Secure Inter-Domain Routing                                    G. Huston
Internet-Draft                                                R. Loomans
Intended status: BCP                                       G. Michaelson
Expires: April 14, 2011                                            APNIC
                                                        October 11, 2010


        A Profile for Resource Certificate Repository Structure
                  draft-ietf-sidr-repos-struct-05.txt

Abstract

   This document defines a profile for the structure of repository
   publication points that contain X.509 / PKIX Resource Certificates,
   Certificate Revocation Lists and signed objects.  This profile
   contains the proposed object naming scheme, the contents of
   repository publication points, and a suggested internal structure of
   a local repository cache that is intended to facilitate
   synchronisation across a distributed collection of repository
   publication points and facilitate certification path construction.

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 April 14, 2011.

Copyright Notice

   Copyright (c) 2010 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



Huston, et al.           Expires April 14, 2011                 [Page 1]


Internet-Draft        ResCert Respository Structure         October 2010


   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
     1.1.  Terminology  . . . . . . . . . . . . . . . . . . . . . . .  3
   2.  RPKI Repository Publication Point Content and Structure  . . .  4
     2.1.  Manifests  . . . . . . . . . . . . . . . . . . . . . . . .  6
     2.2.  CA Repository Publication Points . . . . . . . . . . . . .  6
     2.3.  Multi-Use EE Repository Publication Points . . . . . . . .  8
   3.  Resource Certificate Publication Repository Considerations . .  9
   4.  Certificate Reissuance and Repositories  . . . . . . . . . . . 11
   5.  Synchronising Repositories with a Local Cache  . . . . . . . . 11
   6.  Security Considerations  . . . . . . . . . . . . . . . . . . . 12
   7.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 12
   8.  References . . . . . . . . . . . . . . . . . . . . . . . . . . 13
     8.1.  Normative References . . . . . . . . . . . . . . . . . . . 13
     8.2.  Informative References . . . . . . . . . . . . . . . . . . 13
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 14




























Huston, et al.           Expires April 14, 2011                 [Page 2]


Internet-Draft        ResCert Respository Structure         October 2010


1.  Introduction

   To validate attestations made in the context of the Resource Public
   Key Infrastructure (RPKI) [I-D.ietf-sidr-arch], relying parties (RPs)
   need access to all the X.509 / PKIX Resource Certificates,
   Certificate Revocation Lists (CRLs), and signed objects that
   collectively define the RPKI.

   Each issuer of a certificate, CRL or a signed object makes it
   available for download to RPs through the publication of the object
   in an RPKI repository.

   The repository system is the central clearing-house for all signed
   objects that MUST be globally accessible to all RPs.  When
   certificates, CRLs and signed objects are created, they are uploaded
   to a repository publication point, from whence they can be downloaded
   for use by RPs.

   This document defines a profile for the structure of RPKI
   repositories.  This profile defines the proposed object naming
   scheme, the contents of repository publication points and an internal
   structure of a Repository Cache that is intended to facilitate
   synchronisation across a distributed collection of repositories, in
   support of certificate validation path construction.

   A Resource Certificate attests to a binding of an entity's public key
   to a set of IP address blocks and AS numbers.  The Subject of a
   Resource Certificate can demonstrate that it is the holder of the
   resources enumerate in the certificate by using its private key to
   generate a digital signature (that can be verified using the public
   key from the certificate).

1.1.  Terminology

   It is assumed that the reader is familiar with the terms and concepts
   described in "Internet X.509 Public Key Infrastructure Certificate
   and Certificate Revocation List (CRL) Profile" [RFC5280], and "X.509
   Extensions for IP Addresses and AS Identifiers" [RFC3779].

   In addition, the following terms are used in this document:

   Repository Object (or Object):
      This refers to a terminal object in a repository publication
      point.  A terminal object is conventionally implemented as a file
      in a publicly accessible directory, where the file is not a
      directory itself, although other forms of objects that have an
      analogous public appearance to a file are encompassed by this
      term.



Huston, et al.           Expires April 14, 2011                 [Page 3]


Internet-Draft        ResCert Respository Structure         October 2010


   Repository Publication Point:
      This refers to a collection of Repository Objects that are
      published at a common publication point.  This is conventionally
      implemented as a directory in a publicly accessible filesystem
      that is identified by a URI [RFC3986], although other forms of
      local storage that have an analogous public appearance to a simple
      directory of files are also encompassed by this term.

   Repository Instance:
      This refers to a collection of one or more Repository Publication
      Points that share a common publication instance.  This
      conventionally is implemented as a collection of filesystem
      directories that share a common URI prefix, where each directory
      is also identifiable by its own unique URI.

   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.  RPKI Repository Publication Point Content and Structure

   The RPKI does not require that a single repository instance contain
   all published RPKI objects.  Instead, the RPKI repository system is
   comprised of multiple repository instances.  Each individual
   repository instance is composed of one or more repository publication
   points.  Each repository publication point is used by one or more
   entities referenced in RPKI certificates, as defined in the
   certificate's Subject Information Authority (SIA) extension.

   This section describes the collection of objects (RPKI certificates,
   CRLs, manifests and signed objects) held in repository publication
   points.

   For every Certification Authority (CA) certificate in the RPKI there
   is a corresponding repository publication point that is the
   authoritative publication point for all current certificates and CRLs
   issued by this CA.  For every End-entity (EE) certificate in the RPKI
   there is a repository publication point that holds all current signed
   objects that can be verified via this EE certificate.  In both cases
   certificate's SIA extension contains a URI [RFC3986] that references
   this repository publication point and identifies the repository
   access mechanisms.  Additionally, a certificate's Authority
   Information Access (AIA) extension contains a URI that references the
   authoritative location for the Certification Authority (CA)
   certificate under which the given certificate was issued.

   For example, if the subject of certificate A has issued certificates



Huston, et al.           Expires April 14, 2011                 [Page 4]


Internet-Draft        ResCert Respository Structure         October 2010


   B and C, then the AIA extensions of certificates B and C both point
   to the publication point for the certificate A object, and the SIA
   extension of certificate A points to a repository publication point
   (directory) containing certificates B and C (see Figure 1).

                      +--------+
           +--------->| Cert A |<----+
           |          |  AIA   |     |
           |  +--------- SIA   |     |
           |  |       +--------+     |
           |  |                      |
           |  |  +-------------------|------------------+
           |  |  |                   |                  |
           |  +->|   +--------+      |   +--------+     |
           |     |   | Cert B |      |   | Cert C |     |
           |     |   | CRLDP-------+ |   | CRLDP-----+  |
           +----------- AIA   |    | +----- AIA   |  |  |
                 |   |  SIA------+ |     |  SIA------------+
                 |   +--------+  | |     +--------+  |  |  |
                 |               | V                 V  |  |
                 |               | +-----------------+  |  |
                 |               | | CRL issued by A |  |  |
                 | A's Repository| +-----------------+  |  |
                 | Directory     |                      |  |
                 +---------------|----------------------+  |
                                 |                         |
       +----------------+        |    +----------------+   |
       | B's Repository |<-------+    | C's Repository |<--+
       |  Directory     |             |  Directory     |
       +----------------+             +----------------+

   Figure 1.  Use of AIA and SIA extensions in the RPKI.

   In Figure 1, certificates B and C are issued by (CA) A. Therefore,
   the AIA extensions of certificates B and C point to (certificate) A,
   and the SIA extension of certificate A points to the repository
   publication point of CA A's subordinate products, which includes
   certificates B and C, as well as the CRL issued by A. The CRL
   Distribution Points (CRLDP) extension in certificates B and C both
   point to the Certificate Revocation List (CRL) issued by A.

   In this distributed repository structure an instance of a CA's
   repository publication point contains all published certificates
   issued by that CA, and the CRL issued by that CA.  An End Entity's
   (EE's) repository publication point contains all the published
   objects that are verified via the associated EE certificate.





Huston, et al.           Expires April 14, 2011                 [Page 5]


Internet-Draft        ResCert Respository Structure         October 2010


2.1.  Manifests

   Every repository publication point MUST contain a manifest
   [I-D.ietf-sidr-rpki-manifests].  The manifest contains a list of the
   names of all objects, as well as the hash value of each object's
   contents, that are currently published by a CA, or by an EE.

   An authority MAY perform a number of object operations on a
   publication repository within the scope of a repository change before
   issuing a single manifest that covers all the operations within the
   scope of this change.  Repository operators SHOULD implement some
   form of directory management regime function on the repository to
   ensure that RPs who are performing retrieval operations on the
   repository are not exposed to intermediate states during changes to
   the repository and the associated manifest.

2.2.  CA Repository Publication Points

   A CA Certificate has two accessMethod elements specified in its SIA
   field.  The id-ad-caRepository accessMethod element has an associated
   accessLocation element that points to the repository publication
   point of the certificates issued by this CA, as specified in
   [I-D.ietf-sidr-res-certs].  The id-ad-rpkiManifest accessMethod
   element has an associated accessLocation element that points to the
   manifest object, as an object URI (as distinct to a directory URI),
   that is associated with this CA.

   A CA's publication repository contains the current (non-expired and
   non-revoked) certificates issued by this CA, the most recent CRL
   issued by this CA, the current manifest, and all other current signed
   objects that can be verified using a "single-use" EE certificate
   [I-D.ietf-sidr-res-certs] issued by this CA.

   The CA's manifest contains the names of this collection of objects,
   together with the hash value of each object's contents, with the
   single exception of the manifest itself.

   The RPKI design requires that a CA be uniquely associated with a
   single key pair.  Thus, the administrative entity that is a CA
   performs key rollover by generating a new CA certificate with a new
   Subject name, as well as a new key pair [I-D.ietf-sidr-keyroll].
   (The reason for the new Subject name is that in the context of the
   RPKI the Subject names in all certificates issued by a CA are
   intended to be unique, and because the RPKI key rollover procedure
   creates a new instance of a CA with the new key, the name constraint
   implies the need for a new Subject name for the CA with the new key.)
   In such cases the entity SHOULD continue to use the same repository
   publication point for both CA instances during the key rollover,



Huston, et al.           Expires April 14, 2011                 [Page 6]


Internet-Draft        ResCert Respository Structure         October 2010


   ensuring that the value of the AIA extension in indirect subordinate
   objects that refer to the certificates issued by this CA remain valid
   across the key rollover, and that the re-issuance of subordinate
   certificates in a key rollover is limited to the collection of
   immediate subordinate products of this CA.  In such cases the
   repository publication point will contain the CRL, manifest and
   subordinate certificates of both CA instances.

   The following paragraphs provide guidelines for naming objects in a
   CA's repository publication point:

   CRL:
      When a CA issues a new CRL, it replaces the previous CRL (issued
      under the same CA key pair) in the repository publication point.
      CAs MUST NOT continue to publish previous CRLs in the repository
      publication point.  Thus, it SHOULD replace (overwrite) previous
      CRLs signed by the same CA (instance).  A non-normative guideline
      for naming such objects is that the file name chosen for the CRL
      in the repository be a value derived from the public key of the CA
      One such method of generating a CRL publication name is described
      in section 2.1 of [RFC4387]; convert the 160-bit hash of a CA's
      public key value into a 27-character string using a modified form
      of Base64 encoding, with an additional modification as proposed in
      section 5, table 2, of [RFC4648].  The filename extension of
      ".crl" MUST be used, to denote the file as a CRL.

   Manifest:
      When a new instance of a manifest is published, it SHOULD replace
      the previous manifest, to avoid confusion.  CAs MUST NOT continue
      to publish previous CA manifests in the repository publication
      point.  A non-normative guideline for naming such objects is that
      the filename chosen for the manifest in the publication repository
      be a value derived from the public key part of the entity's key
      pair, using the algorithm described for CRLs above for generation
      of filenames.  The filename extension of ".mft" MUST be used, to
      denote the object as a manifest.

   Certificates:
      Within the RPKI framework it is possible that a CA MAY issue a
      series of certificates to the same subject name, the same subject
      public key, and the same resource collection.  However, a relying
      party requires access only to the most recently published
      certificate in such a series.  Thus, the such a series of
      certificates SHOULD share the same filename.  This ensures that
      each successive issued certificate in such a series effectively
      overwrites the previous instance of the certificate.  A non-
      normative guideline for naming such objects is for the CA to adopt
      a (local) policy requiring a subject to use a unique key pair for



Huston, et al.           Expires April 14, 2011                 [Page 7]


Internet-Draft        ResCert Respository Structure         October 2010


      each unique instance of a certificate series issued to the same
      subject, thereby the CA to use a file name generation scheme based
      on the subject's public key, e.g., using the algorithm described
      above for CRLs above.  Published certificates MUST use a filename
      extension of ".cer" to denote the object as a certificate.

   Signed Objects:
      Within the RPKI framework there are two kinds of EE certificates:
      "single-use" EE certificates (that are used to verify a single
      object), and "multi-use" EE certificates (that may be used to
      verify multiple objects).  In the case of "multi-use" EE
      certificates the repository publication point is described in the
      following section.  In the case of a "single-use" EE certificate,
      the single signed object is published in the repository
      publication point referenced by the SIA of the CA certificate that
      issued the "single-use" EE certificate.  A non-normative guideline
      for naming such objects is for the filename of such objects to be
      derived from the associated EE certificate's public key, applying
      the algorithm described above.  Published objects MUST NOT use the
      filename extensions ".crl", ".mft", or ".cer".

2.3.  Multi-Use EE Repository Publication Points

   EE repository publication points are used only in conjunction with
   "multi-use" EE Certificates.  In this case the EE Certificate has two
   accessMethods specified in its SIA field.  The id-
   adsignedObjectRepository accessMethod has an associated
   accessLocation that points to the repository publication point of the
   objects verified by this EE certificate, as specified in
   [I-D.ietf-sidr-res-certs].  The id-ad-rpkiManifest accessMethod has
   an associated access location that points to the manifest, as an
   object URI (as distinct from a directory URI), associated with this
   repository publication point.  This manifest describes all the signed
   objects that are to be found in that publication point that can be
   verified by this EE certificate, and the hash value of each product
   (excluding the manifest itself) [I-D.ietf-sidr-rpki-manifests].

   In the case of multi-use EE, the repository publication point
   contains all published objects that can be verified using the EE's
   public key, and a manifest of all such signed objects.  A multi-use
   EE's manifest is limited in scope to listing the objects verified by
   this multi-use EE certificate.

   The objects published in a multi-use EE repository publication point
   do not form a logical, temporal sequence, and thus the filenames
   associated with each instance of these objects MUST be unique per
   multi-use EE.




Huston, et al.           Expires April 14, 2011                 [Page 8]


Internet-Draft        ResCert Respository Structure         October 2010


   It is consistent with this specification, but NOT recommended
   practice, that all subordinate multi-use EE certificates of a given
   CA share a common repository publication point.  This common
   repository publication point MAY be shared with that of the given CA,
   bit this, too, is NOT recommended practice.  In this case, the
   repository publication point would contain multiple manifest objects,
   one for each (multi-use) EE certificate associated with this common
   publication point (and, potentially, additional manifests generated
   by the CA's that also share this common repository publication
   point).  In such a scenario it is necessary to ensure that the set of
   filenames used by each multi-use EE are unique.  A non-normative
   guideline is for a multi-use EE to use a common base name component
   that is generated from the public key of the multi-use EE
   certificate, in the manner described above for CRL names.  The choice
   of whether to use a common single publication repository or a
   dedicated publication repository for each multi-use EE and CA is an
   implementation choice.


3.  Resource Certificate Publication Repository Considerations

   Each issuer MAY publish its issued certificates and CRL in any
   repository.  However, there are a number of considerations that guide
   the choice of a suitable repository publication structure:

      *  The publication repository SHOULD be hosted on a highly
         available service and high capacity publication platform.

      *  The publication repository MUST be available using RSYNC
         [RFC5781].  Support of additional retrieval mechanisms is the
         choice of the repository operator.  The supported retrieval
         mechanisms MUST be consistent with the accessMethod element
         value(s) specified in the SIA of the associated CA or EE.

      *  Each CA repository publication point SHOULD contain the
         products of this CA, including those objects that can be
         verified by single-use EE certificates that have been issued by
         this CA.  The signed products of related CA's that are operated
         by the same entity MAY share this CA repository publication
         point.  Aside from subdirectories, any other objects SHOULD NOT
         be placed in a repository publication point.

         Any such subdirectory SHOULD be the repository publication
         point of a CA or EE certificate that is contained in the CA
         directory.  These considerations also apply recursively to
         subdirectories of these directories.





Huston, et al.           Expires April 14, 2011                 [Page 9]


Internet-Draft        ResCert Respository Structure         October 2010


      *  Signed Objects are published in the location indicated by the
         SIA field of the EE certificate used to verify the signature of
         each object.  The choice of the repository publication point is
         determined by the nature of the corresponding EE certificate.
         In the case of a "multi-use" EE certificate signed objects are
         published in the EE repository publication point referenced by
         the SIA extension of the EE certificate in question.  In the
         case of a "single-use" EE certificate the signed object is
         published in the repository publication point of the CA
         certificate that issued the EE certificate.  The SIA extension
         of the single use EE certificate references this object rather
         than the repository publication
         directory[I-D.ietf-sidr-res-certs].

      *  It is recommended in Section 2.1 that repository operators
         SHOULD implement some form of directory management regime
         function on the repository to ensure that RPs who are
         performing retrieval operations on the repository are not
         exposed to intermediate states during changes to the repository
         and the associated manifest.  Notwithstanding the following
         commentary, RPs SHOULD NOT assume that a consistent repository
         and manifest state is assured, and organise their retrieval
         operations accordingly (see Section 5).

         The manner in which a repository operator can implement a
         directory update regime that mitigates the risk of the manifest
         and directory contents being inconsistent, to some extent, is
         dependant on the operational characteristics of the filesystem
         that hosts the repository, so the following comments are non-
         normative in terms of any implicit guidelines for repository
         operators.

         A commonly used technique to avoid exposure to inconsistent
         retrieval states during updates to a large directory, is to
         batch a set of changes to be made, create a working copy of the
         directory's contents, and then perform the batch of changes to
         this local copy of the directory.  On completion, rename the
         filesystem symbolic link of the repository directory name to
         point to this working copy of the directory.  The old
         repository directory contents can be purged at a slightly later
         time.  However, it is noted that the outcomes of this technique
         in terms of ensuring the integrity of client synchronization
         functions performed over the directory depend on the
         interaction between the supported access mechanisms and the
         local filesystem behaviour.  It is probable that this technique
         will not remove all possibilities for RPs to see inconsistent
         states between the manifest and the repository.




Huston, et al.           Expires April 14, 2011                [Page 10]


Internet-Draft        ResCert Respository Structure         October 2010


4.  Certificate Reissuance and Repositories

   If a CA certificate is reissued, e.g., due to changes in the set of
   resources contained in the number resource extensions, it should not
   be necessary to reissue all certificates issued under it.  Because
   these certificates contains AIA extensions that point to the
   publication point for the CA certificate, a CA SHOULD use a name for
   its repository publication point that persists across certificate
   reissuance events.  That is, reissued CA certificates SHOULD use the
   same repository publication point as previously issued CA
   certificates having the same subject and subject public key, such
   that certificate reissuance SHOULD intentionally overwrite the
   previously issued certificate within the repository publication
   point.

   It is noted in section Section 2.2 that when a CA performs a key
   rollover the entity SHOULD use a name for its repository publication
   point that persists across key rollover.  In such cases the
   repository publication point will contain the CRLs, and manifests of
   both CA instances as a transient state in the key rollover procedure.
   The RPKI key rollover procedure [I-D.ietf-sidr-keyroll] requires that
   the subordinate products of the old CA are overwritten in the common
   repository publication point by subordinate products issued by the
   new CA.


5.  Synchronising Repositories with a Local Cache

   It is possible to perform the validation-related task of certificate
   path construction using retrieval of individual certificates and
   certificate revocation lists using online retrieval of individual
   certificates, sets of candidate certificates and certificate
   revocation lists based on the AIA, SIA and CRLDP certificate fields.
   This is NOT recommended in circumstances where speed and efficiency
   are relevant considerations.

   To enable efficient validation of RPKI certificates, CRLs, and signed
   objects, it is recommended that each relying party maintain a local
   repository containing a synchronized copy of all valid certificates,
   current certificate revocation lists, and all related signed objects.

   The general approach to repository synchronisation is one of a "top-
   down" walk of the distributed repository structure.  This commences
   with the collection of locally selected trust anchor material
   corresponding to the local choice of Trust Anchors, which can be used
   to load the initial set of self-signed resource certificate(s) that
   form the "seed" of this process [I-D.ietf-sidr-ta].  The process then
   populates the local repository cache will all valid certificates that



Huston, et al.           Expires April 14, 2011                [Page 11]


Internet-Draft        ResCert Respository Structure         October 2010


   have been issued by these issuers.  This procedure can be recursively
   applied to each of these subordinate certificates.  Such a repository
   traversal process SHOULD support a locally configured maximal chain
   length from the initial trust anchors to the current working
   validation point in order to ensure that the process does not follow
   a loop or a non-terminating certificate chain.

   RPs SHOULD ensure that this local synchronisation uses the retrieved
   manifests [I-D.ietf-sidr-rpki-manifests] to ensure that they are
   synchronising against a current consistent state of each repository
   publication point.  It is noted in Section 3 that a repository
   operator cannot assure RPs that when the repository publication point
   contents are updated that the manifest contents and the repository
   contents will be precisely aligned at all times.  RPs SHOULD use a
   retrieval algorithm that takes this potential for transient
   inconsistency into account.  Possible algorithms for the RP to
   mitigate this situation include performing the synchronisation across
   the repository twice in succession, or performing a manifest
   retrieval both before and after the synchronisation of the directory
   contents, and repeating the synchronization function if the second
   copy of the manifest differs from the first.


6.  Security Considerations

   Repositories are not assumed to be integrity-protected databases, and
   repository retrieval operations MAY be vulnerable to various forms of
   "man-in-the-middle" attacks.  Corruption of retrieved objects is
   detectable by a relying party through the validation of the signature
   associated with each retrieved object.  Replacement of newer
   instances of an object with an older instance of the same object is
   detectable through the use of manifests.  Insertion of revoked,
   deleted certificates is detected through the retrieval and processing
   of CRLs at scheduled intervals.  However, even the use of manifests
   and CRLs will not allow a relying party to detect all forms of
   substitution attacks based on older (but not expired) valid objects.


7.  IANA Considerations

   [There are no IANA considerations in this document.]


8.  References







Huston, et al.           Expires April 14, 2011                [Page 12]


Internet-Draft        ResCert Respository Structure         October 2010


8.1.  Normative References

   [I-D.ietf-sidr-arch]
              Lepinski, M. and S. Kent, "An Infrastructure to Support
              Secure Internet Routing", draft-ietf-sidr-arch-11.txt
              (work in progress), September 2010.

   [I-D.ietf-sidr-res-certs]
              Huston, G., Michaelson, G., and R. Loomans, "A Profile for
              X.509 PKIX Resource Certificates",
              draft-ietf-sidr-res-certs-18.txt (work in progress),
              May 2010.

   [I-D.ietf-sidr-rpki-manifests]
              Austein, R., Huston, G., Kent, S., and M. Lepinski,
              "Manifests for the Resource Public Key Infrastructure",
              draft-ietf-sidr-rpki-manifests (work in progress),
              May 2010.

8.2.  Informative References

   [I-D.ietf-sidr-keyroll]
              Huston, G., Michaelson, G., and S. Kent, "CA Key Rollover
              in the RPKI", draft-ietf-sidr-keyroll-02.txt (work in
              progress), October 2010.

   [I-D.ietf-sidr-ta]
              Michaelson, G., Kent, S., and G. Huston, "A Profile for
              Trust Anchor Material for the Resource Certificate PKI",
              draft-ietf-sidr-ta-04.txt (work in progress), May 2010.

   [RFC3779]  Lynn, C., Kent, S., and K. Seo, "X.509 Extensions for IP
              Addresses and AS Identifiers", RFC 3779, June 2004.

   [RFC3986]  Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform
              Resource Identifier (URI): Generic Syntax", STD 66,
              RFC 3986, January 2005.

   [RFC4387]  Gutmann, P., "Internet X.509 Public Key Infrastructure
              Operational Protocols: Certificate Store Access via HTTP",
              RFC 4387, February 2006.

   [RFC4648]  Josefsson, S., "The Base16, Base32, and Base64 Data
              Encodings", RFC 4648, October 2006.

   [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



Huston, et al.           Expires April 14, 2011                [Page 13]


Internet-Draft        ResCert Respository Structure         October 2010


              (CRL) Profile", RFC 5280, May 2008.

   [RFC5781]  Weiler, S., Ward, D., and R. Housley, "The rsync URI
              Scheme", RFC 5781, February 2010.


Authors' Addresses

   Geoff Huston
   APNIC

   Email: gih@apnic.net
   URI:   http://www.apnic.net


   Robert Loomans
   APNIC

   Email: robertl@apnic.net
   URI:   http://www.apnic.net


   George Michaelson
   APNIC

   Email: ggm@apnic.net
   URI:   http://www.apnic.net
























Huston, et al.           Expires April 14, 2011                [Page 14]