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Versions: (draft-richardson-btns-abstract-api) 00 01 02

Network Working Group                                      M. Richardson
Internet-Draft                                                       SSW
Expires: May 6, 2009                                    November 2, 2008


          An abstract interface between applications and IPsec
                  draft-ietf-btns-abstract-api-02.txt

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Copyright Notice

   Copyright (C) The IETF Trust (2008).















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Abstract

   This document explains in the abstract (no language bindings are
   provided) how an application may learn that IPsec has been applied to
   a conversation or specify that IPsec should be used.  Though this is
   useful in general it is particularly useful for applications that
   wish to use BTNS (Better Than Nothing Security -- a mode of IPsec
   keying), either in conjunction with channel binding or otherwise.


Table of Contents

   1.      Overview . . . . . . . . . . . . . . . . . . . . . . . . .  3
   2.      Introduction . . . . . . . . . . . . . . . . . . . . . . .  4
   3.      Objects involved . . . . . . . . . . . . . . . . . . . . .  5
   3.1.    Scope of Protection Token  . . . . . . . . . . . . . . . .  5
   3.2.    Scope of Identity Token  . . . . . . . . . . . . . . . . .  6
   3.3.    Validity period of Protection Token  . . . . . . . . . . .  6
   3.4.    Validity period of Identity Token  . . . . . . . . . . . .  6
   3.5.    Serialization  . . . . . . . . . . . . . . . . . . . . . .  6
   3.5.1.  Serialization of Protection Token  . . . . . . . . . . . .  6
   3.5.2.  Serialization of Identity Token  . . . . . . . . . . . . .  7
   4.      Name space . . . . . . . . . . . . . . . . . . . . . . . .  8
   5.      pToken discovery . . . . . . . . . . . . . . . . . . . . .  9
   6.      pToken templates . . . . . . . . . . . . . . . . . . . . . 10
   7.      Properties of pToken objects . . . . . . . . . . . . . . . 11
   8.      Properties of iToken objects . . . . . . . . . . . . . . . 12
   9.      Accessors Functions  . . . . . . . . . . . . . . . . . . . 14
   10.     Use Cases  . . . . . . . . . . . . . . . . . . . . . . . . 15
   11.     Security Considerations  . . . . . . . . . . . . . . . . . 16
   12.     IANA Considerations  . . . . . . . . . . . . . . . . . . . 17
   13.     Acknowledgments  . . . . . . . . . . . . . . . . . . . . . 18
   14.     TRACKING . . . . . . . . . . . . . . . . . . . . . . . . . 19
   15.     References . . . . . . . . . . . . . . . . . . . . . . . . 21
   15.1.   Normative references . . . . . . . . . . . . . . . . . . . 21
   15.2.   Non-normative references . . . . . . . . . . . . . . . . . 21
           Author's Address . . . . . . . . . . . . . . . . . . . . . 22
           Intellectual Property and Copyright Statements . . . . . . 23













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1.  Overview

   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 [RFC2119].














































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2.  Introduction

   Implementation of application protocols that depend on IPsec
   [RFC4301] tend to depend on configuration of IPsec, without having
   any portable (or even non-portable) way to ensure that IPsec is being
   used properly.  This state of affairs is unfortunate, as it limits
   use of IPsec and encourages applications not to rely on IPsec, which
   in environments that do use IPsec, may lead to redundant
   cryptographic protection layers.

   This document describes an abstract application programming interface
   (API) that is intended to interface applications with IPsec.  It is
   abstract in that no programming language specific bindings are given
   here, nor is this API specified in terms of familiar APIs such as the
   "BSD sockets API," for example.  Programming language specific
   bindings, and operating system specific bindings are left to other
   documents.


































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3.  Objects involved

   There are two major kinds of objects that are defined by this
   document.  These are the Protection Token (pToken) and the Identity
   Token (iToken).  Both objects are abstracted into unique opaque
   tokens which may be manipulated only indirectly by applications.
   Here we use the term "opaque token" to mean much what "object" means
   in a typical object-oriented programming language, but with no public
   fields (only methods or generic functions).  Additionally, the iToken
   may be serialized -- that is, converted, by application of a suitable
   function, into an octet string that can later be imported to create a
   new iToken object that is equivalent to the original (though a value
   equality test applied to both iTokens may fail).

   Each object has a series of attributes associated with it.  The API
   provides a mechanism to query the value of attributes of the token.
   The attributes are where all of the content of the objects are.

   Each token has a scope - the place and time in which it can be
   considered valid.  There are many conflicting qualities that one
   would wish for the token, and the result is a different compromise
   among these qualities for each token type.  The tokens should be:

      easy to allocate and release

      automatically cleaned up when an application terminates (both
      properly and improperly)

      easily compared (for equivalence)

      easily interfaced with existing APIs (such as the BSD sockets API,
      in that case as "auxiliary data")

   We use terms such as "process" and "address space" without explaining
   them or providing references, much as with "object."  The terms refer
   to pervasive, common concepts in operating systems theory and
   practice over the past several decades.

3.1.  Scope of Protection Token

   The protection token has a per-process (i.e. per-address space)
   scope, though it may be inherited by child processes in operating
   systems that have a "fork()" operation.  It SHOULD always be possible
   to obtain a current protection token for an established connection
   (whether for a connection-oriented transport protocol or for a
   "connected" UDP socket). that is equivalent to any previous
   protection token that was obtained.  The scope of the token is not
   related to any specific underlying Security Associations used by



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   IPsec, but to the entire set of past, current and future SAs that
   will be used by IPsec to protect that connection
   [I-D.ietf-btns-connection-latching].

3.2.  Scope of Identity Token

   The identity token also has a per-process scope, but is serializable
   such that its serialized form has a per-system or even universal,
   scope.  (We have to consider whether we want universal scope for
   serialized iTokens, much as with exported name objects in the GSS-
   API, which would mean agreeing on a standard, extensible
   representation and encoding.)

3.3.  Validity period of Protection Token

   A pToken is valid only within the scope of a single process (though
   it may be inherited by child processes which share the parent's
   address space with copy on write semantics).  The token may not be
   serialized, and, therefore, may not be saved in any long term
   storage.

   It is permitted for one protection token to be replaced with another
   (equivalent) protection token due to a node moving, suspending and
   resuming, or due to extended network outages, however the underlying
   identity token would be guaranteed to be the same.  This would most
   likely occur with unconnected sockets, where due to the outage/
   downtime, the keying system was unable to maintain a keying channel,
   and had to re-create the keys from scratch.

3.4.  Validity period of Identity Token

   The iToken may be valid across the entire system, although it may
   need to be turned into an external representation (serialization).
   Some forms of identity token may be valid across systems, but in
   general an identity token is only valid in reference to a local
   policy.  (See [RFC2692]).

3.5.  Serialization

   Serialization refers to the process of turning an in memory object
   into a format which can be saved on disk, and re-imported by the same
   implementation.  This document does not require a specification for
   the serialization format, only that it be possible.  The format is a
   local matter.

3.5.1.  Serialization of Protection Token

   There is no requirement to serialize the protection token, or the



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   attributes contained within.  There is a desire to serialize
   templates for protection tokens such that a set of minimum security
   requirements can be saved for future connections to the same peer.

3.5.2.  Serialization of Identity Token

   There is a desire to be able to to serialize the identity token in
   such a way that future communications can be confirmed to be with the
   same identity as before.










































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4.  Name space

   All symbols (functions, macros, etc.) defined by this API are
   prefixed with "ipsec_".  Specific rules for capitalizations should be
   driven by the specific language binding.

   Whenever sensible, the enumerated values defined in [RFC2367] are
   used if appropriate.











































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5.  pToken discovery

   An application that receives a connection using accept(2) (or
   recvmsg(2)), or makes a connection using connect(2), needs to get a
   protection token that is associated with the socket.

   For connected sockets (UDP, TCP, some SCTP modes, etc.), the
   protection token MUST not change during the lifetime of the socket,
   so a simple process is appropriate.
   ([I-D.ietf-btns-connection-latching])

   As the pToken will not change during the connection. (see notes about
   re-keying).  A simple function is provided to return a pToken from a
   file descriptor.  Many implementations are likely to implement this
   using getsockopt(2), but an interface in those terms is not specified
   in order to keep it more abstract, and therefore more portable.

   For unconnected sockets (such as UDP and some SCTP modes), each
   datagram received may be received may arrive from a different source,
   and therefore may have different protections applied.  A protection
   token needs to be returned with each datagram, so it must be returned
   as ancillary data with recvmsg(2).

   A server using unconnected sockets, would receive a protection token
   as ancillary data, and then would provide the same protection token
   as ancillary data on the corresponding sendmsg(2) call.

























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6.  pToken templates

   A pToken template is a type of pToken which is used only when setting
   up a connection, or setting up a socket to listen for connections.

   Properties which are not set on a pToken, are assumed to be do-not-
   care values.












































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7.  Properties of pToken objects

      privacyProtected - boolean.  Set to false if the connection has
      either no privacy configured (AH, ESP-null), or if the privacy
      configured is known to be untrustworthy by the administrator.
      Returns true otherwise.  (XXX: False does not mean that there will
      be no IPsec, but that it should not be considered useful)

      integrityProtected - boolean.  Set to false if there is no data
      integrity protection other than the UDP/TCP checksum.

      compressionAvailable - boolean.  Set to true if data count sent/
      received from socket may not map linearly to data sent/received on
      wire.

      policyName - string.  A handle which describes the system policy
      which was used (or is desired), to establish the connection.  This
      is a string, such as: "secure", "ospf", "iSCSI", "very-secure",
      "do-not-tell-mom-secure", "minimum-security", "was-posted-on-
      usenet-security".

      iToken - object.  Set to iToken object which represents identity
      of remote system.

      remote_iToken - object.  Set to iToken object which was used to
      represent our identity to the remote system.

      tunnelMode - boolean.  Set if tunnel mode was used, or if it is
      desired.

      ipoptionsProtected - boolean.  Set if ip options (and IPv6 header
      extensions), are protected.

      auditString - string. readonly.  Not part of a template.  Valid
      only after connection establishment.  Contains a string which can
      be used in system auditing and logging functions which describes
      the details of the IPsec SA that was negotiated.  No structure of
      this string may be assumed.  No session keys are disclosed by this
      string.

      informationString - string. readonly.  Not part of a template.
      Valid only after connection establishment.  Contains a string
      which can be displayed to a user, informing them of what kind of
      security association was established for this connection.  This
      string may be localized.  No session keys are disclosed by this
      string.





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8.  Properties of iToken objects

      auditString - string. readonly on responder and readonly on
      initiator after connection establishment.  Contains a string which
      can be used in system auditing and logging functions which
      describes the remote identity, and the method by which it was
      authenticated (i.e. it may list the CA or origin of a public key)

      authenticationMethod - enumerated type.  Indicates which method
      was used to authenticate the peer, possible values are:

         NONE - the peer was not authenticated in anyway

         BTNS - the peer was authenticated using an inline key which was
         not verified in anyway

         LEAPOFFAITH - the peer was authenticated using a key which was
         previously cached, but was previously received inline, and was
         not verified in anyway.

         PRESHAREDKEY - the peer was authenticated using a unique pre-
         shared key

         GROUPKEY - the peer was authenticated using a non-unique pre-
         shared key

         XAUTH - the type of phase1/PARENT-SA is not relevant, as the
         peer was authenticated using a username/password.

         EAP - the type of phase1/PARENT-SA is not relevant, as the peer
         was authenticated using an EAP method.  (Additional properties
         may provide more information)

         PKIX_TRUSTED - the peer was authenticated using a PKIX/X.509
         certificate that was found in the trusted store.

         PKIX_INLINE - the peer was authenticated using a PKIX/X.509
         certificate that was transmitted inline, and was verified by
         using a Certificate Authority that was found in the trusted
         store.

         PKIX_OFFLINE - the peer was authenticated using a PKIX/X.509
         certificate that was retrieved out-of-band (such as by LDAP or
         HTTP), and was verified by using a Certificate Authority that
         was found in the trusted store.






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      certificateAuthorityDN - string. readonly. the Distinguished Name
      (DN) of certificate authority that was used to verify the key (for
      methods that involved PKIX)

      certificateDN - string. readonly. the DN of the peer that was
      authenticated

      pubKeyID - string. readonly. a somewhat unique identifier for the
      public key.  A suggestion is to use the first 9 base64 digits of
      the RFC3110 public key modulus, but this is a local matter.

      channelBinding - binary blog. readonly. provides the concatenated
      set of public keys






































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9.  Accessors Functions

   Methods to access the properties of the two objects are specific to
   the language in which the bindings are done.  See YYYY for
   C-bindings.














































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10.  Use Cases

   Explain slides from IETF68.
















































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11.  Security Considerations

   Probably lots to say here.  Please help.
















































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12.  IANA Considerations

   There are no registries created by this document.  The names (and
   language specific enum, if applicable) of the pToken and iToken
   properties are internal to a single system, and therefore do not need
   standardization.













































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13.  Acknowledgments

   stuff
















































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14.  TRACKING

   Document RCS tracking info


   $Revision: 1.7 $
   $Log: ietf-btns-abstract-api.xml,v $
   Revision 1.7  2008/11/03 02:45:52  mcr
      spell check and updated references

   Revision 1.6  2008/02/18 02:37:45  mcr
   updated edits.

   Revision 1.5  2007/07/24 22:15:51  nico

   New abstract, new intro, various minor changes (scope of objects,
   etc...).

   Revision 1.4  2007/07/24 03:30:19  mcr
           edits to token scope, in collaboration with Nico.

   Revision 1.3  2007/07/19 20:09:50  mcr
           added more properties to describe the type of the SA.

   Revision 1.2  2007/07/19 19:45:55  mcr
           edits from 2007-07-19 discussion.

   Revision 1.1  2007/06/25 15:34:08  mcr
      renamed drafts in Makefile

   Revision 1.3  2007/05/14 19:56:37  mcr
     added abstract

   Revision 1.2  2007/05/12 20:38:56  mcr
     fixed id string

   Revision 1.1  2007/05/12 01:31:00  mcr
     updates to abstract api document

   Revision 1.4 2007/02/16 03:24:09 mcr
         updated to make XML happy, and dates corrected
   Revision 1.3 2007/02/16 03:04:44 mcr
         C API document.
   Revision 1.2 2006/03/21 22:02:47 mcr
         added API requirements and skeleton of original API spec
   Revision 1.1 2006/03/21 21:04:43 mcr
         added documents from ipsp WG
   Revision 1.1 2003/06/03 20:45:06 mcr



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         initial template

                        Figure 1: document tracking
















































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15.  References

15.1.  Normative references

   [I-D.ietf-btns-connection-latching]
              Williams, N., "IPsec Channels: Connection Latching",
              draft-ietf-btns-connection-latching-07 (work in progress),
              April 2008.

   [I-D.ietf-btns-core]
              Williams, N. and M. Richardson, "Better-Than-Nothing-
              Security: An Unauthenticated Mode of IPsec",
              draft-ietf-btns-core-07 (work in progress), August 2008.

   [I-D.ietf-btns-prob-and-applic]
              Touch, J., Black, D., and Y. Wang, "Problem and
              Applicability Statement for Better Than Nothing Security
              (BTNS)", draft-ietf-btns-prob-and-applic-07 (work in
              progress), July 2008.

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

   [RFC2367]  McDonald, D., Metz, C., and B. Phan, "PF_KEY Key
              Management API, Version 2", RFC 2367, July 1998.

   [RFC2692]  Ellison, C., "SPKI Requirements", RFC 2692,
              September 1999.

15.2.  Non-normative references

   [RFC4301]  Kent, S. and K. Seo, "Security Architecture for the
              Internet Protocol", RFC 4301, December 2005.


















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Author's Address

   Michael C. Richardson
   Sandelman Software Works
   470 Dawson Avenue
   Ottawa, ON  K1Z 5V7
   CA

   Email: mcr@sandelman.ottawa.on.ca
   URI:   http://www.sandelman.ottawa.on.ca/









































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Full Copyright Statement

   Copyright (C) The IETF Trust (2008).

   This document is subject to the rights, licenses and restrictions
   contained in BCP 78, and except as set forth therein, the authors
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Acknowledgment

   Funding for the RFC Editor function is provided by the IETF
   Administrative Support Activity (IASA).





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