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Versions: (draft-austein-sidr-rpki-oob-setup) 00 01 02 03 04 05 06 07 08 09 RFC 8183

Network Working Group                                         R. Austein
Internet-Draft                                      Dragon Research Labs
Intended status: Standards Track                            July 2, 2014
Expires: January 3, 2015


       An Out-Of-Band Setup Protocol For RPKI Production Services
                   draft-ietf-sidr-rpki-oob-setup-01

Abstract

   This note describes a simple out-of-band protocol to ease setup of
   the RPKI provisioning and publication protocols between two parties.
   The protocol is encoded in a small number of XML messages, which can
   be passed back and forth by any mutually agreeable secure means.

   This setup protocol is not part of the provisioning or publication
   protocol, rather, it is intended to simplify configuration of these
   protocols by setting up relationships and exchanging BPKI keying
   material.

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 January 3, 2015.

Copyright Notice

   Copyright (c) 2014 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



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   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  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Overview of the BPKI  . . . . . . . . . . . . . . . . . . . .   3
   3.  Protocol Elements . . . . . . . . . . . . . . . . . . . . . .   4
     3.1.  Nomenclature  . . . . . . . . . . . . . . . . . . . . . .   4
     3.2.  Common Protocol Elements  . . . . . . . . . . . . . . . .   5
     3.3.  Protocol Messages . . . . . . . . . . . . . . . . . . . .   5
       3.3.1.  <child_request/>  . . . . . . . . . . . . . . . . . .   5
       3.3.2.  <parent_response/>  . . . . . . . . . . . . . . . . .   6
       3.3.3.  <publisher_request/>  . . . . . . . . . . . . . . . .   8
       3.3.4.  <repository_response/>  . . . . . . . . . . . . . . .   9
     3.4.  <authorization/>  . . . . . . . . . . . . . . . . . . . .  10
     3.5.  <error/>  . . . . . . . . . . . . . . . . . . . . . . . .  11
   4.  Protocol Walk-Through . . . . . . . . . . . . . . . . . . . .  12
   5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  17
   6.  Security Considerations . . . . . . . . . . . . . . . . . . .  17
   7.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .  17
   8.  Normative References  . . . . . . . . . . . . . . . . . . . .  17
   Appendix A.  RelaxNG Schema . . . . . . . . . . . . . . . . . . .  17
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .  19

1.  Introduction

   This note describes a small XML-based out-of-band protocol used to
   set up relationships between parents and children in the RPKI
   provisioning protocol ([RFC6492]) and between publishers and
   repositories in the RPKI publication protocol
   ([I-D.ietf-sidr-publication]).

   The basic function of this protocol is public key exchange, in the
   form of self-signed BPKI X.509 certificates, but workshop experience
   has demonstrated that it's simpler for the user if we also bundle the
   other configuration information needed to bring up a new player into
   the messages used in the key exchange.

   The underlying transport for this protocol is deliberately
   unspecified.  It might be a USB stick, a web interface secured with
   conventional HTTPS, PGP-signed email, a T-shirt printed with a QR
   code, or a carrier pigeon.

   Since much of the purpose of this protocol is key exchange,
   authentication and integrity of the key exchange MUST be ensured via



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   external means.  Typically such means will tie directly to a new or
   existing business relationship

2.  Overview of the BPKI

   Several protocols related to RPKI provisioning use signed CMS
   messages ([RFC5652] to authenticate the underlying XML-based
   protocols.  Verification of these CMS messages requires X.509
   certificates.  The PKI that holds these certificates is distinct from
   the RPKI, and contains no RFC 3779 resources.  We refer to this as
   the "Business PKI" (BPKI), to distinguish it from the RPKI.  The "B"
   is a hint that the certificate relationships in the BPKI are likely
   to follow and become part of existing contractual relationships
   between the issuers and subjects of this PKI.

   The RPKI provisioning protocol does not dictate a particular
   structure for the BPKI, beyond the basic requirement that it be
   possible for one party to sign and the other party to verify the CMS
   messages.  This allows a certain amount of flexibility to allow an
   Internet registry to reuse an existing PKI as the BPKI if that makes
   sense in their context.

   In order to keep this protocol simple, we adopt a somewhat
   constrained model of the BPKI.  The first two operations in this
   protocol are an exchange of public keys between child and parent for
   use in the provisioning protocol, the latter two operations in this
   protocol are an exchange of public keys between publisher and
   repository for use in the publication protocol.  In each of these
   operations, the sending party includes its public key, in the form of
   a self-signed X.509 CA certificate.  The private keys corresponding
   to the exchanged certificates are not used to sign CMS messages
   directly; instead, the exchanged CA certificates are the issuers of
   the BPKI end-entity (EE) certificates which will be included in the
   CMS messages and can be used, along with the exchanged certificates,
   to verify the CMS messages.

   Details of how to tie the exchanged certificates into an
   implementation's local BPKI are left to the implementation, but the
   recommended approach is to cross-certify the received public key and
   subject name under one's own BPKI, using a Basic Constraints
   extension with cA = TRUE, pathLenConstraint = 0, indicating that the
   cross-certified certificate is a CA certificate which is allowed to
   issue EE certificates but is not allowed to issue CA certificates.
   See section 4.2.1.9 of [RFC5280] for more information about the Basic
   Constraints extension.

   For example, suppose that Alice and Bob each have their own self-
   signed BPKI certificates:



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             Issuer:       CN = Alice CA
             Subject:      CN = Alice CA
             Public Key:   [Alice CA Public Key]
             BasicConstraints: cA = TRUE

             Issuer:       CN = Bob CA
             Subject:      CN = Bob CA
             Public Key:   [Bob CA Public Key]
             BasicConstraints: cA = TRUE

   Alice sends Bob her self-signed BPKI certificate, and Bob cross-
   certifies its public key and subject name under Bob's own self-signed
   BPKI certificate:

             Issuer:       CN = Bob CA
             Subject:      CN = Alice CA
             Public Key:   [Alice CA Public Key]
             BasicConstraints: cA = TRUE, pathLenConstraint = 0

   Later, when Bob receives a CMS message from Alice, Bob can verify
   this message via a trust chain back to Bob's own trust anchor:

             Issuer:       CN = Alice CA
             Subject:      CN = Alice EE
             Public Key:   [Alice EE Public Key]

   [[Need some text detailing required and allowed values in the
   certificates: 2048-bit RSA, what extensions, ....  But once we go
   there we also have to provide a path for algorithm agility.]]

3.  Protocol Elements

   Each message in the protocol is a distinct XML element in the "http:/
   /www.hactrn.net/uris/rpki/rpki-setup/" XML namespace.

3.1.  Nomenclature

   All of the protocols configured by this setup protocol have their own
   terminology for their actors, but in the context of this protocol
   that terminology becomes somewhat confusing.  All of the players in
   this setup protocol issue certificates, are the subjects of other
   certificates, operate servers, and, in most cases, act as clients for
   one protocol or another.  Therefore, this note uses its own terms for
   the actors in this protocol.

   Child:  An entity acting in the client ("subject") role of the
      provisioning protocol defined in [RFC6492].




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   Parent:  An entity acting in the server ("issuer") role of the
      provisioning protocol defined in [RFC6492].

   Publisher:  An entity acting in the client role of the publication
      protocol defined in [I-D.ietf-sidr-publication].

   Repository:  An entity acting in the server role of the publication
      protocol defined in [I-D.ietf-sidr-publication].

   Note that a given entity might act in more than one of these roles;
   for example, in one of the simplest cases, the child is the same
   entity as the publisher, while the parent is the same entity as the
   repository.

3.2.  Common Protocol Elements

   The first XML attribute in each message is a version field.  This
   document describes version 1 of the protocol.

   Most messages contain, among other things, a self-signed BPKI X.509
   certificate.  These certificates are represented as XML elements
   whose text value is the Base64 text encoding the DER representation
   of the X.509 certificate.

   A number of attributes contain "handles".  A handle in this protocol
   is a text string in the US-ASCII character set consisting of letters,
   digits, and the special characters "/", "-", and "_".  This protocol
   places no special semantics on the structure of these handles,
   although implementations might.  Handles are protocol elements, not
   necessarily meaningful to humans, thus the simplicity of a restricted
   character set makes more sense than the complex rules which would be
   needed for internationalized text.

3.3.  Protocol Messages

   The core of this protocol consists of four message types,
   representing the basic request and response semantics needed to
   configure a RPKI engine to talk to its parent and its repository via
   the provisioning and publication protocols, respectively.

3.3.1.  <child_request/>

   The <child_request/> message is an initial setup request from a
   provisioning protocol child to its provisioning protocol parent.

   Fields in the <child_request/> message:





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   version:  The version attribute specifies the protocol version.  This
      note describes protocol version 1.

   child_handle:  The child_handle attribute is what the child calls
      itself.  This is just a hint from the child to the parent, the
      parent need not honor it.

   child_bpki_ta:  The <child_bpki_ta/> element is the child's BPKI
      identity, a self-signed X.509 BPKI certificate, encoded in Base64.

      This CA certificate will be the issuer of the BPKI EE certificates
      corresponding to private keys that the child will use when sending
      provisioning protocol messages to the parent.

   ---------------------------------------------------------------------
   <child_request
       child_handle="Bob"
       version="1"
       xmlns="http://www.hactrn.net/uris/rpki/rpki-setup/">
     <child_bpki_ta>
       R29kIGlzIHJlYWwgdW5sZXNzIGRlY2xhcmVkIGludGVnZXI=
     </child_bpki_ta>
   </child_request>
   ---------------------------------------------------------------------

3.3.2.  <parent_response/>

   The <parent_response/> message is a response from a provisioning
   protocol parent to a provisioning protocol child that had previously
   sent a <child_request/> message.

   Fields in the <parent_response/> message:

   version:  The version attribute specifies the protocol version.  This
      note describes protocol version 1.

   service_uri:  The service_uri attribute contains an HTTP URL that the
      child should contact for up-down ([RFC6492]) service.

   child_handle:  The child_handle attribute is the parent's name for
      the child.  This might or might not match the child_handle from
      the <child_request/> message.  If they do not match, the parent
      wins, because the parent gets to dictate the names in the
      provisioning protocol.  This value is the sender field in
      provisioning protocol request messages and the recipient field in
      provisioning protocol response messages.





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   parent_handle:  The parent_handle attribute is the parent's name for
      itself.  This value is the recipient field in provisioning
      protocol request messages and the sender field in provisioning
      protocol response messages.

   parent_bpki_ta:  The <parent_bpki_ta/> element is the parent's BPKI
      identity, a self-signed X.509 BPKI certificate.

      This certificate is the issuer of the BPKI EE certificates
      corresponding to private keys that the parent will use to sign
      provisioning protocol messages to the child.

   offer:  If an <offer/> element is present, the parent is offering
      publication service to the child.  The <offer/> element, if
      present, is empty.

   referral:  If a <referral/> element is present, it suggests a third-
      party publication services that the child might use, and contains:

      referrer:  A referrer attribute, containing the handle by which
         the publication repository knows the parent,

      contact_uri:  An optional contact_uri attribute that the child may
         be able to follow for more information, and

      Authorization token:  The text of the <referral/> element is the
         Base64 encoding of a signed authorization token granting the
         child the right to use a portion of the parent's namespace at
         the publication repository in question.  See Section 3.4 for
         details on the authorization token.

   ---------------------------------------------------------------------
   <parent_response
       child_handle="Bob-42"
       parent_handle="Alice"
       service_uri="http://a.example/up-down/Alice/Bob-42"
       version="1"
       xmlns="http://www.hactrn.net/uris/rpki/rpki-setup/">
     <parent_bpki_ta>
       WW91IGNhbiBoYWNrIGFueXRoaW5nIHlvdSB3YW50IHdpdGggVEVDTyBhbmQgRERU
     </parent_bpki_ta>
     <offer/>
   </parent_response>
   ---------------------------------------------------------------------







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   ---------------------------------------------------------------------
   <parent_response
       child_handle="Carol"
       parent_handle="Bob"
       service_uri="http://bob.example/up-down/Bob/Carol"
       version="1"
       xmlns="http://www.hactrn.net/uris/rpki/rpki-setup/">
     <parent_bpki_ta>
       R29kIGlzIHJlYWwgdW5sZXNzIGRlY2xhcmVkIGludGVnZXI=
     </parent_bpki_ta>
     <referral
         referrer="Alice/Bob-42">
       R28sIGxlbW1pbmdzLCBnbyE=
     </referral>
   </parent_response>
   ---------------------------------------------------------------------

3.3.3.  <publisher_request/>

   The <publisher_request/> message is a setup request from a publisher
   to a repository.

   Fields in the <publisher_request/> message:

   version:  The version attribute specifies the protocol version.  This
      note describes protocol version 1.

   publisher_handle:  The publisher_handle attribute is the publisher's
      name for itself.  This is just a hint, the repository need not
      honor it.

   publisher_bpki_ta:  The <publisher_bpki_ta/> element is the
      publisher's BPKI identity, a self-signed X.509 BPKI certificate.
      This certificate is the issuer of the BPKI EE certificates
      corresponding to private keys that the publisher will use to sign
      publication protocol messages to the repository.

   referral:  If a <referral/> element is present, it contains:

      referrer:  A referrer attribute containing the publication handle
         of the referring parent, and

      Authorization token:  The text of the <referral/> element is the
         Base64 encoding of a signed authorization token granting the
         publisher the right to use a portion of its parent's namespace
         at this repository.  See Section 3.4 for details on the
         authorization token.




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      These fields are copies of values that a parent provided to the
      child in the <parent_response/> message (see Section 3.3.2).  The
      referrer attribute is present to aid lookup of the corresponding
      certificate by the repository.  Note that the repository operator
      makes the final decision on whether to grant publication service
      to the prospective publisher.  The <referral/> element just
      conveys a parent's grant of permission to use a portion of that
      parent's namespace.

   ---------------------------------------------------------------------
   <publisher_request
       publisher_handle="Bob"
       version="1"
       xmlns="http://www.hactrn.net/uris/rpki/rpki-setup/">
     <publisher_bpki_ta>
       R29kIGlzIHJlYWwgdW5sZXNzIGRlY2xhcmVkIGludGVnZXI=
     </publisher_bpki_ta>
   </publisher_request>
   ---------------------------------------------------------------------

3.3.4.  <repository_response/>

   The <repository_response/> message is a repository's response to a
   publisher which has previously sent a <publisher_request/> message.

   Fields in the <repository_response/> message:

   version:  The version attribute specifies the protocol version.  This
      note describes protocol version 1.

   service_uri:  The service_uri attribute contains an HTTP URL that the
      publisher should contact for publication service
      ([I-D.ietf-sidr-publication]).

   publisher_handle:  The publisher_handle attribute is the repository's
      name for the publisher.  This may or may not match the
      publisher_handle attribute in the publisher's <publisher_request/>
      message.

   sia_base:  The sia_base attribute is the rsync:// URI for the base of
      the publication space allocated to the publisher.

   repository_bpki_ta:  The <repository_bpki_ta/> element is the
      repository's BPKI identity, a self-signed X.509 BPKI certificate.







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   ---------------------------------------------------------------------
   <repository_response
       publisher_handle="Alice/Bob-42"
       service_uri="http://a.example/publication/Alice/Bob-42"
       sia_base="rsync://a.example/rpki/Alice/Bob-42/"
       version="1"
       xmlns="http://www.hactrn.net/uris/rpki/rpki-setup/">
     <repository_bpki_ta>
       WW91IGNhbiBoYWNrIGFueXRoaW5nIHlvdSB3YW50IHdpdGggVEVDTyBhbmQgRERU
     </repository_bpki_ta>
   </repository_response>
   ---------------------------------------------------------------------

3.4.  <authorization/>

   The <authorization/> element is a separate message which is signed
   with CMS, then included as the Base64 content of <referral/> elements
   in other messages.

   The eContentType for the signed CMS message is id-ct-xml.

   Fields in the <authorization/> element:

   version:  The version attribute specifies the protocol version.  This
      note describes protocol version 1.

   authorized_sia_base:  The value of the authorized_sia_base attribute
      is the rsync:// URI of the base of the namespace which the
      referrer is delegating.

   bpki_ta:  The <bpki_ta/> element is the identity of the entity to
      whom the referrer is delegating the portion of the namespace named
      in the authorized_sia_base attribute.  The identity is represented
      as a self-signed X.509 BPKI certificate.

   ---------------------------------------------------------------------
   <authorization
       authorized_sia_base="rsync://a.example/rpki/Alice/Bob-42/Carol/"
       version="1"
       xmlns="http://www.hactrn.net/uris/rpki/rpki-setup/">
     SSd2ZSBoYWQgZnVuIGJlZm9yZS4gIFRoaXMgaXNuJ3QgaXQu
   </authorization>
   ---------------------------------------------------------------------








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3.5.  <error/>

   The <error/> element is an optional message which can be used in
   response to any of the core protocol messages described in
   Section 3.3.

   Whether an <error/> element is an appropriate way to signal errors
   back to the sender of a protocol message depends on details of the
   implementation which are outside this specification.  For example, if
   this protocol is embedded in a web portal interface which is designed
   to let a human being upload and download these messages via upload
   and download forms, a human-readable error message may be more
   appropriate.  On the other hand, a portal intended to be driven by a
   robotic client might well want to use an <error/> message to signal
   errors.  Similar arguments apply to non-web encapsulations (email,
   USB stick, ...); the primary factor is likely to be whether the
   implementation expects the error to be handled by a human being or by
   a program.

   Fields in the <error/> message:

   version:  The version attribute specifies the protocol version.  This
      note describes protocol version 1.

   reason:  The reason attribute contains a code indicating what was
      wrong with the message.  This version of the protocol defines the
      following codes:

      syntax-error:  Receiver could not parse the offending message.

      authentication-failure:  Receiver could not authenticate the
         offending message.

      refused:  Receiver refused to perform the requested action.

   Offending message:  The <error/> element contains a verbatim copy of
      the message to which this error applies.














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   ---------------------------------------------------------------------
   <error
       reason="refused"
       version="1"
       xmlns="http://www.hactrn.net/uris/rpki/rpki-setup/">
     <child_request
         child_handle="Carol">
       <child_bpki_ta>
         SSd2ZSBoYWQgZnVuIGJlZm9yZS4gIFRoaXMgaXNuJ3QgaXQu
       </child_bpki_ta>
     </child_request>
   </error>
   ---------------------------------------------------------------------

4.  Protocol Walk-Through

   This section walks through a few simple examples of the protocol in
   use, and stars our old friends, Alice, Bob, and Carol.  In this
   example, Alice is the root of a RPKI tree, Bob wants to get address
   and ASN resources from Alice, and Carol wants to get some of those
   resources in turn from Bob.  Alice offers publication service, which
   is used by all three.

   Alice, Bob, and Carol each generates his or her own self-signed BPKI
   certificate.

   Bob constructs a <child_request/> message and sends it to Alice:

   ---------------------------------------------------------------------
   <child_request
       child_handle="Bob"
       version="1"
       xmlns="http://www.hactrn.net/uris/rpki/rpki-setup/">
     <child_bpki_ta>
       R29kIGlzIHJlYWwgdW5sZXNzIGRlY2xhcmVkIGludGVnZXI=
     </child_bpki_ta>
   </child_request>
   ---------------------------------------------------------------------

   o  Bob's preferred handle is "Bob", so Bob uses that when setting
      child_handle.

   o  <child_bpki_ta/> is Bob's self-signed BPKI certificate.

   Alice replies with a <parent_response/> message, but Alice already
   has 41 other children named Bob, so she calls this one "Bob-42".
   Alice's provisioning protocol server happens to use a RESTful URL
   scheme so that it can find the expected validation context for the



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   provisioning protocol CMS message just by looking at the URL, so the
   service URL she provides to Bob includes both her name and Bob's.
   Alice offers publication service, so she offers to let Bob use it;
   Alice doesn't have to do this, she could just omit this and leave Bob
   to find publication service on his own, but Alice is trying to be
   helpful to her customer Bob.  Bob doesn't have to accept Alice's
   offer, but may choose to do so.

   ---------------------------------------------------------------------
   <parent_response
       child_handle="Bob-42"
       parent_handle="Alice"
       service_uri="http://a.example/up-down/Alice/Bob-42"
       version="1"
       xmlns="http://www.hactrn.net/uris/rpki/rpki-setup/">
     <parent_bpki_ta>
       WW91IGNhbiBoYWNrIGFueXRoaW5nIHlvdSB3YW50IHdpdGggVEVDTyBhbmQgRERU
     </parent_bpki_ta>
     <offer/>
   </parent_response>
   ---------------------------------------------------------------------

   o  <parent_bpki_ta/> is Alice's own self-signed BPKI certificate.

   Bob receives Alice's <parent_response/> and extracts the fields Bob's
   RPKI engine will need to know about (child_handle, parent_handle,
   service_uri, and <parent_bpki_ta/>).  Bob also sees the repository
   offer, decides to take Alice up on this offer, and constructs a
   <publisher_request/> message accordingly:

   ---------------------------------------------------------------------
   <publisher_request
       publisher_handle="Bob"
       version="1"
       xmlns="http://www.hactrn.net/uris/rpki/rpki-setup/">
     <publisher_bpki_ta>
       R29kIGlzIHJlYWwgdW5sZXNzIGRlY2xhcmVkIGludGVnZXI=
     </publisher_bpki_ta>
   </publisher_request>
   ---------------------------------------------------------------------

   Alice receives Bob's request to use Alice's publication service,
   decides to honor the offer she made, and sends back a
   <repository_response/> message in response.  Alice recognizes Bob as
   one of her own children, because she's already seen Bob's self-signed
   BPKI certificate, so she allocates publication space to Bob under her
   own publication space, so that relying parties who rsync her products




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   will pick up Bob's products automatically without needing an
   additional fetch operation.

   ---------------------------------------------------------------------
   <repository_response
       publisher_handle="Alice/Bob-42"
       service_uri="http://a.example/publication/Alice/Bob-42"
       sia_base="rsync://a.example/rpki/Alice/Bob-42/"
       version="1"
       xmlns="http://www.hactrn.net/uris/rpki/rpki-setup/">
     <repository_bpki_ta>
       WW91IGNhbiBoYWNrIGFueXRoaW5nIHlvdSB3YW50IHdpdGggVEVDTyBhbmQgRERU
     </repository_bpki_ta>
   </repository_response>
   ---------------------------------------------------------------------

   Bob should now have everything he needs to talk to Alice both for
   provisioning and for publication.

   A more interesting case is Bob's child, Carol.  Carol wants to get
   her resources from Bob, and, like Bob, does not particularly want to
   operate a publication service.  Bob doesn't have a publication
   service of his own to offer, but he can refer Carol to Alice, along
   with his permission for Carol to use a portion of the namespace that
   Alice gave him.

   Carol's <child_request/> to Bob looks very similar to Bob's earlier
   request to Alice:

   ---------------------------------------------------------------------
   <child_request
       child_handle="Carol"
       version="1"
       xmlns="http://www.hactrn.net/uris/rpki/rpki-setup/">
     <child_bpki_ta>
       SSd2ZSBoYWQgZnVuIGJlZm9yZS4gIFRoaXMgaXNuJ3QgaXQu
     </child_bpki_ta>
   </child_request>
   ---------------------------------------------------------------------

   Bob's <parent_response/> to Carol also looks a lot like Alice's
   response to Bob, except that Bob includes a <referral/> element
   instead of an <offer/> element.  Carol is an only child, so Bob
   leaves her name alone:







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   ---------------------------------------------------------------------
   <parent_response
       child_handle="Carol"
       parent_handle="Bob"
       service_uri="http://bob.example/up-down/Bob/Carol"
       version="1"
       xmlns="http://www.hactrn.net/uris/rpki/rpki-setup/">
     <parent_bpki_ta>
       R29kIGlzIHJlYWwgdW5sZXNzIGRlY2xhcmVkIGludGVnZXI=
     </parent_bpki_ta>
     <referral
         referrer="Alice/Bob-42">
       R28sIGxlbW1pbmdzLCBnbyE=
     </referral>
   </parent_response>
   ---------------------------------------------------------------------

   Bob's response includes a <referral/> element with a referrer
   attribute of "Alice/Bob-42", since that's Bob's name to Alice's
   repository.  The Base64-encoded authorization token is an
   <authorization/> element in a CMS message that can be verified
   against Bob's self-signed BPKI certificate, using a BPKI EE
   certificate included in the CMS wrapper.  The <authorization/> text
   is Carol's self-signed BPKI certificate; Bob's signature over this
   element indicates Bob's permission for Carol to use the indicated
   portion of Bob's publication space.

   ---------------------------------------------------------------------
   <authorization
       authorized_sia_base="rsync://a.example/rpki/Alice/Bob-42/Carol/"
       version="1"
       xmlns="http://www.hactrn.net/uris/rpki/rpki-setup/">
     SSd2ZSBoYWQgZnVuIGJlZm9yZS4gIFRoaXMgaXNuJ3QgaXQu
   </authorization>
   ---------------------------------------------------------------------

   Carol, not wanting to have to run a publication service, presents
   Bob's referral to Alice in the hope that Alice will let Carol use
   Alice's publication service.  So Carol constructs a
   <publisher_request/> message including the referral information
   received from Bob, and sends it all to Alice:










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   ---------------------------------------------------------------------
   <publisher_request
       publisher_handle="Carol"
       version="1"
       xmlns="http://www.hactrn.net/uris/rpki/rpki-setup/">
     <publisher_bpki_ta>
       SSd2ZSBoYWQgZnVuIGJlZm9yZS4gIFRoaXMgaXNuJ3QgaXQu
     </publisher_bpki_ta>
     <referral
         referrer="Alice/Bob-42">
       R28sIGxlbW1pbmdzLCBnbyE=
     </referral>
   </publisher_request>
   ---------------------------------------------------------------------

   Alice sees the signed authorization token Bob gave to Carol, checks
   its signature, and unpacks it.  When the signature proves valid and
   the contained BPKI TA matches Carol's, Alice knows that Bob is
   willing to let Carol use a portion of Bob's namespace.  Given this,
   Alice is willing to provide publication service to Carol in the
   subtree allocated by Bob for this purpose, so Alice sends back a
   <repository_response/>:

   ---------------------------------------------------------------------
   <repository_response
       publisher_handle="Alice/Bob-42/Carol"
       service_uri="http://a.example/publication/Alice/Bob-42/Carol"
       sia_base="rsync://a.example/rpki/Alice/Bob-42/Carol/"
       version="1"
       xmlns="http://www.hactrn.net/uris/rpki/rpki-setup/">
     <repository_bpki_ta>
       WW91IGNhbiBoYWNrIGFueXRoaW5nIHlvdSB3YW50IHdpdGggVEVDTyBhbmQgRERU
     </repository_bpki_ta>
   </repository_response>
   ---------------------------------------------------------------------

   Once Carol receives this response, Carol should be good to go.

   In theory the publication referral mechanism can extend indefinitely
   (for example, Carol can refer her child Dave to Alice for publication
   service and it should all work).  In practice, this has not yet been
   implemented, much less tested.  In order to keep the protocol
   relatively simple, we've deliberately ignored perverse cases such as
   Bob being willing to refer Carol to Alice but not wanting Carol to be
   allowed to refer Dave to Alice.






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5.  IANA Considerations

   Blah.

6.  Security Considerations

   As stated in Section 1, the basic function of this protocol is an
   exchange of public keys to be used as BPKI trust anchors.  Integrity
   and authentication of these exchanges MUST be ensured via external
   mechanisms deliberately left unspecified in this protocol.

7.  Acknowledgements

   The author would like to thank: Byron Ellacott, George Michaelson,
   Leif Johansson, Matsuzaki Yoshinobu, Michael Elkins, Randy Bush,
   Seiichi Kawamura, Tim Bruijnzeels, and anybody else who helped along
   the way whose name the author has temporarily forgotten.

8.  Normative References

   [I-D.ietf-sidr-publication]
              Weiler, S., Sonalker, A., and R. Austein, "A Publication
              Protocol for the Resource Public Key Infrastructure
              (RPKI)", draft-ietf-sidr-publication-05 (work in
              progress), February 2014.

   [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, May 2008.

   [RFC5652]  Housley, R., "Cryptographic Message Syntax (CMS)", RFC
              5652, STD 70, September 2009.

   [RFC6492]  Huston, G., Loomans, R., Ellacott, B., and R. Austein, "A
              Protocol for Provisioning Resource Certificates", RFC
              6492, February 2012.

Appendix A.  RelaxNG Schema

   Here is a RelaxNG schema describing the protocol elements.

   # $Id: rpki-setup.rnc 2408 2013-05-24 13:16:55Z sra $

   default namespace = "http://www.hactrn.net/uris/rpki/rpki-setup/"

   version = "1"




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   base64  = xsd:base64Binary { maxLength="512000" }
   handle  = xsd:string { maxLength="255" pattern="[\-_A-Za-z0-9/]*" }
   uri     = xsd:anyURI { maxLength="4096" }
   any     = element * { attribute * { text }*, ( any | text )* }

   authorization_token = base64
   bpki_ta = base64

   start |= child_request
   start |= parent_response
   start |= publisher_request
   start |= repository_response
   start |= authorization
   start |= error

   child_request =
   element child_request {
     attribute version { version },
     attribute child_handle { handle },
     element child_bpki_ta { bpki_ta }
   }

   parent_response =
   element parent_response {
     attribute version { version },
     attribute service_uri { uri },
     attribute child_handle { handle },
     attribute parent_handle { handle },
     element parent_bpki_ta { bpki_ta },
     element offer { empty }?,
     element referral {
       attribute referrer { handle },
       attribute contact_uri { uri }?,
       authorization_token
     }*
   }

   publisher_request =
   element publisher_request {
     attribute version { version },
     attribute publisher_handle { handle },
     element publisher_bpki_ta { bpki_ta },
     element referral {
       attribute referrer { handle },
       authorization_token
     }*
   }




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   repository_response =
   element repository_response {
     attribute version { version },
     attribute service_uri { uri },
     attribute publisher_handle { handle },
     attribute sia_base { uri },
     element repository_bpki_ta { bpki_ta }
   }

   authorization =
   element authorization {
     attribute version { version },
     attribute authorized_sia_base { uri },
     bpki_ta
   }

   error =
   element error {
     attribute version { version },
     attribute reason {
       "syntax-error" |
       "authentication-failure" |
       "refused"
     },
     any?
   }

Author's Address

   Rob Austein
   Dragon Research Labs

   Email: sra@hactrn.net


















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