\
Network Working Group                                        R. Gagliano
Internet-Draft                                             Cisco Systems
Intended status: Standards Track                                 S. Kent
Expires: February 3, 2012                               BBN Technologies
                                                               S. Turner
                                                              IECA, Inc.
                                                          August 2, 2011


                 Algorithm Agility Procedure for RPKI.
                  draft-ietf-sidr-algorithm-agility-03

Abstract

   This document specifies the process that Certification Authorities
   (CAs) and Relying Parties (RP) participating in the Resource Public
   Key Infrastructure (RPKI) will need to follow to transition to a new
   (and probably cryptographically stronger) algorithm set.  The process
   is expected to be completed in a time scale of months or years.
   Consequently, no emergency transition is specified.  The transition
   procedure defined in this document supports only a top-down migration
   (parent migrates before children).

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 February 3, 2012.

Copyright Notice

   Copyright (c) 2011 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



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   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.


Table of Contents

   1.  Requirements notation  . . . . . . . . . . . . . . . . . . . .  3
   2.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  4
   3.  Terminology  . . . . . . . . . . . . . . . . . . . . . . . . .  6
   4.  Key Rollover steps for algorithm migration . . . . . . . . . .  8
     4.1.  Milestones definition  . . . . . . . . . . . . . . . . . .  8
     4.2.  Process overview . . . . . . . . . . . . . . . . . . . . .  8
     4.3.  Phase 0  . . . . . . . . . . . . . . . . . . . . . . . . . 10
     4.4.  Phase 1  . . . . . . . . . . . . . . . . . . . . . . . . . 11
     4.5.  Phase 2  . . . . . . . . . . . . . . . . . . . . . . . . . 11
     4.6.  Phase 3  . . . . . . . . . . . . . . . . . . . . . . . . . 12
     4.7.  Phase 4  . . . . . . . . . . . . . . . . . . . . . . . . . 12
     4.8.  Return to Phase 0  . . . . . . . . . . . . . . . . . . . . 13
   5.  Multi Algorithm support in the RPKI provisioning protocol  . . 14
   6.  Validation of multiple instance of signed products . . . . . . 15
   7.  Revocations  . . . . . . . . . . . . . . . . . . . . . . . . . 16
   8.  Key rollover . . . . . . . . . . . . . . . . . . . . . . . . . 17
   9.  Repository structure . . . . . . . . . . . . . . . . . . . . . 18
   10. IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 19
   11. Security Considerations  . . . . . . . . . . . . . . . . . . . 20
   12. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 21
   13. References . . . . . . . . . . . . . . . . . . . . . . . . . . 22
     13.1. Normative References . . . . . . . . . . . . . . . . . . . 22
     13.2. Informative References . . . . . . . . . . . . . . . . . . 23
   Appendix A.  Change Log  . . . . . . . . . . . . . . . . . . . . . 24
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 25
















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1.  Requirements notation

   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].














































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2.  Introduction

   The RPKI must accommodate transitions between the public keys used by
   CAs.  Transitions of this sort are usually termed "key rollover".
   Planned key rollover will occur at regular intervals throughout the
   life of the RPKI, as each CA changes its public keys, in a non-
   coordinated fashion.  (By non-coordinated we mean that the time at
   which each CA elects to change its keys is locally determined, not
   coordinated across the RPKI.)  Moreover, because a key change might
   be necessitated by suspected private key compromise, one can never
   assume coordination of these events among all of the CAs in the RPKI.
   In an emergency key rollover, the old certificate is revoked and a
   new certificate with a new key is issued.  The mechanisms to perform
   a key rollover in RPKI (either planned or in an emergency), while
   maintaining the same algorithm suite, are covered in
   [I-D.ietf-sidr-keyroll].

   This document describes the mechanism to perform a key rollover in
   RPKI due to the migration to a new signature algorithm suite.  A
   signature algorithm suite encompasses both a signature algorithm
   (with a specified key size range) and a one-way hash algorithm.  It
   is anticipated that the RPKI will require the adoption of updated key
   sizes and/or different algorithm suites over time.  This document
   treats the adoption of a new hash algorithm while retaining the
   current signature algorithm as equivalent to an algorithm migration,
   and requires the CA to change its key.  Migration to a new algorithm
   suite will be required in order to maintain an acceptable level of
   cryptographic security and protect the integrity of certificates,
   CRLs and signed objects in the RPKI.  All of the data structures in
   the RPKI explicitly identify the signature and hash algorithms being
   used.  However, experience has demonstrated that the ability to
   represent algorithm IDs is not sufficient to enable migration to new
   algorithm suites (algorithm agility).  One also must ensure that
   protocols, infrastructure elements, and operational procedures also
   accommodate migration from one algorithm suite to another.  Algorithm
   migration is expected to be very infrequent, but it also will require
   support of a "current" and "next" suite for a prolonged interval,
   probably several years.

   This document defines how entities in the RPKI execute (planned) CA
   key rollover when the algorithm suite changes.  The description
   covers actions by CAs, repository operators, and RPs.  It describes
   the behavior required of both CAs and RPs to make such key changes
   work in the RPKI context, including how the RPKI repository system is
   used to support key rollover.

   This document does not specify any algorithm suite.




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   This document does not specify any algorithm suite per se. The RPKI
   Certificate Policy (CP) [I-D.ietf-sidr-cp] mandates the use of the
   algorithms defined in [I-D.ietf-sidr-rpki-algs] by CAs and RPs.  When
   an algorithm transition is initiated, [I-D.ietf-sidr-rpki-algs] will
   be updated (as defined in Section 4.1 of this document) redefining
   the required algorithm(s) for compliant RPKI CAs and RPs under the
   CP.












































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3.  Terminology

   This document assumes 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],
   "X.509 Extensions for IP Addresses and AS Identifiers" [RFC3779], and
   "A Profile for Resource Certificate Repository Structure"
   [I-D.ietf-sidr-repos-struct].  Additional terms and conventions use
   din examples are provided below.

   Algorithm migration  A planned transition from one signature and hash
               algorithm to a new signature and hash algorithm.

   Algorithm Suite A  The "current" algorithm suite used for hashing and
               signing, in examples in this document

   Algorithm Suite B  The "next" algorithm suite used for hashing and
               signing, used in examples in this document

   Algorithm Suite C  The "old" algorithm suite used for hashing and
               signing, used in examples in this document

   CA X        The CA that issued CA Y's certificate (i.e., CA Y's
               parent), used in examples this document.

   CA Y        The CA that is changing keys and/or algorithm suites,
               used in examples this document

   CA Z        A CA that is a "child" of CA Y, used in examples this
               document

   Certificate re-issuance (unilateral)  A CA MAY reissue a certificate
               to a subordinate Subject without the involvement of the
               Subject.  The public key, resource extensions, and most
               other fields are copied from the current Subject
               certificate into the next Subject certificate.  The
               Issuer name MAY change, if necessary to reflect the
               Subject name in the CA certificate under which the
               reissued certificate will be validated.  The validity
               interval also MAY be changed.  This action is defined as
               a unilateral certificate re-issuance.

   Non-Leaf CA A CA that issues certificates to other CAs is a non-leaf
               CA.







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   Leaf CA     A leaf CA is a CA that issues only EE certs.

   PoP (proof of possession)  Execution of a protocol that demonstrates
               to an issuer that a subject requesting a certificate
               possesses the private key corresponding to the public key
               in the certificate submitted by the subject.

   Signed Product Set (or Set)  A collection of certificates, signed
               objects, a CRL and a manifest that are associated by
               virtue of being verifiable under the same parent CA
               certificate








































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4.  Key Rollover steps for algorithm migration

   The "current" RPKI algorithm suite (Suite A) is defined in the RPKI's
   CP document, by reference to [I-D.ietf-sidr-rpki-algs].  When a
   migration of the RPKI algorithm suite is needed, the first step MUST
   be an update of the [I-D.ietf-sidr-rpki-algs] document that will
   include all the information described in Section 4.3.

4.1.  Milestones definition

   CA Ready Algorithm B Date  - After this date, all (non-leaf) CAs MUST
               be ready to process a request from a child CA to issue a
               certificate under the Algorithm B suite.

   CA Go Algorithm B Date  - After this date, all (non-leaf) CAs MUST
               have re-issued all of its signed product set under the
               Algorithm B suite.

   RP Ready Algorithm B Date  - After this date, all RPs MUST be
               prepared to process signed material issued under the
               Algorithm B suite.

   Twilight Algorithm B  - After this date, a CA MAY cease issuing
               signed products under the Algorithm A suite.  Also, after
               this date, a RP MAY cease to validate signed materials
               issued under the Algorithm A suite.

   End Of Life (EOL) Algorithm A  - After this date every CA MUST NOT
               generate certificates, CRLs, or other RPKI signed objects
               under the Algorithm A suite.  Also, after this date, no
               RP SHOULD accept as valid any certificate, CRL or signed
               object using the Algorithm A suite.

4.2.  Process overview

   The migration process described in this document involves a series of
   steps that MUST be executed in chronological order by CAs and RPs.
   The only milestone at which both CAs and RPs take action at the same
   moment is the "EOL Algorithm A" date.  Due to the decentralized
   nature of the RPKI infrastructure, it is expected that the process
   will take several months or even years.

   In order to facilitate the transition, CAs will start issuing
   certificates using the Algorithm B in a hierarchical top-down order.
   In our example, CA Y will issue certificates using the Algorithm B
   suite only after CA X has started to do so (CA Y Ready Algorithm B
   Date > CA X Ready Algorithm B Date).  This ordered transition avoids
   issuance of "mixed" suite certificates, e.g., a CA certificate signed



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   using Suite A, containing a key from Suite B. In the RPKI, a CA MUST
   NOT sign a CA certificate carrying a subject key that corresponds to
   an algorithm suite that differs from the one used to sign the
   certificate.

   The algorithm agility model described here does not prohibit a CA
   issuing an EE certificate with a subject public key from a different
   algorithm suite, if that certificate is not used to verify repository
   objects.  This exception to the mixed algorithm suite certificate
   rule is allowed because an EE certificate that is not used to verify
   repository objects does not interfere with the ability of RPs to
   download and verify repository content.  Nonetheless, every CA in the
   RPKI is required to perform a Proof of Possession (PoP) check for the
   subject public key when issuing a certificate.  In general a subject
   cannot assume that a CA is capable of supporting a different
   algorithm.  However, if the subject is closely affiliated with the
   CA, it is reasonable to assume that there are ways for the subject to
   know whether the CA can support a request to issue an EE certificate
   containing a specific, different public key algorithm.  This document
   does not specify how a subject can determine whether a CA is capable
   of issuing a mixed suite EE certificate, because it anticipates that
   such certificates will be issued only in contexts where the subject
   and CA are sufficiently closely affiliated (for example, an ISP
   issuing certificates to devices that it manages).

   The following figure gives an overview of the process:

   Process for RPKI CAs:

     Phase 0    Phase 1   Phase 2             Phase 4  Phase 0
   -----------x---------x-------------------x--------x-----------
     ^        ^         ^                   ^        ^
     |        |         |                   |        |
    (1)      (2)       (3)                 (5)      (6)

   Process for RPKI RPs:

               Phase 0              Phase 3   Phase 4  Phase 0
   -------------------------------x---------x--------x-----
     ^                            ^         ^        ^
     |                            |         |        |
    (1)                          (4)       (5)      (6)

   (1) RPKI's algorithm document updated.
   (2) CA Ready Algorithm B Date
   (3) CA Go Algorithm B Date
   (4) RP Ready Algorithm B Date
   (5) Twilight Date



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   (6) End Of Live (EOL) Date

4.3.  Phase 0

   Phase 0 is the initial phase of the process, throughout this phase
   the algorithm suite A is the only supported algorithm suite in RPKI.

   The first milestone, which will initiate the migration process, is
   updating the [I-D.ietf-sidr-rpki-algs] document with the following
   definitions for the RPKI:

   o  Algorithm Suite A

   o  Algorithm Suite B

   o  CA Ready Algorithm B Date

   o  CA Go Algorithm B Date

   o  RP Ready Algorithm B Date

   o  Twilight Date

   o  EOL Date

   All Dates MUST be represented using the local UTC date-time format
   specified in [RFC3339].

   As an example, during Phase 0, CAs X, Y and Z are required to
   generate signed product sets using only the Algorithm Suite A. Also,
   RPs are required to validate signed product sets issued using only
   Algorithm Suite A.

   CA X-Certificate-Algorithm-Suite-A (Cert-XA)
           |
           |-> CA-Y-Certificate-Algorithm-Suite-A (Cert-YA)
                   |-> CA-Z-Certificate-Algorithm-Suite-A (Cert-ZA)
                           |-> CA-Z-CRL-Algorithm-Suite-A (CRL-ZA)
                           |-> CA-Z-Signed-Objects-Algorithm-Suite-A
                   |-> CA-Y-CRL-Algorithm-Suite-A (CRL-YA)
                   |-> CA-Y-Signed-Objects-Algorithm-Suite-A
           |-> CA-X-CRL-Algorithm-Suite-A (CRL-XA)
           |-> CA-X-Signed-Objects-Algorithm-Suite-A

   Note: Cert-XA represent the certificate for CA X, that is signed
   using the algorithm suite A.





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4.4.  Phase 1

   Phase 1 starts at the CA Ready Algorithm B Date.  During Phase 1, all
   (non-leaf) CAs MUST be ready to process a request from a child CA to
   issue or revoke a certificate using the Algorithm B suite.

   As the transition will happen using a (hierarchic) top-down model, a
   child CA will be able to issue certificates using the Algorithm B
   suite only after its parent CA has issued its own.  The RPKI
   provisioning protocol can identify if a parent CA is capable of
   issuing certificates using the Algorithm Suite B, and can identify
   the corresponding algorithm suite in each Certificate Signing Request
   (see Section 5).

   The following figure shows the status of repository entries for the
   three example CAs during this Phase.  Two distinct certificate chains
   are maintained and CA Z has not yet requested any material using the
   Algorithm B suite.

   CA X-Certificate-Algorithm-Suite-A (Cert-XA)
           |
           |-> CA-Y-Certificate-Algorithm-Suite-A (Cert-YA)
                   |-> CA-Z-Certificate-Algorithm-Suite-A (Cert-ZA)
                           |-> CA-Z-CRL-Algorithm-Suite-A (CRL-ZA)
                           |-> CA-Z-Signed-Objects-Algorithm-Suite-A
                   |-> CA-Y-CRL-Algorithm-Suite-A (CRL-YA)
                   |-> CA-Y-Signed-Objects-Algorithm-Suite-A
           |-> CA-X-CRL-Algorithm-Suite-A (CRL-XA)
           |-> CA-X-Signed-Objects-Algorithm-Suite-A

   CA X-Certificate-Algorithm-Suite-B (Cert-XB)
           |
           |-> CA-Y-Certificate-Algorithm-Suite-B (Cert-YB)
                   |-> CA-Y-CRL-Algorithm-Suite-B (CRL-YB)
                   |-> CA-Y-Signed-Objects-Algorithm-Suite-B
           |-> CA-X-CRL-Algorithm-Suite-B (CRL-XB)
           |-> CA-X-Signed-Objects-Algorithm-Suite-B

4.5.  Phase 2

   Phase 2 starts at the CA Go Algorithm B Date.  At the start of this
   phase, all signed product sets MUST be available using both Algorithm
   Suite A and Algorithm Suite B. During this phase, RPs MUST be
   prepared to validate sets issued using Algorithm Suite A and MAY be
   prepared to validate sets issued using the Algorithm Suite B.

   An RP that validates all signed product sets using both Algorithm
   Suite A or Algorithm Suite B, SHOULD expect the same results.



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   However, an object that validates using either Algorithm Suite A or
   Algorithm Suite B MUST be considered valid.  A detailed analysis on
   the validation of multiple instance of signed objects is included in
   Section 6.

   The following figure shows the status of the repository entries for
   the three example CAs throughout this phase, where all signed objects
   are available using both algorithm suites.

   CA X-Certificate-Algorithm-Suite-A (Cert-XA)
           |
           |-> CA-Y-Certificate-Algorithm-Suite-A (Cert-YA)
                   |-> CA-Z-Certificate-Algorithm-Suite-A (Cert-ZA)
                           |-> CA-Z-CRL-Algorithm-Suite-A (CRL-ZA)
                           |-> CA-Z-Signed-Objects-Algorithm-Suite-A
                   |-> CA-Y-CRL-Algorithm-Suite-A (CRL-YA)
                   |-> CA-Y-Signed-Objects-Algorithm-Suite-A
           |-> CA-X-CRL-Algorithm-Suite-A (CRL-XA)
           |-> CA-X-Signed-Objects-Algorithm-Suite-A

   CA X-Certificate-Algorithm-Suite-B (Cert-XB)
           |
           |-> CA-Y-Certificate-Algorithm-Suite-B (Cert-YB)
                   |-> CA-Z-Certificate-Algorithm-Suite-B (Cert-ZB)
                           |-> CA-Z-CRL-Algorithm-Suite-B (CRL-ZB)
                           |-> CA-Z-Signed-Objects-Algorithm-Suite-B
                   |-> CA-Y-CRL-Algorithm-Suite-B (CRL-YB)
                   |-> CA-Y-Signed-Objects-Algorithm-Suite-B
           |-> CA-X-CRL-Algorithm-Suite-B (CRL-XB)
           |-> CA-X-Signed-Objects-Algorithm-Suite-B

4.6.  Phase 3

   Phase 3 starts at the RP Ready Algorithm B Date.  During this phase,
   all signed product sets are available using both algorithm suites and
   all RPs MUST be able to validate them using either suite.  An object
   that validates using either Algorithm Suite A or Algorithm Suite B
   MUST be considered as valid.  It is RECOMMENDED that RPs utilize only
   Suite B for validation throughout this phase, in preparation for
   Phase 4.

   There are no changes to the CA behavior throughout this phase.

4.7.  Phase 4

   Phase 4 starts at the Algorithm A Twilight Date.  At that date, the
   Algorithm A is labeled as "old" and the Algorithm B is labeled as
   "current":



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   Before Twilight                 -->     After Twilight

   Algorithm Suite A ("current")   -->     Algorithm Suite C ("old")
   Algorithm Suite B ("new")       -->     Algorithm Suite A ("current")

   During this phase, all signed product sets MUST be issued using
   Algorithm Suite A (formerly B) and MAY be issued using Algorithm
   Suite C (formerly A).  All signed products sets issued using Suite A
   MUST be published at their corresponding publication points, but
   signed products sets issued using Suite C MAY be published at their
   corresponding publication points.  Also, every RP MUST validate
   signed product sets using Suite A but also MAY validate signed
   product sets using Suite C.

   The following figure describe a possible status for the repositories
   of the example CAs.  In this case, CA Z no longer issues signed
   products using the Algorithm Suite C.

   CA X-Certificate-Algorithm-Suite-C (Cert-XC)
           |
           |-> CA-Y-Certificate-Algorithm-Suite-C (Cert-YC)
                   |-> CA-Y-CRL-Algorithm-Suite-C (CRL-YC)
                   |-> CA-Y-Signed-Objects-Algorithm-Suite-C
           |-> CA-X-CRL-Algorithm-Suite-C (CRL-XC)
           |-> CA-X-Signed-Objects-Algorithm-Suite-C

   CA X-Certificate-Algorithm-Suite-A (Cert-XA)
           |
           |-> CA-Y-Certificate-Algorithm-Suite-A (Cert-YA)
                   |-> CA-Z-Certificate-Algorithm-Suite-A (Cert-ZA)
                           |-> CA-Z-CRL-Algorithm-Suite-A (CRL-ZA)
                           |-> CA-Z-Signed-Objects-Algorithm-Suite-A
                   |-> CA-Y-CRL-Algorithm-Suite-A (CRL-YA)
                   |-> CA-Y-Signed-Objects-Algorithm-Suite-A
           |-> CA-X-CRL-Algorithm-Suite-A (CRL-XA)
           |-> CA-X-Signed-Objects-Algorithm-Suite-A


4.8.  Return to Phase 0

   Phase 0 starts at the EOL Algorithm Date.  At this phase, ALL signed
   product sets using Algorithm Suite C MUST be considered invalid.  CAs
   MUST neither issue nor publish signed products using Algorithm Suite
   C.

   This phase closes the loop as Algorithm Suite A is the only required
   algorithm suite in RPKI.




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5.  Multi Algorithm support in the RPKI provisioning protocol

   The migration described in this document is a top-down process, where
   two synchronization issues need to be solved between child and parent
   CAs:

   o  A child CA needs to identify which algorithm suites are supported
      by its parent CA

   o  A child CA needs to identify which algorithm suite should be used
      to sign a Certificate Signing Request (CSR)

   The RPKI provisioning protocol [I-D.ietf-sidr-rescerts-provisioning]
   supports multiple algorithms suites by implementing a different
   resource classes for each suite.  Several different resource classes
   also may use the same algorithm suite for different resource sets.

   A child CA that wants to identify which algorithm suites are
   supported by its parent CA MUST perform the following tasks:

   1.  Establish a provisioning protocol session with its parent CA

   2.  Perform a "list" command as described in Section 3.3.1 of
       [I-D.ietf-sidr-rescerts-provisioning]

   3.  From the Payload in the "list response" resource class, extract
       the "issuer's certificate" for each class.  The Algorithm Suite
       for each class will match the Algorithm Suite used to issue the
       corresponding "issuer's certificate".

   A child CA that wants to specify an Algorithm Suite to its parent CA
   (e.g., in a certificate request) MUST perform the following tasks:

   1.  Perform the tasks to identify the resource class for each
       Algorithm Suite supported by its parent CA (as above).

   2.  Identify the corresponding resource class in the appropriate
       provisioning protocol command (e.g. "issue" or "revoke")

   Upon receipt of a certificate request from a child CA, a parent CA
   will verify the PoP of the private key.  If a child CA requests
   issuing a certificate using an algorithm suite that does not match a
   resource class, the PoP validation will fail and the request will not
   be performed.







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6.  Validation of multiple instance of signed products

   During Phases 1,2,3 and 4, two algorithm suites will be valid
   simultaneously in RPKI.  In this section, we describe the RP behavior
   when validating instances of the same signed product but signed with
   different algorithm suites.  As a general rule, the validation of
   signed products using different algorithm suites are independent and
   the RP MUST NOT keep any relationship between the different
   hierarchies.

   During Phase 1 two (corresponding) files for an object MAY be
   available for each signed product, one signed under Algorithm Suite A
   and one under Algorithm Suite B.  When an RP validates these signed
   products, if either instance of an object validates, the product is
   accepted.  A failure to validate one instance of a product, under
   either algorithm Suite MUST NOT cause the RP to reject the other
   instance of the product.  Because both instances of such products
   MUST contain the same resources, relying on either instance will
   yield the same outcome.

   During Phases 2 and 3 of this process, two (corresponding) instances
   of all signed products MUST be available to RPs.  As in Phase 1, when
   an RP validates these signed products, if either instance validates,
   the product is accepted.  A failure to validate one instance of a
   product, under either algorithm Suite MUST NOT cause the RP to reject
   the other instance of the product.  Also, as above, if only one
   instance of a signed product can be validated, subordinate products
   issued under the other (non-validated) algorithm suite cannot be
   used, and thus SHOULD NOT be processed (or even retrieved).

   During Phase 4 two (corresponding) files for an object MAY be
   available for each signed product, one signed under Algorithm Suite A
   and one under Algorithm Suite C.  When an RP validates these signed
   products, if either instance of an object validates, the product is
   accepted.  A failure to validate one instance of a product, under
   either algorithm Suite MUST NOT cause the RP to reject the other
   instance of the product.  Because both instances of such products
   MUST contain the same resources, relying on either instance will
   yield the same outcome.












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7.  Revocations

   As the algorithm migration process mandates the maintenance of two
   parallel certificate hierarchies, revocations requests for each
   algorithm suite MUST be handled independently.  A Child CA MUST
   request revocation of a certificate relative to a specific algorithm
   suite.

   During phase 2 and phase 3, the two parallel certificate hierarchies
   are designed to carry identical information.  Consequently, a child
   CA requesting the revocation of a certificate during these two phases
   MUST perform that request for both algorithm suites (A and B).  A
   non-leaf CA is NOT required to verify that its child CAs comply with
   this requirement.





































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8.  Key rollover

   Key rollover (without algorithm changes) is effected independently
   for each algorithm suite and MUST follow the process described in
   [I-D.ietf-sidr-keyroll].














































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9.  Repository structure

   The two parallel hierarchies that will exist during the transition
   process SHOULD have independent publications points.  The repository
   structures for each algorithm suite are described in
   [I-D.ietf-sidr-repos-struct].













































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10.  IANA Considerations

   No IANA requirements
















































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11.  Security Considerations

   An algorithm transition in RPKI should be a very infrequent event and
   it requires wide community consensus.  The events that may lead to an
   algorithm transition may be related to a weakness of the
   cryptographic strength of the algorithm suite in use by RPKI, which
   is normal to happen over time.  The procedure described in this
   document will take months or years to complete an algorithm
   transition.  During that time, the RPKI system will be vulnerable to
   any cryptographic weakness that may have triggered this procedure.

   This document does not describe an emergency mechanism for algorithm
   migration.  Due to the distributed nature of RPKI, and the very large
   number of CAs and RPs, the authors do not believe it is feasible to
   effect an emergency algorithm migration procedure.

   If a CA does not complete its migration to the new algorithm suite as
   described in this document (after the EOL of the "old" algorithm
   suite), its signed product set will not longer be valid.
   Consequently, the RPKI may, at the end of Phase 4, have a smaller
   number of valid signed products than before starting the process.
   Conversely, a RP that does not follow this process will lose the
   ability to validate signed products issued under the new algorithm
   suite.  The resulting incomplete view of routing info from the RPKI
   (as a result of a failure by CAs or RPs to complete the transition)
   could degrade routing in the public Internet.

























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12.  Acknowledgements

   The authors would like to acknowledge the work of the SIDR working
   group co-chairs (Sandra Murphy and Chris Morrow) as well as the
   contributions given by Geoff Huston, Arturo Servin and Brian Weis.














































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13.  References

13.1.  Normative References

   [I-D.ietf-sidr-cp]
              Kent, S., Kong, D., Seo, K., and R. Watro, "Certificate
              Policy (CP) for the Resource PKI (RPKI",
              draft-ietf-sidr-cp-17 (work in progress), April 2011.

   [I-D.ietf-sidr-keyroll]
              Huston, G., Michaelson, G., and S. Kent, "CA Key Rollover
              in the RPKI", draft-ietf-sidr-keyroll-05 (work in
              progress), December 2010.

   [I-D.ietf-sidr-repos-struct]
              Huston, G., Loomans, R., and G. Michaelson, "A Profile for
              Resource Certificate Repository Structure",
              draft-ietf-sidr-repos-struct-06 (work in progress),
              November 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-21 (work in progress),
              December 2010.

   [I-D.ietf-sidr-rescerts-provisioning]
              Huston, G., Loomans, R., Ellacott, B., and R. Austein, "A
              Protocol for Provisioning Resource Certificates",
              draft-ietf-sidr-rescerts-provisioning-10 (work in
              progress), June 2011.

   [I-D.ietf-sidr-rpki-algs]
              Huston, G., "A Profile for Algorithms and Key Sizes for
              use in the Resource Public Key Infrastructure",
              draft-ietf-sidr-rpki-algs-04 (work in progress),
              November 2010.

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

   [RFC2560]  Myers, M., Ankney, R., Malpani, A., Galperin, S., and C.
              Adams, "X.509 Internet Public Key Infrastructure Online
              Certificate Status Protocol - OCSP", RFC 2560, June 1999.

   [RFC3339]  Klyne, G., Ed. and C. Newman, "Date and Time on the
              Internet: Timestamps", RFC 3339, July 2002.




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

   [RFC4193]  Hinden, R. and B. Haberman, "Unique Local IPv6 Unicast
              Addresses", RFC 4193, October 2005.

   [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.

13.2.  Informative References

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




































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Appendix A.  Change Log

   From 02 to 03:

   1.  Explicitely named than "mixed" certificates are not allowed for
       CA certs but may be possible for EE certs that are not used to
       validate repository objects.

   From 01 to 02:

   1.  Add reference to Multi-Objects validation

   2.  EOL Data is the only milestone that RP and CA take actions "at
       the same time".

   3.  Updated references

   4.  Editorial

   From 00 to 01:

   1.  Include text to clarify former Suites

   2.  Include text that documents that an RP that validates an object
       signed with either suites in Phase 2 MUST consider it as valid

   From individual submission to WG item:

   1.  Change form "laisez faire" to "top-down"

   2.  Included Multi Algorithm support in the RPKI provisioning
       protocol

   3.  Included Validation of multiple instance of signed products

   4.  Included Revocations

   5.  Included Key rollover

   6.  Included Repository structure

   7.  Included Security Considerations

   8.  Included Acknowledgements







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Authors' Addresses

   Roque Gagliano
   Cisco Systems
   Avenue des Uttins 5
   Rolle,   1180
   Switzerland

   Email: rogaglia@cisco.com


   Stephen Kent
   BBN Technologies
   10 Moulton St.
   Cambridge, MA  02138
   USA

   Email: kent@bbn.com


   Sean Turner
   IECA, Inc.
   3057 Nutley Street, Suite 106
   Fairfax, VA  22031
   USA

   Email: turners@ieca.com
























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