Keystore Model
draft-ietf-netconf-keystore-02

"An arbitrary name for this trusted host-key. Must be
             unique across all lists of trusted host-keys (not just
             this list) so that a leafref to it from another module
             can resolve to unique values.

             Note that, for when the SSH client is able to listen
             for call-home connections as well, there is no reference
             identifier (e.g., hostname, IP address, etc.) that it
             can use to uniquely identify the server with.  The
             call-home draft recommends SSH servers use X.509v3
             certificates (RFC6187) when calling home.";
        }
        leaf host-key {  // rename to 'data'?
          type binary;
          mandatory true;
          description  // is this the correct type?
            "An OneAsymmetricKey 'publicKey' structure as specified
             by RFC 5958, Section 2 encoded using the ASN.1
             distinguished encoding rules (DER), as specified
             in ITU-T X.690.";
          reference
            "RFC 5958:
                Asymmetric Key Packages
             ITU-T X.690:

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                Information technology - ASN.1 encoding rules:
                Specification of Basic Encoding Rules (BER),
                Canonical Encoding Rules (CER) and Distinguished
                Encoding Rules (DER).";
        }
      }
    }
  }

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

}

<CODE ENDS>

3.  Design Considerations

   This document uses PKCS #10 [RFC2986] for the "generate-certificate-
   signing-request" action.  The use of Certificate Request Message
   Format (CRMF) [RFC4211] was considered, but is was unclear if there
   was market demand for it, and so support for CRMF has been left out
   of this specification.  If it is desired to support CRMF in the
   future, placing a "choice" statement in both the input and output
   statements, along with an "if-feature" statement on the CRMF option,
   would enable a backwards compatible solution.

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   This document puts a limit of the number of elliptical curves
   supported by default.  This was done to match industry trends in IETF
   best practice (e.g., matching work being done in TLS 1.3).  If
   additional algorithms are needed, they MAY be augmented in by another
   module, or added directly in a future version of this document.

   For the trusted-certificates list, Trust Anchor Format [RFC5914] was
   evaluated and deemed inappropriate due to this document's need to
   also support pinning.  That is, pinning a client-certificate to
   support NETCONF over TLS client authentication.

4.  Security Considerations

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

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

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

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

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

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

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

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

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

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

5.  IANA Considerations

5.1.  The IETF XML Registry

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

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

5.2.  The YANG Module Names Registry

   This document registers one YANG module in the YANG Module Names
   registry [RFC6020].  Following the format in [RFC6020], the the
   following registration is requested:

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

6.  Acknowledgements

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

7.  References

7.1.  Normative References

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

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

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

   [RFC5958]  Turner, S., "Asymmetric Key Packages", RFC 5958,
              DOI 10.17487/RFC5958, August 2010,
              <http://www.rfc-editor.org/info/rfc5958>.

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

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

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7.2.  Informative References

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

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

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

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

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

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

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

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Appendix A.  Change Log

A.1.  server-model-09 to 00

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

   o  Removed key-usage parameter from generate-private-key action.

   o  Now /private-keys/private-key/certificates/certificate/name must
      be globally unique (unique across all private keys).

   o  Added top-level 'trusted-ssh-host-keys' and 'user-auth-
      credentials' to support SSH client modules.

A.2.  keychain-00 to keystore-00

   o  Renamed module from "keychain" to "keystore" (Issue #3)

A.3.  00 to 01

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

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

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

A.4.  01 to 02

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

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

   o  Fixed up a few description statements.

Author's Address

   Kent Watsen
   Juniper Networks

   EMail: kwatsen@juniper.net

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