Internet DRAFT - draft-weis-sobgp-certificates
draft-weis-sobgp-certificates
Network Working Group B. Weis, Editor
Internet-Draft Cisco Systems
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February, 2006
Secure Origin BGP (soBGP) Certificates
draft-weis-sobgp-certificates-04.txt
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Copyright Notice
Copyright (C) The Internet Society (2006).
Abstract
This document describes the format of digital certificates that are
used by the Secure Origin BGP (soBGP) extensions to BGP, as well as
acceptable use of those certificates. Included are certificates
providing authentication, authorization, and policy distribution.
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Table of Contents
1.0 Introduction......................................................3
1.1 Key Words.......................................................3
1.2 Terminology.....................................................3
2.0 Overview..........................................................4
2.1 soBGP Certificate Certificates Overview.........................5
3.0 Authentication Certificate (Entitycert)...........................8
3.1 Format..........................................................8
3.2 Creation........................................................9
3.3 Distribution...................................................11
3.4 Validation.....................................................11
3.5 Revocation and Expiration......................................14
4.0 Authorization and Policy Certificates............................14
4.1 Authorization Certificates (Authcert)..........................15
4.2 Prefix Policy Certificates (PrefixPolicycert)..................18
4.3 AS Policy Certificates (ASPolicycert)..........................21
4.4 Common Processing..............................................24
5.0 Authorization and Policy Certificate Attributes..................24
5.1 Certificate Header (HDR).......................................24
5.2 The Originating Autonomous System (ORIG-AS)....................25
5.3 Authorized Autonomous System (AUTH-AS).........................25
5.4 The Serial Number (SN).........................................25
5.5 Originating AS Entitycert URL (ORIG-EC-URL)....................26
5.6 Originating AS ASPolicycert URL (ORIG-AP-URL)..................26
5.7 The Address Prefix (PREFIX)....................................27
5.8 Signature (SIG)................................................28
5.9 Authorization Certificate (AUTHCERT)...........................29
5.10 Prefix Policies (P-POLICY)....................................29
5.11 Attached Transit Autonomous Systems (TRANSIT).................31
5.12 Attached Non-transit Autonomous Systems (NON-TRANSIT).........31
5.13 Revoked Entity Certificate List (EC-CRL)......................32
5.14 Authorization Certificate Validity List (AC-VALID)............33
5.15 Prefix Policy Certificate Validity List (PPC-VALID)...........34
6.0 Security Considerations..........................................35
6.1 Entitycerts....................................................35
6.2 Authcerts......................................................35
6.3 PrefixPolicycerts..............................................36
6.4 ASPolicycerts..................................................36
6.5 Entitycert Uniform Resource Locators...........................36
7.0 IANA Considerations..............................................37
7.1 soBGP Certificate Attribute Values.............................37
7.2 Signature Type.................................................37
7.3 Policies Type..................................................37
7.4 Validity Ranges................................................38
8.0 Acknowledgments..................................................38
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9.0 References.......................................................38
9.1 Normative References...........................................38
Appendix A. Example Certificates.....................................40
A.1. Entitycert....................................................40
A.2. Authcert......................................................43
Editor's Address.....................................................44
Intellectual Property Statement......................................45
Copyright Statement..................................................45
1.0 Introduction
There is a great deal of concern over the security of routing systems
within the Internet. This is particularly true in relation to the
Border Gateway Protocol [BGP], the protocol used to provide routing
information between Autonomous Systems (ASes). Secure Origin BGP
(soBGP) provides a method that ASes can use to determine the
correctness of BGP messages received by their BGP routers. It also
provides a method for ASes to detect implausible routes reported in a
BGP Update AS_PATH, and acts as an aid in detecting misconfigured
routers advertising incorrect routes.
Secure Origin BGP does not define changes to BGP Updates. Rather, it
provides authorization and path policy "out-of-band" from the BGP
Updates. An AS compares the information claimed in BGP Updates to the
soBGP policy, and makes judgments to the fitness of the claim.
Secure Origin BGP distributes authorization and policy as digitally
signed objects, which can be distributed in many ways. To aid
interoperability, extensions have been defined in [SOBGP-BGP] that
support distribution of the digitally signed soBGP objects within BGP
itself.
The Secure Origin BGP architecture is discussed in [SOBGP-ARCH]. That
document describes the operation of soBGP, and various deployment
models. Extensions to RADIUS to support soBGP in some of those
deployment models are defined in [SOBGP-RADIUS].
This document defines the format of the digitally signed objects used
by soBGP, as well as the operations to be performed on those objects.
Furthermore, a trust model under which the soBGP digitally signed
objects can be arranged is described.
1.1 Key Words
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL
NOT","SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in
this document are to be interpreted as described in [RFC2119].
1.2 Terminology
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This document frequently uses the following terms:
AS Policy Certificate (ASPolicycert)
A digital certificate that asserts routing policy for an
Autonomous System.
Authorization Certificates (Authcerts)
A digital certificate that asserts that an Autonomous System is
authorized to advertise a particular prefix.
Entity
Institutional participants within soBGP. These include Regional
Internet Registry (RIR) authorities, Local Internet Registry
(LIR) authorities, Internet Service Providers (ISPs), Certificate
Authorities (CAs), and other organizations participating in
soBGP. Most Entities participate in the routing system. An soBGP
Entity must have an Autonomous System (AS) number assigned to it
as a unique identity, even if it does not source routes within
the routing system.
Entity Certificate (Entitycert)
An X.509 certificate that asserts a mapping between an Autonomous
System identifier and a public key.
Prefix Policy Certificate (Prefixpolicycert)
A digital certificate mapping usage policy to one or more
prefixes.
Regional Internet Registry (RIR)
An entity recognized by IANA and tasked with managing IP address
space within a wide geographical area. RIRs allocate address
space to Local Internet Registries and other entities.
Local Internet Registry (LIR)
An entity that allocates address space to the users of the
network services that it provides.
2.0 Overview
Secure Origin BGP (soBGP) uses digital certificates as a means of
attesting authentication, authorization, and policy for entities in
the routing system. All soBGP digital certificates contain an
identity of the entity to which the certificate applies, a set of
attributes, identification of the certificate issuer, and a digital
signature created by the issuer.
Depending on the purpose of the digital certificate, the identity to
which the certificate applies may or may not be the issuer of the
certificate. For example, some digital certificates provide a means
for one entity to attest authorization of some resource to another
entity. In this case, the attesting entity will issue the
certificate. In other cases, an entity attests some policy about
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itself, and so issues the certificate itself. The detailed
descriptions of each soBGP certificates below define which case
applies to each certificate type.
Digital certificates involving entities from different
administrative domains are organized into a trust structure called a
Public Key Infrastructure (PKI). A PKI can be organized in a number
of ways: hierarchical, distributed, bridged, or in a "web of trust".
The soBGP certificates in this memo can be deployed in any of these
trust structures. However, one likely trust model is described more
fully below.
2.1 soBGP Certificate Certificates Overview
Secure Origin BGP refers to participants within the routing system
as entities. Entities may have one or more roles within soBGP. They
may act as a trusted signer of digital certificate, an authorizer of
address blocks, and/or as a route originator.
Each entity must have an Autonomous System (AS) number, issued from
an authorized entity (e.g., Regional Internet Registry), to
participate in soBGP. The AS number is the primary method of
identification with soBGP. All entities are known by their AS
number, even those that may not ordinarily advertise routes (e.g., a
Certificate Authority).
Each soBGP entity has an Entity Certificate (Entitycert). An
Entitycert provides an attestation that a particular cryptographic
public key can be used to verify signatures from the subject AS
identified in the Entitycert. In other words, the Entitycert
distributes the public key of an AS. The public key will be used by
other entities to verify that other soBGP certificates claiming to
be signed by the AS are genuine. Entitycerts are X.509 certificates
as specified by [RFC3280].
Secure Origin BGP provides a method of verifying that an AS is
authorized to advertise certain prefixes. The authorization to
advertise prefixes or a given address space is validated through
Authorization Certificates (Authcerts). Authcerts are digitally
signed objects issued by entities (e.g., ISPs) that provide proof of
prefix allocation.
An AS given an Authcert (e.g., an ISP customer) may assign local
policy to be used with the prefixes listed in the Authcert. The AS
does this by issuing another type of digitally signed object, called
a Prefix Policy Certificate (PrefixPolicycert).
Policies specific to an Autonomous System are provided through AS
Policy Certificates (ASPolicycerts). This policy enables another
entity to develop a graph of plausible paths through the routing
system, and aids in detecting impossible and fraudulent paths. It
also provides a means for the AS to distribute Certificate
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Revocation Lists for Entitycerts that it has signed, and Validation
Lists that describe which authorization and policy certificates are
valid for the AS.
Authcerts, PrefixPolicycerts, and ASPolicycerts are verified using
public keys embedded in Entitycerts. The receiver of a certificate
uses the issuing AS number to identify the appropriate Entitycert.
Figure 1 illustrates the relationship between soBGP certificates
associated with a single AS (AS 2). An arrow in this figure
indicates a signature operation. The public key contained in the
certificate at the tail of the arrow is used to verify the validity
of the certificate at the head of the arrow.
+------------+
| AS 1 |
+-------| Entitycert |
/ +------------+
/ |
+ |
| |
v v
+----------+ +------------+ +------------------+
| AS 2 | | AS 2 | | AS 2 |
| Authcert | | Entitycert |-------> | PrefixPolicycert |
+----------+ +------------+ +------------------+
|
| +------------------+
| | AS 2 |
+---------> | ASPolicycert |
+------------------+
Figure 1. Relationship between soBGP certificates associated with a
single Entity (AS 2)
In Figure 1, AS 1 (e.g., an ISP) allocates a prefix to AS 2 (e.g., a
customer of the ISP). AS 1 also issues an Authcert to AS 2, thereby
proving that AS 2 may legitimately use that prefix. In this example,
AS 1 also acts as an Entitycert issuer for AS 2. AS 2 then creates
two policy certificates: one specifying particular policy for the
authorized prefix, and one specifying particular policy for the AS.
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+------------+ +------------+
| AS 1 | | AS 100 |
| Entitycert |<-----| Entitycert |
+------------+ +------------+
| |
| |
| |
v v
+----------+ +------------+ +------------------+
| AS 2 | | AS 2 | | AS 2 |
| Authcert | | Entitycert |-------> | PrefixPolicycert |
+----------+ +------------+ +------------------+
|
| +------------------+
| | AS 2 |
+---------> | ASPolicycert |
+------------------+
Figure 2. Adding a Certificate Authority
Figure 2 illustrates another possible relationship between soBGP
certificates associated with a single AS (AS 2). In this case, both
AS1 and AS2 have agreed to trust a single certificate authority (AS
100). AS 100 has issued Entitycerts to AS1 and AS2, each which are
verified with the public key of AS 100.
Note that as before AS1 provides proof of prefix allocation in an
Authcert at the time it provides prefix to AS2. However, this is the
only relationship necessary between AS1 (and ISP) and AS2 (its
customer). This organization of certificates benefits ISPs that
choose against being a Certificate Authority for its customers.
Each of the soBGP certificates above are discussed in detail in
subsequent sections of this document.
2.1.1 Digital Signature Algorithms
The RSA Public Key Algorithm [RSA] is a widely deployed public key
algorithm commonly used for digital signatures. Compared to other
public key algorithms, signature verification is efficient. This
property is useful considering the large number of signature
verifications that will be done on soBGP certificates. The RSA
Algorithm is commonly supported in hardware, and is not encumbered by
any known intellectual property claims.
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All soBGP implementations MUST support a digital signature of a SHA-1
digest encrypted with the RSA algorithm. An implementation MAY
support other signature methods (e.g., RSA/SHA-256), but until that
signature method becomes commonly deployed any AS using alternate
signature methods run the risk of their signatures not being
universally verifiable.
3.0 Authentication Certificate (Entitycert)
Entitycerts provide authentication, providing a binding of an
identity (i.e., autonomous system number) to a public key. The
authenticity of the binding is verified with a digital signature,
where the public key of the certificate issuer has been previously
accepted by an receiver as valid. Issuer public keys can either be
manually configured, or are verified through the use of another
issuer's trusted public key
Entitycerts are used to verify, through a trust model, the existence
of an entity within the routing system, and the value of that
entity's public key for use in the routing system. Various trust
models are possible, but a distributed trust model is preferred
because it lends itself to incremental deployment. For more
discussion of a distributed trust model, see Section 3.4.1.
Each entity within the routing system participating in soBGP MUST
generate a public/private key pair. The public key portion of this
pair is then signed, verifying that anyone using this public key is
actually the entity in question. This signature may be provided by
various other trusted parties within the routing system, including
(but not limited to):
- The authority that issued the autonomous system number.
- An external commercial authority that provides digital
certificates for other commercial transactions.
- Any other trusted party within the domain of Internet routing,
such as a well known Service Provider.
- Self-signed if the entity is well known within the routing system.
(See Section 3.4.2 for a discussion on the risk of self-signed
Entitycerts.)
A public key is used to verify the validity of other certificates
transmitted by this entity within the routing system. The public
key, along with other verifying information, is formatted into an
Entitycert, as described in the next section.
3.1 Format
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An Entitycert MUST be formatted as an X.509 certificate, as defined
in [RFC3280]. The Entitycert MUST be generated with a signature of
type sha1withRSAEncryption [RFC3279].
The primary identity in soBGP is the autonomous system number.
Because of this, each entity that issues Entitycerts MUST be
assigned an AS number, even if they do not originate routes into the
internetwork. In accordance with Section 4.2.1.7 of [RFC3280],
issuers MUST verify all parts of the subject alternative name,
including the AS number, before issuing the certificate.
An Entitycert MUST have a subjectAltname critical extension, which
MUST contain the AS number of the subject as an otherName choice.
The AS number is encoded with the OID defined in Section 3.2.1 of
[RFC3779].
An Entitycert MUST have an issuerAltname critical extension, which
MUST contain the AS number of the issuer as an otherName choice. The
AS number is encoded with the OID defined in Section 3.2.1 of
[RFC3779].
The X.509 Issuer and Subject distinguished names are not used by
soBGP. In accordance with Section 4.2.1.7 of [RFC3280], when
subjectAltName is required, the Subject field MAY be empty.
3.2 Creation
An Entitycert is usually created with the following steps:
- The entity requesting an Entitycert generates a signature key pair
- The entity forwards its identity (including its AS number) and the
public key to an Entitycert issuer using the certificate
registration mechanism supported by the issuer.
- The issuing autonomous system verifies that the identity of the
receiving autonomous system, generates an Entitycert including
that identity, and signs it with its own private key.
- The issuing autonomous system returns the Entitycert to the
receiving autonomous system.
When an Entitycert is created, care should be taken as to whether
the Entitycert is authorized to become a CA for other entities. If
the signer authorizes the Entity to become a Certificate Authority
for other entities, then the following X.509v3 Certificate
Extensions MUST be included in an Entitycert:
- Key Usage: The keyCertSign and cRLSign bits MUST be set. The
digitalSignature bit MUST be set, so that the public key in the
certificate may also be used for validating other soBGP
certificates. [Section 4.2.1.3, RFC3280]
- Basic Constraints: The cA Boolean MUST be set, and
pathLenConstraint MAY be set in order to restrict the length of
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the certification path below this certificate. [Section 4.2.1.10,
RFC3280]
If the signer does NOT authorize the Entity to become a Certificate
Authority for other entities, then the following X.509v3 Certificate
Extensions MUST be included in an Entitycert:
- Key Usage: The keyCertSign and cRLSign bits MUST NOT be set. The
digitalSignature bit MUST be set, so that the public key in the
certificate may also be used for validating other soBGP
certificates. [Section 4.2.1.3, RFC3280]
- Basic Constraints: The cA Boolean MUST NOT be set. [Section
4.2.1.10, RFC3280]
3.2.1 Certificate Uniqueness
Digital certificates are created as uniquely named objects, which
allow them to be uniquely identified. For the purposes of soBGP, the
pair of CertificateSerialNumber and AS number in the IssuerAltName
values uniquely identifies Entity Certificates. Note that although
RFC 3280 contains an X.509v3 IssuerName, it is not used within
soBGP.
3.2.2 Certificate Encoding
Entitycerts distributed in [SOBGP-BGP] use their native DER [X.690]
form. If Entitycerts are manually distributed (e.g., through
electronic mail) they may need to be base64 encoded as described in
Section 4.3 of [RFC1421].
3.2.3 Multiplicity of Entitycerts
An autonomous system MAY enroll with more than one issuer, which
results in multiple valid Entitycerts for that AS. There are several
advantages for an AS to obtain Entitycerts from different issues:
- A greater number of other autonomous systems in the distributed
PKI will accept their public key.
- In some cases, other autonomous systems will accept their public
key faster, which increases BGP convergence times.
- An AS can mitigate losing trust within the distributed PKI if one
issuer revokes its entity certificate. While an immediate and
complete revocation is usually desirable in a PKI, it is not
acceptable in a secure routing system. Immediate and complete
revocation by a single issuer would very likely remove access of the
revoked entity to the network. Such an event could be catastrophic
if the entity is an ISP and its customers. Furthermore, the sudden
exit of a major ISP due to revocation could negatively affect the
entire routing system.
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If an entity detects that an autonomous system has valid Entitycerts
from different issuers, the entity SHOULD treat the various
Entitycerts as independent. Revocation from one issuer does not
necessarily imply that Entitycerts from other issuers are invalid.
An issuer may revoke a certificate for reasons other than private
key compromise or loss.
If an issuer revokes an entity certificate and states key compromise
as the reason for revocation, a receiving entity SHOULD also treat
this state as specific to the issuer. Note that if the state of one
issuer were instead considered transitive, the erroneous revocation
of a single issuer would result in a denial of service attack on the
victim autonomous system.
In the face of inconsistent state from different issuers, a receiver
MAY choose to trust one issuer over another. For example, a receiver
may choose to prefer the result of an issuer they directly trust to
an issuer that was verified further away in the distributed PKI.
3.3 Distribution
Entitycerts may be distributed using any number of methods, for
example:
- maintained in a directory maintained by the issuing autonomous
system,
- distributed via some out of band mechanism, and/or
- distributed within BGP using extensions defined in [SOBGP-BGP].
To ensure interoperability, the receiving autonomous system SHOULD
distribute its Entitycert within BGP.
3.4 Validation
Validation rules for Entitycerts MUST follow those described in
[RFC3280]. Any device receiving an Entitycert can verify it by
validating the signature on the certificate, along with the
verifying information. Validation of the certificate may include
checking a CRL (see Section 3.5). If a Certificate Revocation List
(CRL) is available for that issuer, it MUST be consulted to verify
that this certificate has not been revoked. Local policy will
determine whether or not a CRL must be available in order to
complete validation of the certificate.
Once validation is complete, the public key contained in this
certificate may be used to verify messages purportedly sent by this
entity.
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3.4.1 Distributed PKI Trust Model
Secure Origin BGP Entitycerts can be organized in various trust
models. A number or variables (e.g., economic factors, government
fiat, and entity deployment schedules) could cause different trust
models to be best suited. This document describes a Distributed PKI
trust model that is flexible and adaptable in many possible
deployment scenarios.
An soBGP entity uses the a distributed PKI paradigm for purposes of
Entitycert validation, where the entity learns the validity of
public keys over time. An entity follows the following procedure for
validating Entitycerts in the distributed PKI.
- A small number of Entitycerts are manually configured and copied
to a device's local configuration. These are implicitly trusted as
being previously verified and authenticated.
- When the entity receives a new Entitycert, it checks to see if it
has the public key of the issuing autonomous system in its
configuration. If so, it attempts to validate the Entitycert,
using the previously known public key, and any revocation material
that is available from the issuer.
- If the new Entitycert proves valid, it is added to the device's
local configuration and may be used to validate subsequently
received Entitycerts.
- If the new Entitycert cannot be validated because the issuer's
public key is not yet available, local policy dictates as to
whether or not the certificate is held awaiting the issuer's
certificate.
Figure 3 shows an example distributed PKI. In this example,
Entitycerts for AS 1 and AS 5 would be manually copied to the local
configuration on the box. Other Entitycerts would be validated using
the usual PKI path validation techniques.
As in Figure 1, an arrow in this figure indicates a signature
operation. The public key contained in the certificate at the tail
of the arrow is used to verify the validity of the certificate at
the head of the arrow.
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+------------+ +------------+
| AS 1 | | AS 5 |
| Entitycert | | Entitycert |
+-----+------+ +---+----+---+
| / \
| / \
| + +
| | |
V V V
+------------+ +------------+ +------------+
| AS 2 | | AS 6 | | AS 7 |
| Entitycert | | Entitycert | | Entitycert |
+---+----+---+ +------------+ +-----+------+
/ \ |
/ \ V
+ + +------------+
| | | AS 8 |
V V | Entitycert |
+------------+ +------------+ +-----+------+
| AS 3 | | AS 4 | |
| Entitycert | | Entitycert | V
+------------+ +------------+ +------------+
| AS 9 |
| Entitycert |
+------------+
Figure 3. Example Distributed PKI
An autonomous system may define local policy to restrict the scope
of the distributed trust. However it should be noted that any local
policy restricting the distributed trust reduces the value of soBGP
authorization and path validation.
One type of local policy would be to accept only a certain "depth"
of Entitycert issuers. For example, consider if AS 6 in Figure 3
only accepted two levels of issuers. AS 6 would only trust ASes
1,2,5,6 and 7 to issue Entitycerts. It would never validate the
Entitycert from ASes 3, 4, 8, and 9.
Note that if the top-level roots in the distributed PKI (AS1 and
AS5) trusted each other enough they could issue certificates for
each other, or "cross-certify". This could simplify the certificate
validation process for all ASes. However, a cross-certified
distributed PKI system is not always appropriate. For example, if
AS1 and AS5 have strikingly different certificate issuance policies
they may not be willing to cross-certify.
3.4.2 Self-signed Entitycerts
Entitycerts MAY be self-signed, but SHOULD only be accepted from
autonomous systems when a method exists of validating that the self-
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signed certificate is genuine. Distribution out-of-band using a
trusted delivery procedure would be one method. An autonomous system
MUST have local policy describing the circumstances under which they
will access self-signed certificates.
Typical users of a self-signed Entitycert would be:
- A commercial authority in the business of providing digital
certificates for many types of commercial transactions
- An Entitycert issuer that is at the top of a hierarchy of issuers
- A well-known trusted party within the domain of Internet routing
3.5 Revocation and Expiration
As described in [RFC3280], any entity issuing an Entitycert may
later need to revoke it. The entity MAY use any available methods
for propagating that revocation list, but SHOULD send it as part of
an AS Policy Certificate (distributed using [SOBGP-BGP]). This
allows autonomous systems that cannot route to the issuing
autonomous system to verify that the Entitycert has not been
revoked.
If an Entitycert is discarded due to revocation, the Authcert and
Policy databases should be examined. Any Authcerts and Policy
certificates that were validated using the discarded certificate
should be removed from the database.
X.509 certificates contain expiration dates. Any device validating
Entitycerts MUST have a time of day clock that is set to real time
in order to properly deal with expired certificates
If an Entitycert is discarded due to expiration, Authcerts or Policy
certificates validated using the discarded certificate remain valid
if another valid Entitycert for the AS can be found containing the
same public key.
4.0 Authorization and Policy Certificates
soBGP defines a set of certificates that make authorization and
local policy claims regarding prefixes, and local policy claims
regarding Autonomous Systems. These certificates are not defined to
be in a X.509 format. Rather, they are defined in a more compact
Type/Length/Value (TLV) format that can be easily transferred
through BGP [SOBGP-BGP].
The certificates share a common set of attributes, which are defined
in later section of this document. The following sections describe
which attributes are relevant to the various certificate types, as
well as the processing semantics for each certificate type.
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Each certificates is formatted as a header block followed by a set
of Type/Length/Value attributes. All TLVs described in the following
sections are REQUIRED to be present in an Authcert unless they are
declared optional.
4.1 Authorization Certificates (Authcert)
Authcerts prove the right of an entity to advertise particular
prefixes. They are generated in a hierarchical manner following the
order of address space allocation (i.e., from RIR, to LIR or ISP, to
customer), and are distributed along with the address space
allocation. Receivers use the Authcert to validate announcements
received in BGP UPDATE messages.
The authorization certificate binds one or more prefix blocks to a
particular autonomous system. It is typically provided by an entity
issuing a prefix block to an autonomous system, and is digitally
signed by the issuing autonomous system. The Authcert can be thought
of as an "Attribute Certificate" in the spirit of RFC 3281, although
it does not follow the syntax of that document.
The authenticity of Authcerts is verified with a digital signature
provided by the issuing autonomous system. Authcerts do not contain
public keys. Rather, they bind an address space to a particular
identity (i.e., Autonomous System).
Including more than one prefix block in an Authcert can reduce the
number of Authcerts necessary. However, note that an Authcert is
bundled with policy as part of Prefix Policy Certificate (discussed
later in this document). If more than one prefix block is included
in the Authcert, then that policy will apply to all of the prefix
blocks.
Multiple entities (i.e., AS numbers) may be authorized to advertise
a prefix block. This is necessary when an organization without an AS
number is multi-homed. See Section 5.3 of [SOBGP-ARCH] for more
details.
4.1.1 Format
Figure 4 describes the format and order of an Authcert. Optional
attributes are represented within brackets. An asterisk following an
attribute indicates that more than one of the attribute may be
present.
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HDR, ORIG-AS, AUTH-AS*, SN, PREFIX*, [ORIG-EC-URL],
[ORIG-AP-URL], SIG
Figure 4. Authcert Format
The ORIG-AS describes the entity that created the certificate. It
serves the same purpose as the issuerName and issuerAltName in an
X.509v3 certificate. The AUTH-AS describes the subject entity to
which the prefix has been allocated. This serves as the subjectName
and subjectAltName in an X.509v3 certificate.
The SN attribute provides a unique serial number for this
certificate. It serves the same purpose as an X.509v3 serialNumber.
The PREFIX attribute describes an address block that has been
assigned to the AS numbers declared in the AUTH-AS attributes.
The ORIG-EC-URL attribute contains a URL to an Entitycert containing
the public key that signed this certificate. The ORIG-AC-URL
attribute contains a URL to the most recent ASPolicycert, which
allows a receiver to verify that this Authcert is still considered
valid by the originating AS.
The SIG attribute contains a digital signature created by the
originating AS.
4.1.2 Creation
An Authcert is usually created by the authorizing Autonomous System
with the following steps:
- Allocate a prefix block to the receiving autonomous system.
- Build an Authcert by adding TLVs containing it's the authorizing
AS number, the receiving (authorized) AS number, the prefix block,
a unique sequence number, and any other information (e.g., URL
pointing to the Entitycert that signed this Authcert.). The
Signature TLV is also included, except for the signature bytes.
- Sign the Authcert by hashing and encrypting the Authcert bytes.
Append the signature to the Signature TLV to complete the
Authcert.
4.1.3 Distribution
Authcerts are distributed as part of a Prefix Policy Certificate, so
that an Autonomous System can reliably match distribution policy to
the prefix block.
4.1.4 Validation
The Authcert is validated using the following steps.
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- Identify the Entitycert that signed the Authcert. The correct
Entitycert is uniquely identified with the Entity Certificate
Issuer Autonomous System and Entity Certificate Serial Number
contained in the Signature TLV. The Entity Certificate Issuer
Autonomous System is compared with the AS number in the Entitycert
IssuerAltName field. The Entity Certificate Serial Number is
compared with the Entitycert CertificateSerialNumber.
- Obtain the Entitycert that signed the Authcert, and validate it.
The Entitycert may be in a local cache (e.g., already received via
BGP extensions), retrieved using the URL in the Authcert, or
through other means. If an entity does not have the validating
public key it MUST NOT assume the Authcert is valid.
- Verify that the autonomous system identifier in SubjectAltName of
the Entitycert matches the Authorizing AS TLV value of the
Authcert.
- If an Authorization Certificate Validity List is available,
validate that the issuer of the Entitycert has not invalidated the
Authcert. Validity lists may be distributed in the signers
ASPolicycert, or a pointer to the list may be distributed in the
Authcert in an Originating AS ASPolicycert URL . If no
Authorization Certificate Validity List is available, an entity
MAY accept the certificate. However if a validity list is received
later, the entity MUST check the validity of all certificates that
had been previously accepted.
- Hash the Authcert bytes, excluding the signature itself.
- Extract the signature from the Authcert.
- Extract the public key from the Entitycert, and use it to decrypt
the signature.
- Verify that the computed hash matches the decrypted hash. If the
hashes do not match, the Authcert MUST be discarded.
- Verify that the Originating AS was authorized to distribute the
prefix to the subject AS. This is done by comparing the address
space allocated to the Originating AS to the prefix that the
Originating AS included in this Authcert. IF the Originating AS
was authorized to allocate the prefix in this Authcert, then the
Authcert is accepted as valid.
4.1.4.1 Self-signed Authcerts
Self-signed Authcerts are dangerous, because a responsible third
party does not assign the authorization contained within the
Authcert. Trusting an autonomous system to declare authorization of
its own address space negates the ability of any third party to
verify suitability of the authorization.
However, the autonomous systems at the highest level of prefix
allocation (e.g. Regional Internet Registries (RIRs) or Local
Internet Registries (LIRs)) may not be able to find a responsible
third party to sign their Authcerts. In this case, self-signed
Authcerts may be unavoidable.
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Authcerts MAY be self-signed, but MUST only be accepted from
autonomous systems that have been locally configured as explicitly
authorized to do so. For example, a device may be configured to
accept Authcerts for the RIR autonomous systems.
4.1.5 Revocation
An entity issuing an Authcert MUST keep an Authcert revocation list.
The entity MAY use any form for propagating that revocation list.
Because BGP routers do not necessarily have synchronized clocks,
Authcerts do not carry expiration times, and thus do not expire.
Revocation is only method of invalidating an Authcert.
Revocation information may be represented as a "validation list". A
validation list includes lists of both valid and invalid (i.e.,
revoked) certificates. Any number not appearing in the list MUST be
considered invalid. Validation list may be more efficient than a
pure revocation list for Authcerts in the case where a large number
of serial numbers have been revoked by an issuer.
An autonomous system MUST include an Authcert validation list in
their AS Policy Certificate (distributed using [SOBGP-BGP]). This
allows autonomous systems that cannot route to the issuing
autonomous system to verify that the Entitycert has not been
revoked.
4.2 Prefix Policy Certificates (PrefixPolicycert)
The PrefixPolicycert carries policy information sourced from route
originators. It provides a specific set of policy regarding one or
more prefix blocks. The owner of the prefix block creates it. There
is only one valid PrefixPolicycert for each prefix block at any
given time.
PrefixPolicycerts are verified with a digital signature provided by
the autonomous system generating the policy. It does not contain a
public key. Rather, it binds a particular policy to a particular
identity (i.e., autonomous system).
5.2.1 Format
Figure 5 describes the format and order of a PrefixPolicycert.
Optional attributes are represented within brackets. An asterisk
following an attribute indicates that more than one of the
attributes may be present.
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HDR, ORIG-AS, SN, AUTHCERT*, P-POLICY,
[ORIG-EC-URL], [ORIG-AP-URL], SIG
Figure 5. PrefixPolicycert Format
The ORIG-AS describes the entity that created the certificate. It
serves the same purpose as the issuerName and issuerAltName in an
X.509v3 certificate.
The SN attribute provides a unique serial number for this
certificate. It serves the same purpose as an X.509v3 serialNumber.
The AUTHCERT attribute designates an Authorization Certificate that
is subject to the policies indicated in this certificate. If
multiple AUTHCERT attributes are present, they are all subject to
the same policy.
The P-POLICY attribute contains specific policy that the originator
is requesting other entities to honor regarding the prefixes
contained in the AUTHCERT attributes.
The ORIG-EC-URL attribute contains a URL to an Entitycert containing
the public key that signed this certificate. The ORIG-AC-URL
attribute contains a URL to the most recent ASpolicycerts, which
allows a receiver to verify that this is PrefixPolicycert is still
considered valid by the originating AS.
The SIG attribute contains a digital signature created by the
originating AS.
4.2.2 Creation
An PrefixPolicycert is created by an autonomous system for prefix
blocks that it owns. An autonomous system creates it with the
following steps:
- Build an PrefixPolicycert by adding TLVs containing its own AS
number, a unique sequence number, policy related to one or more
prefix blocks, and the Authcert or Authcerts defining the prefix
blocks to which this policy applies. The Signature TLV is also
included, except for the signature bytes.
- Sign the Authcert by hashing and encrypting the PrefixPolicycert
bytes. Append the signature to the Signature TLV to complete the
PrefixPolicycert.
4.2.3 Distribution
PrefixPolicycerts may be distributed using any number of methods,
for example:
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- maintained in a directory maintained by the issuing autonomous
system,
- distributed via some out of band mechanism, or
- distributed within BGP using extensions defined in [SOBGP-BGP].
To ensure interoperability, an autonomous system SHOULD distribute
its PrefixPolicycerts within BGP.
4.2.4 Validation
The Authcert included in the Authcert TLV MUST be validated as
correct before the Policy TLV can be accepted. Thus, the Authcert
should be extracted from the PrefixPolicycert and validated before
the PrefixPolicycert is validated.
The PrefixPolicycert is validated using the following steps.
- Identify the Entitycert that signed the PrefixPolicycert. The
correct Entitycert is uniquely identified with the Entity
Certificate Issuer Autonomous System and Entity Certificate Serial
Number contained in the Signature TLV. The Entity Certificate
Issuer Autonomous System is compared with the AS number in the
Entitycert IssuerAltName field. The Entity Certificate Serial
Number is compared with the Entitycert CertificateSerialNumber.
- Obtain the Entitycert that signed the PrefixPolicycert, and
validate it. The Entitycert may be in a local cache (e.g., already
received via BGP extensions), retrieved using the URL in the
Authcert, or through other means. If an entity does not have the
validating public key it MUST NOT assume the PrefixPolicycert is
valid.
- Verify that the autonomous system identifier in SubjectAltName of
the Entitycert matches the Originating Autonomous System TLV value
of the PrefixPolicycert.
- If an Prefix Policy Certificate Validity List is available,
validate that the issuer of the Entitycert has not invalidated the
Authcert. Validity lists may be distributed in the signers
ASPolicycert, or a pointer to the list may be distributed in the
Authcert in an Originating AS ASPolicycert URL. If no Prefix
Policy Certificate Validity List is available, an entity MAY
accept the certificate. However if a validity list is received
later, the entity MUST check the validity of all certificates that
had been previously accepted.
- Hash the PrefixPolicycert bytes, excluding the signature itself.
- Extract the signature from the PrefixPolicycert.
- Extract the public key from the Entitycert, and use it to decrypt
the signature.
- Validate that the computed hash matches the decrypted hash. If the
hashes do not match, the PrefixPolicycert MUST be discarded.
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Once a PrefixPolicycert has been validated, any PrefixPolicycert
that matches the following criteria MUST be discarded:
- has a lower serial number from the same originating AS, and
- includes an Authcert with the same prefix block
4.2.5 Revocation
Any entity issuing an PrefixPolicycert MUST keep a revocation list.
The entity MAY use any form for propagating that revocation list.
Because BGP routers do not necessarily have synchronized clocks,
PrefixPolicycert do not carry expiration times, and thus do not
expire. Revocation is only method of invalidating a
PrefixPolicycert.
Revocation information may be represented as a "validation list". A
validation list includes lists of both valid and invalid (i.e.,
revoked) certificates. Any number not appearing in the list MUST be
considered invalid. Validation list may be more efficient than a
pure revocation list for PrefixPolicycerts in the case where a large
number of serial numbers have been revoked by an issuer.
An autonomous system SHOULD include an PrefixPolicycert validation
list in their AS Policy Certificate (distributed using [SOBGP-BGP]).
This allows autonomous systems that cannot route to the issuing
autonomous system to verify that the Entitycert has not been
revoked.
4.3 AS Policy Certificates (ASPolicycert)
The ASPolicycert provides a specific set of policy relating to an
autonomous system. An administrative entity within the autonomous
system creates it. There is only one valid ASPolicycert for each
autonomous system at any given time.
ASPolicycerts are verified with a digital signature from the
autonomous system generating the policy. It does not contain a
public key. Rather, it binds a particular policy to a particular
identity (i.e., autonomous system).
4.3.1 Format
Figure 6 describes the format and order of a PrefixPolicycert.
Optional attributes are represented within brackets. An asterisk
following an attribute indicates that more than one of the
attributes may be present.
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HDR, ORIG-AS, SN, TRANSIT, NON-TRANSIT,
[EC-CRL], AC-VALID, PPC-VALID,
[ORIG-EC-URL],[ORIG-AP-URL], SIG
Figure 6. ASpolicycert Format
The ORIG-AS describes the entity that created the certificate. It
serves the same purpose as the issuerName and issuerAltName in an
X.509v3 certificate.
The SN attribute provides a unique serial number for this
certificate. It serves the same purpose as an X.509v3 serialNumber.
The TRANSIT attribute declares which entities are transit peers,
through which the originating AS may route packets. The NON-TRANSIT
attribute declares which entities are also peers, but through which
the originating AS will not route packets.
The EC-CRL attribute contains an X.509 CRL declaring which
Entitycerts created by the originating AS have been revoked.
The AC-VALID and PPC-VALID attributes contain validity lists
describing what Authcerts and PrefixPolicycerts created by the
originating AS are valid. Validity lists are more descriptive than
CRLs. See Section 4.1.5 for the rationale of using Validity Lists
rather than CRLs.
The ORIG-EC-URL attribute contains a URL to an Entitycert containing
the public key that signed this certificate. The ORIG-AC-URL
attribute contains a URL to the most recent ASpolicycerts, which
allows a receiver to verify that this is an Authcert still
considered valid by the originating AS.
The SIG attribute contains a digital signature created by the
originating AS.
4.3.2 Creation
An ASPolicycert is created by an autonomous system in order to relay
its own policy. An autonomous system creates it with the following
steps:
- Build an ASPolicycert by adding TLVs containing its own AS number,
a unique sequence number, and policy related to the autonomous
system. The Signature TLV is also included, except for the
signature bytes.
- Sign the Authcert by hashing and encrypting the ASPolicycert
bytes. Append the signature to the Signature TLV to complete the
ASPolicycert .
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4.3.3 Distribution
ASPolicycert may be distributed using any number of methods, for
example:
- maintained in a directory maintained by the issuing autonomous
system,
- distributed via some out of band mechanism, or
- distributed within BGP using extensions defined in [SOBGP-BGP].
To ensure interoperability, an autonomous system SHOULD distribute
its ASPolicycert within BGP.
4.3.4 Validation
The ASPolicycert is validated using the following steps.
- Identify the Entitycert that signed the ASPolicycert. The correct
Entitycert is uniquely identified with the Entity Certificate
Issuer Autonomous System and Entity Certificate Serial Number
contained in the Signature TLV. The Entity Certificate Issuer
Autonomous System is compared with the AS number in the Entitycert
IssuerAltName field. The Entity Certificate Serial Number is
compared with the Entitycert CertificateSerialNumber.
- Obtain the Entitycert that signed the ASPolicycert, and validate
it. The Entitycert may be in a local cache (already received via
BGP extensions), retrieved using the URL in the Authcert, or
through other means. If an entity does not have the validating
public key it MUST NOT assume the ASPolicycert is valid.
- Verify that the autonomous system identifier in SubjectAltName of
the Entitycert matches the Originating Autonomous System TLV value
of the ASPolicycert.
- Hash the ASPolicycert bytes, excluding the signature itself.
- Extract the signature from the ASPolicycert.
- Extract the public key from the Entitycert, and use it to decrypt
the signature.
- Validate that the computed hash matches the decrypted hash. If the
hashes do not match, the ASPolicycert MUST be discarded.
Once an ASPolicycert has been validated, any ASPolicycert with a
lower serial number from the same originating AS MUST be discarded.
4.3.5 Revocation
Each ASPolicycert issued by an autonomous system overrides any
previously issued ASPolicycerts from this autonomous system.
Therefore, revocation is not required.
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If present, a receiver has the opportunity of using the Most Recent
AS Policy Certificate URL in the ASPolicycert to verify that they
have the most recent policy certificate.
4.4 Common Processing
The following sections describe processing that is common to each of
the soBGP TLV-based certificates.
4.4.1 Certificate Uniqueness
Digital certificates are created as uniquely named objects, which
allows them to be uniquely identified. The pair of Authorized
Originator and certificate Serial Number TLV values uniquely
identifies each certificate.
4.4.2 Certificate Encoding
The soBGP TLV-based certificates are distributed through BGP [SOBGP-
BGP] in the TLV form. However if they are manually distributed (e.g.,
through electronic mail) they may need to be base64 encoded as
described in Section 4.3 of [RFC1421].
5.0 Authorization and Policy Certificate Attributes
5.1 Certificate Header (HDR)
Each soBGP certificate begins with a header:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+---------------+---------------+-------------------------------+
| Cert. Marker | Type Id | Length |
+---------------+---------------+-------------------------------+
The header fields are defined as follows:
o Certificate Marker: "162(0xa2), identifying this as an soBGP
certificate.
o Type ID: Identifier denoting the soBGP certificate type.
Type ID Value
-------- -----
AuthCert 1 (0x01)
PrefixPolicycert 2 (0x02)
ASPolicycert 3 (0x03)
o Length: Set to the number of bytes in the certificate,
including the header.
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5.2 The Originating Autonomous System (ORIG-AS)
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-------------------------------+-------------------------------+
| TLV Type | Length |
+-------------------------------+-------------------------------+
| Originating Autonomous System |
+---------------------------------------------------------------+
o TLV type: 1 (0x0001)
o Length: Set to 4.
o Originating Autonomous System: (4 octets), the autonomous
system which originated this certificate. AS numbers containing
only two octets should be placed in the least significant
octets of this four-octet field (the two rightmost octets), the
upper two rightmost bits set to zeros.
Each soBGP certificate MUST include an originating Autonomous System
number. This attribute declares which identity has created the
certificate.
5.3 Authorized Autonomous System (AUTH-AS)
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-------------------------------+-------------------------------+
| TLV Type | Length |
+-------------------------------+-------------------------------+
| Autonomous System |
+---------------------------------------------------------------+
o TLV type: 2 (0x0002)
o Length: Set to 4.
o AS: (4 octets), the autonomous system of an entity authorized
to advertise prefixes within this block. AS numbers containing
only two octets should be placed in the least significant
octets of this four-octet field (the two rightmost octets).
Multiple authorized originator TLVs may be included in the Authcert.
5.4 The Serial Number (SN)
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0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-------------------------------+-------------------------------+
| TLV Type | Length |
+-------------------------------+-------------------------------+
| Serial Number |
+---------------------------------------------------------------+
o TLV type: 3 (0x0003)
o Length: Denotes the length of the URL in octets.
o Serial Number: (An unsigned integer taken from a number space
maintained by the Authorizing AS indicating the serial number
of this certificate.
This attribute MUST be present in each TLV-based soBGP certificate.
The Originating Autonomous System MUST manage the number space of
each certificate type as a monotonically increasing value so that a
relative ordering of certificates is maintained.
5.5 Originating AS Entitycert URL (ORIG-EC-URL)
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-------------------------------+-------------------------------+
| TLV Type | Length |
+-------------------------------+-------------------------------+
| URL |
+----------------
o TLV type: 4 (0x0004)
o Length: Denotes the length of the URL in octets.
o URL: A uniform resource locator indicating a location where the
Originating Autonomous System Entitycert can be found.
This attribute allows a receiver to validate that it has the most
current Entitycert for the originator. This mitigates an attack
where an adversary has been able to stop the propagation of new
Entitycerts.
A conforming implementation is REQUIRED to support this attribute. A
receiving device MAY choose to ignore the URL TLV.
5.6 Originating AS ASPolicycert URL (ORIG-AP-URL)
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0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-------------------------------+-------------------------------+
| TLV Type | Length |
+-------------------------------+-------------------------------+
| URL |
+----------------
o TLV type: 5 (0x0005)
o Length: Denotes the length of the URL in octets.
o URL: A uniform resource locator indicating a location where the
Originating Autonomous System ASPolicycert can be found.
This attribute allows a receiver to validate that it has the most
current policy for the originator. In particular, it allows a
receiver to obtain the most recent Validation Lists generated by the
Originating Autonomous System. Having the most recent Validation
Lists allows a receiver to validate that the Authcerts and
Prefixpolicycerts that they hold for that AS have not been replaced.
This validation mitigates an attack where an adversary has been able
to stop the propagation of ASPolicycerts.
A conforming implementation is REQUIRED to support this attribute. A
receiving device MAY choose to ignore the URL TLV.
5.7 The Address Prefix (PREFIX)
The address prefix TLV defines prefixes which the authorized AS (or
ASes) are allowed to advertise.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-------------------------------+-------------------------------+
| TLV Type | Length |
+-------------------------------+---------------+---------------+
| Address Family Identifier | RESERVED | Subsequent AFI|
+-------------------------------+---------------+---------------+
| NLRI Data |
+----------------
o TLV Type: 6 (0x0006)
o Length (2 octets), set to 4 + the length of the NLRI Data.
o Address Family Identifier: This field carries the identity of
the Network Layer protocol associated with the Network Address
that follows. Presently defined values for this field are
assigned by IANA [IANA-AFN]).
o RESERVED: Set to 0.
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o Subsequent AFI: This field provides additional information
about the type of the Network Layer Reachability Information
carried in the attribute. Values for this field are defined in
Section 5 of [RFC2858].
o NLRI Data: An address prefix as described in Section 4 of
[RFC2858].
5.8 Signature (SIG)
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-------------------------------+-------------------------------+
| TLV Type | Length |
+-------------------------------+-------------------------------+
| Signature Type | Number of Issuers |
+-------------------------------+-------------------------------+
| Entity Certificate Issuer Autonomous System |
+-------------------------------+-------------------------------+
| Entity Certificate Serial Number |
+-------------------------------+-------------------------------+
| ... |
+---------------------------------------------------------------+
| Signature |
+------------------
o TLV type: 7 (0x0007)
o Length: (2 octets), unsigned integer denoting the length of the
payload bytes which follow.
o Signature Type: (2 octets), unsigned integer denoting the type
of signature (the algorithm used to build this signature). Each
possible signing algorithm is assigned an integer from this
field. Signature type 1 is defined as an RSA encryption of a
SHA1 digest using PKCS#1.5 padding.
o Number of Issuers (2 octets): The number of Entitycert
references included in the signature payload. If more than one
Entitycert reference follows, all Entitycerts MUST contain the
same public key for the same authorizing autonomous system.
o Entity Certificate Issuer Autonomous System: (4 octets), the
autonomous system of the entity that provided the Entitycert to
the Authorizing AS. AS numbers containing only two octets
should be placed in the least significant octets of this four-
octet field (the two rightmost octets).
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o Entity Certificate Serial Number: (4 octets), the Entitycert
serial number containing the public key of the Authorizing AS.
o Signature: The signature itself.
The signature is calculated by hashing the bytes of the certificate,
beginning with the certificate header and ending at the byte just
before the signature. The hashed data includes the Signature payload
fields just prior to the signature field in the Signature payload.
The hash is then encrypted using the private key of the authorizing
entity..
5.9 Authorization Certificate (AUTHCERT)
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-------------------------------+-------------------------------+
| TLV Type | Length |
+-------------------------------+-------------------------------+
| Authorization Certificate |
+----------------
o TLV type: 8 (0x0008)
o Length: Set to the length of the Authorization Certificate.
o Authorization Certificate. .
This attribute allows a PrefixPolicycert to bind particular policy
to the prefix block contained in an Authorization Certificate. One
or more Authcert TLVs MUST be included in the PrefixPolicycert.
5.10 Prefix Policies (P-POLICY)
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-------------------------------+-------------------------------+
| TLV Type | Length |
+-------------------------------+-------------------------------+
| Options | SubTVs
+-------------------------------+--------------
o TLV type: 9 (0x0009)
o Length: Set to the sum of the Options size (2) and the length
of the SubTVs.
o Options: (2 octets), a bit field describing various policies
which should be applied to prefixes .
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o SubTVs: (variable length), zero or more fields, the length of
which is determined by the type, as described below.
This attribute is included in a PrefixPolicycert to bind particular
policy to the prefixes contained in an Authcert.
5.10.1 Option bits
The options bit field describes policies that should be applied
to the address prefix described in the TLV. These options are:
o Bit 0: Path Check. If this bit is set, the receiver should not
accept any prefix for which the path cannot be verified as
described in the section Verifying the Path, below.
o Bit 1: Second Hop Check. If this bit is set, the receiver
should not accept any prefix for which the second entry in the
AS PATH cannot be verified as described in the section
Verifying the Second Hop, below.
o Bits 2-15: Reserved for future use.
5.10.2 SubTVs
The Authcert Policy subTVs provide optional policy information for
the block of addresses included in the Authcert indicated; each
subTV is of a fixed length, as determined by its type.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-------------------------------+------------------------------+
| TV Type | Data....
+-------------------------------+-------------------------
o TV Type: (2 octets), An unsigned integer indicating the type of
subTV
Types defined within this specification are:
- Type 1: Must Include AS, 4 octets of data, an AS which must be
included in the AS path of any prefix falling within this block
of addresses.
- Type 2: OR Include AS, 4 octets of data, at least one of the
included OR Include AS' must be included in the AS path of any
prefix falling within this block of addresses.
- Type 3: MUST NOT INCLUDE AS, 4 octets of data, an AS which must
not be included in the AS path of any prefix falling within
this block of addresses
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- Type 4: Maximum Prefix Length, 1 octet of data, the maximum
length of any prefix allowed within this block of prefixes.
5.11 Attached Transit Autonomous Systems (TRANSIT)
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-------------------------------+-------------------------------+
| TLV Type | Length |
+-------------------------------+---------------+---------------+
| Address Family Identifier | RESERVED | Subsequent AFI |
+-------------------------------+---------------+---------------+
| Autonomous Systems |
+-----------------
o TLV type: 4 (0x0004)
o Length: Set to 4 + 4 octets for each autonomous system in the
list.
o Address Family Identifier: This field carries the identity a
the Network Layer protocol. Presently defined values for this
field are specified in RFC 1700 (see the Address Family Numbers
section).
o RESERVED: Set to 0.
o Subsequent AFI: This field provides additional information
about the type of the Network Layer protocol.
o Autonomous Systems: List of autonomous systems which are
connected to the originating autonomous system through some
form of peering arrangement and which may transit traffic from
the origin AS. Each AS number takes four octets. AS number
values containing only two octets should be placed in the least
significant octets of this four-octet field (the two rightmost
octets).
One or more Attached Transit AS TLVs may be included in the
ASPolicycert . Each type 4 TLV indicates an AS which is connected to
the AS which originates this ASPolicycert through a BGP peering
relationship.
5.12 Attached Non-transit Autonomous Systems (NON-TRANSIT)
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0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-------------------------------+-------------------------------+
| TLV Type | Length |
+-------------------------------+---------------+---------------+
| Address Family Identifier | RESERVED | Subsequent AFI|
+-------------------------------+---------------+---------------+
| Autonomous Systems |
+------------------
o TLV type: 5 (0x0005)
o Length: Set to 4 + 4 octets for each autonomous system in the
list.
o Address Family Identifier: This field carries the identity a
the Network Layer protocol. Presently defined values for this
field are specified in RFC 1700 (see the Address Family Numbers
section).
o RESERVED: Set to 0.
o Subsequent AFI: This field provides additional information
about the type of the Network Layer protocol.
o Autonomous Systems: List of autonomous systems which are
connected to the originating autonomous system through some
form of peering arrangement and which may not transit traffic
from the origin AS. Each AS number takes four octets. AS number
values containing only two octets should be placed in the least
significant octets of this four-octet field (the two rightmost
octets).
One or more Attached Non-Transit AS TLVs may be included in the
ASPolicycert. Each type 5 TLV indicates an AS which is connected to
the AS which originates this ASPolicycert through a BGP peering
relationship.
5.13 Revoked Entity Certificate List (EC-CRL)
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-------------------------------+-------------------------------+
| TLV Type | Length |
+-------------------------------+-------------------------------+
| Entity Certificate Revocation List
+----------------
o TLV type: 6 (0x0006)
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o Length: (2 octets), length of TLV data (the list of revoked
Entity Certificates) in octets
o Entity Certificate Revocation List: A revocation list created
by the autonomous system, which includes a list of revoked
Entity Certificates issued by this autonomous system. The
format of the revocation list MUST be as defined in [RFC3280].
A single Revoked Entity Certificate List TLV MAY be included in an
ASPolicycert, or it may be omitted.
When an Entity Certificate Revocation List is received, all
currently held Entitycerts from this issuer MUST be checked against
the CRL. Entitycerts found to be invalid MUST be deleted.
5.14 Authorization Certificate Validity List (AC-VALID)
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-------------------------------+-------------------------------+
| TLV Type | Length |
+-------------------------------+-------------------------------+
| Validity Ranges
+----------------
o TLV type: 7 (0x0007)
o Length: (2 octets), length of TLV data (the list of revoked
Authorization Certificates) in octets
o Validity Ranges: A list of validity subTVs defining which
serial numbers are valid and invalid. Validity ranges are
interpreted in order until a match is found. For more
information on validity lists, see Section 4.1.5.
A single TLV of this type MAY be included in an ASPolicycert, or it
may be omitted.
When an Authorization Certificate Validity List is received, all
currently held Authcerts from this issuer MUST be checked against
the validity list. Authcerts found to be invalid MUST be deleted.
5.14.1 Validity Ranges
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0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-------------------------------+-------------------------------+
| subTV Type | Size of Range |
+-------------------------------+-------------------------------+
| Lowest Authorization Serial Number |
+---------------------------------------------------------------+
o subTV type: (2 octets).
SubTV type Value
---------- -----
VALID 0
INVALID 1
o Size of Range: (2 octets). Number of contiguous serial numbers
defining a range.
o Lowest Authorization Serial Number (4 octets). The lowest value
in the range.
5.15 Prefix Policy Certificate Validity List (PPC-VALID)
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-------------------------------+-------------------------------+
| TLV Type | Length |
+-------------------------------+-------------------------------+
| Validity Ranges
+----------------
o TLV type: 8 (0x0008)
o Length: (2 octets), length of TLV data (the list of revoked
Authorization Certificates) in octets
o Validity Ranges: A list of validity subTVs (as defined in the
previous section) defining which PrefixPolicycert serial
numbers are valid and invalid. Validity ranges are interpreted
in order until a match is found.
A single TLV of this type MAY be included in an ASPolicycert, or it
may be omitted.
When an Prefix Policy Validity List is received, all currently held
PrefixPolicycerts from this issuer MUST be checked against the
validity list. PrefixPolicycerts found to be invalid MUST be
deleted.
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6.0 Security Considerations
This document describes the format of authentication, authorization,
and policy certificates used with [SOBGP-BGP]. Each certificate type
is digitally signed, and therefore requires no external protection
to ensure its integrity. There are no restrictions on how they may
be distributed. Revocation schemes are defined for all certificate
types.
The following sections describe the security considerations of each
of those objects.
6.1 Entitycerts
Entitycerts provide authentication, providing a binding of an
identity (i.e., autonomous system number) to a public key. The
authenticity of the binding is verified with a digital signature,
where the public key of the certificate issuer has been previously
accepted as valid. Issuer public keys can either be manually
configured, or are verified through the use of another issuer's
trusted public key in a PKI.
Certificate issuers MUST maintain certificate revocation lists
(CRLs). Entities verifying Entitycerts SHOULD reference the
certificate revocation lists whenever possible. (Mandating the
consultation of a CRL as part of the verification process is not
possible, because the CRL may not be available at the time
verification is performed. For example, if the issuer maintains the
CRL on a directory server to which routing is not yet setup.)
Issuers SHOULD distribute their CRLs within their AS Policy
Certificates to increase the likelihood of a receiver having the CRL
available.
Self-signed Entitycerts may be necessary in order to start a chain
of trust. However self-signed Entitycerts MUST be manually validated
as accurate before the enclosed public key is used; else the trust
structure becomes meaningless. The use of self-signed Entitycerts
accepted in the distributed PKI should be limited in order to
maintain an orderly system.
6.2 Authcerts
Authcerts provide authorization, where the issuer of a prefix block
certifies that it has given that prefix block to a specific
autonomous system. Receivers use the Authcert to validate
announcements received in BGP UPDATE messages.
The authenticity of Authcerts is verified with a digital signature,
where the public key of the certificate issuer is distributed in an
Entitycert. Before a receiver can verify the Authcert, they MUST
first check that the verifying Entitycert is authentic.
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The Authcert issuer MUST keep an Authcert validation list describing
which certificates are valid, and which are invalid. The receivers
of an Authcert SHOULD consult the Authcert validation list to ensure
that the authorization has not been revoked.
Autonomous systems may need to authorize their own use of prefix
blocks if the autonomous system that issued their prefix blocks does
not issue them an Authcert. However, such self-signed Authcerts are
dangerous, since unrestricted use of self-signed Authcerts defeats
the goal of authorization. Thus an entity MUST accept self-signed
Authcerts only from autonomous systems that have been explicitly
configured as trusted to claim authorization without the
confirmation of a third party. Examples of such entities are
Regional Internet Registries.
6.3 PrefixPolicycerts
PrefixPolicycerts bind policy generated by an autonomous system for
prefix blocks that they advertise. This policy is bound to a
particular Authcert, which verifies that they are authorized to
advertise those prefix blocks.
PrefixPolicycerts are verified with a digital signature, where the
public key of the certificate issuer is distributed in an
Entitycert. Before a receiver can verify the PrefixPolicycert, they
MUST first verify that the verifying Entitycert is authentic.
6.4 ASPolicycerts
ASPolicycerts contain policy generated by an autonomous system, and
contain policy about the autonomous system itself. The policy
includes its neighbor autonomous systems, which can be used by other
entities to validate valid inter-connections. The policy can also
include revocation and validation lists (Authcert,
PrefixPolicycert).
ASPolicycerts are verified with a digital signature, where the
public key of the certificate issuer is distributed in an
Entitycert. Before a receiver can verify the ASPolicycerts, they
MUST first verify that the verifying Entitycert is authentic.
6.5 Entitycert Uniform Resource Locators
Authcerts, PrefixPolicycerts, and ASPolicycerts may contain a URL
that references the Entitycert used to validate it. Care should be
taken in evaluating the URL since it is not yet known to be valid
and could be used to propagate a denial of service attack.
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7.0 IANA Considerations
This document defines three certificate types, each of which contains
a series of TLVs. IANA is expected to maintain a registry of all the
values defined, according to the following sections.
7.1 soBGP Certificate Attribute Values
The following Type values in soBGP certificate TLVs are to be defines
as follows:
o Type values 1 through 4, 14 and 65535 are assigned in this
document.
o Type values 5 through 13 and 15 through 16575 MUST be assigned
using the "IETF Consensus" policy defined in RFC 2434
[RFC2434].
o Type values 16576 through 32895 SHOULD be assigned using the
"Specification Required" policy defined in RFC 2434 [RFC2434].
o Type values 32896 through 65534 are for "Private Use" as defined
in RFC 2434 [RFC2434].
7.2 Signature Type
The Signature TLV Signature Type field:
o Type values 1 is assigned in this document.
o Type values 2 through 16575 MUST be assigned using the "IETF
Consensus" policy defined in RFC 2434 [RFC2434].
o Type values 16576 through 32895 SHOULD be assigned using the
"Specification Required" policy defined in RFC 2434 [RFC2434].
o Type values 32896 through 65534 are for "Private Use" as defined
in RFC 2434 [RFC2434].
7.3 Policies Type
The Policies Type has two name spaces: Options flags and SubTVs.
The Options Field:
o Bits 0 and 1 are assigned in this document.
o Bits 2 thru 7 MUST be assigned using the "IETF Consensus"
policy defined in RFC 2434 [RFC2434].
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o Bits 8 thru 15 are for "Private Use" as defined in RFC 2434
[RFC2434].
The subTV TV Type field:
o TV Type values 1 through 3 are assigned in this document.
o TV Type values 4 through 16575 MUST be assigned using the "IETF
Consensus" policy defined in RFC 2434 [RFC2434].
o TV Type values 16576 through 32895 SHOULD be assigned using the
"Specification Required" policy defined in RFC 2434 [RFC2434].
o TV Type values 32896 through 65534 are for "Private Use" as
defined in RFC 2434 [RFC2434].
7.4 Validity Ranges
o Type values 1 through 2 are assigned in this document.
o Type values 3 through 16575 MUST be assigned using the "IETF
Consensus" policy defined in RFC 2434 [RFC2434].
o Type values 16576 through 32895 SHOULD be assigned using the
"Specification Required" policy defined in RFC 2434 [RFC2434].
o Type values 32896 through 65534 are for "Private Use" as defined
in RFC 2434 [RFC2434].
8.0 Acknowledgments
A large number of people contributed to or provided valuable feedback
on this document; we've tried to include all of them here (in no
particular order), but might have missed a few: James Ng, Russ White,
Alvaro Retana, Dave Cook, John Scudder, David Ward, Martin Djernaes,
Max Pritikin, Chris Lonvick, Tim Gage, Scott Fanning, Barry Friedman,
Jim Duncan, Yi Yang, Robert Adams, Tony Tauber, Iljitsch van Beijnum,
Ed Lewis, Bora Akyol, and Jonathan Natale.
9.0 References
9.1 Normative References
[IANA-AFN] http://www.iana.org/assignments/address-family-numbers
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Level", BCP 14, RFC 2119, March 1997.
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[RFC2434] Narten, T., and H. Alvestrand,, "Guidelines for Writing an
IANA Considerations Section in RFCs", RFC 2434, October 1998.
[RFC2858] Bates, T., Chandra, R., Katz, D., and Y. Rekhter,
"Multiprotocol Extensions for BGP-4", RFC 2858, June 2000.
[RFC3279] Polk, T., et. al., " Algorithms and Identifiers for the
Internet X.509 Public Key Infrastructure Certificate and Certificate
Revocation List (CRL) Profile", RFC 3279, April 2002.
[RFC3280] Housley, R., et. al., "Internet X.509 Public Key
Infrastructure Certificate and CRL Profile", RFC 3280, April 2002.
[RFC3779] Lynn, C., Kent, S. and K. Seo, "X.509 Extensions for IP
Addresses and AS Identifiers", draft-ietf-pkix-x509-ipaddr-as-extn-
03.txt, RFC 3779, June 2004.
[SOBGP-ARCH] White, R. (editor), "Architecture and Deployment
Considerations for Secure Origin BGP (soBGP)", draft-white-sobgp-
architecture-01.txt, Work in Progress, February 11, 2005.
[SOBGP-BGP] Ng, J. (editor), "Extensions to BGP to Support Secure
Origin BGP (soBGP)", draft-ng-sobgp-extensions-02.txt, Work in
Progress, April 2004.
[SOBGP-RADIUS] Lonvick, C., "RADIUS Attributes for soBGP Support",
draft-lonvick-sobgp-radius-04.txt, Work in Progress, February 13,
2004.
[X.690] International Telecommunication Union, "ITU-T Recommendation
X.660 Information Technology - ASN.1 encoding rules: Specification
of Basic Encoding Rules (BER), Canonical Encoding Rules (CER) and
Distinguished Encoding Rules (DER), 1997.
9.2 Informative References
[RFC3281] Farrell, S., and R. Housley, " An Internet Attribute
Certificate Profile for Authorization", RFC 3281, April 2002.
[RFC3552] E. Rescorla, et. al., "Guidelines for Writing RFC Text on
Security Considerations", RFC 3552, July 2003.
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Appendix A. Example Certificates
This section contains several examples of soBGP certificates. The
first example is an Entitycert, followed by an Authcert.
A.1. Entitycert
This section contains an annotated hex dump of an 862 byte
Entitycert. In this example, AS 100 is a large ISP that has created a
self-signed certificate. Because it is self-signed, AS 100 has placed
its own identity in both the subjectAltName and issuerAltName. AS 100
can now act as a Certificate Server for its customers.
This certificate was processed using Peter Gutman's dumpasn1 utility
(invoked with -ail flags) to generate the output. The source for the
dumpasn1 utility is available at
http://www.cs.auckland.ac.nz/~pgut001/dumpasn1.c.
0 870: SEQUENCE {
4 590: SEQUENCE {
8 3: [0] {
10 1: INTEGER 2
: }
13 9: INTEGER 00 98 3A 42 D0 83 4C 30 55
24 13: SEQUENCE {
26 9: OBJECT IDENTIFIER sha1withRSAEncryption (1 2 840 113549
1 1 5)
: (PKCS #1)
37 0: NULL
: }
39 62: SEQUENCE {
41 11: SET {
43 9: SEQUENCE {
45 3: OBJECT IDENTIFIER countryName (2 5 4 6)
: (X.520 id-at (2 5 4))
50 2: PrintableString 'US'
: }
: }
54 19: SET {
56 17: SEQUENCE {
58 3: OBJECT IDENTIFIER stateOrProvinceName (2 5 4 8)
: (X.520 id-at (2 5 4))
63 10: PrintableString 'California'
: }
: }
75 26: SET {
77 24: SEQUENCE {
79 3: OBJECT IDENTIFIER organizationName (2 5 4 10)
: (X.520 id-at (2 5 4))
84 17: PrintableString 'Sample Tier 1 ISP'
: }
: }
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: }
103 30: SEQUENCE {
105 13: UTCTime 18/02/2005 07:10:18 GMT
120 13: UTCTime 18/02/2006 07:10:18 GMT
: }
135 62: SEQUENCE {
137 11: SET {
139 9: SEQUENCE {
141 3: OBJECT IDENTIFIER countryName (2 5 4 6)
: (X.520 id-at (2 5 4))
146 2: PrintableString 'US'
: }
: }
150 19: SET {
152 17: SEQUENCE {
154 3: OBJECT IDENTIFIER stateOrProvinceName (2 5 4 8)
: (X.520 id-at (2 5 4))
159 10: PrintableString 'California'
: }
: }
171 26: SET {
173 24: SEQUENCE {
175 3: OBJECT IDENTIFIER organizationName (2 5 4 10)
: (X.520 id-at (2 5 4))
180 17: PrintableString 'Sample Tier 1 ISP'
: }
: }
: }
199 290: SEQUENCE {
203 13: SEQUENCE {
205 9: OBJECT IDENTIFIER rsaEncryption (1 2 840 113549 1 1 1)
: (PKCS #1)
216 0: NULL
: }
218 271: BIT STRING, encapsulates {
223 266: SEQUENCE {
227 257: INTEGER
: 00 BD 51 5E D0 01 BD CC A1 46 49 A3 F8 FC 81 07
: 60 68 A3 E1 9E E4 38 4D CC 8E D5 B0 C8 FC 27 4F
: 1D 63 8B 69 61 61 45 53 63 95 85 29 5B 9D 33 F5
: E2 22 CF 3E CA A4 64 3F B9 01 44 B6 09 9C 6E 75
: BF 9E E1 D5 67 23 AC 2C C9 99 A5 A6 CB DA 0A CE
: 4F 60 93 E9 FF 1F 56 26 B2 3D 53 2A AE B2 F1 9D
: 9F 4A DF AB 60 01 2D 5A 30 A2 BA D4 1E 98 34 47
: 35 3E A2 F9 36 19 8C BE 86 22 3A F1 EB 9F D0 90
: 86 6D 3B F4 0A 51 56 3D 5B 95 A6 43 C6 9B 04 E3
: 0B 66 C3 82 F8 17 A8 54 57 E0 0D A9 58 17 E9 1A
: EA 7E FA E6 1B 6B 8A 2A E1 2D 5B 2A 24 3B D0 1D
: 87 5B BF B9 CF 48 42 04 57 A9 E1 64 6C 0A 6E 00
: A4 1C A6 EA B2 F9 39 F8 76 48 4B 3C F0 AA 14 A1
: 1D 44 83 76 F7 BC 8F A5 0D A9 76 A4 8F 00 3C BC
: 1B 7D AC EE 94 BD D4 A9 AE 2C 99 3C D2 4F 71 E1
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: A8 32 CF A9 27 90 F7 18 A9 D5 23 83 09 73 47 FE
: 55
488 3: INTEGER 65537
: }
: }
: }
493 103: [3] {
495 101: SEQUENCE {
497 29: SEQUENCE {
499 3: OBJECT IDENTIFIER subjectKeyIdentifier (2 5 29 14)
: (X.509 id-ce (2 5 29))
504 22: OCTET STRING, encapsulates {
506 20: OCTET STRING
: FC 2B 62 B0 F0 20 80 BB 66 2F D3 B9 59 8B 0F E7
: 9E 2C BC C4
: }
: }
528 12: SEQUENCE {
530 3: OBJECT IDENTIFIER basicConstraints (2 5 29 19)
: (X.509 id-ce (2 5 29))
535 5: OCTET STRING, encapsulates {
537 3: SEQUENCE {
539 1: BOOLEAN TRUE
: }
: }
: }
542 26: SEQUENCE {
544 3: OBJECT IDENTIFIER subjectAltName (2 5 29 17)
: (X.509 id-ce (2 5 29))
549 19: OCTET STRING, encapsulates {
551 17: SEQUENCE {
553 15: [0] {
555 8: OBJECT IDENTIFIER
: bgp-autonomousSysNum (1 3 6 1 5 5 7 1 8)
: (PKIX private extension)
565 3: [0] {
567 1: INTEGER 100
: }
: }
: }
: }
: }
570 26: SEQUENCE {
572 3: OBJECT IDENTIFIER issuerAltName (2 5 29 18)
: (X.509 id-ce (2 5 29))
577 19: OCTET STRING, encapsulates {
579 17: SEQUENCE {
581 15: [0] {
583 8: OBJECT IDENTIFIER
: bgp-autonomousSysNum (1 3 6 1 5 5 7 1 8)
: (PKIX private extension)
593 3: [0] {
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595 1: INTEGER 100
: }
: }
: }
: }
: }
: }
: }
: }
598 13: SEQUENCE {
600 9: OBJECT IDENTIFIER sha1withRSAEncryption (1 2 840 113549
1 1 5)
: (PKCS #1)
611 0: NULL
: }
613 257: BIT STRING
: 43 6A 45 03 E4 B7 FD 6B 57 9F 75 A5 F4 1F 63 73
: 6C 27 33 2B 05 9B 16 17 D0 3B 1C 71 9C C0 34 EF
: 49 64 D2 31 50 0C 65 FF 75 92 D4 A9 6A 88 FD 97
: 3A ED 84 A2 47 49 B9 06 B4 0F 72 D4 56 DA 56 94
: D1 5B 0E AD C2 61 FE 67 CB 44 05 55 3E BC D4 3F
: C6 8E 32 EF F5 00 17 8C CB 31 37 1C C0 F3 EA E8
: BD 81 8B D2 B6 AB 64 A2 49 C3 10 AE 50 35 35 BD
: E9 5D 53 87 98 13 91 DC 7B 03 ED FB 87 BF F3 D1
: 98 18 B4 A5 56 F5 D3 5D 97 7D F1 C0 FC 8A 77 3C
: 1F 6B 50 06 59 2C 4A 93 A2 C0 57 E7 A3 33 2B DC
: 98 41 E0 90 4E 29 5A 15 60 6A 72 D7 A0 87 14 3A
: AB CE D9 69 C7 67 0C 89 DA 27 00 2E FC 6D F4 E0
: 10 B1 1B 3C DA CA 6D AF 88 23 0B 02 52 4C BD 22
: 12 BA 77 8B B6 40 CB C2 FE F8 32 6D CC B3 2F 6D
: FF 0D E4 55 E8 2C A6 EC 66 12 86 D5 6B 3D F8 95
: 1F E3 0A AB B0 33 35 AB 79 0B 79 BF 8E D4 FA 7D
: }
A.2. Authcert
This section contains an annotated hex dump of a 183 byte Authcert.
In this example, AS 101 has authorized AS 200 to use the prefix
12.1/16.
This certificate was processed using a special purpose utility to
generate the output.
0 183 : HEADER
: CERTIFICATE MARKER 162
: TYPE_ID 1
4 8 : ATTRIBUTE TYPE 1 (Originating Autonomous System)
: AS NUMBER 101
12 8 : ATTRIBUTE TYPE 2 (Authorized Autonomous System)
: AS NUMBER 200
20 8 : ATTRIBUTE TYPE 3 (Serial Number)
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: SERIAL NUMBER 43
28 11 : ATTRIBUTE TYPE 6 (Address Prefix)
: AFI 1 SAFI 1
: PREFIX 12.1/16
39 144 : ATTRIBUTE TYPE 7 (Signature)
: SIGNATURE TYPE 1
: ISSUERS
: ISSUER AS 101
: ENTITYCERT SERIAL NUMBER 17
: SIGNATURE
: 29 0A 72 67 92 33 C7 62 62 AD 36 4A 45 D6 F2 F5
: D1 1E 31 31 22 7F 7B 79 9F E7 99 02 2F F5 1F 06
: 64 3C 22 C9 C9 FB EB 3B D7 86 CC DB 56 32 1C 7E
: 86 A6 CD 0A 09 50 E2 AD 5A D9 66 39 EE 3D 27 10
: 14 C3 BA 04 29 0C D0 95 26 08 D9 E6 AF E9 0C 33
: D8 D6 BD D6 83 0E C2 2B A4 A5 B4 89 8C CA BC A2
: BB A4 40 87 AF 50 02 53 2C FD 9A 83 78 64 DE DB
: D4 BC 91 5C AB E9 7D BF 17 84 C9 34 A5 6D 3D 0D
Editor's Address
Brian Weis
Cisco Systems
170 W. Tasman Drive,
San Jose, CA 95134-1706, USA
(408) 526-4796
bew@cisco.com
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Acknowledgement
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Weis Expires August, 2006 [Page 45]
