The I in RPKI does not stand for Identity
draft-ietf-sidrops-rpki-has-no-identity-06

Network Working Group                                            R. Bush
Internet-Draft                        Arrcus & Internet Initiative Japan
Intended status: Standards Track                              R. Housley
Expires: 16 October 2022                                  Vigil Security
                                                           14 April 2022

               The I in RPKI does not stand for Identity
               draft-ietf-sidrops-rpki-has-no-identity-06

Abstract

   There is a false notion that Internet Number Resources (INRs) in the
   RPKI can be associated with the real-world identity of the 'holder'
   of an INR.  This document attempts to put that notion to rest.

Requirements Language

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
   "OPTIONAL" in this document are to be interpreted as described in BCP
   14 [RFC2119] [RFC8174] when, and only when, they appear in all
   capitals, as shown here.

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
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   This Internet-Draft will expire on 16 October 2022.

Copyright Notice

   Copyright (c) 2022 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

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   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents (https://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
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   provided without warranty as described in the Revised BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  The RPKI is for Authorization . . . . . . . . . . . . . . . .   3
   3.  Discussion  . . . . . . . . . . . . . . . . . . . . . . . . .   4
   4.  Security Considerations . . . . . . . . . . . . . . . . . . .   5
   5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   6
   6.  Acknowledgments . . . . . . . . . . . . . . . . . . . . . . .   6
   7.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   6
     7.1.  Normative References  . . . . . . . . . . . . . . . . . .   6
     7.2.  Informative References  . . . . . . . . . . . . . . . . .   6
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   7

1.  Introduction

   The Resource Public Key Infrastructure (RPKI), see [RFC6480],
   "Represents the allocation hierarchy of IP address space and
   Autonomous System (AS) numbers," which are collectively known as
   Internet Number Resources (INRs).  Since initial deployment, the RPKI
   has grown to include other similar resource and routing data, e.g.
   Router Keying for BGPsec, [RFC8635].

   In security terms, the phrase "Public Key" implies there is also a
   corresponding private key [RFC5280].  The RPKI provides strong
   authority to the current holder of INRs; however, some people a have
   a desire to use RPKI private keys to sign arbitrary documents as the
   INR 'holder' of those resources with the inappropriate expectation
   that the signature will be considered an attestation to the
   authenticity of the document content.  But in reality, the RPKI
   certificate is only an authorization to speak for the explicitly
   identified INRs; it is explicitly not intended for authentication of
   the 'holders' of the INRs.  This situation is emphasized in
   Section 2.1 of [RFC6480].

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   It has been suggested that one could authenticate real-world business
   transactions with the signatures of INR holders.  E.g.  Bill's Bait
   and Sushi could use the private key attesting to that they are the
   holder of their AS in the RPKI to sign a Letter of Authorization
   (LOA) for some other party to rack and stack hardware owned by BB&S.
   Unfortunately, while this may be technically possible, it is neither
   appropriate nor meaningful.

   The I in RPKI actually stands for "Infrastructure," as in Resource
   Public Key Infrastructure, not for "Identity".  In fact, the RPKI
   does not provide any association between INRs and the real world
   holder(s) of those INRs.  The RPKI provides authorization to make
   assertions only regarding named IP address blocks, AS numbers, etc.

   In short, avoid the desire to use RPKI certificates for any purpose
   other than the verification of authorizations associated with the
   delegation of INRs or attestations related to INRs.  Instead,
   recognize that these authorizations and attestations take place
   irrespective of the identity of a RPKI private key holder.

2.  The RPKI is for Authorization

   The RPKI was designed and specified to sign certificates for use
   within the RPKI itself and to generate Route Origin Authorizations
   (ROAs), [RFC6480], for use in routing.  Its design intentionally
   precluded use for attesting to real-world identity as, among other
   issues, it would expose the Certification Authority (CA) to
   liability.

   That the RPKI does not authenticate real-world identity is by design.
   If it tried to do so, aside from the liability, it would end in a
   world of complexity with no proof of termination, as X.400 learned.

   Registries such as the Regional Internet Registries (RIRs) provide
   INR to real-world identity mapping through WHOIS, [RFC3912], and
   similar services.  They claim to be authoritative, at least for the
   INRs which they allocate.

   PKI operations MUST NOT be performed with RPKI certificates other
   than exactly as described, and for the purposes described, in
   [RFC6480].  That is, RPKI-based credentials of INRs MUST NOT be used
   to authenticate real-world documents or transactions without some
   formal external authentication of the INR and the authority for the
   actually anonymous INR holder to authenticate the particular document
   or transaction.

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   I.e., RPKI-based credentials of INRs MUST NOT be used to authenticate
   real-world documents or transactions without some formal external
   authentication of the INR and the authority for the actually
   anonymous INR holder to authenticate the particular document or
   transaction.

   Given sufficient external, i.e. non-RPKI, verification of authority,
   the use of RPKI-based credentials seems superfluous.

3.  Discussion

   The RPKI base document, [RFC6480], Section 2.1 says explicitly "An
   important property of this PKI is that certificates do not attest to
   the identity of the subject."

   The Template for a Certification Practice Statement (CPS) for the
   Resource PKI (RPKI) [RFC7382] Section 3.1, Naming, makes very clear
   that "The Subject name in each certificate SHOULD NOT be meaningful;"
   and goes on to do so at some length.

   Normally, the INR holder does not hold the private key attesting to
   their resources; the Certification Authority (CA) does.  The INR
   holder has a real-world business relationship with the CA for which
   they have likely signed real-world documents.

   As the INR holder does not have the keying material, they rely on the
   CA, to which they presumably present credentials, to manipulate their
   INRs.  These credentials may be userid/password (with two factor
   authentication one hopes), a hardware token, client browser
   certificates, etc.

   Hence schemes such as [I-D.ietf-sidrops-rpki-rta] and
   [I-D.ietf-sidrops-rpki-rsc] must go to great lengths to extract the
   supposedly relevant keys from the CA.

   For some particular INR, say Bill's Bait and Sushi's Autonomous
   System (AS) number, someone out on the net probably has the
   credentials to the CA account in which BB&S's INRs are registered.
   That could be the owner of BB&S, Roberto's Taco Stand, an IT vendor,
   or the Government of Elbonia.  One simply can not know.

   In large organizations, INR management is often compartmentalized
   with no authority over anything beyond dealing with INR registration.
   The INR manager for Bill's Bait and Sushi is unlikely to be
   authorized to conduct bank transactions for BB&S, or even to
   authorize access to BB&S's servers in some colocation facility.

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   Then there is the temporal issue.  The holder of that AS may be BB&S
   today when some document was signed, and could be the Government of
   Elbonia tomorrow.  Or the resource could have been administratively
   moved from one CA to another, likely requiring a change of keys.  If
   so, how does one determine if the signature on the real-world
   document is still valid?

   While Ghostbuster Records [RFC6493] may seem to identify real-world
   entities, their semantic content is completely arbitrary, and does
   not attest to holding of any INRs.  They are merely clues for
   operational support contact in case of technical RPKI problems.

   Usually, before registering INRs, CAs require proof of an INR holding
   via external documentation and authorities.  It is somewhat droll
   that the CPS Template, [RFC7382], does not mention any diligence the
   CA must, or even might, conduct to assure the INRs are in fact owned
   by a registrant.

   That someone can provide 'proof of possession' of the private key
   signing over a particular INR should not be taken to imply that they
   are a valid legal representative of the organization in possession of
   that INR.  They could be just an INR administrative person.

   Autonomous System Numbers do not identify real-world entities.  They
   are identifiers some network operators 'own' and are only used for
   loop detection in routing.  They have no inherent semantics other
   than uniqueness.

4.  Security Considerations

   Attempts to use RPKI data to authenticate real-world documents or
   other artifacts requiring identity are invalid and misleading.

   When a document is signed with the private key associated with an
   RPKI certificate, the signer is speaking for the INRs, the IP address
   space and Autonomous System (AS) numbers, in the certificate.  This
   is not an identity; this is an authorization.  In schemes such as
   [I-D.ietf-sidrops-rpki-rta] and [I-D.ietf-sidrops-rpki-rsc] the
   signed message further narrows this scope of INRs.  The INRs in the
   message are a subset of the INRs in the certificate.  If the
   signature is valid, the message content comes from a party that is
   authorized to speak for that subset of INRs.

   Control of INRs for an entity could be used to falsely authorize
   transactions or documents for which the INR manager has no authority.

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5.  IANA Considerations

   This document has no IANA Considerations.

6.  Acknowledgments

   The authors thank George Michaelson and Job Snijders for lively
   discussion, Geoff Huston for some more formal text, Ties de Kock for
   useful suggestions, and last but not least, Biff for the loan of
   Bill's Bait and Sushi.

7.  References

7.1.  Normative References

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,
              <https://www.rfc-editor.org/info/rfc2119>.

   [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, DOI 10.17487/RFC5280, May 2008,
              <https://www.rfc-editor.org/info/rfc5280>.

   [RFC6480]  Lepinski, M. and S. Kent, "An Infrastructure to Support
              Secure Internet Routing", RFC 6480, DOI 10.17487/RFC6480,
              February 2012, <https://www.rfc-editor.org/info/rfc6480>.

   [RFC7382]  Kent, S., Kong, D., and K. Seo, "Template for a
              Certification Practice Statement (CPS) for the Resource
              PKI (RPKI)", BCP 173, RFC 7382, DOI 10.17487/RFC7382,
              April 2015, <https://www.rfc-editor.org/info/rfc7382>.

   [RFC8174]  Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
              2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
              May 2017, <https://www.rfc-editor.org/info/rfc8174>.

   [RFC8635]  Bush, R., Turner, S., and K. Patel, "Router Keying for
              BGPsec", RFC 8635, DOI 10.17487/RFC8635, August 2019,
              <https://www.rfc-editor.org/info/rfc8635>.

7.2.  Informative References

   [I-D.ietf-sidrops-rpki-rsc]
              Snijders, J., Harrison, T., and B. Maddison, "Resource
              Public Key Infrastructure (RPKI) object profile for Signed

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              Checklist (RSC)", Work in Progress, Internet-Draft, draft-
              ietf-sidrops-rpki-rsc-06, 12 February 2022,
              <https://www.ietf.org/archive/id/draft-ietf-sidrops-rpki-
              rsc-06.txt>.

   [I-D.ietf-sidrops-rpki-rta]
              Michaelson, G. G., Huston, G., Harrison, T., Bruijnzeels,
              T., and M. Hoffmann, "A profile for Resource Tagged
              Attestations (RTAs)", Work in Progress, Internet-Draft,
              draft-ietf-sidrops-rpki-rta-00, 21 January 2021,
              <https://www.ietf.org/archive/id/draft-ietf-sidrops-rpki-
              rta-00.txt>.

   [RFC3912]  Daigle, L., "WHOIS Protocol Specification", RFC 3912,
              DOI 10.17487/RFC3912, September 2004,
              <https://www.rfc-editor.org/info/rfc3912>.

   [RFC6493]  Bush, R., "The Resource Public Key Infrastructure (RPKI)
              Ghostbusters Record", RFC 6493, DOI 10.17487/RFC6493,
              February 2012, <https://www.rfc-editor.org/info/rfc6493>.

Authors' Addresses

   Randy Bush
   Arrcus & Internet Initiative Japan
   5147 Crystal Springs
   Bainbridge Island, WA 98110
   United States of America
   Email: randy@psg.com

   Russ Housley
   Vigil Security, LLC
   516 Dranesville Road
   Herndon, VA,  20170
   United States of America
   Email: housley@vigilsec.com

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