Network Working Group
Internet Engineering Task Force (IETF) C. Martinez
Internet-Draft
Request for Comments: 9691 LACNIC
Intended status:
Category: Standards Track G. Michaelson
Expires: 17 November 2024
ISSN: 2070-1721 T. Harrison
APNIC
T. Bruijnzeels
RIPE NCC
R. Austein
Dragon Research Labs
16 May
November 2024
RPKI
Resource Public Key Infrastructure (RPKI) Signed Object Objects for Trust
Anchor Key
draft-ietf-sidrops-signed-tal-16 Keys (TAKs)
Abstract
A Trust Anchor Locator (TAL) is used by Relying Parties (RPs) in the
Resource Public Key Infrastructure (RPKI) to locate and validate a
Trust Anchor (TA) Certification Authority (CA) certificate certificates used in
RPKI validation. This document defines an RPKI signed object for a
Trust Anchor Key (TAK), (TAK) that can be used by a TA to signal the
location(s) of the accompanying CA certificate for the current public
key to RPs, as well as the successor public key and the location(s)
of its CA certificate. This object helps to support planned key
rollovers without impacting RPKI validation.
Status of This Memo
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provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents an Internet Standards Track document.
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(IETF). Note that other groups may also distribute
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Internet-Drafts are draft documents valid the IETF community. It has
received public review and has been approved for a maximum publication by the
Internet Engineering Steering Group (IESG). Further information on
Internet Standards is available in Section 2 of RFC 7841.
Information about the current status of six months this document, any errata,
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material or to cite them other than as "work in progress."
This Internet-Draft will expire on 17 November 2024.
https://www.rfc-editor.org/info/rfc9691.
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Table of Contents
1. Overview
1.1. Requirements Notation . . . . . . . . . . . . . . . . . . . . 3
2. Overview . . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. TAK Object Definition . . . . . . . . . . . . . . . . . . . . 4
3.1.
2.1. The TAK Object Content Type . . . . . . . . . . . . . . . 4
3.2.
2.2. The TAK Object eContent . . . . . . . . . . . . . . . . . 4
3.2.1.
2.2.1. TAKey . . . . . . . . . . . . . . . . . . . . . . . . 5
3.2.2.
2.2.2. TAK . . . . . . . . . . . . . . . . . . . . . . . . . 5
3.3.
2.3. TAK Object Validation . . . . . . . . . . . . . . . . . . 5
4.
3. TAK Object Generation and Publication . . . . . . . . . . . . 6
5.
4. Relying Party Use . . . . . . . . . . . . . . . . . . . . . . 7
5.1.
4.1. Manual update Update of TA public key details . . . . . . . . . 9
6. Public Key Details
5. Maintaining Multiple TA Key Pairs . . . . . . . . . . . . . . 9
7.
6. Performing TA Key Rolls . . . . . . . . . . . . . . . . . . . 11
7.1.
6.1. Phase 1: Add a TAK for Key Pair 'A' . . . . . . . . . . . 11
7.2.
6.2. Phase 2: Add a Key Pair 'B' . . . . . . . . . . . . . . . 11
7.3.
6.3. Phase 3: Update TAL to point to 'B' . . . . . . . . . . . 11
7.4.
6.4. Phase 4: Remove Key Pair 'A' . . . . . . . . . . . . . . 12
8.
7. Using TAK objects Objects to distribute Distribute TAL data . . . . . . . . . . 12
9. Data
8. Deployment Considerations . . . . . . . . . . . . . . . . . . 13
9.1.
8.1. Relying Party Support . . . . . . . . . . . . . . . . . . 13
9.2.
8.2. Alternate Transition Models . . . . . . . . . . . . . . . 13
10.
9. Operational Considerations . . . . . . . . . . . . . . . . . 14
10.1.
9.1. Acceptance Timers . . . . . . . . . . . . . . . . . . . 14
11.
10. Security Considerations . . . . . . . . . . . . . . . . . . . 14
11.1.
10.1. Previous Keys . . . . . . . . . . . . . . . . . . . . . 14
11.2.
10.2. TA Compromise . . . . . . . . . . . . . . . . . . . . . 15
11.3.
10.3. Alternate Transition Models . . . . . . . . . . . . . . 15
12.
11. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 15
12.1.
11.1. Content Type . . . . . . . . . . . . . . . . . . . . . . 16
12.2.
11.2. Signed Object . . . . . . . . . . . . . . . . . . . . . 16
12.3.
11.3. File Extension . . . . . . . . . . . . . . . . . . . . . 16
12.4.
11.4. Module Identifier . . . . . . . . . . . . . . . . . . . 16
12.5.
11.5. Registration of Media Type application/
rpki-signed-tal . . . . . . . . . . . . . . . . . . . . 17
13. Implementation Status . . . . . . . . . . . . . . . . . . . . 18
13.1. APNIC . . . . . . . . . . . . . . . . . . . . . . . . . 18
13.2. rpki-client . . . . . . . . . . . . . . . . . . . . . . 19
13.3. rpki-rs . . . . . . . . . . . . . . . . . . . . . . . . 19
14. Revision History . . . . . . . . . . . . . . . . . . . . . . 19
15. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 20
16. application/rpki-signed-tal
12. References . . . . . . . . . . . . . . . . . . . . . . . . . 20
16.1.
12.1. Normative References . . . . . . . . . . . . . . . . . . 20
16.2.
12.2. Informative References . . . . . . . . . . . . . . . . . 22
Appendix A. ASN.1 Module . . . . . . . . . . . . . . . . . . . . 22
Acknowledgments
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 23
2.
1. Overview
A Trust Anchor Locator (TAL) [RFC8630] is used by Relying Parties
(RPs) in the Resource Public Key Infrastructure (RPKI) to locate and
validate Trust Anchor (TA) Certification Authority (CA) certificates
used in RPKI validation. However, until now, there has been no in-
band way of notifying RPs of updates to a TAL. In-band An in-band
notification means that TA operators can be more confident of RPs
being aware of key rollover operations.
This document defines a new RPKI signed object that can be used to
document the location(s) of the TA CA certificate for the current TA
public key, as well as the value of the successor public key and the
location(s) of its TA CA certificate. This allows RPs to be notified
automatically of such changes, changes and enables TAs to stage a successor
public key so that planned key rollovers can be performed without
risking the invalidation of the RPKI tree under the TA. We call this
object the Trust Anchor Key (TAK) object.
When RPs are first bootstrapped, they use a TAL to discover the
public key and location(s) of the CA certificate for a TA. The RP
can then retrieve and validate the CA certificate, certificate and subsequently
validate the manifest [RFC9286] and Certificate Revocation List (CRL)
published by that TA (section (Section 5 of [RFC6487]). However, before
processing any other objects, it will first validate the TAK object, object
if it is present. If the TAK object lists only the current public
key, then the RP continues processing as it would in the absence of a
TAK object. If the TAK object includes a successor public key, the
RP starts a 30-day acceptance timer for that key, key and then continues
standard top-down validation with the current public key. If, during
the following validation runs up until the expiry of the acceptance
timer, the RP has not observed any changes to the public keys and
certificate URLs listed in the TAK object, then the RP will fetch the
successor public key, update its local state with that public key and
its associated certification location(s), and continue processing
using that public key.
The primary motivation for this work is being able to migrate from a
Hardware Security Module (HSM) produced by one vendor to one produced
by another, where the first vendor does not support exporting private
keys for use by the second. There may be other scenarios in which
key rollover is useful, though.
2.1.
1.1. Requirements Notation
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.
3.
2. TAK Object Definition
The TAK object makes use of the template for RPKI digitally signed
objects [RFC6488], which defines a Cryptographic Message Syntax (CMS)
[RFC5652] wrapper for the content content, as well as a generic validation
procedure for RPKI signed objects. Therefore, to complete the
specification of the TAK object (see Section 4 of [RFC6488]), this
document defines: defines the following:
* The the OID (in Section 3.1) (Section 2.1) that identifies the signed object as being a TAK. (This
TAK (this OID appears within the eContentType in the
encapContentInfo object, as well as the content-type signed
attribute in the signerInfo object.) object)
* The the ASN.1 syntax for the TAK eContent, in Section 3.2. eContent (Section 2.2)
* The the additional steps required to validate a TAK, in Section 3.3.
3.1. TAK (Section 2.3)
2.1. The TAK Object Content Type
This document specifies an OID for the TAK object as follows:
id-ct-signedTAL OBJECT IDENTIFIER ::=
{ iso(1) member-body(2) us(840) rsadsi(113549) pkcs(1) pkcs9(9)
smime(16) ct(1) 50 }
This OID MUST appear in both the eContentType in the encapContentInfo
object and the content-type signed attribute in the signerInfo object
(see [RFC6488]).
3.2.
2.2. The TAK Object eContent
The content of a TAK object is ASN.1 encoded using the Distinguished
Encoding Rules (DER) [X.690], [X.690] and is defined per the module in
Appendix A.
3.2.1.
2.2.1. TAKey
This structure defines a TA public key, key similar to that from
[RFC8630]. It contains a sequence of zero or more comments, one or
more certificate URIs, and a SubjectPublicKeyInfo.
*
comments: This field is semantically equivalent to the comment
section defined in section Section 2.2 of [RFC8630]. Each comment is
human-readable informational UTF-8 text [RFC3629], conforming to
the restrictions defined in Section 2 of [RFC5198]. The leading
"#" character that is used to denote a comment in [RFC8630] is
omitted here.
*
certificateURIs: This field is semantically equivalent to the URI
section defined in section Section 2.2 of [RFC8630]. It MUST contain at
least one CertificateURI element. Each CertificateURI element
contains the IA5String representation of either an rsync URI
[RFC5781],
[RFC5781] or an HTTPS URI [RFC9110].
*
subjectPublicKeyInfo: This field contains a SubjectPublicKeyInfo
(section
(Section 4.1.2.7 of [RFC5280]) in the DER format [X.690].
3.2.2.
2.2.2. TAK
*
version: The version number of the TAK object MUST be 0.
*
current: This field contains the TA public key of the repository in
which the TAK object is published.
*
predecessor: This field contains the TA public key that was in use
for this TA immediately prior to the current TA public key, if
applicable.
*
successor: This field contains the TA public key to be used in place
of the current public key, if applicable, after expiry of the
relevant acceptance timer.
3.3.
2.3. TAK Object Validation
To determine whether a TAK object is valid, the RP MUST perform the
following checks in addition to those specified in [RFC6488]:
* The eContentType OID matches the OID described in Section 3.1. 2.1.
* The TAK object appears as the product of a TA CA certificate (i.e.
(i.e., the TA CA certificate is itself is the issuer of the End-Entity End-
Entity (EE) certificate of the TAK object).
* The TA CA has published only one TAK object in its repository for
this public key, and this object appears on the manifest as the
only entry using the ".tak" extension (see [RFC6481]).
* The EE certificate of this TAK object describes its Internet
Number Resources (INRs) using the "inherit" attribute.
* The decoded TAK content conforms to the format defined in
Section 3.2. 2.2.
* The SubjectPublicKeyInfo value of the current TA public key in the
TAK object matches that of the TA CA certificate used to issue the
EE certificate of the TAK object.
If any of these checks does do not succeed, the RP MUST ignore the TAK
object and proceed as though it were not listed on the manifest.
The RP is not required to compare its current set of certificateURIs
for the current public key with those listed in the TAK object. The
RP MAY alert the user that these sets of certificateURIs do not
match, match
with a view to the user manually updating the set of certificateURIs
in their configuration. The However, the RP MUST NOT automatically
update its configuration to use these certificateURIs in the event of inconsistency, though,
inconsistency because the migration of users to new certificateURIs
should happen by way of the successor public key process.
4.
3. TAK Object Generation and Publication
A non-normative guideline for naming this object is that the filename
chosen for the TAK object 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 in section Section 2.2 of [RFC6481] for
generation of filenames. The filename extension of ".tak" MUST be
used to denote the object as a TAK.
In order to generate a TAK object, the TA MUST perform the following
actions:
* The TA MUST generate a one-time-use EE certificate for the TAK.
* This EE certificate MUST have a unique key pair.
* This EE certificate MUST have a Subject Information Access (SIA)
[RFC6487] extension access description field with an accessMethod
OID value of id-ad-signedObject, where the associated
accessLocation references the publication point of the TAK as an
object URL.
* As described in [RFC6487], the EE certificate used for this object
must include an [RFC3779] extension. However, because the
resource set is irrelevant to this object type, this certificate
MUST describe its Internet Number Resources (INRs) INRs using the "inherit" attribute, attribute rather than
explicitly describing a resource set.
* This EE certificate MUST have a "notBefore" time that matches or
predates the moment that the TAK will be published.
* This EE certificate MUST have a "notAfter" time that reflects the
intended duration for which this TAK will be published. If the EE
certificate for a TAK object is expired, it MUST no longer be
published, but it MAY be replaced by a newly generated TAK object
with equivalent content and an updated "notAfter" time.
* The current TA public key for the TAK MUST match that of the TA CA
certificate under which the TAK was issued.
In distribution contexts that support media types, the "application/
rpki-signed-tal" media type can be used for TAK objects.
5.
4. Relying Party Use
Relying Parties
RPs MUST keep a record of the current public key for each configured
TA, as well as the URI(s) where the CA certificate for this public
key may be retrieved. This record is typically bootstrapped by the
use of a pre-configured (and unsigned) TAL file [RFC8630].
When performing top-down validation, RPs MUST first validate and
process the TAK object for its current known public key, key by performing
the following steps:
* A CA certificate is retrieved and validated from the known URIs as
described in sections Sections 3 and 4 of [RFC8630].
* The manifest and CRL for this certificate are then validated as
described in [RFC6487] and [RFC9286].
* The If the TAK object, if object is present, it is validated as described in
Section 3.3. 2.3.
If the TAK object includes a successor public key, then the RP must
verify the successor public key by doing the following:
* performing perform top-down validation using the successor public key, key in
order to validate the TAK object for the successor TA; TA,
* ensuring ensure that a valid TAK object exists for the successor TA; TA,
* ensuring ensure that the successor TAK object's current public key matches
the initial TAK object's successor public key; key, and
* ensuring ensure that the successor TAK object's predecessor public key
matches the initial TAK object's current public key.
If any of these steps fails, then the successor public key has failed
verification.
If the successor public key passes verification, verification and the RP has not
seen that successor public key on the previous successful validation
run for this TA, then the RP:
* sets an acceptance timer of 30 days for this successor public key
for this TA; TA,
* cancels the existing acceptance timer for this TA (if applicable); applicable),
and
* continues standard top-down validation as described in [RFC6487]
using the current public key.
If the successor public key passes verification, verification and the RP has seen
that successor public key on the previous successful validation run
for this TA:
* if the relevant acceptance timer has not expired, the RP continues
standard top-down validation using the current public key;
* otherwise, the RP updates its current known public key details for
this TA to be those of the successor public key, and then begins
top-down validation again using the successor public key.
If the successor public key does not pass verification, verification or if the TAK
object does not include a successor public key, the RP cancels the
existing acceptance timer for this TA (if applicable).
An RP MUST NOT use a successor public key for top-down validation
outside of the process described above, except for the purpose of
testing that the new public key is working correctly. This allows a
TA to publish a successor public key for a period of time, allowing
RPs to test it, it while still being able to rely on RPs using the
current public key for their production RPKI operations.
A successor public key may have the same SubjectPublicKeyInfo value
as the current public key: key; this will be the case where a TA is
updating the certificateURIs for that public key.
5.1.
4.1. Manual update Update of TA public key details Public Key Details
A Relying Party may opt not to not support the automatic transition of TA
public key data, as defined in the previous section. Section 4. An alternative approach is
for the Relying Party to alert the user when a new successor public
key is seen, seen and also when the relevant acceptance timer has expired. The
user can then manually transition to the new TA public key data.
This process ensures that the benefits of the acceptance timer period
are still realised, as compared with TA public key update based on a
TAL distributed out-of-band out of band by a TA.
6.
5. Maintaining Multiple TA Key Pairs
Although an RP that can process TAK objects will only ever use one
public key for validation (either the current public key, key or the
successor public key, key once the relevant acceptance timer has expired),
an RP that cannot process TAK objects will continue to use the public
key details per its TAL (or equivalent manual configuration)
indefinitely. As a result, even when a TA is using a TAK object in
order to migrate clients to a new public key, the TA may have to
maintain the previous key pair for a period of time alongside the new
key pair in order to ensure continuity of service for older clients.
For each TA key pair that a TA maintains, the signed material for
these key pairs MUST be published under different directories in the
context of the 'id-ad-caRepository' and 'id-ad-rpkiManifest' Subject
Information Access descriptions contained on the CA certificates
[RFC6487]. Publishing objects under the same directory is
potentially confusing for RPs, RPs and could lead to object invalidity in
the event of file name filename collisions.
Also, the CA certificates for each maintained key pair, pair and the
content published for each key pair, pair MUST be equivalent (except for
the TAK object). In other words, for the purposes of RPKI
validation, it MUST NOT make a difference which of the public keys is
used as a starting point.
This means that the IP and Autonomous System (AS) resources contained
on all current CA certificates for the maintained TA key pairs MUST
be the same. Furthermore, for any delegation of IP and AS resources
to a child, child CA, the TA MUST have an equivalent CA certificate
published under each of its key pairs. Any updates in delegations
MUST be reflected under each of its key pairs. A TA SHOULD NOT
publish any other objects besides a CRL, a Manifest, manifest, a single TAK
object, and any number of CA certificates for delegation to child
CAs.
If a TA uses a single remote publication server for its key pairs, pairs per
[RFC8181], then it MUST include all <publish/> and <withdraw/>
Protocol Data Units (PDUs) for the products of each of its key pairs
in a single query, query in order to reduce the risk of RPs seeing
inconsistent data in the TA's RPKI repositories.
If a TA uses multiple publication servers, then the content for
different key pairs will be out of sync at times. The TA SHOULD
ensure that the duration of these moments is limited to the shortest
possible time. Furthermore, the following should be observed:
* In cases where a CA certificate is revoked, revoked or replaced by a
certificate with a reduced set of resources, these changes will
not take effect fully until all the relevant repository
publication points have been updated. Given that TA private key
operations are normally performed infrequently, this is unlikely
to be a problem: problem; if the revocation or shrinking of an issued CA
certificate is staged for days/weeks, then experiencing a delay of
several minutes for the repository publication points to be
updated is relatively insignificant.
* In cases where a CA certificate is replaced by a certificate with
an extended set of resources, the TA MUST inform the receiving CA
only after all of its repository publication points have been
updated. This ensures that the receiving CA will not issue any
products that could be invalid if an RP uses a TA public key just
before the CA certificate was due to be updated.
Finally, note that the publication locations of CA certificates for
delegations to child CAs under each key pair will be different, and
therefore different;
therefore, the Authority Information Access 'id-ad-caIssuers' values
(section
(Section 4.8.7 of [RFC6487]) on certificates issued by the child CAs
may not be as expected when performing top-down validation, depending
on the TA public key that is used. However, these values are not
critical to top-down validation, so RPs performing such validation
MUST NOT reject a certificate simply because this value is not as
expected.
7.
6. Performing TA Key Rolls
In this
This section we describe describes how present-day RPKI TAs that use only one key pair,
pair and that do not use TAK objects, objects can use a TAK object to perform a
planned key rollover.
7.1.
6.1. Phase 1: Add a TAK for Key Pair 'A'
Before adding a successor public key, a TA may want to confirm that
it can maintain a TAK object for its current key pair only. We will
refer to this key pair as key pair 'A' throughout this section.
7.2.
6.2. Phase 2: Add a Key Pair 'B'
The TA can now generate a new key pair, pair called 'B'. The private key
of this key pair MUST now be used to create a new CA certificate for
the associated public key, key and to issue equivalent CA certificates for
delegations to child CAs, CAs as described in Section 6. 5.
At this point, the TA can also construct a new TAL file [RFC8630] for
the public key of key pair 'B', 'B' and test locally test that the validation
outcome for the new public key is equivalent to that of the other
current public key(s).
When the TA is certain that the content for both public keys is
equivalent,
equivalent and wants to initiate the migration from 'A' to 'B', it
issues a new TAK object under key pair 'A', with the public key from
that key pair as the current public key for that object, the public
key from key pair 'B' as the successor public key, and no predecessor
public key. It also issues a TAK object under key pair 'B', with the
public key from that key pair as the current public key for that
object, the public key from key pair 'A' as the predecessor public
key, and no successor public key.
Once this has happened, RP clients will start seeing the new public
key and setting acceptance timers accordingly.
7.3.
6.3. Phase 3: Update TAL to point to 'B'
At about the time that the TA expects clients to start setting the
public key from key pair 'B' as the current public key, the TA must
release a new TAL file for that public key. It SHOULD use a
different set of URIs in the TAL compared to the TAK file, file so that the
TA can learn the proportion of RPs that can successfully validate and
use the updated TAK objects.
To support RPs that do not take account of TAK objects, the TA should
continue operating key pair 'A' for a period of time after the
expected migration of clients to the public key from 'B'. The length
of that period of time is a local policy matter for that TA: TA; for
example, it might operate the key pair until no clients are
attempting to validate using the associated public key, for example.
7.4. key.
6.4. Phase 4: Remove Key Pair 'A'
The TA SHOULD now remove all content from the repository used by key
pair 'A', 'A' and destroy the private key for that key pair. RPs
attempting to rely on a TAL for the public key from key pair 'A' from
this point will not be able to perform RPKI validation for the TA, TA and
will have to update their local state manually, manually by way of a new TAL
file.
8.
7. Using TAK objects Objects to distribute Distribute TAL data Data
Relying Parties must be configured with RPKI Trust Anchor data in
order to function correctly. This Trust Anchor data is typically
distributed in the Trust Anchor Locator (TAL) TAL format defined in RFC
8630. [RFC8630]. A TAK object can
also serve as a format for distribution of this data, though, because
the TAKey data stored in the TAK object contains the same data that
would appear in a TAL for the associated Trust Anchor.
Relying Parties may support conversion of TAK objects into TAL files.
Relying Parties that support conversion MUST validate the TAK object
using the process from section 3.3. Section 2.3. One exception to the standard
validation process in this context is that a Relying Party MAY treat
a TAK object as valid, even though it is associated with a Trust
Anchor that the Relying Party is not currently configured to trust.
If the Relying Party is relying on this exception when converting a
given TAK object, the Relying Party MUST communicate that fact to the
user.
When converting a TAK object, a Relying Party MUST default to
producing a TAL file based on the 'current' TAKey in the TAK object,
though it MAY optionally support producing TAL files based on the
'predecessor' and 'successor' TAKeys.
When converting a TAK object, a Relying Party MUST include in the TAL
file any
comments from the corresponding TAKey. TAKey in the TAL file.
If TAK object validation fails, then the Relying Party MUST NOT
produce a TAL file based on the TAK object.
Users should be aware that TAK objects distributed out-of-band out of band have
similar security properties to TAL files (i.e. (i.e., there is no
authentication). In particular, TAK objects that are not signed by
TAs with which the Relying Party is currently configured should only
be used if the source that distributes them is one the user trusts to
distribute TAL files.
If a Relying Party is not transitioning to new Trust Anchor data
using the automatic process described in section 5 Section 4 or the partially- partially
manual process described in section 5.1, Section 4.1, then the user will have to
rely on an out-of-band mechanism for validating and updating the
Trust Anchor data for the Relying Party. Users in this situation
should take similar care when updating a trust anchor using a TAK
object file as when using a TAL file to update TA data.
9.
8. Deployment Considerations
9.1.
8.1. Relying Party Support
Publishing TAK objects while RPs do not support this standard will
result in those RPs rejecting these objects. It is not expected that
this will result in the invalidation of any other object under a
Trust Anchor.
Some RPs may purposefully not support this mechanism: mechanism; for example,
they may be implemented or configured such that they are unable to
update local current public key data. TA operators should take this
into consideration when planning key rollover. However, these RPs
would ideally still notify their operators of planned key rollovers, rollovers
so that the operator could update the relevant configuration
manually.
9.2.
8.2. Alternate Transition Models
Alternate models of TAL update updates exist and are complementary to this
mechanism. For example, TAs can liaise directly with RP software
developers to include updated and reissued TAL files in new code
releases,
releases and use existing code update mechanisms in the RP community
to distribute the changes.
Additionally, these non-TA channels for distributing TAL data may
themselves rely on monitoring for TAK objects and then updating update the TAL
data in their distributions or packages accordingly. In this way,
TAK objects may be useful even for RPs that don't implement in-
band in-band
support for the protocol.
Non-TA channels for distributing TAL data should ensure, so far as is
possible, that their update mechanisms take account of any changes
that a user has made to their local TA public key configuration. For
example, if a new public key is published for a TA, but the non-TA
channel's mechanism is able to detect that a user had removed the
TA's previous public key from their local TA public key configuration
such that the user no longer relies on it, then the mechanism should
not by default add the new public key to the user's TA public key
configuration.
10. configuration
by default.
9. Operational Considerations
10.1.
9.1. Acceptance Timers
Acceptance timers are used in TAK objects in order to permit RPs to
test that the new public key is working correctly. This in turn In turn, this
means that the TA operator will be able to gain confidence in the
correct functioning of the new public key before RPs are relying on
that in their production RPKI operations. If a successor public key
is not working correctly, a TA may remove that public key from the
current TAK object.
A TA that removes a successor public key from a TAK object SHOULD NOT
add the same successor public key back into the TAK object for that
TA. This is because there may be an RP that has fetched the TAK
object while the successor public key was listed in it, it and has
started an acceptance timer accordingly, accordingly but has not fetched the TAK
object during the period when the successor public key was not listed
in it. If the unchanged successor public key is added back into the
TA, such an RP will transition to using the new TA public key more
quickly than other RPs, which may, in turn, make debugging and
similar more complicated. A simple way of addressing this problem in
a situation where the TA operator doesn't want to reissue the
SubjectPublicKeyInfo content for the successor public key that was
withdrawn is to update the URL set for the successor public key, key since
RPs must take that URL set into account for the purposes of
initiating and cancelling acceptance timers.
11.
10. Security Considerations
11.1.
10.1. Previous Keys
A TA needs to consider the length of time for which it will maintain
previously-current
previously current key pairs and their associated repositories. An
RP that is seeded with old TAL data will run for 30 days using the
previous public key before migrating to the next public key, key due to
the acceptance timer requirements, and this 30-day delay applies to
each new key pair that has been issued since the old TAL data was
initially published. It In these instances, it may be better in these instances for the TA
to send error responses when receiving requests for the old
publication URLs, URLs so that the RP reports an error to its operator and
the operator seeds it with up-to-date TAL data immediately.
Once a TA has decided not to maintain a previously-current previously current key pair
and its associated repository, the TA SHOULD destroy the associated
private key. The TA SHOULD also reuse the TA CA certificate URLs
from the previous TAL data for the next TAL that it generates. These
measures will help to mitigate the risk of an adversary gaining
access to the private key and its associated publication points in
order to send invalid/incorrect invalid or incorrect data to RPs seeded with the TAL
data for the corresponding public key.
11.2.
10.2. TA Compromise
TAK objects do not offer protection against compromise of the current
TA private key or the successor TA private key. TA private key
compromise in general is out of scope for this document.
While it is possible for a malicious actor to use TAK objects to
cause RPs to transition from the current TA public key to a successor
TA public key, such action is predicated on the malicious actor
having compromised the current TA private key in the first place, so place;
thus, TAK objects do not alter the security considerations relevant
to this scenario.
11.3.
10.3. Alternate Transition Models
Section 9.2 8.2 describes other ways in which a TA may transition from
one key pair to another. Transition by way of an in-band process
reliant on TAK objects is not mandatory for TAs or RPs, though the
fact that the TAK objects are verifiable by way of the currently- currently
trusted TA public key is a benefit compared with to existing out-of-band
mechanisms for TA public key distribution.
There will be a period of time where both the current public key and
the successor public key are available for use, and RPs that are
initialised at different points of the transition process, process or from
different out-of-band sources, sources may be using either the current public
key or the successor public key. TAs are required to ensure ensure, so far
as is possible possible, that for the purposes of RPKI validation, it makes there is no difference which public key is used.
12. used
for the purposes of RPKI validation.
11. IANA Considerations
12.1.
11.1. Content Type
IANA is asked to register has registered an object identifier OID for one content type in the "SMI Security
for S/MIME CMS Content Type (1.2.840.113549.1.9.16.1)" registry as
follows:
+=========+=================+=============+
| Decimal | Description | References
--------+--------------------------------+--------------- |
+=========+=================+=============+
| 50 | id-ct-signedTAL | [section 3.1]
* Section 2.1 |
+---------+-----------------+-------------+
Table 1
Description: id-ct-signedTAL
*
OID: 1.2.840.113549.1.9.16.1.50
*
Specification: [section 3.1]
12.2. Section 2.1
11.2. Signed Object
IANA is asked to add has added the following to the "RPKI Signed Objects" registry:
+==================+============================+=============+
| Name | OID | Reference
-----------------+----------------------------+--------------- |
+==================+============================+=============+
| Trust Anchor Key | 1.2.840.113549.1.9.16.1.50 | [section 3.1] Section 2.1 |
+------------------+----------------------------+-------------+
Table 2
IANA is has also asked to add added the following note to the "RPKI Signed Objects"
registry:
| Objects of the types listed in this registry, as well as RPKI
| resource certificates and CRLs, are expected to be validated using
| the RPKI.
12.3.
11.3. File Extension
IANA is asked to add an has added the following item for the Signed TAL file extension
to the "RPKI Repository Name Schemes" registry created by [RFC6481] as follows: [RFC6481]:
+====================+==================+===========+
| Filename Extension | RPKI Object | Reference
--------------------+--------------------------+---------------- |
+====================+==================+===========+
| .tak | Trust Anchor Key | [this document]
12.4. RFC 9691 |
+--------------------+------------------+-----------+
Table 3
11.4. Module Identifier
IANA is asked to register has registered an object identifier OID for one module identifier in the "SMI
Security for S/MIME Module Identifier (1.2.840.113549.1.9.16.0)"
registry as follows:
+=========+================================+============+
| Decimal | Description | References
--------+--------------------------------+--------------- |
+=========+================================+============+
| 74 | RPKISignedTrustAnchorList-2021 | [this document]
* RFC 9691 |
+---------+--------------------------------+------------+
Table 4
Description: RPKISignedTrustAnchorList-2021
*
OID: 1.2.840.113549.1.9.16.0.74
*
Specification: [this document]
12.5. RFC 9691
11.5. Registration of Media Type application/rpki-signed-tal
IANA is asked to register has registered the media type "application/rpki-signed-
tal" "application/rpki-signed-tal" in
the "Media Types" registry as follows:
Type name: application
Subtype name: rpki-signed-tal
Required parameters: N/A
Optional parameters: N/A
Encoding considerations: binary
Security considerations: Carries an RPKI Signed TAL. This media
type contains no active content. See the Security Considerations
section of RFC XXXX 9691 for further information.
Interoperability considerations: N/A
Published specification: RFC XXXX 9691
Applications that use this media type: RPKI operators
Fragment identifier considerations: N/A
Additional information:
Content: This media type is for a signed object, as defined in
RFC 6488, which contains trust anchor key material as defined
in RFC XXXX. 9691.
Magic number(s): N/A
File extension(s): .tak
Macintosh file type code(s): N/A
Person & email address to contact for further information:
iesg@ietf.org
Intended usage: COMMON
Restrictions on usage: N/A
Author: sidrops WG
Change controller: IESG
13. Implementation Status
NOTE: Please remove this section and the reference to RFC 7942 prior
to publication 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 RFC 7942, "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".
13.1. APNIC
* Responsible Organization: Asia-Pacific Network Information Centre
* Location: https://github.com/APNIC-net/rpki-signed-tal-demo
* Description: A proof-of-concept for relying party TAK usage.
* Level of Maturity: This is a proof-of-concept implementation.
* Coverage: This implementation includes all of the features
described in version 16 of this specification, except for writing
TAL files based on TAK data. The repository includes a link to
various test TALs that can be used for testing TAK scenarios, too.
* Contact Information: Tom Harrison, tomh@apnic.net
13.2. rpki-client
* Responsible Organization: Job Snijders, the OpenBSD project
* Location: https://www.rpki-client.org
* Description: A relying party implementation which can validate
TAKs.
* Level of Maturity: Mature. Trust Anchor operators are encouraged
to use rpki-client as part of smoke testing to help ensure high
levels of standards compliance when introducing changes, and use
rpki-client in a continuous monitoring fashion to help maintain
high levels of operational excellence.
* Coverage: This implementation includes all features except TAK
acceptance timers.
* Contact information: Job Snijders, job@fastly.com
13.3. rpki-rs
* Responsible Organization: Tim Bruijnzeels, tim@ripe.net
* Location: https://github.com/NLnetLabs/rpki-rs/tree/signed-tal
* Description: Library support for encoding and decoding TAK
objects.
* Level of Maturity: This is a proof-of-concept implementation.
* Coverage: This implementation includes support for encoding and
decoding TAK objects.
* Contact information: Tim Bruijnzeels, tim@ripe.net
14. Revision History
03 - Last draft under Tim's authorship.
04 - First draft with George's authorship. No substantive revisions.
05 - First draft with Tom's authorship. No substantive revisions.
06 - Rob Kisteleki's critique.
07 - Switch to two-key model.
08 - Keepalive.
09 - Acceptance timers, predecessor keys, no long-lived CRL/MFT.
10 - Using TAK objects for distribution of TAL data.
11 - Manual update guidance, additional security considerations,
identifier updates.
12 - TAK object comments.
13 - Removal of compromise text, extra RP support text, key
destruction text, media type registration, signed object registry
note.
14 - Keepalive.
15 - Additional implementation notes and editorial updates.
16 - Updates from Secdir and IESG reviews.
16.
12. References
16.1.
12.1. 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>.
[RFC3629] Yergeau, F., "UTF-8, a transformation format of ISO
10646", STD 63, RFC 3629, DOI 10.17487/RFC3629, November
2003, <https://www.rfc-editor.org/info/rfc3629>.
[RFC3779] Lynn, C., Kent, S., and K. Seo, "X.509 Extensions for IP
Addresses and AS Identifiers", RFC 3779,
DOI 10.17487/RFC3779, June 2004,
<https://www.rfc-editor.org/info/rfc3779>.
[RFC5198] Klensin, J. and M. Padlipsky, "Unicode Format for Network
Interchange", RFC 5198, DOI 10.17487/RFC5198, March 2008,
<https://www.rfc-editor.org/info/rfc5198>.
[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>.
[RFC5781] Weiler, S., Ward, D., and R. Housley, "The rsync URI
Scheme", RFC 5781, DOI 10.17487/RFC5781, February 2010,
<https://www.rfc-editor.org/info/rfc5781>.
[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>.
[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>.
[RFC8181] Weiler, S., Sonalker, A., and R. Austein, "A Publication
Protocol for the Resource Public Key Infrastructure
(RPKI)", RFC 8181, DOI 10.17487/RFC8181, July 2017,
<https://www.rfc-editor.org/info/rfc8181>.
[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>.
[RFC9110] Fielding, R., Ed., Nottingham, M., Ed., and J. Reschke,
Ed., "HTTP Semantics", STD 97, RFC 9110,
DOI 10.17487/RFC9110, June 2022,
<https://www.rfc-editor.org/info/rfc9110>.
[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>.
[X.690] ITU-T Recommendation X.690 (2002) | ISO/IEC 8825-1:2002, ITU-T, "Information technology - ASN.1 encoding rules:
Specification of Basic Encoding Rules (BER), Canonical
Encoding Rules (CER) and Distinguished Encoding Rules
(DER)", 2002.
16.2. ITU-T Recommendation X.690, ISO/IEC 8825-1:2002,
2002, <https://www.itu.int/rec/T-REC-X.690-200207-S/en>.
12.2. Informative References
[RFC5652] Housley, R., "Cryptographic Message Syntax (CMS)", STD 70,
RFC 5652, DOI 10.17487/RFC5652, September 2009,
<https://www.rfc-editor.org/info/rfc5652>.
[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>.
Appendix A. ASN.1 Module
This appendix includes the ASN.1 module for the TAK object.
<CODE BEGINS>
RPKISignedTrustAnchorList-2021
{ iso(1) member-body(2) us(840) rsadsi(113549) pkcs(1)
pkcs9(9) smime(16) mod(0) 74 }
DEFINITIONS EXPLICIT TAGS ::=
BEGIN
IMPORTS
CONTENT-TYPE
FROM CryptographicMessageSyntax-2009 -- in [RFC5911]
{ iso(1) member-body(2) us(840) rsadsi(113549) pkcs(1)
pkcs-9(9) smime(16) modules(0) id-mod-cms-2004-02(41) }
SubjectPublicKeyInfo
FROM PKIX1Explicit-2009 -- in [RFC5912]
{ iso(1) identified-organization(3) dod(6) internet(1)
security(5) mechanisms(5) pkix(7) id-mod(0)
id-mod-pkix1-explicit-02(51) } ;
ct-signedTAL CONTENT-TYPE ::=
{ TYPE TAK IDENTIFIED BY
id-ct-signedTAL }
id-ct-signedTAL OBJECT IDENTIFIER ::= { iso(1) member-body(2)
us(840) rsadsi(113549) pkcs(1) pkcs9(9) smime(16) ct(1) 50 }
CertificateURI ::= IA5String
TAKey ::= SEQUENCE {
comments SEQUENCE SIZE (0..MAX) OF UTF8String,
certificateURIs SEQUENCE SIZE (1..MAX) OF CertificateURI,
subjectPublicKeyInfo SubjectPublicKeyInfo
}
TAK ::= SEQUENCE {
version INTEGER DEFAULT 0,
current TAKey,
predecessor [0] TAKey OPTIONAL,
successor [1] TAKey OPTIONAL
}
END
<CODE ENDS>
Acknowledgments
The authors wish to thank Martin Hoffmann for a thorough review of
the document, Russ Housley for multiple reviews of the ASN.1
definitions and for providing a new module for the TAK object, Job
Snijders for the extensive suggestions around TAK object structure/
distribution and rpki-client implementation work, and Ties de Kock
for text/suggestions around TAK/TAL distribution and general security
considerations.
Authors' Addresses
Carlos Martinez
LACNIC
Rambla Mexico 6125
11400 Montevideo
Uruguay
Email: carlos@lacnic.net
URI: https://www.lacnic.net/
George G. Michaelson
Asia Pacific Network Information Centre
6 Cordelia St
South Brisbane QLD 4101
Australia
Email: ggm@apnic.net
Tom Harrison
Asia Pacific Network Information Centre
6 Cordelia St
South Brisbane QLD 4101
Australia
Email: tomh@apnic.net
Tim Bruijnzeels
RIPE NCC
Stationsplein 11
Amsterdam
The Netherlands
Email: tim@ripe.net
URI: https://www.ripe.net/
Rob Austein
Dragon Research Labs
Email: sra@hactrn.net