Internet Engineering Task Force Charles Lynn
Internet Draft Stephen Kent
draft-ietf-pkix-x509-ipaddr-as-extn-00.txt Karen Seo
Expires August 2002 BBN Technologies
February 2002
X.509 Extensions for IP Addresses and AS Identifiers
Status of this Memo
This document is an Internet Draft and is in full conformance with
all provisions of Section 10 of [RFC2026]. Internet Drafts are
working documents of the Internet Engineering Task Force (IETF), its
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Copyright (C) The Internet Society 2002. All Rights Reserved.
Abstract
This document defines two private X.509 v3 certificate extensions.
The first binds a list of IP address blocks, or prefixes, to the
subject of a certificate. The second binds a list of Autonomous
System Identifiers to the subject of a certificate. These extensions
may be used to convey the authorization of the subject to use the IP
addresses and Autonomous System identifiers contained in the
extensions.
Please send comments on this draft to the ietf-pkix@imc.org mail
list.
Table of Contents
Status of this Memo . . . . . . . . . . . . . . . . . . . . . . . 1
Abstract . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Table of Contents . . . . . . . . . . . . . . . . . . . . . . . . 1
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
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2. IP Address Delegation Extension . . . . . . . . . . . . . . . 4
2.1. Context . . . . . . . . . . . . . . . . . . . . . . . . . . 4
2.2. Specification . . . . . . . . . . . . . . . . . . . . . . . 4
2.2.1. OID . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
2.2.2. Criticality. . . . . . . . . . . . . . . . . . . . . . . . 5
2.2.3. Syntax . . . . . . . . . . . . . . . . . . . . . . . . . . 5
2.2.3.1. Type IPAddrBlocks . . . . . . . . . . . . . . . . . . . 6
2.2.3.2. Type IPAddressFamily . . . . . . . . . . . . . . . . . . 6
2.2.3.3. Element addressFamily . . . . . . . . . . . . . . . . . 6
2.2.3.4. Element ipAddressChoice and Type IPAddressChoice . . . . 6
2.2.3.5. Element inherit . . . . . . . . . . . . . . . . . . . . 6
2.2.3.6. Element addressesOrRanges . . . . . . . . . . . . . . . 7
2.2.3.7. Type IPAddressOrRange . . . . . . . . . . . . . . . . . 7
2.2.3.8. Element addressPrefix and Type IPAddress . . . . . . . . 7
2.2.3.9. Element addressRange and Type IPAddressRange . . . . . . 8
2.3. IP Address Delegation Extension Certification Path
Validation . . 9
3. Autonomous System Identifier Delegation Extension . . . . . . 9
3.1. Context. . . . . . . . . . . . . . . . . . . . . . . . . . . 9
3.2. Specification. . . . . . . . . . . . . . . . . . . . . . . . 10
3.2.1. OID. . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
3.2.2. Criticality . . . . . . . . . . . . . . . . . . . . . . . 10
3.2.3. Syntax . . . . . . . . . . . . . . . . . . . . . . . . . 10
3.2.3.1. Type ASIdentifiers . . . . . . . . . . . . . . . . . . . 11
3.2.3.2. Elements asnum, rdi, and Type ASIdentifierChoice . . . . 11
3.2.3.3. Element inherit . . . . . . . . . . . . . . . . . . . . 11
3.2.3.4. Element asIdOrRanges . . . . . . . . . . . . . . . . . . 12
3.2.3.5. Type ASIdOrRange . . . . . . . . . . . . . . . . . . . . 12
3.2.3.6. Element id . . . . . . . . . . . . . . . . . . . . . . . 12
3.2.3.7. Element range . . . . . . . . . . . . . . . . . . . . . 12
3.2.3.8. Type ASRange . . . . . . . . . . . . . . . . . . . . . . 12
3.2.3.9. Elements min and max . . . . . . . . . . . . . . . . . . 12
3.2.3.10. Type ASId . . . . . . . . . . . . . . . . . . . . . . . 12
3.3. Autonomous System Identifier Delegation Extension
Certification Path Validation . . 12
4. Security Considerations . . . . . . . . . . . . . . . . . . . 13
5. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 13
Appendix A -- Examples of IP Address Delegation Extensions . . . . 13
Appendix B -- Example of an AS Identifier Delegation Extension . . 17
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Disclaimer . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Authors' Address . . . . . . . . . . . . . . . . . . . . . . . . . 19
Intellectual Property Rights . . . . . . . . . . . . . . . . . . . 19
Full Copyright Statement . . . . . . . . . . . . . . . . . . . . . 20
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1. Introduction
This document defines two private X.509 v3 certificate extensions.
The first binds a list of IP address blocks, or prefixes, to the
subject (private key holder) of a certificate. The second binds a
list of Autonomous System (AS) Identifiers to the subject of a
certificate. These extensions convey that the subject "owns" or is
authorized to use the IP address blocks and AS Identifiers contained
in the extensions. The issuer of the certificate would typically be
the entity (e.g., IANA, a regional registry, ISP) who owns the set of
IP address blocks and AS Identifiers from which the subject's IP
address blocks or AS Identifiers have been taken and who made the
delegation of the resources to the subject. These certificates
provide a scalable means of verifying the ownership of IP address
prefixes and AS Identifiers, e.g., they can be used by routing
protocols such as Secure BGP [S-BGP] to verify legitimacy/correctness
of routing information.
It is assumed that the reader is familiar with the terms and concepts
described in [PKIX-1], [RFC2459] (PKIX X.509 certificate profile),
[RFC791] (IPv4), [RFC2373] (IPv6). Some relevant terms include:
advertise - (see [RFC1771]).
delegate - Transfer ownership of an IP address block or AS identifier
through issuance of a certificate to the new owner.
downstream service provider (DSP) - Second or lower tier internet
service provider.
initial octet - the first octet in the value of a DER encoded BIT
STRING [X.690].
IP v4 address (IPv4) - a 32-bit identifier written as four decimal
numbers, each in the range 0 to 255, separated by "."s. 10.5.0.5
is an example.
IP v6 address (IPv6) - a 128-bit identifier written as eight
hexadecimal quantities, each in the range 0 to ffff, separated by
":"s. 2001:0:2:3:0:0:0:1 is an example. One string of :0:
quantities may be replaced by "::", thus 2001:0:2:3::1 represents
the same address as the immediately preceding example. (See
[RFC2373]).
own - for an IP address prefix, being authorized to specify the AS
that may originate advertisement of the prefix throughout the
Internet. For an Autonomous System Identifier, being authorized
to operate a network(s) that identifies itself to other network
operators using that Autonomous System Identifier. Or, for
either, being authorized to delegate ownership to another entity.
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subsequent octets - the second through last octets in the value of a
DER encoded BIT STRING [X.690].
The keywords MUST, MUST NOT, REQUIRED, SHALL, SHALL NOT, SHOULD,
SHOULD NOT, RECOMMENDED, MAY, and OPTIONAL, when they appear in this
document, are to be interpreted as described in [RFC2119].
2. IP Address Delegation Extension
This extension conveys the delegation of ownership of IP addresses to
the subject by binding those addresses to a public key belonging to
the subject.
2.1. Context
IP address space is currently managed by a hierarchy nominally rooted
at ICANN, but managed by Internet Regional Registries (e.g., APNIC,
ARIN, and RIPE). ICANN delegates IP address space to the Registries,
who in turn delegate IP address space to internet service providers
(ISPs), who delegate IP address space to down stream providers
(DSPs), etc. Any level in the hierarchy can also delegate IP address
space to organizations who are end entities, i.e., organizations who
will not be re-delegating any of their space to other organizations.
The IP address delegation extension is intended to enable
verification of this ownership of IP address blocks, i.e., of the
authorization of an entity to use or delegate IP address space.
Accordingly, it makes sense to take advantage of the inherent
authoritativeness of the existing hierarchy for delegating IP address
space. Thus the PKI hierarchy for issuing certificates with this
extension SHOULD parallel the IP address delegation hierarchy. The
roots of the PKI hierarchy will be the regional Internet Registries
(i.e., APNIC, ARIN, RIPE, etc.), the next level down will be the
ISPs, etc. An example of one use of this extension is a router using
it to verify the authorization of an organization to originate a BGP
UPDATE advertising a path to a particular IP address block [S-BGP].
2.2. Specification
2.2.1. OID
The OID for this extension is id-pe-ipAddrBlock.
id-pe-ipAddrBlock OBJECT IDENTIFIER ::= { id-pe 7 }
where [RFC2459] defines
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id-pkix OBJECT IDENTIFIER ::= { iso(1) identified-organization(3)
dod(6) internet(1) security(5) mechanisms(5) pkix(7) }
id-pe OBJECT IDENTIFIER ::= { id-pkix 1 }
2.2.2. Criticality
This extension can be CRITICAL or NOT CRITICAL at the discretion of
the CA issuing the certificate. The intended use of this extension
is to connote ownership of the block(s) of IP addresses identified in
the extension. A CA might well mark the extension as CRITICAL to
convey the notion that a relying party must understand the semantics
of the extension to make use of the certificate. Newly created
applications that would make use of certificates containing this
extension would be expected to recognize the extension. However,
many common application implementations (e.g., browsers) that might
make use of certificates that contain this extension, (as clients not
as replying parties) do not tolerate CRITICAL private extensions, and
thus a CA may choose to not mark this extension as CRITICAL, to avoid
compatibility problems with these application implementations.
2.2.3. Syntax
id-pe-ipAddrBlock OBJECT IDENTIFIER ::= { id-pe 7 }
IPAddrBlocks ::= SEQUENCE OF IPAddressFamily
IPAddressFamily ::= SEQUENCE {
addressFamily OCTET STRING (SIZE (2..3)), -- AFI & opt SAFI
ipAddressChoice IPAddressChoice }
IPAddressChoice ::= CHOICE {
inherit BOOLEAN, -- Inherit from Issuer
addressesOrRanges SEQUENCE OF IPAddressOrRange }
IPAddressOrRange ::= CHOICE {
addressPrefix IPAddress,
addressRange IPAddressRange }
IPAddressRange ::= SEQUENCE {
min IPAddress,
max IPAddress }
IPAddress ::= BIT STRING
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2.2.3.1. Type IPAddrBlocks
The IPAddrBlocks type is a sequence of IPAddressFamily types.
2.2.3.2. Type IPAddressFamily
The IPAddressFamily type is a sequence containing an addressFamily
and ipAddressChoice element.
2.2.3.3. Element addressFamily
The addressFamily element is an OCTET STRING containing a two-octet
Address Family Identifier (AFI), in network byte order, optionally
followed by a one-octet Subsequent Address Family Identifier (SAFI).
AFI's and SAFI's are specified in [IANA] and [RFC2283], respectively.
There MUST be only one IPAddressFamily sequence per unique
combination of AFI and SAFI. Each sequence MUST be ordered by
ascending addressFamily values (treating the octets as unsigned
quantities). An addressFamily without a SAFI MUST precede one that
contains a SAFI. When both IPv4 and IPv6 addresses are specified,
the IPv4 addresses MUST precede the IPv6 addresses (since the IPv4
AFI of 0001 is less than the IPv6 AFI of 0002).
2.2.3.4. Element ipAddressChoice and Type IPAddressChoice
The ipAddressChoice element is of type IPAddressChoice. The
IPAddressChoice type is a CHOICE of either an inherit or
addressesOrRanges element.
2.2.3.5. Element inherit
If the IPAddressChoice choice contains the inherit element, then the
BOOLEAN MUST be TRUE. In this case, the set of authorized IP
addresses for the specified AFI and optional SAFI is taken from the
Issuer's certificate, or the Issuer's Issuer's certificate,
recursively, until a certificate containing an IPAddressChoice
containing an addressesOrRanges element is located. If no
authorization is being granted for a particular AFI and optional
SAFI, then there SHOULD NOT be an IPAddressFamily member for that
AFI/SAFI in the IPAddrBlocks sequence; i.e., the AFI/SAFI should be
omitted rather than setting inherit BOOLEAN to FALSE.
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2.2.3.6. Element addressesOrRanges
The addressesOrRanges element is a sequence of IPAddressOrRange
types. The addressPrefixes and addressRange elements MUST be sorted
using the representation IP address/prefix length. Note that the
bytes in this representation (a.b.c.d/length for IPv4 or
s:t:u:v:w:x:y:z/length for IPv6) are not in the same order as occurs
in a DER encoded BIT STRING. For example, given two addressPrefixes:
IP addr/length DER encoding
-------------- --------------
10.32.0.0/12 03 03 04 0a 20
10.64.0.0/16 03 03 00 0a 40
the prefix 10.32.0.0/12 MUST come before the prefix 10.64.0.0/16
since 32 is less than 64; whereas if one were to sort by the DER BIT
STRINGs, the order would be reversed as the unused bits octet would
sort in the opposite order. Any pair of IPAddressOrRange choices in
an extension MUST NOT overlap each other. Any contiguous address
prefixes or ranges MUST be combined into a single range or, when
possible, a single prefix.
2.2.3.7. Type IPAddressOrRange
The IPAddressOrRange type is a CHOICE of either an addressPrefix (an
IP address Prefix) or an addressRange (an IP address range) element.
2.2.3.8. Element addressPrefix and Type IPAddress
The addressPrefix element is an IPAddress type. The IPAddress type
defines a range of IP addresses in which the most significant (left-
most) N bits of the address remain constant while the remaining bits
(32 - N for IPv4, or 128 - N for IPv6) may be either zero or one. A
prefix is written as the constant octets followed by a "/" and the
number of constant bits (N). For example, the IPv4 prefix 10.64/12
corresponds to the addresses 10.64.0.0 to 10.79.255.255 while
10.64/11 corresponds to 10.64.0.0 to 10.95.255.255. The IPv6 prefix
2001:0:2/48 represents addresses 2001:0:2:: to
2001:0:2:ffff:ffff:ffff:ffff:ffff.
An IP address prefix is encoded as a BIT STRING. The DER encoding of
a BIT STRING uses the initial octet of the string to specify how many
of the least significant bits of the last subsequent octet are
unused. DER encoding specifies that these unused bits MUST be set to
zero. The special case of all IP address blocks, i.e., a prefix of
all zero bits -- "0/0", MUST be encoded per DER with a length octet
of one, an initial octet of zero, and no subsequent octets -- 0x03,
0x01, 0x00. Note that the number of trailing zero bits is
significant for IP addresses. For example, the DER encoding of
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10.64/12, 0x03, 0x03, 0x04, 0x0a, 0x40, is different than 10.64/11,
encoded as 0x03, 0x03, 0x05, 0x0a, 0x40.
2.2.3.9. Element addressRange and Type IPAddressRange
The addressRange element is of type IPAddressRange. The
IPAddressRange type consists of a SEQUENCE containing a minimum
(element min) and maximum (element max) IP address. Each IP address
is encoded as a BIT STRING. The semantic interpretation of the
minimum address in an IPAddressRange is that all the unspecified bits
(for the full length of the IP address) are zero-bits (0). The
semantic interpretation of the maximum address is that all the
unspecified bits are one-bits (1).
Note that an IP address prefix can be encoded as a range, where the
minimum and maximum values would be identical. However, a range of
IP addresses MUST, whenever possible, be encoded as a single prefix
and NOT be encoded as a range.
1) Address ranges (bit strings) should be sorted into ascending order
by most-significant address bits
2) Contiguous prefixes and/or ranges MUST be combined into a single
prefix (whenever possible) or range.
Let "LMBx" denote the "Left Most Bits of x".
3) If a range is of the form minimum IP address = <n LMBp><zeros>
and maximum IP address = <n LMBp><ones>,
where n >= 0, then the prefix form MUST be used:
BIT STRING ((8 - (n mod 8)) mod 8) <n LMBp><zero pad last byte>
else the min/max form MUST be used.
Example:
128.0.0.0 = 1000 0000.0000 0000.0000 0000.0000 0000
to 143.255 255 255 = 1000 1111.1111 1111.1111 1111.1111 1111
BIT STRING 4 128 -- 1000
4) A min/max form with minimum IP address = <(i - 1) LMBn><1><zeros>
and maximum IP address = <(j - 1) LMBx><0><ones>
MUST be encoded as:
SEQUENCE {
BIT STRING ((8 - (i mod 8)) mod 8) <i LMBn><zero pad last byte>
BIT STRING ((8 - (j mod 8)) mod 8) <j LMBx><zero pad last byte>
}
I.e., all trailing zero bits are removed from the min and all
trailing 1 bits are removed from the max.
Example:
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129.64.0.0 = 1000 0001.0100 0000.0000 0000.0000 0000
to 143.255.255.255 = 1000 1111.1111 1111.1111 1111.1111 1111
SEQUENCE {
BIT STRING 6 129 64 -- 1000 0001.01
BIT STRING 4 128 -- 1000
}
To simplify the comparison of IP address blocks when performing
certificate path validation, a maximum IP address MUST contain at
least one bit whose value is 1, i.e., the subsequent octets may
neither be omitted nor all zero.
NOTE: this specification could require that the least
significant bit in the encoding of the max BIT STRING be a 1.
This would insure that a broken ASN.1 DER encoder that removes
all trailing zero bits, when DER encoding a BIT STRING, does
not silently change the semantics of the max element.
SHOULD THE SPECIFICATION REQUIRE THIS DEFENSIVE ACTION?
2.3. IP Address Delegation Extension Certification Path Validation
Certification path validation of a certificate containing the IP
address delegation extension requires additional processing. As each
certificate in a path is validated, the IP addresses in the IP
address delegation extension of that certificate must be subsumed by
IP addresses in the IP address delegation extension in the issuer's
certificate.
3. Autonomous System Identifier Delegation Extension
This extension conveys the delegation of ownership of Autonomous
System (AS) identifiers to the subject by binding those AS
identifiers to a public key belonging to the subject.
3.1. Context
AS identifier delegation is currently managed by a hierarchy with
roots at ICANN and the Internet Registries (APNIC, ARIN, RIPE, etc.).
ICANN delegates AS identifiers to the Registries, who in turn
delegate AS identifiers to organizations who are end entities, i.e.,
will not be re-delegating any of their identifiers to other
organizations. The AS identifier delegation extension is intended to
enable verification of this ownership of AS identifiers, i.e., of the
authorization of an entity to use these AS identifiers. Accordingly,
it makes sense to take advantage of the inherent authoritativeness of
the existing hierarchy for delegating AS identifiers. Thus the PKI
hierarchy for issuing certificates with this extension SHOULD
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parallel the AS identifier delegation hierarchy. The roots of the
PKI hierarchy will be the regional Internet Registries (i.e., APNIC,
ARIN, RIPE, etc.). An example of one use of this extension is a
router using it to verify the authorization of an organization to
prepend an AS Number to the AS_PATH attribute of a BGP UPDATE
[S-BGP].
3.2. Specification
3.2.1. OID
The OID for this extension is id-pe-autonomousSysId.
id-pe-autonomousSysId OBJECT IDENTIFIER ::= { id-pe 8 }
where [RFC2459] defines
id-pkix OBJECT IDENTIFIER ::= { iso(1) identified-organization(3)
dod(6) internet(1) security(5) mechanisms(5) pkix(7) }
id-pe OBJECT IDENTIFIER ::= { id-pkix 1 }
3.2.2. Criticality
This extension can be CRITICAL or NOT CRITICAL at the discretion of
the CA issuing the certificate. The intended use of this extension
is to connote ownership of the AS identifiers in the extension. A CA
might well mark the extension as CRITICAL to convey the notion that a
relying party must understand the semantics of the extension to make
use of the certificate. Newly created applications that would make
use of certificates containing this extension would be expected to
recognize the extension. However, many common application
implementations (e.g., browsers) that might make use of certificates
that contain this extension, (as clients not as replying parties) do
not tolerate CRITICAL private extensions, and thus a CA may choose to
not mark this extension as CRITICAL, to avoid compatibility problems
with these application implementations.
3.2.3. Syntax
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id-pe -autonomousSysId OBJECT IDENTIFIER ::= { id-pe 8 }
ASIdentifiers ::= SEQUENCE {
asnum [0] EXPLICIT ASIdentifierChoice OPTIONAL,
rdi [1] EXPLICIT ASIdentifierChoice OPTIONAL}
ASIdentifierChoice ::= CHOICE {
inherit BOOLEAN, -- Inherit from Issuer
asIdsOrRanges SEQUENCE OF ASIdOrRange }
ASIdOrRange ::= CHOICE {
id ASId,
range ASRange }
ASRange ::= SEQUENCE {
min ASId,
max ASId }
ASId ::= INTEGER
3.2.3.1. Type ASIdentifiers
The ASIdentifiers type is a SEQUENCE containing one or more forms of
Autonomous System identifiers -- AS numbers (in the asnum element) or
Routing Domain Identifiers (in the rdi element). When the
ASIdentifiers type contains multiple forms of identifiers, the asnum
entry will precede the rdi entry. AS numbers are used by BGP and
Routing Domain Identifiers are specified in the IDRP.
3.2.3.2. Elements asnum, rdi, and Type ASIdentifierChoice
The asnum and rdi elements are both of type ASIdentifierChoice. The
ASIdentifierChoice type is a CHOICE of either the inherit or
asIdsOrRanges element.
3.2.3.3. Element inherit
If the ASIdentifierChoice choice contains the inherit element, then
the BOOLEAN MUST be TRUE. In this case, the set of authorized AS
identifiers is taken from the Issuer's certificate, or the Issuer's
Issuer's certificate, recursively, until a certificate containing an
ASIdentifierChoice containing an sasIdsOrRanges element is located.
If no authorization is being granted for a particular form of AS
identifier then there SHOULD NOT be an asnum/rdi member in the
ASIdentifiers sequence; i.e., the member should be omitted rather
than setting inherit BOOLEAN to FALSE.
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3.2.3.4. Element asIdsOrRanges
The asIdsOrRanges element is a SEQUENCE of ASIdOrRange types. Any
pair of items in the asIdsOrRanges SEQUENCE MUST NOT overlap.
3.2.3.5. Type ASIdOrRange
The ASIdOrRange type is a CHOICE of either a single integer (ASId) or
a single sequence (ASRange).
3.2.3.6. Element id
The id element has type ASId.
3.2.3.7. Element range
The range element has type ASRange.
3.2.3.8. Type ASRange
The ASRange type is a SEQUENCE of a min and a max element and is used
to specify a range of AS identifier values.
3.2.3.9. Elements min and max
The min and max elements have type ASId. The min element is used to
specify the value of the minimum AS identifier in the range and the
max elements specifies the value of the maximum AS identifier in the
range.
3.2.3.10. Type ASId
The ASId type is an INTEGER.
3.3. Autonomous System Identifier Delegation Extension Certification
Path Validation
Certification path validation of a certificate containing the
Autonomous System identifier delegation extension requires additional
processing. As each certificate in a path is validated, the AS
identifiers in the Autonomous System identifier delegation extension
of that certificate must be subsumed by the AS identifiers in the
Autonomous System identifier delegation extension in the issuer's
certificate.
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4. Security Considerations
This specification describes two private X.509 extensions. Since
X.509 certificates are digitally signed, no additional integrity
service is necessary. Certificates with these extensions need not be
kept secret, and unrestricted and anonymous access to these
certificates has no security implications.
However, security factors outside the scope of this specification
will affect the assurance provided to certificate users. This
section highlights critical issues that should be considered by
implementors, administrators, and users.
These extensions represent authorization information, i.e., ownership
of IP addresses and/or AS identifiers. They were developed to
support a secure version of BGP, but may be employed in other
contexts. In the secure BGP context, certificates containing these
extensions function as capabilities, i.e., the certificate asserts
that the holder of the private key (the Subject) owns the IP
addresses and/or AS identifiers represented in the extension(s). As
a result of this capability model, the Subject field is largely
irrelevant for security purposes, contrary to common PKI conventions.
5. Acknowledgements
The authors would like to acknowledge the contributions to this
specification by Charles Gardiner and Russ Housley.
Providing feedback could get your name here!
Appendix A -- Examples of IP Address Delegation Extensions
A non-critical X.509 v3 certificate extension that specifies:
IPv4 unicast address prefixes
1) 10.0.32/20 i.e., 10.0.32.0 to 10.0.47.255
2) 10.0.64/24 i.e., 10.0.64.0 to 10.0.64.255
3) 10.1/16 i.e., 10.1.0.0 to 10.1.255.255
4) 10.2.48/20 i.e., 10.2.48.0 to 10.2.63.255
5) 10.2.64/24 i.e., 10.2.64.0 to 10.2.64.255
6) 10.3/16 i.e., 10.3.0.0 to 10.3.255.255
and
7) inherits all IPv6 addresses from the Issuer's certificate
would be (in hexadecimal):
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30 44 Extension {
06 08 2b06010505070107 extnID 1.3.6.1.5.5.7.1.7
critical FALSE (thus omitted)
04 38 extnValue {
30 36 IPAddrBlocks {
30 2b IPAddressFamily {
04 03 0001 01 addressFamily: IPv4 Unicast
IPAddressChoice {
30 24 addressesOrRanges {
IPAddressOrRange {
03 04 04 0a0020 addressPrefix 10.0.32/20
} -- IPAddressOrRange
IPAddressOrRange {
03 04 00 0a0040 addressPrefix 10.0.64/24
} -- IPAddressOrRange
IPAddressOrRange {
03 03 00 0a01 addressPrefix 10.1/16
} -- IPAddressOrRange
IPAddressOrRange {
30 0c addressRange {
03 04 04 0a0230 min 10.2.48.0
03 04 00 0a0240 max 10.2.64.255
} -- addressRange
} -- IPAddressOrRange
IPAddressOrRange {
03 03 00 0a03 addressPrefix 10.3/16
} -- IPAddressOrRange
} -- addressesOrRanges
} -- IPAddressChoice
} -- IPAddressFamily
30 07 IPAddressFamily {
04 02 0002 addressFamily: IPv6
IPAddressChoice {
01 01 ff inherit: TRUE from Issuer
} -- IPAddressChoice
} -- IPAddressFamily
} -- IPAddrBlocks
} -- extnValue
} -- Extension
This example illustrates how the prefixes and ranges are sorted.
+ Prefix 1 precedes prefix 2, even though the number of unused bits
(4) in prefix 1 is larger than the number of unused bits (0) in
prefix 2.
+ Prefix 2 precedes prefix 3 even though the number of octets (4) in
the BIT STRING encoding of prefix 2 is larger than the number of
octets (3) in the BIT STRING encoding of prefix 3.
+ Prefixes 4 and 5 are adjacent (representing the range of address
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from 10.2.48.0 to 10.2.64.255), so MUST be combined into a range
(since the range cannot be encoded by a single prefix).
+ Note that the six trailing zero bits in the max element of the
range are significant to the semantic interpretation of the value
(as all unused bits are interpreted to be 1's, not 0's). The four
trailing zero bits in the min element are not significant and MUST
be removed (thus the (4) unused bits in the encoding of the min
element). (DER encoding requires that unused bits in the last
subsequent octet be set to zero.)
+ The range formed by prefixes 4 and 5 precedes prefix 6 even though
the SEQUENCE encoding for a range (30) is larger than the encoding
for a BIT STRING (03) used to encode a prefix.
+ The IPv4 information precedes the IPv6 information since the
address family identifier for IPv4 (0001) is less than the
identifier for IPv6 (0002).
An extension specifying the IPv6 prefix 2001:0:2/48 and the IPv4
prefixes 10/8 and 172.16/12, and which inherits all IPv4 multicast
addresses from the issuer's certificate would be:
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30 3b Extension {
06 08 2b06010505070107 extnID 1.3.6.1.5.5.7.1.7
critical FALSE (thus omitted)
04 2f extnValue {
30 2d IPAddrBlocks {
30 10 IPAddressFamily {
04 03 0001 01 addressFamily: IPv4 Unicast
IPAddressChoice {
30 09 addressesOrRanges {
IPAddressOrRange {
03 02 00 0a addressPrefix 10/8
} -- IPAddressOrRange
IPAddressOrRange {
03 03 04 b010 addressPrefix 172.16/12
} -- IPAddressOrRange
} -- addressesOrRanges
} -- IPAddressChoice
} -- IPAddressFamily
30 08 IPAddressFamily {
04 03 0001 02 addressFamily: IPv4 Multicast
IPAddressChoice {
01 01 ff inherit: TRUE from Issuer
} -- IPAddressChoice
} -- IPAddressFamily
30 0f IPAddressFamily {
04 02 0002 addressFamily: IPv6
IPAddressChoice {
30 09 addressesOrRanges {
IPAddressOrRange {
03 07 00 200100000002 addressPrefix 2001:0:2/48
} -- IPAddressOrRange
} -- addressesOrRanges
} -- IPAddressChoice
} -- IPAddressFamily
} -- IPAddrBlocks
} -- extnValue
} -- Extension
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Appendix B -- Example of an AS Identifier Delegation Extension
An extension that specifies AS Numbers 135, 3000 to 3999, and 5001,
and which inherits all Routing Domain Identifiers from the issuers
certificate would be (in hexadecimal):
30 29 Extension {
06 08 2b06010505070108 extnID 1.3.6.1.5.5.7.1.8
critical FALSE (thus omitted)
04 1d extnValue {
30 1b ASIdentifiers {
a0 14 asnum
ASIdentifierChoice {
30 12 asIdsOrRanges {
ASIdOrRange {
02 02 0087 ASId
} -- ASIdOrRange
ASIdOrRange {
30 08 ASRange {
02 02 0bb8 min
02 02 0f9f max
} -- ASRange
} -- ASIdOrRange
ASIdOrRange {
02 02 1389 ASId
} -- ASIdOrRange
} -- asIdsOrRanges
} -- ASIdentifierChoice
} -- asnum
a1 03 rdi {
ASIdentifierChoice {
01 01 ff inherit
} -- ASIdentifierChoice
} -- rdi
} -- ASIdentifiers
} -- extnValue
} -- Extension
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References
[IANA] IANA web page, http://www.iana.org, has assignments for
several number spaces, including "Address Family Numbers".
[PKIX-1] R. Housley, W. Ford, W. Polk, D. Solo, "Internet X.509
Public Key Infrastructure Certificate and CRL Profile",
draft-ietf-pkix-new-part1-08.txt, July 2001.
[PKIX-ALG] Bassham, L., Housley, R., and W. Polk, "Internet X.509
Public Key Infrastructure Representation of Public Keys
and Digital Signatures,"
draft-ietf-pkix-ipki-pkalgs-00.txt, July 14, 2000.
[RFC1700] Reynolds, J., and J. Postel, "Assigned Numbers", STD 2,
RFC 1700, October 1994. (see also
http://www.iana.org/iana/assignments.html)
[RFC2026] Bradner, S., "The Internet Standards Process -- Revision
3", RFC 2026, BCP 00009, October 1996.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Level", BCP 14, RFC 2119, March 1997.
[RFC2373] R. Hinden, S. Deering, "IP Version 6 Addressing
Architecture", RFC 2373, July 1998.
[RFC2459] Housley, R., Ford, W., Polk, W., Solo, D., "Internet X.509
Public Key Infrastructure Certificate and CRL Profile",
RFC 2459, January 1999.
[S-BGP] S. Kent, C. Lynn, and K. Seo, "Secure Border Gateway Protocol
(S-BGP)," IEEE JSAC Special Issue on Network Security,
April 2000.
[X.509] ITU-T Recommendation X.509 (1997 E): "Information
Technology - Open Systems Interconnection - The Directory:
Authentication Framework", June 1997.
[X.690] ITU-T Recommendation X.690 (1997) | ISO/IEC 8825-1:1998,
"Information Technology - ASN.1 Encoding Rules:
Specification of Basic Encoding Rules (BER), Canonical
Encoding Rules (CER) and Distinguished Encoding Rules
(DER)".
Disclaimer
The views and specification here are those of the authors and are not
necessarily those of their employers. The authors and their
employers specifically disclaim responsibility for any problems
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arising from correct or incorrect implementation or use of this
specification.
Authors' Address
Charles Lynn
BBN Technologies
10 Moulton St.
Cambridge, MA 02138
USA
Phone: +1 (617) 873-3367
Email: CLynn@BBN.Com
Stephen Kent
BBN Technologies
10 Moulton St.
Cambridge, MA 02138
USA
Phone: +1 (617) 873-3988
Email: Kent@BBN.Com
Karen Seo
BBN Technologies
10 Moulton St.
Cambridge, MA 02138
USA
Phone: +1 (617) 873-3152
Email: KSeo@BBN.Com
Intellectual Property Rights
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proprietary rights by implementors or users of this specification can
be obtained from the IETF Secretariat.
The IETF invites any interested party to bring to its attention any
Expires August 2002 Lynn, Kent, Seo [Page 19]
Internet Draft X.509 Extensions for IP Addr and AS ID February 2002
copyrights, patents or patent applications, or other proprietary
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Expires August 2002 Lynn, Kent, Seo [Page 20]
