RFC8181: A Publication Protocol for the Resource Public Key Infrastructure (RPKI)
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Internet Engineering Task Force (IETF) S. Weiler
Request for Comments: 8181 W3C / MIT
Category: Standards Track A. Sonalker
ISSN: 2070-1721 STEER Tech
R. Austein
Dragon Research Labs
July 2017
A Publication Protocol for the Resource Public Key Infrastructure (RPKI)
Abstract
This document defines a protocol for publishing Resource Public Key
Infrastructure (RPKI) objects. Even though the RPKI will have many
participants issuing certificates and creating other objects, it is
operationally useful to consolidate the publication of those objects.
Even in cases where a certificate issuer runs its own publication
repository, it can be useful to run the certificate engine itself on
a different machine from the publication repository. This document
defines a protocol which addresses these needs.
Status of This Memo
This is an Internet Standards Track document.
This document is a product of the Internet Engineering Task Force
(IETF). It represents the consensus of the IETF community. It has
received public review and has been approved for 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 this document, any errata,
and how to provide feedback on it may be obtained at
http://www.rfc-editor.org/info/rfc8181.
Weiler, et al. Standards Track [Page 1]
RFC 8181 RPKI Publication Protocol July 2017
Copyright Notice
Copyright (c) 2017 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Historical Note . . . . . . . . . . . . . . . . . . . . . 4
1.2. Terminology . . . . . . . . . . . . . . . . . . . . . . . 5
2. Protocol Specification . . . . . . . . . . . . . . . . . . . 5
2.1. Common XML Message Format . . . . . . . . . . . . . . . . 6
2.2. Publication and Withdrawal . . . . . . . . . . . . . . . 7
2.3. Listing the Repository . . . . . . . . . . . . . . . . . 8
2.4. Error Handling . . . . . . . . . . . . . . . . . . . . . 8
2.5. Error Codes . . . . . . . . . . . . . . . . . . . . . . . 9
2.6. XML Schema . . . . . . . . . . . . . . . . . . . . . . . 10
3. Examples . . . . . . . . . . . . . . . . . . . . . . . . . . 12
3.1. <publish/> Query, No Existing Object . . . . . . . . . . 12
3.2. <publish/> Query, Overwriting Existing Object . . . . . . 12
3.3. <withdraw/> Query . . . . . . . . . . . . . . . . . . . . 13
3.4. <success/> Reply . . . . . . . . . . . . . . . . . . . . 13
3.5. <report_error/> with Optional Elements . . . . . . . . . 13
3.6. <report_error/> without Optional Elements . . . . . . . . 14
3.7. Error Handling with Multi-Element Queries . . . . . . . . 14
3.7.1. Multi-Element Query . . . . . . . . . . . . . . . . . 14
3.7.2. Successful Multi-Element Response . . . . . . . . . . 15
3.7.3. Failure Multi-Element Response, First Error Only . . 15
3.7.4. Failure Multi-Element Response, All Errors . . . . . 16
3.8. <list/> Query . . . . . . . . . . . . . . . . . . . . . . 16
3.9. <list/> Reply . . . . . . . . . . . . . . . . . . . . . . 17
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 17
5. Security Considerations . . . . . . . . . . . . . . . . . . . 18
6. References . . . . . . . . . . . . . . . . . . . . . . . . . 19
6.1. Normative References . . . . . . . . . . . . . . . . . . 19
6.2. Informative References . . . . . . . . . . . . . . . . . 20
Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . 21
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 21
Weiler, et al. Standards Track [Page 2]
RFC 8181 RPKI Publication Protocol July 2017
1. Introduction
This document assumes a working knowledge of the Resource Public Key
Infrastructure (RPKI), which is intended to support improved routing
security on the Internet. See [RFC6480] for an overview of the RPKI.
In order to make participation in the RPKI easier, it is helpful to
have a few consolidated repositories for RPKI objects, thus saving
every participant from the cost of maintaining a new service.
Similarly, relying parties using the RPKI objects will find it faster
and more reliable to retrieve the necessary set from a smaller number
of repositories.
These consolidated RPKI object repositories will in many cases be
outside the administrative scope of the organization issuing a given
RPKI object. In some cases, outsourcing operation of the repository
will be an explicit goal: some resource holders who strongly wish to
control their own RPKI private keys may lack the resources to operate
a 24x7 repository or may simply not wish to do so.
The operator of an RPKI publication repository may well be an
Internet registry which issues certificates to its customers, but it
need not be; conceptually, operation of an RPKI publication
repository is separate from operation of an RPKI Certification
Authority (CA).
Even in cases where a resource holder operates both a certificate
engine and a publication repository, it can be useful to separate the
two functions, as they have somewhat different operational and
security requirements.
This document defines an RPKI publication protocol which allows
publication either within or across organizational boundaries and
which makes fairly minimal demands on both the CA engine and the
publication service.
The authentication and message integrity architecture of the
publication protocol is essentially identical to the architecture
used in [RFC6492] because the participants in this protocol are the
same CA engines as in RFC 6492; this allows reuse of the same
"Business PKI" (BPKI) (see Section 1.2) infrastructure used to
support RFC 6492. As in RFC 6492, authorization is a matter of
external configuration: we assume that any given publication
repository has some kind of policy controlling which certificate
engines are allowed to publish, modify, or withdraw particular RPKI
objects, most likely following the recommendation in [RFC6480],
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RFC 8181 RPKI Publication Protocol July 2017
Section 4.4; the details of this policy are a private matter between
the operator of a certificate engine and the operator of the chosen
publication repository.
The following diagram attempts to convey where this publication
protocol fits into the overall data flow between the certificate
issuers and relying parties:
+------+ +------+ +------+
| CA | | CA | | CA |
+------+ +------+ +------+
| | | Publication protocol
| | | business relationship
+-------+ | +--------+ perhaps set up by
| | | RFC 8183
+----v---v--v-----+
| |
| Publication |
| Repository |
| |
+-----------------+ Distribution protocols
| rsync or RRDP
+--------------+----------------+
| | |
+-------v-----+ +------v------+ +------v------+
| Relying | | Relying | | Relying |
| Party | | Party | | Party |
+-------------+ +-------------+ +-------------+
The publication protocol itself is not visible to relying parties: a
relying party sees the public interface of the publication server,
which is an rsync or RPKI Repository Delta Protocol (RRDP) [RFC8182]
server.
Operators of certificate engines and publication repositories may
find [RFC8183] a useful tool in setting up the pairwise relationships
between these servers, but they are not required to use it.
1.1. Historical Note
This protocol started out as an informal collaboration between
several of the early RPKI implementers, and while it was always the
designers' intention that the resulting protocol end up on the IETF
Standards Track, it took a few years to get there because
standardization of other pieces of the overall RPKI protocol space
was more urgent. The Standards Track version of this publication
Weiler, et al. Standards Track [Page 4]
RFC 8181 RPKI Publication Protocol July 2017
protocol preserves the original XML namespace and protocol version
scheme in order to maintain backwards compatibility with running code
implemented against older versions of the specification.
1.2. Terminology
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.
"Publication engine" and "publication server" are used
interchangeably to refer to the server providing the service
described in this document.
"Business Public Key Infrastructure" ("Business PKI" or "BPKI")
refers to a PKI, separate from the RPKI, used to authenticate clients
to the publication engine. We use the term "Business PKI" here
because an Internet registry might already have a PKI for
authenticating its clients and might wish to reuse that PKI for this
protocol. There is, however, no requirement to reuse such a PKI.
2. Protocol Specification
The publication protocol uses XML [XML] messages wrapped in signed
Cryptographic Message Syntax (CMS) messages, carried over HTTP
transport [RFC7230]. The CMS encapsulation is identical to that used
in Section 3.1 (and subsections) of RFC 6492 [RFC6492].
The publication protocol uses a simple request/response interaction.
The client passes a request to the server, and the server generates a
corresponding response.
A message exchange commences with the client initiating an HTTP POST
with a content type of "application/rpki-publication", with the
message object as the body. The server's response will similarly be
the body of the response with a content type of "application/
rpki-publication".
The content of the POST and the server's response will be a well-
formed CMS [RFC5652] object with OID = 1.2.840.113549.1.7.2 as
described in Section 3.1 of [RFC6492].
The CMS signatures are used to protect the integrity of the protocol
messages and to authenticate the client and server to each other.
Authorization to perform particular operations is a local matter,
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RFC 8181 RPKI Publication Protocol July 2017
perhaps determined by contractual agreements between the operators of
any particular client-server pair, but in any case is beyond the
scope of this specification.
2.1. Common XML Message Format
The XML schema for this protocol is below in Section 2.6. The basic
XML message format looks like this:
<msg
type="query"
version="4"
xmlns="http://www.hactrn.net/uris/rpki/publication-spec/">
<!-- Zero or more PDUs -->
</msg>
<msg
type="reply"
version="4"
xmlns="http://www.hactrn.net/uris/rpki/publication-spec/">
<!-- Zero or more PDUs -->
</msg>
As noted above, the outermost XML element is encapsulated in a signed
CMS message. Query messages are signed by the client, and reply
messages are signed by the server.
Common attributes:
version: The value of this attribute is the version of this
protocol. This document describes version 4.
type: The possible values of this attribute are "reply" and "query".
A query PDU may be one of three types: <publish/>, <withdraw/>, or
<list/>.
A reply PDU may be one of three types: <success/>, <list/>, or
<report_error/>.
The <publish/> and <withdraw/> PDUs include a "tag" attribute to
facilitate bulk operation. When performing bulk operations, a CA
engine will probably find it useful to specify a distinct tag value
for each <publish/> or <withdraw/> PDU, to simplify matching an error
with the PDU which triggered it. The tag attribute is mandatory, to
simplify parsing, but a CA engine which has no particular use for
tagging MAY use any syntactically legal value, including simply using
the empty string for all tag fields.
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This document describes version 4 of this protocol. An
implementation which understands only this version of the protocol
MUST reject messages with a different protocol version attribute,
signaling the error as described in Section 2.4. Since "4" is
currently the only value allowed for the version attribute in the
schema (Section 2.6), an incorrect protocol version can be detected
either by checking the version attribute directly or as a schema
validation error. Any future update to this protocol which is either
syntactically or semantically incompatible with the current version
will need to increment the protocol version number.
2.2. Publication and Withdrawal
The publication protocol uses a common message format to request
publication of any RPKI object. This format was chosen specifically
to allow this protocol to accommodate new types of RPKI objects
without needing changes to this protocol.
Both the <publish/> and <withdraw/> PDUs have a payload of a tag and
an rsync URI [RFC3986] [RFC5781]. The <publish/> query also contains
the DER object to be published, encoded in Base64 ([RFC4648],
Section 4, with line breaks within the Base64 text permitted but not
required).
Both the <publish/> and <withdraw/> PDUs also have a "hash"
attribute, which carries a hash of an existing object at the
specified repository URI, encoded as a hexadecimal string. For
<withdraw/> PDUs, the hash MUST be present, as this operation makes
no sense if there is no existing object to withdraw. For <publish/>
PDUs, the hash MUST be present if the publication operation is
overwriting an existing object, and it MUST NOT be present if this
publication operation is writing to a new URI where no prior object
exists. Presence of an object when no "hash" attribute has been
specified is an error, as is absence of an object or an incorrect
hash value when a "hash" attribute has been specified. Any such
errors MUST be reported using the <report_error/> PDU.
The hash algorithm is SHA-256 [SHS], to simplify comparison of
publication protocol hashes with RPKI manifest hashes.
The intent behind the "hash" attribute is to allow the client and
server to detect any disagreements about the effect that a <publish/>
or <withdraw/> PDU will have on the repository.
Note that every publish and withdraw action requires a new manifest,
thus every publish or withdraw action will involve at least two
objects.
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Processing of a query message is handled atomically: either the
entire query succeeds or none of it does. When a query message
contains multiple PDUs, failure of any PDU may require the server to
roll back actions triggered by earlier PDUs.
When a query message containing <publish/> or <withdraw/> PDUs
succeeds, the server returns a single <success/> reply.
When a query fails, the server returns one or more <report_error/>
reply PDUs. Typically, a server will only generate one
<report_error/> corresponding to the first query PDU that failed, but
servers MAY return multiple <report_error/> PDUs at the implementer's
discretion.
2.3. Listing the Repository
The <list/> operation allows the client to ask the server for a
complete listing of objects which the server believes the client has
published. This is intended primarily to allow the client to recover
upon detecting (probably via use of the "hash" attribute; see
Section 2.2) that they have somehow lost synchronization.
The <list/> query consists of a single PDU. A <list/> query MUST be
the only PDU in a query -- it may not be combined with any <publish/>
or <withdraw/> queries.
The <list/> reply consists of zero or more PDUs, one per object
published in this repository by this client, each PDU conveying the
URI and hash of one published object.
2.4. Error Handling
Errors are handled at two levels.
Errors that make it impossible to decode a query or encode a response
are handled at the HTTP layer. 4xx and 5xx HTTP response codes
indicate that something bad happened.
In all other cases, errors result in an XML <report_error/> PDU.
Like the rest of this protocol, <report_error/> PDUs are CMS-signed
XML messages and thus can be archived to provide an audit trail.
<report_error/> PDUs only appear in replies, never in queries.
The "tag" attribute of the <report_error/> PDU associated with a
<publish/> or <withdraw/> PDU MUST be set to the same value as the
"tag" attribute in the PDU which generated the error. A client can
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RFC 8181 RPKI Publication Protocol July 2017
use the "tag" attribute to determine which PDU caused processing of
an update to fail.
The error itself is conveyed in the "error_code" attribute. The
value of this attribute is a token indicating the specific error that
occurred.
The body of the <report_error/> element contains two sub-elements:
1. An optional text element <error_text/>, which, if present,
contains a text string with debugging information intended for
human consumption.
2. An optional element <failed_pdu/>, which, if present, contains a
verbatim copy of the query PDU whose failure triggered the
<report_error/> PDU. The quoted element must be syntactically
valid.
See Section 3.7 for examples of a multi-element query and responses.
2.5. Error Codes
These are the defined error codes as well as some discussion of each.
Text similar to these descriptions may be sent in an <error_text/>
element to help explain the error encountered.
xml_error: Encountered an XML problem. Note that some XML errors
may be severe enough to require error reporting at the HTTP layer,
instead. Implementations MAY choose to report any or all XML
errors at the HTTP layer.
permission_failure: Client does not have permission to update this
URI.
bad_cms_signature: Bad CMS signature.
object_already_present: An object is already present at this URI,
yet a "hash" attribute was not specified. A "hash" attribute must
be specified when overwriting or deleting an object. Perhaps
client and server are out of sync?
no_object_present: There is no object present at this URI, yet a
"hash" attribute was specified. Perhaps client and server are out
of sync?
no_object_matching_hash: The "hash" attribute supplied does not
match the "hash" attribute of the object at this URI. Perhaps
client and server are out of sync?
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RFC 8181 RPKI Publication Protocol July 2017
consistency_problem: Server detected an update that looks like it
will cause a consistency problem (e.g., an object was deleted, but
the manifest was not updated). Note that a server is not required
to make such checks. Indeed, it may be unwise for a server to do
so. This error code just provides a way for the server to explain
its (in-)action.
other_error: A meteor fell on the server.
2.6. XML Schema
The following is a [RELAX-NG] compact form schema describing the
publication protocol.
This schema is normative: in the event of a disagreement between this
schema and the document text above, this schema is authoritative.
# RELAX NG schema for RPKI publication protocol.
default namespace =
"http://www.hactrn.net/uris/rpki/publication-spec/"
# This is version 4 of the protocol.
version = "4"
# Top-level PDU is either a query or a reply.
start |= element msg {
attribute version { version },
attribute type { "query" },
query_elt
}
start |= element msg {
attribute version { version },
attribute type { "reply" },
reply_elt
}
# Tag attributes for bulk operations.
tag = attribute tag { xsd:token { maxLength="1024" } }
# Base64-encoded DER stuff.
base64 = xsd:base64Binary
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RFC 8181 RPKI Publication Protocol July 2017
# Publication URIs.
uri = attribute uri { xsd:anyURI { maxLength="4096" } }
# Digest of an existing object (hexadecimal).
hash = attribute hash { xsd:string { pattern = "[0-9a-fA-F]+" } }
# Error codes.
error |= "xml_error"
error |= "permission_failure"
error |= "bad_cms_signature"
error |= "object_already_present"
error |= "no_object_present"
error |= "no_object_matching_hash"
error |= "consistency_problem"
error |= "other_error"
# <publish/> and <withdraw/> query elements
query_elt |= (
element publish { tag, uri, hash?, base64 } |
element withdraw { tag, uri, hash }
)*
# <success/> reply
reply_elt |= element success { empty }
# <list/> query and reply
query_elt |= element list { empty }
reply_elt |= element list { uri, hash }*
# <report_error/> reply
reply_elt |= element report_error {
tag?,
attribute error_code { error },
element error_text { xsd:string { maxLength="512000" }}?,
element failed_pdu { query_elt }?
}*
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RFC 8181 RPKI Publication Protocol July 2017
3. Examples
Following are examples of various queries and the corresponding
replies for the RPKI publication protocol.
Note that the authors have taken liberties with the Base64, hash, and
URI text in these examples in the interest of making the examples fit
nicely into RFC text format. Similarly, these examples do not show
the CMS signature wrapper around the XML, just the XML payload.
3.1. <publish/> Query, No Existing Object
<msg
type="query"
version="4"
xmlns="http://www.hactrn.net/uris/rpki/publication-spec/">
<!-- body is base64(new-object) -->
<publish
tag=""
uri="rsync://wombat.example/Alice/01a97a70ac477f06.cer">
SGVsbG8sIG15IG5hbWUgaXMgQWxpY2U=
</publish>
</msg>
3.2. <publish/> Query, Overwriting Existing Object
<msg
type="query"
version="4"
xmlns="http://www.hactrn.net/uris/rpki/publication-spec/">
<!-- hash is hex(SHA-256(old-object)) -->
<!-- body is base64(new-object) -->
<publish
hash="01a97a70ac477f06"
tag="foo"
uri="rsync://wombat.example/Alice/01a97a70ac477f06.cer">
SGVsbG8sIG15IG5hbWUgaXMgQWxpY2U=
</publish>
</msg>
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RFC 8181 RPKI Publication Protocol July 2017
3.3. <withdraw/> Query
<msg
type="query"
version="4"
xmlns="http://www.hactrn.net/uris/rpki/publication-spec/">
<!-- hash is hex(SHA-256(old-object)) -->
<withdraw
hash="01a97a70ac477f06"
tag="foo"
uri="rsync://wombat.example/Alice/01a97a70ac477f06.cer"/>
</msg>
3.4. <success/> Reply
<msg
type="reply"
version="4"
xmlns="http://www.hactrn.net/uris/rpki/publication-spec/">
<success/>
</msg>
3.5. <report_error/> with Optional Elements
<msg
type="reply"
version="4"
xmlns="http://www.hactrn.net/uris/rpki/publication-spec/">
<report_error
error_code="no_object_matching_hash"
tag="foo">
<error_text>
Can't delete an object I don't have
</error_text>
<failed_pdu>
<publish
hash="01a97a70ac477f06"
tag="foo"
uri="rsync://wombat.example/Alice/01a97a70ac477f06.cer">
SGVsbG8sIG15IG5hbWUgaXMgQWxpY2U=
</publish>
</failed_pdu>
</report_error>
</msg>
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RFC 8181 RPKI Publication Protocol July 2017
3.6. <report_error/> without Optional Elements
<msg
type="reply"
version="4"
xmlns="http://www.hactrn.net/uris/rpki/publication-spec/">
<report_error
error_code="object_already_present"
tag="foo"/>
</msg>
3.7. Error Handling with Multi-Element Queries
3.7.1. Multi-Element Query
<msg
type="query"
version="4"
xmlns="http://www.hactrn.net/uris/rpki/publication-spec/">
<publish
tag="Alice"
uri="rsync://wombat.example/Alice/01a97a70ac477f06.cer">
SGVsbG8sIG15IG5hbWUgaXMgQWxpY2U=
</publish>
<withdraw
hash="f46a4198efa3070e"
tag="Bob"
uri="rsync://wombat.example/Bob/f46a4198efa3070e.cer"/>
<publish
tag="Carol"
uri="rsync://wombat.example/Carol/32e0544eeb510ec0.cer">
SGVsbG8sIG15IG5hbWUgaXMgQ2Fyb2w=
</publish>
<withdraw
hash="421ee4ac65732d72"
tag="Dave"
uri="rsync://wombat.example/Dave/421ee4ac65732d72.cer"/>
<publish
tag="Eve"
uri="rsync://wombat.example/Eve/9dd859b01e5c2ebd.cer">
SGVsbG8sIG15IG5hbWUgaXMgRXZl
</publish>
</msg>
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RFC 8181 RPKI Publication Protocol July 2017
3.7.2. Successful Multi-Element Response
<msg
type="reply"
version="4"
xmlns="http://www.hactrn.net/uris/rpki/publication-spec/">
<success/>
</msg>
3.7.3. Failure Multi-Element Response, First Error Only
<msg
type="reply"
version="4"
xmlns="http://www.hactrn.net/uris/rpki/publication-spec/">
<report_error
error_code="no_object_matching_hash"
tag="Dave">
<failed_pdu>
<withdraw
hash="421ee4ac65732d72"
tag="Dave"
uri="rsync://wombat.example/Dave/421ee4ac65732d72.cer"/>
</failed_pdu>
</report_error>
</msg>
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RFC 8181 RPKI Publication Protocol July 2017
3.7.4. Failure Multi-Element Response, All Errors
<msg
type="reply"
version="4"
xmlns="http://www.hactrn.net/uris/rpki/publication-spec/">
<report_error
error_code="no_object_matching_hash"
tag="Dave">
<failed_pdu>
<withdraw
hash="421ee4ac65732d72"
tag="Dave"
uri="rsync://wombat.example/Dave/421ee4ac65732d72.cer"/>
</failed_pdu>
</report_error>
<report_error
error_code="object_already_present"
tag="Eve">
<failed_pdu>
<publish
tag="Eve"
uri="rsync://wombat.example/Eve/9dd859b01e5c2ebd.cer">
SGVsbG8sIG15IG5hbWUgaXMgRXZl
</publish>
</failed_pdu>
</report_error>
</msg>
3.8. <list/> Query
<msg
type="query"
version="4"
xmlns="http://www.hactrn.net/uris/rpki/publication-spec/">
<list/>
</msg>
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3.9. <list/> Reply
<msg
type="reply"
version="4"
xmlns="http://www.hactrn.net/uris/rpki/publication-spec/">
<list
hash="eb719b72f0648cf4"
uri="rsync://wombat.example/Fee/eb719b72f0648cf4.cer"/>
<list
hash="c7c50a68b7aa50bf"
uri="rsync://wombat.example/Fie/c7c50a68b7aa50bf.cer"/>
<list
hash="f222481ded47445d"
uri="rsync://wombat.example/Foe/f222481ded47445d.cer"/>
<list
hash="15b94e08713275bc"
uri="rsync://wombat.example/Fum/15b94e08713275bc.cer"/>
</msg>
4. IANA Considerations
IANA has registered the "application/rpki-publication" media type as
follows:
Type name: application
Subtype name: rpki-publication
Required parameters: None
Optional parameters: None
Encoding considerations: binary
Security considerations: Carries an RPKI publication protocol
message, as defined in RFC 8181.
Interoperability considerations: None
Published specification: RFC 8181
Applications which use this media type: HTTP
Additional information:
Magic number(s): None
File extension(s): None
Macintosh File Type Code(s): None
Person & email address to contact for further information:
Rob Austein <sra@hactrn.net>
Intended usage: COMMON
Author/Change controller: IETF
Weiler, et al. Standards Track [Page 17]
RFC 8181 RPKI Publication Protocol July 2017
5. Security Considerations
The RPKI publication protocol and the data it publishes use entirely
separate PKIs for authentication. The published data is
authenticated within the RPKI, and this protocol has nothing to do
with that authentication, nor does it require that the published
objects be valid in the RPKI. The publication protocol uses a
separate BPKI to authenticate its messages.
Each RPKI publication protocol message is wrapped in a signed CMS
message, which provides message integrity protection and an auditable
form of message authentication. Because of these protections at the
application layer, and because all the data being published are
intended to be public information in any case, this protocol does
not, strictly speaking, require the use of HTTPS or other transport
security mechanisms. There may, however, be circumstances in which a
particular publication operator may prefer HTTPS over HTTP anyway, as
a matter of (BPKI) CA policy. Use of HTTP versus HTTPS here is,
essentially, a private matter between the repository operator and its
clients. Note, however, that even if a client/server pair uses HTTPS
for this protocol, message authentication for this protocol is still
based on the CMS signatures, not HTTPS.
Although the hashes used in the <publish/> and <withdraw/> PDUs are
cryptographically strong, the digest algorithm was selected for
convenience in comparing these hashes with the hashes that appear in
RPKI manifests. The hashes used in the <publish/> and <withdraw/>
PDUs are not particularly security sensitive because these PDUs are
protected by the CMS signatures. Because of this, the most likely
reason for a change to this digest algorithm would be to track a
corresponding change in the digest algorithm used in RPKI manifests.
If and when such a change happens, it will require incrementing the
version number of this publication protocol, but given that the most
likely implementation of a publication server uses these hashes as
lookup keys in a database, bumping the protocol version number would
be a relatively minor portion of the effort of changing the
algorithm.
Compromise of a publication server, perhaps through mismanagement of
BPKI private keys, could lead to a denial-of-service attack on the
RPKI. An attacker gaining access to BPKI private keys could use this
protocol to delete (withdraw) RPKI objects, leading to routing
changes or failures. Accordingly, as in most PKIs, good key
management practices are important.
Weiler, et al. Standards Track [Page 18]
RFC 8181 RPKI Publication Protocol July 2017
6. References
6.1. Normative References
[RELAX-NG] Clark, J., "RELAX NG Compact Syntax", OASIS Committee
Specification, November 2002,
<https://www.oasis-open.org/committees/relax-ng/
compact-20021121.html>.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<http://www.rfc-editor.org/info/rfc2119>.
[RFC3986] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform
Resource Identifier (URI): Generic Syntax", STD 66,
RFC 3986, DOI 10.17487/RFC3986, January 2005,
<http://www.rfc-editor.org/info/rfc3986>.
[RFC4648] Josefsson, S., "The Base16, Base32, and Base64 Data
Encodings", RFC 4648, DOI 10.17487/RFC4648, October 2006,
<http://www.rfc-editor.org/info/rfc4648>.
[RFC5652] Housley, R., "Cryptographic Message Syntax (CMS)", STD 70,
RFC 5652, DOI 10.17487/RFC5652, September 2009,
<http://www.rfc-editor.org/info/rfc5652>.
[RFC5781] Weiler, S., Ward, D., and R. Housley, "The rsync URI
Scheme", RFC 5781, DOI 10.17487/RFC5781, February 2010,
<http://www.rfc-editor.org/info/rfc5781>.
[RFC6492] Huston, G., Loomans, R., Ellacott, B., and R. Austein, "A
Protocol for Provisioning Resource Certificates",
RFC 6492, DOI 10.17487/RFC6492, February 2012,
<http://www.rfc-editor.org/info/rfc6492>.
[RFC7230] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer
Protocol (HTTP/1.1): Message Syntax and Routing",
RFC 7230, DOI 10.17487/RFC7230, June 2014,
<http://www.rfc-editor.org/info/rfc7230>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <http://www.rfc-editor.org/info/rfc8174>.
Weiler, et al. Standards Track [Page 19]
RFC 8181 RPKI Publication Protocol July 2017
[SHS] National Institute of Standards and Technology, "Secure
Hash Standard (SHS)", FIPS PUB 180-4,
DOI 10.6028/NIST.FIPS.180-4, August 2015,
<http://nvlpubs.nist.gov/nistpubs/FIPS/
NIST.FIPS.180-4.pdf>.
[XML] Cowan, J., "Extensible Markup Language (XML) 1.1", W3C
Consortium Recommendation REC-xml11-20060816, October
2002, <http://www.w3.org/TR/2002/CR-xml11-20021015>.
6.2. Informative References
[RFC6480] Lepinski, M. and S. Kent, "An Infrastructure to Support
Secure Internet Routing", RFC 6480, DOI 10.17487/RFC6480,
February 2012, <http://www.rfc-editor.org/info/rfc6480>.
[RFC8182] Bruijnzeels, T., Muravskiy, O., Weber, B., and R. Austein,
"The RPKI Repository Delta Protocol (RRDP)", RFC 8182,
DOI 10.17487/RFC8182, July 2017,
<http://www.rfc-editor.org/info/rfc8182>.
[RFC8183] Austein, R., "An Out-of-Band Setup Protocol for Resource
Public Key Infrastructure (RPKI) Production Services",
RFC 8183, DOI 10.17487/RFC8183, July 2017,
<http://www.rfc-editor.org/info/rfc8183>.
Weiler, et al. Standards Track [Page 20]
RFC 8181 RPKI Publication Protocol July 2017
Acknowledgements
The authors would like to thank: Geoff Huston, George Michaelson,
Oleg Muravskiy, Paul Wouters, Randy Bush, Rob Loomans, Robert
Kisteleki, Tim Bruijnzeels, Tom Petch, and anybody else who helped
along the way but whose name(s) the authors have temporarily
forgotten.
Authors' Addresses
Samuel Weiler
W3C / MIT
Email: weiler@csail.mit.edu
Anuja Sonalker
STEER Tech
Email: anuja@steer-tech.com
Rob Austein
Dragon Research Labs
Email: sra@hactrn.net
Weiler, et al. Standards Track [Page 21]