wdiff rfc9981.original rfc9981.txt

Internet Engineering Task Force (IETF) T. Harrison
Internet-Draft
Request for Comments: 9981 G. Michaelson
Updates: 9286 (if approved) APNIC
Intended status:
Category: Standards Track J. Snijders
Expires: 25 July 2026 21 January
ISSN: 2070-1721 BSD
May 2026

Resource Public Key Infrastructure (RPKI) Manifest Number Handling
draft-ietf-sidrops-manifest-numbers-09

Abstract

The Resource Public Key Infrastructure (RPKI) makes use of signed
objects called manifests, "manifests", each of which includes a "manifest
number". This document updates RFC9286 RFC 9286 by specifying issuer and RP
Relying Party (RP) behaviour when a manifest number reaches the
largest possible value, a situation not considered in RFC9286. RFC 9286.

Status of This Memo

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provisions of BCP 78 and BCP 79.

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Internet-Drafts are draft documents valid the IETF community. It has
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Internet Standards is available in Section 2 of RFC 7841.

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This Internet-Draft will expire on 25 July 2026.
https://www.rfc-editor.org/info/rfc9981.

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Table of Contents

1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Requirements Language . . . . . . . . . . . . . . . . . . 3
2. Manifest Number Handling . . . . . . . . . . . . . . . . . . 4
3. Manifest Filenames . . . . . . . . . . . . . . . . . . . . . 4
4. Manifest SIA Verification . . . . . . . . . . . . . . . . . . 5
5. RFC8488 Comparison . . . . . . . . . . . . . . . . . . . . . 5 with RFC 8488
6. General Repository Handling . . . . . . . . . . . . . . . . . 5
7. Operational Considerations . . . . . . . . . . . . . . . . . 5
8. Security Considerations . . . . . . . . . . . . . . . . . . . 6
9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6
10. Implementation status . . . . . . . . . . . . . . . . . . . . 6
10.1. rpki-client . . . . . . . . . . . . . . . . . . . . . . 7
10.2. Routinator . . . . . . . . . . . . . . . . . . . . . . . 7
11. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 7
12. References . . . . . . . . . . . . . . . . . . . . . . . . . 7
12.1.
10.1. Normative References . . . . . . . . . . . . . . . . . . 7
12.2.
10.2. Informative References . . . . . . . . . . . . . . . . . 8
Acknowledgements
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 9

1. Introduction

The Resource Public Key Infrastructure (RPKI) [RFC6480] makes use of
signed objects [RFC6488] called manifests "manifests" [RFC9286]. A manifest
lists each file that an issuer intends to include within an RPKI
repository [RFC6481], and [RFC6481]. Manifests can also be used to detect certain
forms of attack against a repository. Manifests include a "manifest
number" (manifestNumber), which an issuer must increment by one
whenever it issues a new manifest, and Relying Parties (RPs) are
required to verify that a newly-retrieved newly retrieved manifest for a given
Certification Authority (CA) has a higher manifestNumber than the previously-
previously validated manifest (Section 4.2.1 of [RFC9286]).

However, the manifestNumber field is 20 octets in length (i.e.,
bounded), and no behaviour is specified for when a manifestNumber
reaches the largest possible value (2^159-1). When that value is
reached, some RP implementations will accept a new manifest for the
CA only once the current manifest has expired, while others will not
accept a new manifest at all.

While it is practically impossible for an issuer to reach the largest
possible value under normal operating conditions (it would require
that the issuer issue one manifest per second for
23,171,956,451,847,141,650,870 quintillion years), there is still a
chance that it could be reached due to bugs in the issuance or
publication systems or incorrect/inadvertent use of those systems.
For example:

* Incrementing by large values when issuing manifests, such that the
time to reach that largest value is reduced.

* Reissuing new manifests in an infinite delay-free loop, such that
the manifestNumber increases by a large value in a comparatively
short period of time.

* Inadvertently setting the manifestNumber to the largest possible
value, such that the issuer will no longer be able to publish
usable manifests for that repository.

These scenarios might also arise in combination and be more severe as
a result. For example, a CA might increase the manifestNumber by a
large value on reissuance, reissuance and also reissue the manifest more
frequently than is necessary.

For a subordinate CA, the risk of repository invalidation due to such
a problem can be addressed by the issuer using the key rollover
process [RFC6489] to get a new CA certificate. RPs will treat this
new certificate as though it represents a distinct CA, and CA; the
manifestNumber can be reset at that point.

However, this option is not available for RPKI Trust Anchors (TAs).
If a TA publishes a manifest with the largest-possible manifestNumber
value, then it is difficult to rely on the TA after that point, since
(as described previously) some RPs will not accept a new manifest
until the current one has expired, while others will reject all new
manifests indefinitely. Particularly in the case of TAs, the
manifest validity period may be quite long, too. Issuing a new TA
and distributing the associated Trust Anchor Locator (TAL) [RFC8630]
to clients would involve a large amount of work for TA operators and
RPs. Additionally, depending on the RP implementation being used,
there would be a limited degree of RPKI protection by way of that TA
for the time between the issuance of the problematic manifest and the
installation of the new TAL.

In order to avoid these problems, this document updates [RFC9286] by
defining how issuers and RPs can handle this scenario in order to
facilitate ongoing use of an affected repository.

1.1. 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.

2. Manifest Number Handling

For a given CA, an RP MUST NOT reject a new manifest issued by that
CA on the basis of it not having a higher manifestNumber than a
previously-validated
previously validated manifest if the new manifest has a different
filename from that of the previously-validated previously validated manifest. In other
words, an RP has to reset its stored manifestNumber for a given CA if
the CA changes the filename of its manifest. This is an update to
the requirements set out in Section 4.2.1 of [RFC9286].

With this behaviour, it is possible for a CA to be configured such
that
that, any time it issues a new manifest, it uses a new filename for
that manifest. If a CA were configured in this way, the
manifestNumber validation set out in Section 4.2.1 of [RFC9286] would
have no purpose. To avoid this outcome, CAs SHOULD NOT use new
filenames for manifests except in situations where such a change is
necessary to address the invalidity problem described in this
document. Similarly, an RP MUST alert its operators when a manifest
filename changes for a given CA.

[RFC9286] requires that RPs perform two replay-related checks on
newly-retrieved
newly retrieved manifests: firstly,

1. Check that the purported new manifest has a greater
manifestNumber than the cached manifest, and secondly,

2. Check that the purported new manifest has a more recent
thisUpdate than the cached manifest.

An RP that implements the behaviour in this section will momentarily
omit the manifestNumber check following a manifest filename change.
So long as the RP still performs the second check described above, it
will be protected against replay attacks.

3. Manifest Filenames

A CA specifies its manifest URI by way of an SIA a Subject Information
Access (SIA) entry with an accessMethod of id-ad-rpkiManifest
(Section 4.8.8.1 of [RFC6487]). For the purposes of this document,
the manifest filename is the final segment of the path of the
accessLocation URI from that SIA entry.

Section 4.8.8.1 of [RFC6487] states that a CA may include in its
certificate multiple id-ad-rpkiManifest SIA entries. For
comparisons, an RP may use the filename from any one of the id-ad-
rpkiManifest SIA entries in the previously-validated previously validated CA certificate.
If that filename does not appear in any of the id-ad-rpkiManifest SIA
entries in the CA certificate that is currently being validated, then
the manifest filename has changed for the purposes of this document.

The corollary of the behaviour defined in the previous paragraph is
that a CA that includes multiple id-ad-rpkiManifest SIA entries in
its certificate and wants to rely on the behaviour defined in this
document MUST ensure that none of the manifest filenames in the
previous CA certificate appear in the newly-issued newly issued CA certificate.
If one of the manifest filenames from the previous CA certificate
appears in the newly-issued newly issued CA certificate, then an RP that is using
that manifest filename for comparisons will determine that the
manifest filename for the CA has not changed, changed and will therefore not
reset its stored manifestNumber for the CA.

4. Manifest SIA Verification

To avoid certain forms of replay attack, RPs MUST verify that the URI
in the accessLocation in one of the id-ad-signedObject accessMethod
instances in the manifest's Subject Information Access (SIA) SIA extension exactly matches the URI
presented in the RPKI Repository Delta Protocol (RRDP) [RFC8182]
"publish" element or the path presented by remote rsync servers. If
this verification check is unsuccessful, then the fetch has failed,
and the RP MUST proceed per Section 6.6 of [RFC9286].

5. RFC8488 Comparison with RFC 8488

Section 3.2.1 of [RFC8488] describes a manifest selection manifest-selection approach
for RPs that involves collecting all unexpired, unexpired valid manifests for a
CA,
CA and then selecting from that collection the manifest that has the
highest manifestNumber. The approach set out in this document is
different from that approach.

6. General Repository Handling

Section 2 contains a specific update to [RFC9286] for the handling of
manifest numbers, in order to address one potential permanent
invalidity scenario. RPs that encounter other permanent invalidity
scenarios should also consider how those can be addressed such that
the scenario does not require the relevant CA or TA to perform a key
rollover operation. For example, in the event that an RP recognises
that a permanent invalidity scenario has occurred, the RP could alert
the operator and provide an option to the operator to stop relying on
cached data for the affected repository, repository so that the CA can rectify
the problem.

7. Operational Considerations

CA software may opt to support the manifest number reset
functionality in various ways. For example, it could change the
manifest filename when the manifestNumber reaches a certain
threshold, or it could alert the operator in this scenario and
request confirmation that the filename should be changed.

8. Security Considerations

The RPKI primarily exists to support and improve security of the
global Internet routing system. Reliability improvements to the RPKI
itself, such as outlined in this document, strengthen its
dependability (see Section 8 of [RFC6480]).

See Section 2, Paragraph 3 regarding the effect of skipping the
manifestNumber check with respect to replay attacks. To protect
against replay attacks in the absence of this check, RPs should
ensure that they are verifying the thisUpdate value per the
requirements of [RFC9286].

Section 4 describes an additional protection against certain forms of
replay attack.

Although this document updates [RFC9286], the security considerations
from [RFC9286] remain relevant.

9. IANA Considerations

This document has no actions for IANA. IANA actions.

10. Implementation status

This section is to be removed before publishing as an RFC.

This section records the status of known implementations of the
protocol defined by this specification at the time of posting of this
Internet-Draft, and is based on a proposal described in [RFC7942].
The description of implementations in this section is intended to
assist the IETF in its decision processes in progressing drafts to
RFCs. Please note that the listing of any individual implementation
here does not imply endorsement by the IETF. Furthermore, no effort
has been spent to verify the information presented here that was
supplied by IETF contributors. This is not intended as, and must not
be construed to be, a catalog of available implementations or their
features. Readers are advised to note that other implementations may
exist.

According to [RFC7942], "this will allow reviewers and working groups
to assign due consideration to documents that have the benefit of
running code, which may serve as evidence of valuable experimentation
and feedback that have made the implemented protocols more mature.
It is up to the individual working groups to use this information as
they see fit".

10.1. rpki-client

* Responsible Organization: OpenBSD
* Location: https://www.rpki-client.org
* Description: This implementation supports the behaviour described
in this document.
* Level of Maturity: This is a production implementation.
* Coverage: This implementation includes all of the features
described in this specification.
* Contact Information: Job Snijders, job@sobornost.net

10.2. Routinator

* Responsible Organization: NLNetLabs
* Location: https://github.com/NLnetLabs/routinator
* Description: This implementation supports the behaviour described
in this document.
* Level of Maturity: This is a production implementation.
* Coverage: This implementation supports the manifest number
handling changes described in this specification.
* Contact Information: NLNetLabs, labs@nlnetlabs.nl

11. Acknowledgements

The authors would like to thank Theo Buehler, Ben Maddison, Rob
Austein, Tim Bruijnzeels, Russ Housley, Mohamed Boucadair, Luigi
Iannone, Daniele Ceccarelli, Darren Dukes, Ines Robles, Barry Leiba,
Éric Vyncke, Gorry Fairhurst, Andy Newton, Roman Danyliw, Mike
Bishop, and Deb Cooley for their review and feedback on this
document.

12. References

12.1.

10.1. 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>.

[RFC6487] Huston, G., Michaelson, G., and R. Loomans, "A Profile for
X.509 PKIX Resource Certificates", RFC 6487,
DOI 10.17487/RFC6487, February 2012,
<https://www.rfc-editor.org/info/rfc6487>.

[RFC6488] Lepinski, M., Chi, A., and S. Kent, "Signed Object
Template for the Resource Public Key Infrastructure
(RPKI)", RFC 6488, DOI 10.17487/RFC6488, February 2012,
<https://www.rfc-editor.org/info/rfc6488>.

[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>.

[RFC8182] Bruijnzeels, T., Muravskiy, O., Weber, B., and R. Austein,
"The RPKI Repository Delta Protocol (RRDP)", RFC 8182,
DOI 10.17487/RFC8182, July 2017,
<https://www.rfc-editor.org/info/rfc8182>.

[RFC9286] Austein, R., Huston, G., Kent, S., and M. Lepinski,
"Manifests for the Resource Public Key Infrastructure
(RPKI)", RFC 9286, DOI 10.17487/RFC9286, June 2022,
<https://www.rfc-editor.org/info/rfc9286>.

12.2.

10.2. Informative References

[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>.

[RFC6481] Huston, G., Loomans, R., and G. Michaelson, "A Profile for
Resource Certificate Repository Structure", RFC 6481,
DOI 10.17487/RFC6481, February 2012,
<https://www.rfc-editor.org/info/rfc6481>.

[RFC6489] Huston, G., Michaelson, G., and S. Kent, "Certification
Authority (CA) Key Rollover in the Resource Public Key
Infrastructure (RPKI)", BCP 174, RFC 6489,
DOI 10.17487/RFC6489, February 2012,
<https://www.rfc-editor.org/info/rfc6489>.

[RFC7942] Sheffer, Y. and A. Farrel, "Improving Awareness of Running
Code: The Implementation Status Section", BCP 205,
RFC 7942, DOI 10.17487/RFC7942, July 2016,
<https://www.rfc-editor.org/info/rfc7942>.

[RFC8488] Muravskiy, O. and T. Bruijnzeels, "RIPE NCC's
Implementation of Resource Public Key Infrastructure
(RPKI) Certificate Tree Validation", RFC 8488,
DOI 10.17487/RFC8488, December 2018,
<https://www.rfc-editor.org/info/rfc8488>.

[RFC8630] Huston, G., Weiler, S., Michaelson, G., Kent, S., and T.
Bruijnzeels, "Resource Public Key Infrastructure (RPKI)
Trust Anchor Locator", RFC 8630, DOI 10.17487/RFC8630,
August 2019, <https://www.rfc-editor.org/info/rfc8630>.

Acknowledgements

The authors would like to thank Theo Buehler, Ben Maddison, Rob
Austein, Tim Bruijnzeels, Russ Housley, Mohamed Boucadair, Luigi
Iannone, Daniele Ceccarelli, Darren Dukes, Maria Ines Robles, Barry
Leiba, Éric Vyncke, Gorry Fairhurst, Andy Newton, Roman Danyliw, Mike
Bishop, and Deb Cooley for their review and feedback on this
document.

Authors' Addresses

Tom Harrison
Asia Pacific Network Information Centre
6 Cordelia St
South Brisbane QLD 4101
Australia
Email: tomh@apnic.net

George G. Michaelson
Asia-Pacific Network Information Centre
6 Cordelia St
South Brisbane QLD 4101
Australia
Email: ggm@apnic.net

Job Snijders
BSD Software Development
Amsterdam
The Netherlands
Email: job@sobornost.net job@bsd.nl
URI: https://www.bsd.nl