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NETWORK WORKING GROUP                                        N. Williams
Internet-Draft                                                       Sun
Expires: April 19, 2006                                 October 16, 2005


        Extended Generic Security Service Mechanism Inquiry APIs
             draft-ietf-kitten-extended-mech-inquiry-01.txt

Status of this Memo

   By submitting this Internet-Draft, each author represents that any
   applicable patent or other IPR claims of which he or she is aware
   have been or will be disclosed, and any of which he or she becomes
   aware will be disclosed, in accordance with Section 6 of BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
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   Drafts.

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   material or to cite them other than as "work in progress."

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   http://www.ietf.org/shadow.html.

   This Internet-Draft will expire on April 19, 2006.

Copyright Notice

   Copyright (C) The Internet Society (2005).

Abstract

   This document introduces new application programming interfaces
   (APIs) to the Generic Security Services API (GSS-API) for extended
   mechanism attribute inquiry.  These interfaces are primarily intended
   for use in mechanism composition, but also to reduce instances of
   hardcoding of mechanism identifiers in GSS applications.

   These interfaces include: mechanism attributes and attribute sets, a
   function for inquiring the attributes of a mechanism, a function for
   indicating mechanisms that posses given attributes, and a function



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   for displaying mechanism attributes.


Table of Contents

   1.      Conventions used in this document  . . . . . . . . . . . .  3
   2.      Introduction . . . . . . . . . . . . . . . . . . . . . . .  3
   3.      New GSS-API Interfaces . . . . . . . . . . . . . . . . . .  3
   3.1.    Mechanism Attributes and Attribute Sets  . . . . . . . . .  3
   3.2.    Determination of Attribute Sets of Composite Mechs . . . .  4
   3.3.    List of Known Mechanism Attributes . . . . . . . . . . . .  4
   3.4.    Mechanism Attribute Sets of Existing Mechs . . . . . . . .  6
   3.5.    New GSS-API Function Interfaces  . . . . . . . . . . . . .  8
   3.5.1.  GSS_Indicate_mechs_by_attr() . . . . . . . . . . . . . . .  8
   3.5.2.  GSS_Inquire_attrs_for_mech() . . . . . . . . . . . . . . .  9
   3.5.3.  GSS_Display_mech_attr()  . . . . . . . . . . . . . . . . . 10
   3.5.4.  New Major Status Values  . . . . . . . . . . . . . . . . . 10
   3.5.5.  C-Bindings . . . . . . . . . . . . . . . . . . . . . . . . 10
   4.      Requirements for Mechanism Designers . . . . . . . . . . . 11
   5.      IANA Considerations  . . . . . . . . . . . . . . . . . . . 11
   6.      Security considerations  . . . . . . . . . . . . . . . . . 11
   7.      References . . . . . . . . . . . . . . . . . . . . . . . . 12
   7.1.    Normative  . . . . . . . . . . . . . . . . . . . . . . . . 12
   7.2.    Normative  . . . . . . . . . . . . . . . . . . . . . . . . 12
           Author's Address . . . . . . . . . . . . . . . . . . . . . 13
           Intellectual Property and Copyright Statements . . . . . . 14

























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1.  Conventions used in this document

   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 [RFC2119].


2.  Introduction


3.  New GSS-API Interfaces

   GSS-API applications face, today, the problem of how to select from
   multiple GSS-API mechanisms that may be available.  For example,
   applications that support mechanism negotiation directly often have
   to be careful not to use SPNEGO to avoid two-layer mechanism
   negotiation, but since SPNEGO may be indicated by
   GSS_Indicate_mechs() and since there's no way to know that a
   mechanism negotiates mechanisms other than to hardcode the OIDs of
   such mechanisms, such applications must hardcode the SPNEGO OID.
   This problem is likely to be exacerbated by the introduction of
   composite mechanisms.

   To address this problem we introduce a new concept: that of mechanism
   attributes.  By allowing applications to query the set of attributes
   associated with individual mechanisms and to find out which
   mechanisms support a given set of attributes we allow applications to
   select mechanisms based on their attributes yet without having to
   hardcode mechanism OIDs.

   Section 3.1 describes the mechanism attributes concept.  Sections
   3.5.1, 3.5.2 and 3.5.3 describe three new interfaces that deal in
   mechanisms and attribute sets:

   o  GSS_Indicate_mechs_by_attrs()
   o  GSS_Inquire_attrs_for_mech()
   o  GSS_Display_mech_attr()

3.1.  Mechanism Attributes and Attribute Sets

   An abstraction for the features provided by pseudo-mechanisms is
   needed in order to facilitate the programmatic selection of
   mechanisms as well as for the programmatic composition of mechanisms.

   Two data types are needed: one for individual mechanism attributes
   and one for mechanism attribute sets.  To simplify the mechanism
   attributes interfaces we reuse the 'OID' and 'OID set' data types and
   model individual mechanism attribute types as OIDs.



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   To this end we define an open namespace of mechanism attributes and
   assign them arcs off of this OID:

   <TBD> [1.3.6.1.5.5.12 appears to be available, registration w/ IANA
   TBD]

3.2.  Determination of Attribute Sets of Composite Mechs

   Each mechanism, composite or otherwise, has a set of mechanism
   attributes that it supports as specified.

   The mechanism attribute set of a composite mechanism is to be
   determined by the top-most stackable pseudo-mechanism of the
   composite according to its own attribute set and that of the
   remainder of the composite mechanism stack below it.

   It may well be that some composite mechanisms' attribute sets consist
   of the union of those of their every component, however this need not
   be the case and MUST NOT be assumed.

   Every stackable pseudo-mechanism's specification MUST specify the
   rules for determining the mechanism attribute set of mechanisms
   composed by it.

3.3.  List of Known Mechanism Attributes

   +-------------------------+--------+--------------------------------+
   | Mech Attr Name          |    OID | Arc Name                       |
   |                         |    Arc |                                |
   +-------------------------+--------+--------------------------------+
   | GSS_C_MA_MECH_CONCRETE  |    (1) | concrete-mech                  |
   | GSS_C_MA_MECH_STACKABLE |    (2) | pseudo-mech                    |
   | GSS_C_MA_MECH_COMPOSITE |    (3) | composite-mech                 |
   | GSS_C_MA_MECH_NEGO      |    (4) | mech-negotiation-mech          |
   | GSS_C_MA_MECH_GLUE      |    (5) | mech-glue                      |
   | GSS_C_MA_NOT_MECH       |    (6) | not-mech                       |
   | GSS_C_MA_DEPRECATED     |    (7) | mech-deprecated                |
   | GSS_C_MA_NOT_DFLT_MECH  |    (8) | mech-not-default               |
   | GSS_C_MA_ITOK_FRAMED    |    (9) | initial-is-framed              |
   | GSS_C_MA_AUTH_INIT      |   (10) | auth-init-princ                |
   | GSS_C_MA_AUTH_TARG      |   (11) | auth-targ-princ                |
   | GSS_C_MA_AUTH_INIT_INIT |   (12) | auth-init-princ-initial        |
   | GSS_C_MA_AUTH_TARG_INIT |   (13) | auth-targ-princ-initial        |
   | GSS_C_MA_AUTH_INIT_ANON |   (14) | auth-init-princ-anon           |
   | GSS_C_MA_AUTH_TARG_ANON |   (15) | auth-targ-princ-anon           |
   | GSS_C_MA_DELEG_CRED     |   (16) | deleg-cred                     |
   | GSS_C_MA_INTEG_PROT     |   (17) | integ-prot                     |
   | GSS_C_MA_CONF_PROT      |   (18) | conf-prot                      |



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   | GSS_C_MA_MIC            |   (19) | mic                            |
   | GSS_C_MA_WRAP           |   (20) | wap                            |
   | GSS_C_MA_PROT_READY     |   (21) | prot-ready                     |
   | GSS_C_MA_REPLAY_DET     |   (22) | replay-detection               |
   | GSS_C_MA_OOS_DET        |   (23) | oos-detection                  |
   | GSS_C_MA_CBINDINGS      |   (24) | channel-bindings               |
   | GSS_C_MA_CBINDINGS_BIDI |   (25) | channel-bindings-bidirectional |
   | GSS_C_MA_CBINDINGS_NEGO |   (26) | channel-bindings-negotiate     |
   | GSS_C_MA_PFS            |   (27) | pfs                            |
   | GSS_C_MA_COMPRESS       |   (28) | compress                       |
   | GSS_C_MA_CTX_TRANS      |   (29) | context-transfer               |
   | <reserved>              | (30..) |                                |
   +-------------------------+--------+--------------------------------+

                                  Table 1

   +-------------------------+-----------------------------------------+
   | Mech Attr Name          | Purpose                                 |
   +-------------------------+-----------------------------------------+
   | GSS_C_MA_MECH_CONCRETE  | Indicates that a mech is neither a      |
   |                         | pseudo- mechanism nor a composite       |
   |                         | mechanism.                              |
   | GSS_C_MA_MECH_STACKABLE | Indicates that a mech is a              |
   |                         | pseudo-mechanism.                       |
   | GSS_C_MA_MECH_COMPOSITE | Indicates that a mech is a composite    |
   |                         | mechanism.                              |
   | GSS_C_MA_MECH_NEGO      | Indicates that a mech negotiates other  |
   |                         | mechs (e.g., SPNEGO has this            |
   |                         | attribute).                             |
   | GSS_C_MA_MECH_GLUE      | Indicates that the OID is not for a     |
   |                         | mechanism but for the GSS-API itself.   |
   | GSS_C_MA_NOT_MECH       | Indicates that the OID is known, yet    |
   |                         | also known not to be the OID of any     |
   |                         | GSS-API mechanism (or the GSS-API       |
   |                         | itself).                                |
   | GSS_C_MA_DEPRECATED     | Indicates that a mech (or its OID) is   |
   |                         | deprecated and MUST NOT be used as a    |
   |                         | default mechanism.                      |
   | GSS_C_MA_NOT_DFLT_MECH  | Indicates that a mech (or its OID) MUST |
   |                         | NOT be used as a default mechanism.     |
   | GSS_C_MA_ITOK_FRAMED    | Indicates that the given mechanism's    |
   |                         | initial context tokens are properly     |
   |                         | framed as per-section 3.1 of rfc2743.   |
   | GSS_C_MA_AUTH_INIT      | Indicates support for authentication of |
   |                         | initiator to acceptor.                  |
   | GSS_C_MA_AUTH_TARG      | Indicates support for authentication of |
   |                         | acceptor to initiator.                  |
   | GSS_C_MA_AUTH_INIT_INIT | Indicates support for initial           |



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   |                         | authentication of initiator to          |
   |                         | acceptor.                               |
   | GSS_C_MA_AUTH_TARG_INIT | Indicates support for initial           |
   |                         | authentication of acceptor to           |
   |                         | initiator.                              |
   | GSS_C_MA_AUTH_INIT_ANON | Indicates support for initiator         |
   |                         | anonymity.                              |
   | GSS_C_MA_AUTH_TARG_ANON | Indicates support for acceptor          |
   |                         | anonymity.                              |
   | GSS_C_MA_DELEG_CRED     | Indicates support for credential        |
   |                         | delegation.                             |
   | GSS_C_MA_INTEG_PROT     | Indicates support for per-message       |
   |                         | integrity protection.                   |
   | GSS_C_MA_CONF_PROT      | Indicates support for per-message       |
   |                         | confidentiality protection.             |
   | GSS_C_MA_MIC            | Indicates support for MIC tokens.       |
   | GSS_C_MA_WRAP           | Indicates support for WRAP tokens.      |
   | GSS_C_MA_PROT_READY     | Indicates support for per-message       |
   |                         | protection prior to full context        |
   |                         | establishment.                          |
   | GSS_C_MA_REPLAY_DET     | Indicates support for replay detection. |
   | GSS_C_MA_OOS_DET        | Indicates support for out-of-sequence   |
   |                         | detection.                              |
   | GSS_C_MA_CBINDINGS      | Indicates support for channel bindings. |
   | GSS_C_MA_CBINDINGS_BIDI | Indicates that acceptors                |
   |                         | unconditionally indicate to initiators  |
   |                         | whether their channel bindings were     |
   |                         | matched the acceptors', even when the   |
   |                         | acceptor applications use               |
   |                         | GSS_C_NO_CHANNEL_BINDINGS..             |
   | GSS_C_MA_CBINDINGS_NEGO | Indicates that the mech acts as a       |
   |                         | signal for application support for and  |
   |                         | willingness to use channel bindings.    |
   | GSS_C_MA_PFS            | Indicates support for Perfect Forward   |
   |                         | Security.                               |
   | GSS_C_MA_COMPRESS       | Indicates support for compression of    |
   |                         | data inputs to GSS_Wrap().              |
   | GSS_C_MA_CTX_TRANS      | Indicates support for security context  |
   |                         | export/import.                          |
   +-------------------------+-----------------------------------------+

                                  Table 2

3.4.  Mechanism Attribute Sets of Existing Mechs

   The Kerberos V mechanism [RFC1964] [CFX] provides the following
   mechanism attributes:




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   o  GSS_C_MA_MECH_CONCRETE
   o  GSS_C_MA_ITOK_FRAMED
   o  GSS_C_MA_AUTH_INIT
   o  GSS_C_MA_AUTH_TARG
   o  GSS_C_MA_DELEG_CRED
   o  GSS_C_MA_INTEG_PROT
   o  GSS_C_MA_CONF_PROT
   o  GSS_C_MA_MIC
   o  GSS_C_MA_WRAP
   o  GSS_C_MA_PROT_READY
   o  GSS_C_MA_REPLAY_DET
   o  GSS_C_MA_OOS_DET
   o  GSS_C_MA_CBINDINGS
   o  GSS_C_MA_CTX_TRANS (some implementations, using implementation-
      specific exported context token formats)

   The Kerberos V mechanism also has a deprecated OID which has the same
   mechanism attributes as above, and GSS_C_MA_DEPRECATED.

   [The mechanism attributes of the SPKM family of mechanisms will be
   provided in a separate document as SPKM is current being reviewed for
   possibly significant changes due to problems in its specifications.]

   The LIPKEY mechanism offers the following attributes:

   o  GSS_C_MA_MECH_CONCRETE (should be stackable, but does not compose)
   o  GSS_C_MA_ITOK_FRAMED
   o  GSS_C_MA_AUTH_INIT_INIT
   o  GSS_C_MA_AUTH_TARG (from SPKM-3)
   o  GSS_C_MA_AUTH_TARG_ANON (from SPKM-3)
   o  GSS_C_MA_INTEG_PROT
   o  GSS_C_MA_CONF_PROT
   o  GSS_C_MA_REPLAY_DET
   o  GSS_C_MA_OOS_DET
   o  GSS_C_MA_CTX_TRANS (some implementations, using implementation-
      specific exported context token formats)

      (LIPKEY should also provide GSS_C_MA_CBINDINGS, but SPKM-3
      requires clarifications on this point.)

   The SPNEGO mechanism [SPNEGO] provides the following attributes:
   o  GSS_C_MA_MECH_NEGO
   o  GSS_C_MA_ITOK_FRAMED

   The attributes of mechanisms negotiated by SPNEGO are not modified by
   the use of SPNEGO.

   All other mechanisms' attributes will be described elsewhere.



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3.5.  New GSS-API Function Interfaces

   Several new interfaces are given by which, for example, GSS-API
   applications may determine what features are provided by a given
   mechanism, what mechanisms provide what features and what
   compositions are legal.

   These new interfaces are all OPTIONAL.

   In order to preserve backwards compatibility with applications that
   do not use the new interfaces GSS_Indicate_mechs() MUST NOT indicate
   support for any stackable pseduo-mechanisms.  GSS_Indicate_mechs()
   MAY indicate support for some, all or none of the available composite
   mechanisms; which composite mechanisms, if any, are indicated through
   GSS_Indicate_mechs() SHOULD be configurable.  GSS_Acquire_cred() and
   GSS_Add_cred() MUST NOT create credentials for composite mechanisms
   not explicitly requested or, if no desired mechanism or mechanisms
   are given, for composite mechanisms not indicated by
   GSS_Indicate_mechs().

   Applications SHOULD use GSS_Indicate_mechs_by_attr() instead of
   GSS_Indicate_mechs() wherever possible.

   Applications can use GSS_Indicate_mechs_by_attr() to determine what,
   if any, mechanisms provide a given set of features.

   GSS_Indicate_mechs_by_attr() can also be used to indicate (as in
   GSS_Indicate_mechs()) the set of available mechanisms of each type
   (concrete, mechanism negotiation pseudo-mechanism, stackable pseudo-
   mechanism and composite mechanisms).

   Applications may use GSS_Inquire_attrs_for_mech() to test whether a
   given composite mechanism is available and the set of features that
   it offers.

3.5.1.  GSS_Indicate_mechs_by_attr()

   Inputs:
   o  desired_mech_attrs SET OF OBJECT IDENTIFIER -- set of GSS_C_MA_*
      OIDs that the mechanisms indicated in the mechs output parameter
      MUST offer.
   o  except_mech_attrs SET OF OBJECT IDENTIFIER -- set of GSS_C_MA_*
      OIDs that the mechanisms indicated in the mechs output parameter
      MUST NOT offer.

   Outputs:
   o  major_status INTEGER,
   o  minor_status INTEGER,



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   o  mechs SET OF OBJECT IDENTIFIER -- set of mechanisms that support
      -- the desired_mech_attrs but not the except_mech_attrs.

   Return major_status codes:
   o  GSS_S_COMPLETE indicates success; the output mechs parameter MAY
      be the empty set (GSS_C_NO_OID_SET).
   o  GSS_BAD_MECH_ATTR indicates that at least one mechanism attribute
      OID in desired_mech_attrs or except_mech_attrs is unknown to the
      implementation.
   o  GSS_S_FAILURE indicates that the request failed for some other
      reason.

   GSS_Indicate_mechs_by_mech_attrs() returns the set of mechanism OIDs
   that offer at least the desired_mech_attrs but none of the
   except_mech_attrs.

   When desired_mech_attrs and except_mech_attrs are the empty set this
   function acts as a version of GSS_indicate_mechs() that outputs the
   set of all supported mechanisms of all types.  By setting the
   desired_mechs input parameter to a set of a single GSS_C_MA_MECH*
   feature applications can obtain the list of all supported mechanisms
   of a given type (concrete, stackable, etc...).

3.5.2.  GSS_Inquire_attrs_for_mech()

   Inputs:
   o  mech OBJECT IDENTIFIER -- mechanism OID

   Outputs:
   o  major_status INTEGER,
   o  minor_status INTEGER,
   o  mech_attrs SET OF OBJECT IDENTIFIER -- set of mech_attrs OIDs
      (GSS_C_MA_*)

   Return major_status codes:
   o  GSS_S_COMPLETE indicates success; the output mech_attrs parameter
      MAY be the empty set (GSS_C_NO_OID_SET).
   o  GSS_S_BAD_MECH indicates that the mechanism named by the mech
      parameter does not exist or that mech is GSS_C_NO_OID and no
      default mechanism could be determined.
   o  GSS_S_FAILURE indicates that the request failed for some other
      reason.

   GSS_Inquire_mech_attrs_for_mech() indicates the set of mechanism
   attributes supported by a given mechanism.

   Because the mechanism attribute sets of composite mechanisms need not
   be the union of their components', when called to obtain the feature



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   set of a composite mechanism GSS_Inquire_mech_attrs_for_mech()
   obtains it by querying the mechanism at the top of the stack.  See
   Section 3.1.

3.5.3.  GSS_Display_mech_attr()

   Inputs:
   o  mech_attr OBJECT IDENTIFIER -- mechanism attribute OID

   Outputs:
   o  major_status INTEGER,
   o  minor_status INTEGER,
   o  name OCTET STRING, -- name of mechanism attribute (e.g.,
      GSS_C_MA_*)
   o  short_desc OCTET STRING, -- a short description of the mechanism
      attribute
   o  long_desc OCTET STRING -- a longer description of the mechanism
      attribute

   Return major_status codes:
   o  GSS_S_COMPLETE indicates success.
   o  GSS_S_BAD_MECH_ATTR indicates that the mechanism attribute
      referenced by the mech_attr parameter is unknown to the
      implementation.
   o  GSS_S_FAILURE indicates that the request failed for some other
      reason.

   This function can be used to obtain human-readable descriptions of
   GSS-API mechanism attributes.

3.5.4.  New Major Status Values

   A single new major status code is added for GSS_Display_mech_attr():
   o  GSS_S_BAD_MECH_ATTR
   roughly corresponding to GSS_S_BAD_MECH, but applicable to mechanism
   attribute OIDs, rather than to mechanism OIDs.

   For the C-bindings GSS_S_BAD_MECH_ATTR shall have a routine error
   number of 19 (this is shifted to the left by
   GSS_C_ROUTINE_ERROR_OFFSET).

3.5.5.  C-Bindings


      #define GSS_S_BAD_MECH_ATTR (19ul << GSS_C_ROUTINE_ERROR_OFFSET)

      OM_uint32 gss_inquire_mechs_for_mech_attrs(
         OM_uint32         *minor_status,



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         const gss_OID_set  desired_mech_attrs,
         gss_OID_set       *mechs);

      OM_uint32 gss_inquire_mech_attrs_for_mech(
         OM_uint32         *minor_status,
         const gss_OID      mech,
         gss_OID_set       *mech_attrs);

      OM_uint32 gss_display_mech_attr(
         OM_uint32         *minor_status,
         const gss_OID      mech_attr,
         gss_buffer_t       name,
         gss_buffer_t       short_desc,
         gss_buffer_t       long_desc);


   Figure 1


4.  Requirements for Mechanism Designers

   Stackable pseudo-mechanisms specifications MUST:
   o  list the set of GSS-API mechanism attributes associated with them
   o  list their initial mechanism composition rules
   o  specify a mechanism for updating their mechanism composition rules

   All other mechanism specifications MUST:
   o  list the set of GSS-API mechanism attributes associated with them


5.  IANA Considerations

   The namsepace of programming language symbols with names beginning
   with GSS_C_MA_* is reserved for allocation by the IANA.

   Allocation of arcs in the namespace of OIDs relative to the base
   mechanism attribute OID specified in Section 3.1 is reserved to the
   IANA.


6.  Security considerations

   ...


7.  References

7.1.  Normative



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   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997.

   [RFC2743]  Linn, J., "Generic Security Service Application Program
              Interface Version 2, Update 1", RFC 2743, January 2000.

   [RFC2744]  Wray, J., "Generic Security Service API Version 2 :
              C-bindings", RFC 2744, January 2000.

7.2.  Normative

   [RFC1964]  Linn, J., "The Kerberos Version 5 GSS-API Mechanism",
              RFC 1964, June 1996.

   [RFC2478]  Baize, E. and D. Pinkas, "The Simple and Protected GSS-API
              Negotiation Mechanism", RFC 2478, December 1998.



































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Author's Address

   Nicolas Williams
   Sun Microsystems
   5300 Riata Trace Ct
   Austin, TX  78727
   US

   Email: Nicolas.Williams@sun.com










































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