Internet Engineering Task Force (IETF) M. Lepinski

Internet Engineering Task Force (IETF) M. Lepinski
Request for Comments: 6482 S. Kent
Category: Standards Track D. Kong
ISSN: 2070-1721 BBN Technologies
February 2012

A Profile for Route Origin Authorizations (ROAs)

Abstract

This document defines a standard profile for Route Origin
Authorizations (ROAs). A ROA is a digitally signed object that
provides a means of verifying that an IP address block holder has
authorized an Autonomous System (AS) to originate routes to one or
more prefixes within the address block.

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 5741.

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/rfc6482.

Copyright Notice

Copyright (c) 2012 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.

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RFC 6482 Route Origin Authorization February 2012

Table of Contents

1. Introduction ....................................................2
1.1. Terminology ................................................3
2. The ROA Content-Type ............................................3
3. The ROA eContent ................................................3
3.1. version ....................................................4
3.2. asID .......................................................4
3.3. ipAddrBlocks ...............................................4
4. ROA Validation ..................................................5
5. Security Considerations .........................................5
6. Acknowledgments .................................................6
7. References ......................................................6
7.1. Normative References .......................................6
7.2. Informative References .....................................6
Appendix A: ASN.1 Module..........................................8

1. Introduction

The primary purpose of the Resource Public Key Infrastructure (RPKI)
is to improve routing security. (See [RFC6480] for more
information.) As part of this system, a mechanism is needed to allow
entities to verify that an AS has been given permission by an IP
address block holder to advertise routes to one or more prefixes
within that block. A ROA provides this function.

The ROA makes use of the template for RPKI digitally signed objects
[RFC6488], which defines a Crytopgraphic Message Syntax (CMS)
[RFC5652] wrapper for the ROA content as well as a generic validation
procedure for RPKI signed objects. Therefore, to complete the
specification of the ROA (see Section 4 of [RFC6488]), this document
defines:

1. The OID that identifies the signed object as being a ROA.
(This OID appears within the eContentType in the
encapContentInfo object as well as the content-type signed
attribute in the signerInfo object).

2. The ASN.1 syntax for the ROA eContent. (This is the payload
that specifies the AS being authorized to originate routes as
well as the prefixes to which the AS may originate routes.)
The ROA eContent is ASN.1 encoded using the Distinguished
Encoding Rules (DER) [X.690].

3. An additional step required to validate ROAs (in addition to
the validation steps specified in [RFC6488]).

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RFC 6482 Route Origin Authorization February 2012

1.1. Terminology

It is assumed that the reader is familiar with the terms and concepts
described in "Internet X.509 Public Key Infrastructure Certificate
and Certificate Revocation List (CRL) Profile" [RFC5280] and "X.509
Extensions for IP Addresses and AS Identifiers" [RFC3779].

Additionally, this document makes use of the RPKI signed object
profile [RFC6488]; thus, familiarity with that document is assumed.
Note that the RPKI signed object profile makes use of certificates
adhering to the RPKI Resource Certificate Profile [RFC6487]; thus,
familiarly with that profile is also assumed.

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 RFC
2119 [RFC2119].

2. The ROA Content-Type

The content-type for a ROA is defined as routeOriginAuthz and has the
numerical value of 1.2.840.113549.1.9.16.1.24.

This OID MUST appear both within the eContentType in the
encapContentInfo object as well as the content-type signed attribute
in the signerInfo object (see [RFC6488]).

3. The ROA eContent

The content of a ROA identifies a single AS that has been authorized
by the address space holder to originate routes and a list of one or
more IP address prefixes that will be advertised. If the address
space holder needs to authorize multiple ASes to advertise the same
set of address prefixes, the holder issues multiple ROAs, one per AS
number. A ROA is formally defined as:

RouteOriginAttestation ::= SEQUENCE {
version [0] INTEGER DEFAULT 0,
asID ASID,
ipAddrBlocks SEQUENCE (SIZE(1..MAX)) OF ROAIPAddressFamily }

ASID ::= INTEGER

ROAIPAddressFamily ::= SEQUENCE {
addressFamily OCTET STRING (SIZE (2..3)),
addresses SEQUENCE (SIZE (1..MAX)) OF ROAIPAddress }

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RFC 6482 Route Origin Authorization February 2012

ROAIPAddress ::= SEQUENCE {
address IPAddress,
maxLength INTEGER OPTIONAL }

IPAddress ::= BIT STRING

Note that this content appears as the eContent within the
encapContentInfo (see [RFC6488]).

3.1. version

The version number of the RouteOriginAttestation MUST be 0.

3.2. asID

The asID field contains the AS number that is authorized to originate
routes to the given IP address prefixes.

3.3. ipAddrBlocks

The ipAddrBlocks field encodes the set of IP address prefixes to
which the AS is authorized to originate routes. Note that the syntax
here is more restrictive than that used in the IP address delegation
extension defined in RFC 3779. That extension can represent
arbitrary address ranges, whereas ROAs need to represent only
prefixes.

Within the ROAIPAddressFamily structure, addressFamily contains the
Address Family Identifier (AFI) of an IP address family. This
specification only supports IPv4 and IPv6. Therefore, addressFamily
MUST be either 0001 or 0002.

Within a ROAIPAddress structure, the addresses field represents
prefixes as a sequence of type IPAddress. (See [RFC3779] for more
details). If present, the maxLength MUST be an integer greater than
or equal to the length of the accompanying prefix, and less than or
equal to the length (in bits) of an IP address in the address family
(32 for IPv4 and 128 for IPv6). When present, the maxLength
specifies the maximum length of the IP address prefix that the AS is
authorized to advertise. (For example, if the IP address prefix is
203.0.113/24 and the maxLength is 26, the AS is authorized to
advertise any more specific prefix with a maximum length of 26. In
this example, the AS would be authorized to advertise 203.0.113/24,
203.0.113.128/25, or 203.0.113.0/25, but not 203.0.113.0/27.) When
the maxLength is not present, the AS is only authorized to advertise
the exact prefix specified in the ROA.

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RFC 6482 Route Origin Authorization February 2012

Note that a valid ROA may contain an IP address prefix (within a
ROAIPAddress element) that is encompassed by another IP address
prefix (within a separate ROAIPAddress element). For example, a ROA
may contain the prefix 203.0.113/24 with maxLength 26, as well as the
prefix 203.0.113.0/28 with maxLength 28. (Such a ROA would authorize
the indicated AS to advertise any prefix beginning with 203.0.113
with a minimum length of 24 and a maximum length of 26, as well as
the specific prefix 203.0.113.0/28.) Additionally, a ROA MAY contain
two ROAIPAddress elements, where the IP address prefix is identical
in both cases. However, this is NOT RECOMMENDED as, in such a case,
the ROAIPAddress with the shorter maxLength grants no additional
privileges to the indicated AS and thus can be omitted without
changing the meaning of the ROA.

4. ROA Validation

Before a relying party can use a ROA to validate a routing
announcement, the relying party MUST first validate the ROA. To
validate a ROA, the relying party MUST perform all the validation
checks specified in [RFC6488] as well as the following additional
ROA-specific validation step.

o The IP address delegation extension [RFC3779] is present in the
end-entity (EE) certificate (contained within the ROA), and each
IP address prefix(es) in the ROA is contained within the set of IP
addresses specified by the EE certificate's IP address delegation
extension.

5. Security Considerations

There is no assumption of confidentiality for the data in a ROA; it
is anticipated that ROAs will be stored in repositories that are
accessible to all ISPs, and perhaps to all Internet users. There is
no explicit authentication associated with a ROA, since the PKI used
for ROA validation provides authorization but not authentication.
Although the ROA is a signed, application-layer object, there is no
intent to convey non-repudiation via a ROA.

The purpose of a ROA is to convey authorization for an AS to
originate a route to the prefix(es) in the ROA. Thus, the integrity
of a ROA MUST be established. The ROA specification makes use of the
RPKI signed object format; thus, all security considerations in
[RFC6488] also apply to ROAs. Additionally, the signed object
profile uses the CMS signed message format for integrity; thus, ROAs
inherit all security considerations associated with that data
structure.

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RFC 6482 Route Origin Authorization February 2012

The right of the ROA signer to authorize the target AS to originate
routes to the prefix(es) is established through use of the address
space and AS number PKI described in [RFC6480]. Specifically, one
MUST verify the signature on the ROA using an X.509 certificate
issued under this PKI, and check that the prefix(es) in the ROA match
those in the certificate's address space extension.

6. IANA Considerations

IANA has registered the following RPKI Signed Object:

ROA 1.2.840.113549.1.9.16.1.24 [RFC6482]

7. Acknowledgments

The authors wish to thank Charles Gardiner and Russ Housley for their
help and contributions. Additionally, the authors would like to
thank Rob Austein, Roque Gagliano, Danny McPherson, and Sam Weiler
for their careful reviews and helpful comments.

8. References

8.1. Normative References

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

[RFC5652] Housley, R., "Cryptographic Message Syntax (CMS)", STD 70,
RFC 5652, September 2009.

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

[RFC5280] Cooper, D., Santesson, S., Farrell, S., Boeyen, S.,
Housley, R., and W. Polk, "Internet X.509 Public Key
Infrastructure Certificate and Certificate Revocation List
(CRL) Profile", RFC 5280, May 2008.

[RFC6487] Huston, G., Michaelson, G., and R. Loomans, "A Profile for
X.509 PKIX Resource Certificates", RFC 6487, February 2012.

[RFC6488] Lepinski, M., Chi, A., and S. Kent, "Signed Object Template
for the Resource Public Key Infrastructure (RPKI)", RFC
6488, February 2012.

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RFC 6482 Route Origin Authorization February 2012

[X.690] ITU-T Recommendation X.690 (2002) | ISO/IEC 8825-1:2002,
Information technology - ASN.1 encoding rules:
Specification of Basic Encoding Rules (BER), Canonical
Encoding Rules (CER) and Distinguished Encoding Rules
(DER).

8.2. Informative References

[RFC6480] Lepinski, M. and S. Kent, "An Infrastructure to Support
Secure Internet Routing", RFC 6480, February 2012.

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RFC 6482 Route Origin Authorization February 2012

Appendix A: ASN.1 Module

This normative appendix provides an ASN.1 module that specifies the
ROA content in ASN.1 syntax.

RPKI-ROA { iso(1) member-body(2) us(840) rsadsi(113549)
pkcs(1) pkcs9(9) smime(16) mod(0) 61 }

DEFINITIONS EXPLICIT TAGS ::= BEGIN

RouteOriginAttestation ::= SEQUENCE {
version [0] INTEGER DEFAULT 0,
asID ASID,
ipAddrBlocks SEQUENCE (SIZE(1..MAX)) OF ROAIPAddressFamily }

ASID ::= INTEGER

ROAIPAddressFamily ::= SEQUENCE {
addressFamily OCTET STRING (SIZE (2..3)),
addresses SEQUENCE (SIZE (1..MAX)) OF ROAIPAddress }

ROAIPAddress ::= SEQUENCE {
address IPAddress,
maxLength INTEGER OPTIONAL }

IPAddress ::= BIT STRING

END

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RFC 6482 Route Origin Authorization February 2012

Authors' Addresses

Matt Lepinski
BBN Technologies
10 Moulton Street
Cambridge MA 02138
EMail: [email protected]

Stephen Kent
BBN Technologies
10 Moulton Street
Cambridge MA 02138
EMail: [email protected]

Derrick Kong
BBN Technologies
10 Moulton Street
Cambridge MA 02138
EMail: [email protected]

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