Updated IPSEC DOI draft
Derrell Piper <piper@tgv.com> Mon, 09 December 1996 17:11 UTC
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To: ipsec@tis.com
Subject: Updated IPSEC DOI draft
Date: Mon, 09 Dec 1996 08:49:38 -0800
From: Derrell Piper <piper@tgv.com>
Sender: owner-ipsec@ex.tis.com
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Folks,
Here's an updated IPSEC DOI draft that incorporates most of the comments
I've received since its initial posting.
Derrell
------ cut here ------
Network Working Group Derrell Piper
INTERNET-DRAFT cisco Systems
draft-ietf-ipsec-ipsec-doi-02.txt December 9, 1996
The Internet IP Security Domain of Interpretation for ISAKMP
<draft-ietf-ipsec-ipsec-doi-02.txt>
Status of this Memo
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documents of the Internet Engineering Task Force (IETF), its areas,
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Distribution of this memo is unlimited. This draft will expire six
months from date of issue.
1. Abstract
The Internet Security Association and Key Management Protocol
(ISAKMP) defines a framework for security association management and
cryptographic key establishment for the Internet. This framework
consists of defined exchanges and processing guidelines that occur
within a given Domain of Interpretation (DOI). This document details
the Internet IP Security DOI, which is defined to cover the IP
security protocols that use ISAKMP to negotiate their security
associations.
2. Introduction
Within ISAKMP, a Domain of Interpretation is used to group related
protocols using ISAKMP to negotiate security associations. Security
protocols sharing a DOI choose security protocol and cryptographic
transforms from a common namespace and share key exchange protocol
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identifiers. They also share a common interpretation of DOI-specific
payload data content, including the Security Association and
Identification payloads.
Overall, ISAKMP places the following requirements on a DOI
definition:
o define the naming scheme for DOI-specific protocol identifiers
o define the interpretation for the Situation field
o define the set of applicable security policies
o define the syntax for DOI-specific SA Attributes (phase II)
o define the syntax for DOI-specific payload contents
o define additional mappings or Key Exchange types, if needed
The remainder of this document details the instantiation of these
requirements for using the IP Security (IPSEC) protocols to provide
data origin authentication and/or data confidentiality for IP packets
sent between cooperating host systems and/or firewalls.
3. Terms and Definitions
3.1 Requirements Terminology
In this document, the words that are used to define the significance
of each particular requirement are usually capitalised. These words
are:
- MUST
This word or the adjective "REQUIRED" means that the item is an
absolute requirement of the specification.
- SHOULD
This word or the adjective "RECOMMENDED" means that there might
exist valid reasons in particular circumstances to ignore this
item, but the full implications should be understood and the case
carefully weighed before taking a different course.
- MAY
This word or the adjective "OPTIONAL" means that this item is
truly optional. One vendor might choose to include the item
because a particular marketplace requires it or because it
enhances the product, for example; another vendor may omit the
same item.
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4.1 IPSEC Naming Scheme
Within ISAKMP, all DOI's must be registered with the IANA in the
``Assigned Numbers'' RFC [STD-2]. The IANA Assigned Number for the
Internet IP Security DOI is one (1). Within the IPSEC DOI, all
well-known identifiers MUST be registered with the IANA under the
Internet IP Security DOI. Unless otherwise noted, all tables within
this document refer to IANA Assigned Numbers for the IPSEC DOI.
All multi-octet binary values are stored in network byte order.
4.2 IPSEC Situation Definition
Within ISAKMP, the Situation provides information that can be used by
the responder to make a policy determination about how to process the
incoming Security Association request. For the IPSEC DOI, the
Situation field is a four (4) octet bitmask with the following
values.
Situation Value
--------- -----
SIT_IDENTITY_ONLY 0x01
SIT_SECRECY 0x02
SIT_INTEGRITY 0x04
All other values are reserved to IANA.
4.2.1 SIT_IDENTITY_ONLY
The SIT_IDENTITY_ONLY type specifies that the security association
will be identified by source identity information present in an
associated Identification Payload. See Section 4.6.2 for a complete
description of the various Identification types. All IPSEC DOI
implementations MUST support SIT_IDENTITY_ONLY by including an
Identification Payload in at least one of the phase I Oakley
exchanges ([IO], Section 5) and MUST abort any association setup that
does not include an Identification Payload.
If an initiator supports neither SIT_SECRECY nor SIT_INTEGRITY, the
situation consists only of the 4 octet situation bitmap and does not
include the Labeled Domain Identifier field (Figure 1, Section 4.6.1)
or any subsequent label information.
4.2.2 SIT_SECRECY
The SIT_SECRECY type specifies that the security association is being
negotiated in an environment that requires labeled secrecy. If
SIT_SECRECY is present in the Situation bitmap, the Situation field
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will be followed by variable-length data that includes a sensitivity
level and compartment bitmask. See Section 4.6.1 for a complete
description of the Security Association Payload format.
If an initiator does not support SIT_SECRECY, SIT_SECRECY MUST NOT be
set in the Situation bitmap and no secrecy level or category bitmaps
shall be included.
If a responder does not support SIT_SECRECY, a SITUATION-NOT-
SUPPORTED Notification Payload SHOULD be returned and the security
association setup MUST be aborted.
4.2.3 SIT_INTEGRITY
The SIT_INTEGRITY type specifies that the security association is
being negotiated in an environment that requires labeled integrity.
If SIT_INTEGRITY is present in the Situation bitmap, the Situation
field will be followed by variable-length data that includes an
integrity level and compartment bitmask. If SIT_SECRECY is also in
use for the association, the integrity information immediately
follows the variable-length secrecy level and categories. See
section 4.6.1 for a complete description of the Security Association
Payload format.
If an initiator does not support SIT_INTEGRITY, SIT_INTEGRITY MUST
NOT be set in the Situation bitmap and no integrity level or category
bitmaps shall be included.
If a responder does not support SIT_INTEGRITY, a SITUATION-NOT-
SUPPORTED Notification Payload SHOULD be returned and the security
association setup MUST be aborted.
4.3 IPSEC Security Policy Requirement
The IPSEC DOI does not impose specific security policy requirements
on any implementation. Host system policy issues are outside of the
scope of this document.
However, the following sections touch on some of the issues that must
be considered when designing an IPSEC DOI host implementation. This
section should be considered only informational in nature.
4.3.1 Key Management Issues
It is expected that many systems choosing to implement ISAKMP will
strive to provide a protected domain of execution for a combined
ISAKMP/Oakley key management daemon. On protected-mode multiuser
operating systems, this key management daemon will likely exist as a
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separate privileged process.
In such an environment, a formalized API to introduce keying material
into the TCP/IP kernel may be desirable. The PF_KEY API [PFKEY] is
an example of one such API that provides an abstracted key management
interface.
4.3.2 Static Keying Issues
Host systems that implement static keys, either for use directly by
IPSEC, or for authentication purposes (see [IO] Section 5.3), should
take steps to protect the static keying material when it is not
residing in a protected memory domain or actively in use by the
TCP/IP kernel.
For example, on a laptop, one might choose to store the static keys
in a configuration store that is, itself, encrypted under a private
password.
Depending on the operating system and utility software installed, it
may not be possible to protect the static keys once they've been
loaded into the TCP/IP kernel, however they should not be trivially
recoverable on initial system startup without having to satisfy some
additional form of authentication.
4.3.3 Host Policy Issues
It is not realistic to assume that the transition to IPSEC will occur
overnight. Host systems must be prepared to implement flexible
policy lists that describe which systems they desire to speak
securely with and which systems they require speak securely to them.
Some notion of proxy firewall addresses may also be required.
A minimal approach is probably a static list of IP addresses, network
masks, and a security required flag or flags.
A more flexible implementation might consist of a list of wildcard
DNS names (e.g. '*.foo.bar'), an in/out bitmask, and an optional
firewall address. The wildcard DNS name would be used to match
incoming or outgoing IP addresses, the in/out bitmask would be used
to determine whether or not security was to be applied and in which
direction, and the optional firewall address would be used to
indicate whether or not tunnel mode would be needed to talk to the
target system though an intermediate firewall.
4.3.4 Certificate Management
Host systems implementing a certificate-based authentication scheme
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will need a mechanism for obtaining and managing a database of
certificates.
Secure DNS is to be one certificate distribution mechanism, however
the pervasive availability of secure DNS zones, in the short term, is
doubtful for many reasons. What's far more likely is that hosts will
need an ability to import certificates that they acquire through
secure, out-of-band mechanisms, as well as an ability to export their
own certificates for use by other systems.
However, manual certificate management should not be done so as to
preclude the ability to introduce dynamic certificate discovery
mechanisms and/or protocols as they become available.
4.4 IPSEC Assigned Numbers
The following sections list the Assigned Numbers for the IPSEC DOI
Security Protocol Identifiers, Transform Identifiers, and Security
Association Attribute Types.
4.4.1 IPSEC Security Protocol Identifiers
The ISAKMP proposal syntax was specifically designed to allow for the
simultaneous negotiation of multiple security protocol suites within
a single negotiation. As a result, the protocol suites listed below
form the set of protocols that can be negotiated at the same time.
It is a host policy decision as to what protocol suites might be
negotiated together.
The following table lists the values for the Security Protocol
Identifiers referenced in an ISAKMP Proposal Payload for the IPSEC
DOI.
Protocol ID Value
----------- -----
RESERVED 0
PROTO_ISAKMP 1
PROTO_IPSEC_AH 2
PROTO_IPSEC_ESP 3
The values 4-15360 are reserved to IANA. Values 15361-16384 are
reserved for private use.
4.4.1.1 PROTO_ISAKMP
The PROTO_ISAKMP type specifies message protection required during
Phase I of the ISAKMP protocol. The specific protection mechanism
used for the IPSEC DOI is described in [IO]. All implementations
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within the IPSEC DOI MUST support PROTO_ISAKMP.
NB: ISAKMP reserves the value one (1) across all DOI definitions.
4.4.1.2 PROTO_IPSEC_AH
The PROTO_IPSEC_AH type specifies IP packet data origin
authentication. Confidentiality MUST NOT be provided by any
PROTO_IPSEC_AH transform.
4.4.1.3 PROTO_IPSEC_ESP
The PROTO_IPSEC_ESP type specifies IP packet confidentiality. Data
origin authentication, if required, must be provided as part of the
ESP transform. The default ESP transform includes data origin
authentication and replay prevention.
4.4.2 IPSEC ISAKMP Transform Values
As part of an ISAKMP Phase I negotiation, the initiator's choice of
Key Exchange offerings is made using some host system policy
description. The actual selection of Key Exchange mechanism is made
using the standard ISAKMP Proposal Payload. The following table
lists the defined ISAKMP Phase I Transform Identifiers for the
Proposal Payload for the IPSEC DOI.
Transform Value
--------- -----
RESERVED 0
KEY_OAKLEY 1
KEY_MANUAL 2
KEY_KDC 3
The values 4-15360 are reserved to IANA. Values 15361-16384 are
reserved for private use.
4.4.2.1 KEY_OAKLEY
The KEY_OAKLEY type specifies the hybrid ISAKMP/Oakley Diffie-Hellman
key exchange as defined in the [IO] document. All implementations
within the IPSEC DOI MUST support KEY_OAKLEY.
4.4.2.2 KEY_MANUAL
The KEY_MANUAL type specifies that a shared secret key mechanism is
to be used in lieu of a dynamic key mechanism. Specific details of a
static key establishment protocol will be described in a future
document.
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4.4.2.3 KEY_KDC
The KEY_KDC type specifies that a secret-key based Key Distribution
Center will be used to provide dynamic key exchange through a
Kerberos-like ticket protocol. Specific details of a KDC-based key
establishment protocol will be described in a future document.
4.4.3 IPSEC AH Transform Values
The Authentication Header Protocol (AH) defines one mandatory and
several optional transforms used to provide data origin
authentication. The following table lists the defined AH Transform
Identifiers for the ISAKMP Proposal Payload for the IPSEC DOI.
Transform Value
--------- -----
RESERVED 0
AH_MD5_KPDK 1
AH_MD5_HMAC 2
AH_MD5_HMAC_REPLAY 3
AH_SHA_MHAC_REPLAY 4
The values 5-15360 are reserved to IANA. Values 15361-16384 are
reserved for private use.
4.4.3.1 AH_MD5_KPDK
The AH_MD5_KPDK type specifies the AH transform (Key/Pad/Data/Key)
described in RFC-1826 and RFC-1828. This mode should be used only
for compatibility with existing implementations.
4.4.3.2 AH_MD5_HMAC
The AH_MD5_HMAC type specifies the transform described in [HMAC].
This mode should be used only for compatibility with existing
implementations.
4.4.3.3 AH_MD5_HMAC_REPLAY
The AH_MD5_HMAC_REPLAY type specifies the transform described in
[HMACMD5]. This transform MUST be supported by all implementations
and is the preferred AH transform for the IPSEC DOI.
4.4.3.4 AH_SHA_HMAC_REPLAY
The AH_SHA_HMAC_REPLAY type specifies the transform described in
[HMACSHA]. While not required, it is strongly recommended that all
implementations include the AH_SHA_HMAC_REPLAY transform in addition
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to AH_MD5_HMAC_REPLAY.
4.4.4 IPSEC ESP Transform Identifiers
The Encapsulating Security Protocol (ESP) defines one mandatory and
several optional transforms used to provide data confidentiality.
The following table lists the defined ESP Transform Identifiers for
the ISAKMP Proposal Payload for the IPSEC DOI.
Transform ID Value
------------ -----
RESERVED 0
ESP_DES_CBC_TRANSPORT 1
ESP_DES_CBC_TUNNEL 2
ESP_3DES_CBC 3
ESP_DES_CBC_HMAC_REPLAY 4
The values 5-15360 are reserved to IANA. Values 15361-16384 are
reserved for private use.
4.4.4.1 ESP_DES_CBC_TRANSPORT
The ESP_DES_CBC_TRANSPORT type specifies the ESP transform described
in RFC-1827 and RFC-1829, operating in Transport Mode. This mode
should be used only for compatibility with existing implementations.
4.4.4.2 ESP_DES_CBC_TUNNEL
The ESP_DES_CBC_TUNNEL type specifies the ESP transform described in
RFC-1827 and RFC-1829, operating in Tunnel Mode. This mode should be
used only for compatibility with existing implementations.
4.4.4.3 ESP_3DES_CBC
The ESP_3DES_CBC type specifies the transform described in RFC-1851.
This mode should be used only for compatiblity with existing
implementations.
4.4.4.4 ESP_DES_CBC_HMAC_REPLAY
The ESP_DES_CBC_HMAC_REPLAY type specifies the transform described in
[Hughes]. This transform MUST be supported by all implementations
and is the preferred ESP transform for the IPSEC DOI.
4.5 IPSEC Security Association Atttributes
The following SA attribute definitions are used in phase II of an
ISAKMP/Oakley negotation. Attribute types can be either Basic (B) or
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Variable-Length (V). Encoding of these attributes is defined in the
base ISAKMP specification.
Attribute Classes
class value type
-------------------------------------------------
Auth Key Life Type 1 B
Auth Key Life Duration 2 B/V
Enc Key Life Type 3 B
Enc Key Life Duration 4 B/V
SA Life Type 5 B
SA Life Duration 6 B/V
Replay Protection 7 B
Group Description 8 B
CA Distinguished Name 9 B
Class Values
Auth Key Life Type
Enc Key Life Type
SA Life Type
seconds 1
kilobytes 2
Values 3-65000 are reserved to IANA. Values 65001-65535
are for experimental use. For a given "Life Type," the
value of the "Life Duration" attribute defines the actual
length of the component lifetime -- either a number of
seconds, or a number of Kbytes that can be protected.
Replay Protection
not required 0
required 1
Values 2-65000 are reserved to IANA. Values 65001-65535
are for experimental use.
Group Description
default group 1 ([IO], Section 5.5.1)
Values 2-32767 are reserved to IANA. Values 32768-65535
are for private use among mutually consenting parties.
CA Distinguished Name
DNS Security 1 (Section 4.8)
Values 2-32767 are reserved to IANA. Values 32768-65535
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are for private use among mutually consenting parties.
4.5.1 Attribute List Parsing Requirement
In order to allow for flexible semantics, the IPSEC DOI requires that
a conforming ISAKMP implementation MUST correctly parse an attribute
list that contains multiple instances of the same attribute class, so
long as the different attribute entries do not conflict with one
another.
To see why this is important, the following example shows the binary
encoding of a four entry attribute list that specifies an Encryption
Key Lifetime of either 100MB or 24 hours. (See Section 3.3 of
[ISAKMP] for a complete description of the attribute encoding
format.)
Attribute #1:
0x80030001 (AF = 1, type = Enc Key Life Type, value = seconds)
Attribute #2:
0x00040004 (AF = 0, type = Enc Key Duration, length = 4 bytes)
0x00015180 (value = 0x15180 = 86400 seconds = 24 hours)
Attribute #3:
0x80030002 (AF = 1, type = Enc Key Life Type, value = KB)
Attribute #4:
0x00040004 (AF = 0, type = Enc Key Duration, length = 4 bytes)
0x000186A0 (value = 0x186A0 = 100000KB = 100MB)
If conflicting attributes are detected, an ATTRIBUTES-NOT-SUPPORTED
Notification Payload SHOULD be returned and the security association
setup MUST be aborted.
4.6 IPSEC Payload Content
The following sections describe those ISAKMP payloads whose data
representations are dependent on the applicable DOI.
4.6.1 Security Association Payload
The following diagram illustrates the content of the Security
Association Payload for the IPSEC DOI. See Section 4.2 for a
description of the Situation bitmap.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
! Next Payload ! RESERVED ! Payload Length !
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+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
! Domain of Interpretation (IPSEC) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
! Situation (bitmap) !
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
! Labeled Domain Identifier !
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
! Secrecy Length (in octets) ! RESERVED !
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
~ Secrecy Level ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
! Secrecy Cat. Length (in bits) ! RESERVED !
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
~ Secrecy Category Bitmap ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
! Integrity Length (in octets) ! RESERVED !
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
~ Integrity Level ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
! Integ. Cat. Length (in bits) ! RESERVED !
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
~ Integrity Category Bitmap ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1: Security Association Payload Format
The Security Association Payload is defined as follows:
o Next Payload (2 octets) - Identifier for the payload type of
the next payload in the message. If the current payload is
the last in the message, this field will be zero (0).
o RESERVED (1 octet) - Unused, must be zero (0).
o Payload Length (2 octets) - Length, in octets, of the current
payload, including the generic header.
o Domain of Intepretation (4 octets) - Specifies the IPSEC DOI,
which has been assigned the value one (1).
o Situation (4 octets) - Bitmask used to interpret the
remainder of the Security Association Payload. See Section
4.2 for a complete list of values.
o Labeled Domain Identifier (4 octets) - IANA Assigned Number
used to interpret the Secrecy and Integrity information.
o Secrecy Length (2 octets) - Specifies the length, in octets,
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of the secrecy level identifier.
o Secrecy Category Length (2 octets) - Specifies the length, in
bits, of the secrecy category (compartment) bitmap.
o Secrecy Category Bitmap (variable length) - A bitmap used to
designate secrecy categories (compartments) that are
required.
o Integrity Length (2 octets) - Specifies the length, in
octets, of the integrity level identifier.
o Integrity Category Length (2 octets) - Specifies the length,
in bits, of the integrity category (compartment) bitmap.
o Integrity Category Bitmap (variable length) - A bitmap used
to designate integrity categories (compartments) that are
required.
4.6.1.1 Labeled Domain Identifier Values
The following table lists the assigned values for the Labeled Domain
Identifier field contained in the Situation field of the Security
Association Payload.
Domain Value
------- -----
RESERVED 0
The values 1-0x7fffffff are reserved to IANA. Values 0x8000000-
0xffffffff are reserved for private use.
4.6.2 Identification Payload Content
The Identification Payload is used to identify the initiator of the
Security Association. The identity of the initiator SHOULD be used
by the responder to determine the correct host system security policy
requirement for the association. For example, a host might choose to
require data origin authentication without confidentiality (AH) from
a certain set of IP addresses and full authentication with
confidentiality (Hughes) from another range of IP addresses. The
Identification Payload provides information that can be used by the
responder to make this decision.
The following diagram illustrates the content of the Identification
Payload.
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
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+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
! Next Payload ! RESERVED ! Payload Length !
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
! ID Type ! RESERVED !
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
~ Identification Data ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2: Identification Payload Format
The Identification Payload field is defined as follows:
o Next Payload (2 octets) - Identifier for the payload type of
the next payload in the message. If the current payload is
the last in the message, this field will be zero (0).
o RESERVED (1 octet) - Unused, must be zero (0).
o Payload Length (2 octets) - Length, in octets, of the
identification data, including the generic header.
o Identification Type (1 octet) - Value describing the
identity information found in the Identification Data field.
o RESERVED (3 octets) - Unused, must be zero (0).
4.6.2.1 Identifiction Type Values
The following table lists the assigned values for the Identification
Type field found in the Identification Payload.
ID Type Value
------- -----
RESERVED 0
ID_IPV4_ADDR 1
ID_FQDN 2
ID_USER_FQDN 3
ID_IPV4_ADDR_RANGE 4
ID_IPV6_ADDR 5
ID_IPV6_ADDR_RANGE 6
The values 6-500 are reserved to IANA. Values 501-512 are reserved
for private use.
4.6.2.2 ID_IPV4_ADDR
The ID_IPV4_ADDR type specifies a single four (4) octet IPv4 address.
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4.6.2.3 ID_FQDN
The ID_FQDN type specifies a fully-qualified domain name string. An
example of a ID_FQDN is, "foo.bar.com".
4.6.2.4 ID_USER_FQDN
The ID_USER_FQDN type specifies a fully-qualified username string, An
example of a ID_USER_FQDN is, "piper@foo.bar.com".
4.6.2.5 ID_IPV4_ADDR_RANGE
The ID_IPV4_ADDR_RANGE type specifies a range of IPv4 addresses,
represented by two four (4) octet values. The first value is an IPv4
address. The second is an IPv4 network mask. Note that ones (1s) in
the network mask indicate that the corresponding bit in the address
is fixed, while zeros (0s) indicate a "wildcard" bit.
4.6.2.6 ID_IPV6_ADDR
The ID_IPV6_ADDR type specifies a single sixteen (16) octet IPv6
address.
4.6.2.7 ID_IPV6_ADDR_RANGE
The ID_IPV6_ADDR_RANGE type specifies a range of IPv6 addresses,
represented by two sixteen (16) octet values. The first value is an
IPv6 address. The second is an IPv6 network mask. Note that ones
(1s) in the network mask indicate that the corresponding bit in the
address is fixed, while zeros (0s) indicate a "wildcard" bit.
4.7 IPSEC Security Parameter Index (SPI) Encoding
ISAKMP defines the SPI field as eight octets in length, however the
IPSEC transforms use only four octets.
All implementation MUST use the following mapping for the ISAKMP SPI
field in the IPSEC DOI.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
! SPI !
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
! RESERVED !
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 3: ISAKMP SPI Encoding
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The ISAKMP SPI field is defined as follows:
o SPI - Security Paramater Index (4 octets) - contains the
SPI value which identifies the security association.
o RESERVED (4 octets) - Unused, must be zero (0).
4.8 IPSEC Certificate Authorities
The ISAKMP Certificate Request Payload allows either side of an
ISAKMP negotiation to request its peer to provide a certificate chain
needed to authenticate itself. The Certificate Request Payload
includes a list of acceptable Certificate Types and Certificate
Authorities. Appropriate certificate chains are then returned in a
Certificate Payload response.
The IPSEC DOI defines the following Certificate Authorities for the
processing of Certificate Request Payloads. See Section 4.5 for
details on the specific data attribute type values for these CAs.
Certificate Authority
---------------------
DNS Security
4.8.1 DNS Security
This CA type represents the combination of KEY and SIG records, as
defined in [DNSSEC], that can be used for authentication. The
particular encoding required to formulate the Certificate Payload
(response) is TBD.
4.9 IPSEC Key Exchange Requirements
The IPSEC DOI introduces no additional Key Exhange types.
5. Security Considerations
This entire draft pertains to a hybrid protocol, combining Oakley
([OAKLEY]) with ISAKMP ([ISAKMP]), to negotiate and derive keying
material for security associations in a secure and authenticated
manner. Specific discussion of the various security protocols and
transforms identified in this document can be found in the associated
base documents.
Acknowledgements
This document is derived, in part, from previous works by Douglas
Maughan, Mark Schertler, Mark Schneider, Jeff Turner, Dan Harkins,
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INTERNET DRAFT IPSEC DOI December 9, 1996
and Dave Carrel.
References
[DNSSEC] Eastlake, Donald E., Kaufman, Charles W., "Domain Name
System Security Extensions", draft-ietf-dnssec-secext-10.txt.
[HMAC] Krawczyk, H., Bellare, M., Canetti, R., "HMAC: Keyed-Hashing
for Message Authentication", draft-ietf-ipsec-hmac-md5-01.txt.
[HMACMD5] Oehler, M., Glenn, R., "HMAC-MD5 IP Authentication with
Replay Prevention," draft-ietf-ipsec-ah-hmac-md5-03.txt.
[HMACSHA] Chang, S., Glenn, R., "HMAC-SHA IP Authentication with
Replay Prevention," draft-ietf-ipsec-ah-hmac-sha-03.txt.
[Hughes] Hughes, J., Editor, "Combined DES-CBC, HMAC and Replay
Prevention Transform," draft-ietf-ipsec-esp-des-md5-03.txt.
[IO] Carrel, D., Harkins, D., "The Resolution of ISAKMP with Oakley,"
draft-ietf-ipsec-isakmp-oakley-02.txt.
[ISAKMP] Maughan, D., Schertler, M., Schneider, M., and Turner, J.,
"Internet Security Association and Key Management Protocol (ISAKMP),"
draft-ietf-ipsec-isakmp-06.{ps,txt}.
[OAKLEY] H. K. Orman, "The OAKLEY Key Determination Protocol,"
draft-ietf-ipsec-oakley-01.txt.
[PFKEY] McDonald, D. L., Metz, C. W., Phan, B. G., "PF_KEY Key
Management API, Version 2", draft-mcdonald-pf-key-v2-00.txt, work in
progress.
Author's Address:
Derrell Piper <piper@cisco.com>
cisco Systems
101 Cooper St.
Santa Cruz, California, 95060
United States of America
+1 408 457-5384
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- Updated IPSEC DOI draft Derrell Piper