             description
              "Identifies the symmetric key used to encrypt the
               associated key.";
           }
         }
         case asymmetric-key-ref {
           leaf asymmetric-key-ref {
             type ks:asymmetric-key-ref;
             description
              "Identifies the asymmetric key whose public key
               encrypted the associated key.";
           }
         }



Watsen                  Expires 21 February 2021               [Page 31]


Internet-Draft      A YANG Data Model for a Keystore         August 2020


       }
     }

     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
         "A grouping that expands to allow the symmetric key to be
          either stored locally, i.e., within the using data model,
          or 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;



Watsen                  Expires 21 February 2021               [Page 32]


Internet-Draft      A YANG Data Model for a Keystore         August 2020


           }
         }
         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, i.e., within the using data model,
          or a reference to an asymmetric 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:asymmetric-key-pair-grouping;
           }
         }
         case keystore {
           if-feature "keystore-supported";
           leaf keystore-reference {
             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.";
           }
         }
       }
     }

     grouping local-or-keystore-asymmetric-key-with-certs-grouping {



Watsen                  Expires 21 February 2021               [Page 33]


Internet-Draft      A YANG Data Model for a Keystore         August 2020


       description
         "A grouping that expands to allow an asymmetric key and
          its associated certificates to be either stored locally,
          i.e., within the using data model, or a reference to an
          asymmetric key (and its associated certificates) 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: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.";
           }
         }
       }
     }

     grouping local-or-keystore-end-entity-cert-with-key-grouping {
       description
         "A grouping that expands to allow an end-entity certificate
          (and its associated asymmetric key pair) to be either stored
          locally, i.e., within the using data model, or a reference
          to a specific certificate 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



Watsen                  Expires 21 February 2021               [Page 34]


Internet-Draft      A YANG Data Model for a Keystore         August 2020


               "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 associated with
                an asymmetric key stored 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.";
           }
           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;



Watsen                  Expires 21 February 2021               [Page 35]


Internet-Draft      A YANG Data Model for a Keystore         August 2020


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

   }

   <CODE ENDS>








Watsen                  Expires 21 February 2021               [Page 36]


Internet-Draft      A YANG Data Model for a Keystore         August 2020


3.  Support for Built-in Keys

   In some implementations, a server may support built-in keys.  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 primary 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>

   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 value for the list's "key" substatement, so
   that the server can bind the references to the built-in entries.











Watsen                  Expires 21 February 2021               [Page 37]


Internet-Draft      A YANG Data Model for a Keystore         August 2020


   In addition to copying keys into the Keystore in <running>, cleartext
   and encrypted keys may be copied into other parts of configuration,
   but they will lose their connection to having been a built-in value.
   Note that hidden keys cannot be copied into other parts of the
   configuration because doing would lose the key's connection to the
   built-in key, where the key's secret value is stored.  Built-in
   "encrypted" keys MAY be copied into other parts of the configuration
   so long as the reference to the other built-in key that encrypted
   them is maintained.

   Only the referenced keys need to be copied; that is, the keys in
   <running> MAY be a subset, including the whole of the set, of the
   built-in keys defined in <operational>.

   No new built-in keys may be added nor existing built-in changed, with
   exception for associating additional certificates to an existing
   built-in key.

   A server MUST reject attempts to modify any aspect of built-in keys,
   with exception for 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>:
























Watsen                  Expires 21 February 2021               [Page 38]


Internet-Draft      A YANG Data Model for a Keystore         August 2020


   <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:

























Watsen                  Expires 21 February 2021               [Page 39]


Internet-Draft      A YANG Data Model for a Keystore         August 2020


   <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 both the symmetric
   and asymmetric keys on a server to be encrypted, such that
   traditional backup/restore procedures can be used without concern for
   the keys being compromised when in transit.

4.1.  Key Encryption Key

   The ability to encrypt configured keys is predicated on the existence
   of a "key encryption key" (KEK).  There may be any number of KEKs in
   a system.  A KEK, by its namesake, is a key that is used to encrypt
   other keys.  A KEK MAY be either a symmetric key or an asymmetric
   key.

   If a KEK is a symmetric key, then the server MUST provide an API for
   administrators to encrypt other keys without needing to know the
   symmetric key's value.  If the KEK is an asymmetric key, then the
   server MAY provide an API enabling the encryption of other keys or,
   alternatively, let the administrators do so themselves using the
   asymmetric key's public half.




Watsen                  Expires 21 February 2021               [Page 40]


Internet-Draft      A YANG Data Model for a Keystore         August 2020


   A server MUST possess (or be able to possess, in case the KEK has
   been encrypted by another KEK) a KEK's cleartext value so that it can
   decrypt the other keys in the configurion at runtime.

4.2.  Configuring Encrypted Keys

   Each time a new key is configured, it SHOULD be encrypted by a KEK.

   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

   Implementations SHOULD provide an API that simultaneously generates
   and encrypts a key (symmetric or asymmetric) using a KEK.  Thusly
   newly generated key cleartext values are never known to the
   administrators generating the 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
   (e.g., an organization's crypto officer).

   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 KEK
   that encrypted the key.

4.3.  Migrating Configuration to Another Server

   When a KEK is used to encrypt other keys, migrating the configuration
   to another server is only possible if the second server has the same
   KEK.  How the second server comes to have the same KEK is discussed
   in this section.

   In some deployments, mechanisms outside the scope of this document
   may be used to migrate a KEK 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.









Watsen                  Expires 21 February 2021               [Page 41]


Internet-Draft      A YANG Data Model for a Keystore         August 2020


   In other deployments, an organization's crypto officer, possessing a
   KEK's cleartext value, configures the same KEK on the second server,
   presumably as a hidden key or a key protected by access-control
   (e.g., NACM's "default-deny-all), so that the cleartext value is not
   disclosed to regular administrators.  However, this approach creates
   high-coupling to and dependency on the crypto officers that doesn't
   scale in production environments.

   In order to decouple the crypto officers from the regular
   administrators, a special KEK, called the "master key" (MK), may be
   used.

   A MK is commonly a globally-unique built-in (see Section 3)
   asymmetric key.  The private key, due to its long lifetime, is hidden
   (i.e., "hidden-private-key" in Section 2.1.4.5. of
   [I-D.ietf-netconf-crypto-types]).  The public key is often contained
   in an identity certificate (e.g., IDevID).  How to configure a MK
   during the manufacturing process is outside the scope of this
   document.

   It is highly RECOMMENDED that MKs are built-in and hidden but, if
   this is not possible, MKs highly restricted access mechanisms SHOULD
   be used to limit access to the MK's secret data to only highly
   authorized clients (e.g., an organization's crypto officer).  In this
   case, it is RECOMMENDED that the MK is not built-in and hence is,
   effectively, just like a KEK.

   Assuming the server has a MK, the MK can be used to encrypt a "shared
   KEK", which is then used to encrypt the keys configured by regular
   administrators.

   With this extra level of indirection, it is possible for a crypto
   officer to encrypt the same KEK for a multiplicity of servers offline
   using the public key contained in their identity certificates.  The
   crypto officer can then safely handoff the encrypted KEKs to the
   regular administrators responsible for server installations,
   including migrations.

   In order to migrate the 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 encrypted KEK Keystore entry from the first server with
   the encrypted KEK for the second server.  Upon doing this, the
   configuration (containing many encrypted keys) can be loaded into the
   second server while enabling the second server to decrypt all the
   encrypted keys in the configuration.

   The following diagram illustrates this idea:



Watsen                  Expires 21 February 2021               [Page 42]


Internet-Draft      A YANG Data Model for a Keystore         August 2020


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




Watsen                  Expires 21 February 2021               [Page 43]


Internet-Draft      A YANG Data Model for a Keystore         August 2020


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 "cleartext-key" and
      |  "cleartext-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
      |  uncontrolled 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.





Watsen                  Expires 21 February 2021               [Page 44]


Internet-Draft      A YANG Data Model for a Keystore         August 2020


   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 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., "YANG Data Types and Groupings for
              Cryptography", Work in Progress, Internet-Draft, draft-
              ietf-netconf-crypto-types-17, 10 July 2020,
              <https://tools.ietf.org/html/draft-ietf-netconf-crypto-
              types-17>.

   [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>.





Watsen                  Expires 21 February 2021               [Page 45]


Internet-Draft      A YANG Data Model for a Keystore         August 2020


   [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-04, 8 July 2020,
              <https://tools.ietf.org/html/draft-ietf-netconf-http-
              client-server-04>.

   [I-D.ietf-netconf-keystore]
              Watsen, K., "A YANG Data Model for a Keystore", Work in
              Progress, Internet-Draft, draft-ietf-netconf-keystore-19,
              10 July 2020, <https://tools.ietf.org/html/draft-ietf-
              netconf-keystore-19>.

   [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-20, 8 July 2020,
              <https://tools.ietf.org/html/draft-ietf-netconf-netconf-
              client-server-20>.

   [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-20, 8 July 2020,
              <https://tools.ietf.org/html/draft-ietf-netconf-restconf-
              client-server-20>.

   [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-21, 10 July 2020,
              <https://tools.ietf.org/html/draft-ietf-netconf-ssh-
              client-server-21>.

   [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-



Watsen                  Expires 21 February 2021               [Page 46]


Internet-Draft      A YANG Data Model for a Keystore         August 2020


              ietf-netconf-tcp-client-server-07, 8 July 2020,
              <https://tools.ietf.org/html/draft-ietf-netconf-tcp-
              client-server-07>.

   [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-21, 10 July 2020,
              <https://tools.ietf.org/html/draft-ietf-netconf-tls-
              client-server-21>.

   [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-12, 10 July 2020, <https://tools.ietf.org/html/
              draft-ietf-netconf-trust-anchors-12>.

   [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>.



Watsen                  Expires 21 February 2021               [Page 47]


Internet-Draft      A YANG Data Model for a Keystore         August 2020


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




Watsen                  Expires 21 February 2021               [Page 48]


Internet-Draft      A YANG Data Model for a Keystore         August 2020


   *  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>.



Watsen                  Expires 21 February 2021               [Page 49]


Internet-Draft      A YANG Data Model for a Keystore         August 2020


   *  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.





Watsen                  Expires 21 February 2021               [Page 50]


Internet-Draft      A YANG Data Model for a Keystore         August 2020


   *  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".



Watsen                  Expires 21 February 2021               [Page 51]


Internet-Draft      A YANG Data Model for a Keystore         August 2020


   *  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.

A.19.  18 to 19

   *  Updated examples to reflect new "cleartext-" prefix in the crypto-
      types draft.

A.20.  19 to 20

   *  Addressed SecDir comments from Magnus Nystroem and Sandra Murphy.

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, Magnus Nystroem, Martin Bjorklund, Mehmet Ersue, Phil
   Shafer, Radek Krejci, Ramkumar Dhanapal, Reshad Rahman, Sandra
   Murphy, Sean Turner, and Tom Petch.

Author's Address

   Kent Watsen
   Watsen Networks

   Email: kent+ietf@watsen.net



Watsen                  Expires 21 February 2021               [Page 52]


Html markup produced by rfcmarkup 1.129d, available from https://tools.ietf.org/tools/rfcmarkup/