[Docs] [txt|pdf] [Tracker] [Email] [Diff1] [Diff2] [Nits]

Versions: (draft-joseph-pkix-sshextension) 00 01 02 03 04 RFC 7076

Network Working Group                                            M. Joseph
Internet-Draft                                                    J. Susoy
Intended status: Informational                                    P6R, Inc
                                                             Sept 30, 2013


                  P6R's Secure Shell Public Key Subsystem
                  draft-joseph-pkix-p6rsshextension-04.txt

Abstract

   The Secure Shell Public Key Subsystem protocol defines a key distribution
   protocol to provision an SSH server with user's public keys.  However,
   that protocol is limited to provisioning an SSH server.   This document
   describes a new protocol that builds on the protocol defined in RFC 4819
   to allow the provisioning of keys and certificates to a server using the
   SSH transport.

   The new protocol allows the calling client to organize
   keys and certificates in different namespaces on a server.  These
   namespaces can be used by the server to allow a client to configure
   any application running on the server (e.g., SSH, KMIP, SNMP).

   The new protocol provides a server-independent mechanism for clients
   to add public keys, remove public keys, add certificates, remove
   certificates, and list the current set of keys and certificates known by
   the server by namespace (e.g., list all public keys in the SSH
   namespace).

   Rights to manage keys and certificates in a specific namespace are
   specific and limited to the authorized user and are defined as part of
   the server's implementation.   The described protocol is backward
   compatible to version 2 defined by RFC 4819.


Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at http://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 December 17, 2013.



Joseph & Susoy          Expires December 17, 2013               [Page 1]

Internet-Draft     P6R's Secure Shell Public Key Subsystem     Sept 2013


Copyright Notice

   Copyright (c) 2013 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
   (http://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
   2.  Terminology  . . . . . . . . . . . . . . . . . . . . . . . . .  3
   3.  Overview of extensions to the Public Key Subsystem . . . . . .  3
     3.1.  Extended Status Codes  . . . . . . . . . . . . . . . . . .  3
     3.2.  The Version Packet . . . . . . . . . . . . . . . . . . . .  4
     3.3.  The Namespace Attribute  . . . . . . . . . . . . . . . . .  4
   4.  New Operations   . . . . . . . . . . . . . . . . . . . . . . .  4
     4.1.  Adding a Certificate   . . . . . . . . . . . . . . . . . .  4
     4.2.  Removing a Certificate . . . . . . . . . . . . . . . . . .  5
     4.3.  Listing Certificates   . . . . . . . . . . . . . . . . . .  6
     4.4.  Listing Namespaces . . . . . . . . . . . . . . . . . . . .  6
   5.  Extending Public Key Operations  . . . . . . . . . . . . . . .  7
     5.1.  Adding a Public Key  . . . . . . . . . . . . . . . . . . .  7
     5.2.  Removing a Public Key  . . . . . . . . . . . . . . . . . .  7
     5.3.  Listing Public Keys  . . . . . . . . . . . . . . . . . . .  8
   6.  Security Considerations  . . . . . . . . . . . . . . . . . . .  8
   7.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . .  9
   8.  References . . . . . . . . . . . . . . . . . . . . . . . . . .  9
     8.1.  Normative References . . . . . . . . . . . . . . . . . . .  9
         8.2.  Informative References . . . . . . . . . . . . . . . . . .  9
   9.  Authors' Addresses . . . . . . . . . . . . . . . . . . . . . .  9













Joseph & Susoy         Expires December 17, 2013                [Page 2]

Internet-Draft    P6R's Secure Shell Public Key Subsystem      Sept 2013

1.  Introduction

   This document describes a new protocol based on the protocol defined
   in RFC 4819 that can be used to configure public keys and certificates
   in an implementation-independent fashion.  The addition of the concept
   of a namespace which allows the client to organize keys and certificates
   by application or organizational structure is added to the protocol's
   operations.

   P6R's Secure Shell Public Key Subsystem has been designed to run on top
   of the Secure Shell transport layer [3] and user authentication
   protocols [4].  It provides a simple mechanism for the client to
   manage the public keys and certificates on the server related to the
   client.  These keys and certificates are normally used for
   authentication of the client to a service, but can be used for
   encrypting results back to the client as well.  Uploaded keys and
   certificates are meant to be able to configure all protocols running
   on a server (e.g., SSH, SSL, KMIP [8]) that use keys and certificates as
   well as applications that run on a server.

   This document should be read only after reading the Secure Shell Public
   Key Subsystem [1] document.   The new protocol described in this document
   builds on and is meant to be backwards compatible with the protocol
   described in [1].

2.  Terminology

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in RFC 2119 [2].

3.  Overview of extensions to the Public Key Subsystem

   The Public Key Subsystem provides a server-independent mechanism for
   clients to add public keys, remove public keys, list the current
   public keys known by the server, add certificates, remove
   certificates, and list the current set of certificates known by
   the server.  This secure key distribution mechanism is implemented
   by a new SSH subsystem with the name of "publickey@p6r.com".

3.1.  Extended Status Codes

   The status code gives the status in a more machine-readable format
   (suitable for localization), and can have the following values:

        SSH_PUBLICKEY_CERTIFCATE_NOT_FOUND         192
        SSH_PUBLICKEY_CERTIFCATE_NOT_SUPPORTED     193
        SSH_PUBLICKEY_CERTIFCATE_ALREADY_PRESENT   194
        SSH_PUBLICKEY_ACTION_NOT_AUTHORIZED        195
        SSH_PUBLICKEY_CANNOT_CREATE_NAMESPACE      196



Joseph & Susoy       Expires December 17, 2013                  [Page 3]

Internet-Draft    P6R's Secure Shell Public Key Subsystem      Sept 2013

   The meaning of the failure codes is as implied by their names.
   See Security Considerations for the use of the failure code:
   SSH_PUBLICKEY_ACTION_NOT_AUTHORIZED.

3.2.  The Version Packet

   Both sides MUST start a connection by sending a version packet that
   indicates the version of the protocol they are using.

        string "version"
        uint32 protocol-version-number

   This document defines version 3 of the new protocol.  We are using
   version 3 so that it can be backward compatible with the protocol
   defined by RFC 4819 [1].

3.3.  The Namespace Attribute

   The "namespace" attribute is added as an extension to what was
   described in RFC 4819.  The purpose of this attribute is to be able
   to organize the uploaded keys and certificates into groups where
   each group represents an application or organization structure.
   This attribute is a string that should not be longer than 300
   characters and MUST be specified in UTF-8 format [5].

   This new protocol uses the "ssh" namespace for the
   manipulation of public keys in an SSH server and should be
   considered as the default namespace when none is provided.

   As a convention, namespaces used for protocols are lower case strings
   of the protocol's standard abbreviation.  For example, "ssl" should
   be the namespace used for the Secure Sockets Layer protocol.
   Namespaces for applications should contain the product and vendor's
   name. To help determine what namespaces already exist on a server
   a new operation "list-namespaces" is defined in Section 4.

4.  New Operations

   P6R's Public Key Subsystem extends the functionality defined in
   RFC 4819 with the following operations: add-certificate,
   remove-certificate, list-certificates, and list-namespaces.

4.1.  Adding a Certificate

   If the client wishes to add a certificate, the client sends:

        string    "add-certificate"
        string    certificate format name
        string    certificate blob
        boolean   overwrite
        uint32    attribute-count
         string    attrib-name
         string    attrib-value
         bool      critical
        repeated attribute-count times

Joseph & Susoy        Expires December 17, 2013                   [Page 4]

Internet-Draft     P6R's Secure Shell Public Key Subsystem       Sept 2013


   This request MUST include at least the "namespace" attribute so that
   the server knows where to save the certificate to.   Only one namespace
   attribute can be used per add-certificate request.  It is possible
   for the same user to save the same certificate into multiple namespaces
   but this must be done with several separate add-certificate requests.

   If the namespace appearing in an add-certificate request does not
   already exist on a server then it is created by this operation.
   However, if the user is not authorized to create a namespace the server
   MUST return SSH_PUBLICKEY_CANNOT_CREATE_NAMESPACE.

   If the overwrite field is false and the specified certificate already
   exists in the given namespace, the server MUST return
   SSH_PUBLICKEY_CERTIFICATE_ALREADY_PRESENT.  If the server returns this,
   the client SHOULD provide an option to the user to overwrite the
   certificate.  If the overwrite field is true and the specified key
   already exists in the given namespace, but cannot be overwritten, the
   server MUST return SSH_PUBLICKEY_ACCESS_DENIED.

   However, a user may not be authorized to add a certificate to the
   specified namespace.   If the user does not have permission to add
   a certificate then the server MUST return
   SSH_PUBLICKEY_ACTION_NOT_AUTHORIZED.

   Examples of possible "certificate format name" are: "X509",
   "pgp-sign-rsa", and "pgp-sign-dss".  The format of public key and
   certificate blobs are detailed in Section 6.6, "Public Key Algorithms"
   of the SSH Transport Protocol document [3], where X509 certificates
   are to be encoded using a DER [6,7] format in a certificate blob.

4.2.  Removing a Certificate

   If the client wishes to remove a certificate, the client sends:

        string    "remove-certificate"
        string    certificate format name
        string    certificate blob
        uint32    attribute-count
         string    attrib-name
         string    attrib-value
        repeated attribute-count times

   This request MUST include at least the "namespace" attribute so
   that the server knows where to delete the certificate from.  Only
   one namespace attribute can be used per remove-certificate request.
   The server MUST attempt to remove the certificate from the
   the appropriate location.





Joseph & Susoy        Expires December 17, 2013                   [Page 5]

Internet-Draft     P6R's Secure Shell Public Key Subsystem       Sept 2013


        However, a user may not be authorized to remove a certificate from the
    specified namespace.   If the user does not have permission to remove
        the certificate then the server MUST return
        SSH_PUBLICKEY_ACTION_NOT_AUTHORIZED.

        Examples of possible "certificate format name" are: "X509",
        "pgp-sign-rsa", "pgp-sign-dss".

4.3.  Listing Certificates

   If the client wishes to list the known certificates, the client sends:

        string    "list-certificates"

   The server will respond with zero or more of the following responses:

        string    "certificate"
        string    certificate format name
        string    certificate blob
        uint32    attribute-count
         string    attrib-name
         string    attrib-value
        repeated attribute-count times

   There is no requirement that the responses be in any particular
   order.  Whilst some server implementations may send the responses in
   some order, client implementations should not rely on responses being
   in any order.

   This response MUST include at least the "namespace" attribute so that
   a client can tell which namespace the certificate resides.
   Only one namespace attribute can be used per list-certificate request.

   Following the last "certificate" response, a status packet MUST be
   sent.

4.4.  Listing Namespaces

   If the client wishes to know existing namespaces on the server, it
   sends:

        string    "list-namespaces"

    The server will respond with zero or more of the following responses:

        string    "namespace"
        string    namespace name

   It is possible that not all namespaces will be visible to every
   authenticated user.   In this case the responding server will return


Joseph & Susoy        Expires December 17, 2013                   [Page 6]

Internet-Draft     P6R's Secure Shell Public Key Subsystem      Sept 2013


   a subset of existing namespaces.   See Security Considerations below.

   Following the last "namespace" response, a status packet MUST be
   sent.

5.  Extending Public Key Operations

   In addition to adding new operations, this document describes
   extensions to the operations defined in RFC 4819.

5.1.  Adding a Public Key

   If the client wishes to add a public key, the client sends:

        string    "add"
        string    public key algorithm name
        string    public key blob
        boolean   overwrite
        uint32    attribute-count
         string    attrib-name
         string    attrib-value
         bool      critical
        repeated attribute-count times

   This request MAY include one "namespace" attribute so that
   a client can save the public key into a specific namespace.
   It is possible for the same user to save the same key into
   multiple namespaces but will require multiple add requests
   to do so.

   If the namespace appearing in an add public key request does not already
   exist on a server then it is created by this operation.   However, if
   the user is not authorized to create a namespace the server MUST return
   SSH_PUBLICKEY_CANNOT_CREATE_NAMESPACE,

5.2.  Removing a Public Key

   If the client wishes to remove a public key, the client sends:

        string    "remove"
        string    public key algorithm name
        string    public key blob
        uint32    attribute-count
         string    attrib-name
         string    attrib-value
         bool      critical
        repeated attribute-count times




Joseph & Susoy         Expires December 17, 2013                 [Page 7]

Internet-Draft      P6R's Secure Shell Public Key Subsystem    Sept 2013


   This extension allows attributes to be added to a remove request.
   This request MAY include one "namespace" attribute so that
   a client can remove the public key from a specific namespace.

5.3.  Listing Public Keys

   If the client wishes to list the known public keys, the client sends:

        string    "list"
        uint32    attribute-count
         string    attrib-name
         string    attrib-value
         bool      critical
        repeated attribute-count times

   This extension allows attributes to be added to a list request.
   This request MAY include one "namespace" attribute so that
   a client can list the public keys from a specific namespace.

   The server will respond with zero or more of the following responses:

        string    "publickey"
        string    public key algorithm name
        string    public key blob
        uint32    attribute-count
         string    attrib-name
         string    attrib-value
        repeated attribute-count times

   This response MAY include at the "namespace" attribute so that
   a client can tell which namespace the key resides.

6.  Security Considerations

   This protocol assumes that it is run over a secure channel and that
   the endpoints of the channel have been authenticated.  \Thus, this
   protocol assumes that it is externally protected from network-level
   attacks.

   This protocol provides a mechanism that allows key and certificate
   material to be uploaded and manipulated into a server
   application.  It is the responsibility of the server implementation
   to enforce access controls that may be required to limit the access
   allowed for any particular user to that data in a namespace.  For
   example, one user may be allowed to list only the contents of a
   namespace but not add or remove keys or certificates to/from it.
   The server MUST return SSH_PUBLICKEY_ACTION_NOT_AUTHORIZED when a
   user's action goes against its defined access controls.



Joseph & Susoy        Expires December 17, 2013                  [Page 8]

Internet-Draft     P6R's Secure Shell Public Key Subsystem     Sept 2013


   This protocol requires the client to assume that the server will
   correctly implement and observe attributes applied to keys.
   Implementation errors in the server could cause clients to authorize
   keys and certificates for access they were not intended to have, or
   to apply fewer restrictions than were intended.

7.  IANA Considerations

   Although section 3.1 defines four new status codes, these are in
   the 'Private Use' range of IANA's Publickey Subsystem Attributes,
   Registry as defined by section 6.6.1. Conventions in [1].
   No IANA action is requested for this document.

8.  References

8.1.  Normative References

   [1]   J. Galbraith, J. Van Dyke, and  J. Bright, "Secure Shell Public
         Key Subsystem", RFC 4819, March 2007.

   [2]   Bradner, S., "Key words for use in RFCs to Indicate Requirement
         Levels", BCP 14, RFC 2119, March 1997.

   [3]   Ylonen, T. and C. Lonvick, "The Secure Shell (SSH) Transport
         Layer Protocol", RFC 4253, January 2006.

   [4]   Ylonen, T. and C. Lonvick, "The Secure Shell (SSH)
         Authentication Protocol", RFC 4252, January 2006.

   [5]   Yergeau, F., "UTF-8, a transformation format of ISO 10646",
         STD 63, RFC 3629, November 2003.

   [6]   Cooper, D. et al., "Internet X.509 Public Key Infrastructure
         Certificate and Certificate Revocation List (CRL) Profile",
                 RFC 5280, May 2008.

   [7]   ITU-T Recommendation X.690 (2002) | ISO/IEC 8825-1:2002,
         Information technology - ASN.1 encoding rules:
         Specification of Basic Encoding Rules (BER), Canonical
         Encoding Rules (CER) and Distinguished Encoding Rules (DER).

8.1.  Informative References

   [8]   OASIS, Key Management Interoperability Protocol (KMIP) 1.1,
         http://docs.oasis-open.org/kmip/spec/v1.1/os/kmip-spec-v1.1-os.html.
                 24 January 2013.






Joseph & Susoy        Expires December 17, 2013                  [Page 9]

Internet-Draft     P6R's Secure Shell Public Key Subsystem     Sept 2013


9.  Authors' Addresses

   Mark Joseph, PhD
   P6R, Inc
   1840 41st Ave
   Suite 102-139
   Capitola, CA  95010
   US

   Phone: +1 888 452 2580 (x702)
   EMail: mark@p6r.com


   Jim Susoy
   P6R, Inc
   1840 41st Ave
   Suite 102-139
   Capitola, CA  95010
   US

   Phone: +1 888 452 2580 (x701)
   EMail: jim@p6r.com






























Joseph & Susoy        Expires December 12, 2013                 [Page 10]


Html markup produced by rfcmarkup 1.107, available from http://tools.ietf.org/tools/rfcmarkup/