Network Working Group                                           D. Piper

Request for Comments: 2407                               Network Alchemy

Category: Standards Track                                  November 1998



      The Internet IP Security Domain of Interpretation for ISAKMP




Status of this Memo

   This document specifies an Internet standards track protocol for the

   Internet community, and requests discussion and suggestions for

   improvements.  Please refer to the current edition of the "Internet

   Official Protocol Standards" (STD 1) for the standardization state

   and status of this protocol.  Distribution of this memo is unlimited.




Copyright Notice



   Copyright (C) The Internet Society (1998).  All Rights Reserved.




IESG Note



   Section 4.4.4.2 states, "All implememtations within the IPSEC DOI

   MUST support ESP_DES...".  Recent work in the area of cryptanalysis

   suggests that DES may not be sufficiently strong for many

   applications.  Therefore, it is very likely that the IETF will

   deprecate the use of ESP_DES as a mandatory cipher suite in the near

   future.  It will remain as an optional use protocol.  Although the

   IPsec working group and the IETF in general have not settled on an

   alternative algorithm (taking into account concerns of security and

   performance), implementers may want to heed the recommendations of

   section 4.4.4.3 on the use of ESP_3DES.




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, payloads, and processing guidelines

   that occur within a given Domain of Interpretation (DOI).  This

   document defines the Internet IP Security DOI (IPSEC DOI), which

   instantiates ISAKMP for use with IP when IP uses ISAKMP to negotiate

   security associations.



   For a list of changes since the previous version of the IPSEC DOI,

   please see Section 7.




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

   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 Key Exchange types, if needed

     o  define additional Notification Message types, if needed



   The remainder of this document details the instantiation of these

   requirements for using the IP Security (IPSEC) protocols to provide

   authentication, integrity, and/or confidentiality for IP packets sent

   between cooperating host systems and/or firewalls.



   For a description of the overall IPSEC architecture, see [ARCH],

   [AH], and [ESP].




3. Terms and Definitions



   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 [RFC 2119].




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 (IPSEC DOI) is one (1).  Within the IPSEC

   DOI, all well-known identifiers MUST be registered with the IANA

   under the IPSEC DOI.  Unless otherwise noted, all tables within this

   document refer to IANA Assigned Numbers for the IPSEC DOI.  See

   Section 6 for further information relating to the IANA registry 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




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 ([IKE], 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.  Conversely, if the initiator

   supports either SIT_SECRECY or SIT_INTEGRITY, the Labeled Domain

   Identifier MUST be included in the situation payload.




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

   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 Requirements



   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 IKE

   key management daemon.  On protected-mode multiuser operating

   systems, this key management daemon will likely exist as a separate

   privileged process.



   In such an environment, a formalized API to introduce keying material

   into the TCP/IP kernel may be desirable.  The IP Security

   architecture does not place any requirements for structure or flow

   between a host TCP/IP kernel and its key management provider.




4.3.2 Static Keying Issues



   Host systems that implement static keys, either for use directly by

   IPSEC, or for authentication purposes (see [IKE] Section 5.4), 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

   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:

   Situation Identifiers, Protocol Identifiers, Transform Identifiers,

   AH, ESP, and IPCOMP Transform Identifiers, Security Association

   Attribute Type Values, Labeled Domain Identifiers, ID Payload Type

   Values, and Notify Message Type Values.




4.4.1 IPSEC Security Protocol Identifier



   The ISAKMP proposal syntax was specifically designed to allow for the

   simultaneous negotiation of multiple Phase II 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

       PROTO_IPCOMP                        4




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 [IKE].  All implementations

   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 authentication.  The

   default AH transform provides data origin authentication, integrity

   protection, and replay detection.  For export control considerations,

   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.

   Authentication, if required, must be provided as part of the ESP

   transform.  The default ESP transform includes data origin

   authentication, integrity protection, replay detection, and

   confidentiality.




4.4.1.4 PROTO_IPCOMP



   The PROTO_IPCOMP type specifies IP payload compression as defined in

   [IPCOMP].




4.4.2 IPSEC ISAKMP Transform Identifiers



   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_IKE                             1



   Within the ISAKMP and IPSEC DOI framework it is possible to define

   key establishment protocols other than IKE (Oakley).  Previous

   versions of this document defined types both for manual keying and

   for schemes based on use of a generic Key Distribution Center (KDC).

   These identifiers have been removed from the current document.



   The IPSEC DOI can still be extended later to include values for

   additional non-Oakley key establishment protocols for ISAKMP and

   IPSEC, such as Kerberos [RFC-1510] or the Group Key Management

   Protocol (GKMP) [RFC-2093].




4.4.2.1 KEY_IKE



   The KEY_IKE type specifies the hybrid ISAKMP/Oakley Diffie-Hellman

   key exchange (IKE) as defined in the [IKE] document.  All

   implementations within the IPSEC DOI MUST support KEY_IKE.




4.4.3 IPSEC AH Transform Identifiers



   The Authentication Header Protocol (AH) defines one mandatory and

   several optional transforms used to provide authentication,

   integrity, and replay detection.  The following table lists the

   defined AH Transform Identifiers for the ISAKMP Proposal Payload for

   the IPSEC DOI.



   Note: the Authentication Algorithm attribute MUST be specified to

   identify the appropriate AH protection suite.  For example, AH_MD5

   can best be thought of as a generic AH transform using MD5.  To

   request the HMAC construction with AH, one specifies the AH_MD5

   transform ID along with the Authentication Algorithm attribute set to

   HMAC-MD5.  This is shown using the "Auth(HMAC-MD5)" notation in the

   following sections.



       Transform ID                        Value

       ------------                        -----

       RESERVED                            0-1

       AH_MD5                              2

       AH_SHA                              3

       AH_DES                              4



   Note: all mandatory-to-implement algorithms are listed as "MUST"

   implement (e.g. AH_MD5) in the following sections.  All other

   algorithms are optional and MAY be implemented in any particular

   implementation.




4.4.3.1 AH_MD5



   The AH_MD5 type specifies a generic AH transform using MD5.  The

   actual protection suite is determined in concert with an associated

   SA attribute list.  A generic MD5 transform is currently undefined.



   All implementations within the IPSEC DOI MUST support AH_MD5 along

   with the Auth(HMAC-MD5) attribute.  This suite is defined as the

   HMAC-MD5-96 transform described in [HMACMD5].



   The AH_MD5 type along with the Auth(KPDK) attribute specifies the AH

   transform (Key/Pad/Data/Key) described in RFC-1826.



   Use of AH_MD5 with any other Authentication Algorithm attribute value

   is currently undefined.




4.4.3.2 AH_SHA



   The AH_SHA type specifies a generic AH transform using SHA-1.  The

   actual protection suite is determined in concert with an associated

   SA attribute list.  A generic SHA transform is currently undefined.



   All implementations within the IPSEC DOI MUST support AH_SHA along

   with the Auth(HMAC-SHA) attribute.  This suite is defined as the

   HMAC-SHA-1-96 transform described in [HMACSHA].



   Use of AH_SHA with any other Authentication Algorithm attribute value

   is currently undefined.




4.4.3.3 AH_DES



   The AH_DES type specifies a generic AH transform using DES.  The

   actual protection suite is determined in concert with an associated

   SA attribute list.  A generic DES transform is currently undefined.



   The IPSEC DOI defines AH_DES along with the Auth(DES-MAC) attribute

   to be a DES-MAC transform.  Implementations are not required to

   support this mode.



   Use of AH_DES with any other Authentication Algorithm attribute value

   is currently undefined.




4.4.4 IPSEC ESP Transform Identifiers



   The Encapsulating Security Payload (ESP) defines one mandatory and

   many 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.



   Note: when authentication, integrity protection, and replay detection

   are required, the Authentication Algorithm attribute MUST be

   specified to identify the appropriate ESP protection suite.  For

   example, to request HMAC-MD5 authentication with 3DES, one specifies

   the ESP_3DES transform ID with the Authentication Algorithm attribute

   set to HMAC-MD5.  For additional processing requirements, see Section

   4.5 (Authentication Algorithm).



       Transform ID                        Value

       ------------                        -----

       RESERVED                            0

       ESP_DES_IV64                        1

       ESP_DES                             2

       ESP_3DES                            3

       ESP_RC5                             4

       ESP_IDEA                            5

       ESP_CAST                            6

       ESP_BLOWFISH                        7

       ESP_3IDEA                           8

       ESP_DES_IV32                        9

       ESP_RC4                             10

       ESP_NULL                            11



   Note: all mandatory-to-implement algorithms are listed as "MUST"

   implement (e.g. ESP_DES) in the following sections.  All other

   algorithms are optional and MAY be implemented in any particular

   implementation.




4.4.4.1 ESP_DES_IV64



   The ESP_DES_IV64 type specifies the DES-CBC transform defined in

   RFC-1827 and RFC-1829 using a 64-bit IV.




4.4.4.2 ESP_DES



   The ESP_DES type specifies a generic DES transform using DES-CBC.

   The actual protection suite is determined in concert with an

   associated SA attribute list.  A generic transform is currently

   undefined.



   All implementations within the IPSEC DOI MUST support ESP_DES along

   with the Auth(HMAC-MD5) attribute.  This suite is defined as the

   [DES] transform, with authentication and integrity provided by HMAC

   MD5 [HMACMD5].




4.4.4.3 ESP_3DES



   The ESP_3DES type specifies a generic triple-DES transform.  The

   actual protection suite is determined in concert with an associated

   SA attribute list.  The generic transform is currently undefined.



   All implementations within the IPSEC DOI are strongly encouraged to

   support ESP_3DES along with the Auth(HMAC-MD5) attribute.  This suite

   is defined as the [ESPCBC] transform, with authentication and

   integrity provided by HMAC MD5 [HMACMD5].




4.4.4.4 ESP_RC5



   The ESP_RC5 type specifies the RC5 transform defined in [ESPCBC].




4.4.4.5 ESP_IDEA



   The ESP_IDEA type specifies the IDEA transform defined in [ESPCBC].




4.4.4.6 ESP_CAST



   The ESP_CAST type specifies the CAST transform defined in [ESPCBC].




4.4.4.7 ESP_BLOWFISH



   The ESP_BLOWFISH type specifies the BLOWFISH transform defined in

   [ESPCBC].




4.4.4.8 ESP_3IDEA



   The ESP_3IDEA type is reserved for triple-IDEA.




4.4.4.9 ESP_DES_IV32



   The ESP_DES_IV32 type specifies the DES-CBC transform defined in

   RFC-1827 and RFC-1829 using a 32-bit IV.




4.4.4.10 ESP_RC4



   The ESP_RC4 type is reserved for RC4.




4.4.4.11 ESP_NULL



   The ESP_NULL type specifies no confidentiality is to be provided by

   ESP.  ESP_NULL is used when ESP is being used to tunnel packets which

   require only authentication, integrity protection, and replay

   detection.



   All implementations within the IPSEC DOI MUST support ESP_NULL.  The

   ESP NULL transform is defined in [ESPNULL].  See the Authentication

   Algorithm attribute description in Section 4.5 for additional

   requirements relating to the use of ESP_NULL.




4.4.5 IPSEC IPCOMP Transform Identifiers



   The IP Compression (IPCOMP) transforms define optional compression

   algorithms that can be negotiated to provide for IP payload

   compression ([IPCOMP]).  The following table lists the defined IPCOMP

   Transform Identifiers for the ISAKMP Proposal Payload within the



   IPSEC DOI.



       Transform ID                        Value

       ------------                        -----

       RESERVED                            0

       IPCOMP_OUI                          1

       IPCOMP_DEFLATE                      2

       IPCOMP_LZS                          3




4.4.5.1 IPCOMP_OUI



   The IPCOMP_OUI type specifies a proprietary compression transform.

   The IPCOMP_OUI type must be accompanied by an attribute which further

   identifies the specific vendor algorithm.




4.4.5.2 IPCOMP_DEFLATE



   The IPCOMP_DEFLATE type specifies the use of the "zlib" deflate

   algorithm as specified in [DEFLATE].




4.4.5.3 IPCOMP_LZS



   The IPCOMP_LZS type specifies the use of the Stac Electronics LZS

   algorithm as specified in [LZS].




4.5 IPSEC Security Association Attributes



   The following SA attribute definitions are used in Phase II of an IKE

   negotiation.  Attribute types can be either Basic (B) or Variable-

   Length (V).  Encoding of these attributes is defined in the base

   ISAKMP specification.



   Attributes described as basic MUST NOT be encoded as variable.

   Variable length attributes MAY be encoded as basic attributes if

   their value can fit into two octets.  See [IKE] for further

   information on attribute encoding in the IPSEC DOI.  All restrictions

   listed in [IKE] also apply to the IPSEC DOI.



       Attribute Types



             class               value           type

       -------------------------------------------------

       SA Life Type                1               B

       SA Life Duration            2               V

       Group Description           3               B

       Encapsulation Mode          4               B

       Authentication Algorithm    5               B

       Key Length                  6               B

       Key Rounds                  7               B

       Compress Dictionary Size    8               B

       Compress Private Algorithm  9               V



       Class Values



         SA Life Type

         SA Duration



           Specifies the time-to-live for the overall security

           association.  When the SA expires, all keys negotiated under

           the association (AH or ESP) must be renegotiated.  The life

           type values are:



           RESERVED                0

           seconds                 1

           kilobytes               2



           Values 3-61439 are reserved to IANA.  Values 61440-65535 are

           for private 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.



           If unspecified, the default value shall be assumed to be

           28800 seconds (8 hours).



           An SA Life Duration attribute MUST always follow an SA Life

           Type which describes the units of duration.



           See Section 4.5.4 for additional information relating to

           lifetime notification.



         Group Description



           Specifies the Oakley Group to be used in a PFS QM

           negotiation.  For a list of supported values, see Appendix A

           of [IKE].



         Encapsulation Mode

           RESERVED                0

           Tunnel                  1

           Transport               2



           Values 3-61439 are reserved to IANA.  Values 61440-65535 are

           for private use.



           If unspecified, the default value shall be assumed to be

           unspecified (host-dependent).



         Authentication Algorithm

           RESERVED                0

           HMAC-MD5                1

           HMAC-SHA                2

           DES-MAC                 3

           KPDK                    4



           Values 5-61439 are reserved to IANA.  Values 61440-65535 are

           for private use.



           There is no default value for Auth Algorithm, as it must be

           specified to correctly identify the applicable AH or ESP

           transform, except in the following case.



           When negotiating ESP without authentication, the Auth

           Algorithm attribute MUST NOT be included in the proposal.



           When negotiating ESP without confidentiality, the Auth

           Algorithm attribute MUST be included in the proposal and the

           ESP transform ID must be ESP_NULL.



         Key Length

           RESERVED                0



           There is no default value for Key Length, as it must be

           specified for transforms using ciphers with variable key

           lengths.  For fixed length ciphers, the Key Length attribute

           MUST NOT be sent.



         Key Rounds

           RESERVED                0



           There is no default value for Key Rounds, as it must be

           specified for transforms using ciphers with varying numbers

           of rounds.



         Compression Dictionary Size

           RESERVED                0



           Specifies the log2 maximum size of the dictionary.



           There is no default value for dictionary size.



         Compression Private Algorithm



           Specifies a private vendor compression algorithm.  The first

           three (3) octets must be an IEEE assigned company_id (OUI).

           The next octet may be a vendor specific compression subtype,

           followed by zero or more octets of vendor data.




4.5.1 Required Attribute Support



   To ensure basic interoperability, all implementations MUST be

   prepared to negotiate all of the following attributes.



           SA Life Type

           SA Duration

           Auth Algorithm




4.5.2 Attribute Parsing Requirement (Lifetime)



   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.  Currently, the only attributes which requires this

   treatment are Life Type and Duration.



   To see why this is important, the following example shows the binary

   encoding of a four entry attribute list that specifies an SA Lifetime

   of either 100MB or 24 hours.  (See Section 3.3 of [ISAKMP] for a

   complete description of the attribute encoding format.)



     Attribute #1:

       0x80010001  (AF = 1, type = SA Life Type, value = seconds)



     Attribute #2:

       0x00020004  (AF = 0, type = SA Duration, length = 4 bytes)

       0x00015180  (value = 0x15180 = 86400 seconds = 24 hours)



     Attribute #3:

       0x80010002  (AF = 1, type = SA Life Type, value = KB)



     Attribute #4:

       0x00020004  (AF = 0, type = SA 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.




4.5.3 Attribute Negotiation



   If an implementation receives a defined IPSEC DOI attribute (or

   attribute value) which it does not support, an ATTRIBUTES-NOT-SUPPORT

   SHOULD be sent and the security association setup MUST be aborted,

   unless the attribute value is in the reserved range.



   If an implementation receives an attribute value in the reserved

   range, an implementation MAY chose to continue based on local policy.




4.5.4 Lifetime Notification



   When an initiator offers an SA lifetime greater than what the

   responder desires based on their local policy, the responder has

   three choices: 1) fail the negotiation entirely; 2) complete the

   negotiation but use a shorter lifetime than what was offered; 3)

   complete the negotiation and send an advisory notification to the

   initiator indicating the responder's true lifetime.  The choice of

   what the responder actually does is implementation specific and/or

   based on local policy.



   To ensure interoperability in the latter case, the IPSEC DOI requires

   the following only when the responder wishes to notify the initiator:

   if the initiator offers an SA lifetime longer than the responder is

   willing to accept, the responder SHOULD include an ISAKMP

   Notification Payload in the exchange that includes the responder's

   IPSEC SA payload.  Section 4.6.3.1 defines the payload layout for the

   RESPONDER-LIFETIME Notification Message type which MUST be used for

   this purpose.




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         !

   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   !                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 (1 octet) - 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 Interpretation (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, of

        the secrecy level identifier, excluding pad bits.



     o  RESERVED (2 octets) - Unused, must be zero (0).



     o  Secrecy Level (variable length) - Specifies the mandatory

        secrecy level required.  The secrecy level MUST be padded with

        zero (0) to align on the next 32-bit boundary.



     o  Secrecy Category Length (2 octets) - Specifies the length, in

        bits, of the secrecy category (compartment) bitmap, excluding

        pad bits.



     o  RESERVED (2 octets) - Unused, must be zero (0).



     o  Secrecy Category Bitmap (variable length) - A bitmap used to

        designate secrecy categories (compartments) that are required.

        The bitmap MUST be padded with zero (0) to align on the next

        32-bit boundary.



     o  Integrity Length (2 octets) - Specifies the length, in octets,

        of the integrity level identifier, excluding pad bits.



     o  RESERVED (2 octets) - Unused, must be zero (0).



     o  Integrity Level (variable length) - Specifies the mandatory

        integrity level required.  The integrity level MUST be padded

        with zero (0) to align on the next 32-bit boundary.



     o  Integrity Category Length (2 octets) - Specifies the length, in

        bits, of the integrity category (compartment) bitmap, excluding

        pad bits.



     o  RESERVED (2 octets) - Unused, must be zero (0).



     o  Integrity Category Bitmap (variable length) - A bitmap used to

        designate integrity categories (compartments) that are required.

        The bitmap MUST be padded with zero (0) to align on the next

        32-bit boundary.




4.6.1.1 IPSEC Labeled Domain Identifiers



   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




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 authentication and integrity without confidentiality (AH)

   from a certain set of IP addresses and full authentication with

   confidentiality (ESP) from another range of IP addresses.  The

   Identification Payload provides information that can be used by the

   responder to make this decision.



   During Phase I negotiations, the ID port and protocol fields MUST be

   set to zero or to UDP port 500.  If an implementation receives any

   other values, this MUST be treated as an error and the security

   association setup MUST be aborted.  This event SHOULD be auditable.



   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

   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   !  Next Payload !   RESERVED    !        Payload Length         !

   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   !   ID Type     !  Protocol ID  !             Port              !

   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   ~                     Identification Data                       ~

   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+



                  Figure 2: Identification Payload Format



   The Identification Payload fields are defined as follows:



     o  Next Payload (1 octet) - 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  Protocol ID (1 octet) - Value specifying an associated IP

        protocol ID (e.g. UDP/TCP).  A value of zero means that the

        Protocol ID field should be ignored.



     o  Port (2 octets) - Value specifying an associated port.  A value

        of zero means that the Port field should be ignored.



     o  Identification Data (variable length) - Value, as indicated by

        the Identification Type.




4.6.2.1 Identification 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_SUBNET                 4

       ID_IPV6_ADDR                        5

       ID_IPV6_ADDR_SUBNET                 6

       ID_IPV4_ADDR_RANGE                  7

       ID_IPV6_ADDR_RANGE                  8

       ID_DER_ASN1_DN                      9

       ID_DER_ASN1_GN                      10

       ID_KEY_ID                           11



   For types where the ID entity is variable length, the size of the ID

   entity is computed from size in the ID payload header.



   When an IKE exchange is authenticated using certificates (of any

   format), any ID's used for input to local policy decisions SHOULD be

   contained in the certificate used in the authentication of the

   exchange.




4.6.2.2 ID_IPV4_ADDR



   The ID_IPV4_ADDR type specifies a single four (4) octet IPv4 address.




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".  The string should not

   contain any terminators.




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".  The string should

   not contain any terminators.




4.6.2.5 ID_IPV4_ADDR_SUBNET



   The ID_IPV4_ADDR_SUBNET 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_SUBNET



   The ID_IPV6_ADDR_SUBNET 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.




4.6.2.8 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 the

   beginning IPv4 address (inclusive) and the second value is the ending

   IPv4 address (inclusive).  All addresses falling between the two

   specified addresses are considered to be within the list.




4.6.2.9 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 the

   beginning IPv6 address (inclusive) and the second value is the ending

   IPv6 address (inclusive).  All addresses falling between the two

   specified addresses are considered to be within the list.




4.6.2.10 ID_DER_ASN1_DN



   The ID_DER_ASN1_DN type specifies the binary DER encoding of an ASN.1

   X.500 Distinguished Name [X.501] of the principal whose certificates

   are being exchanged to establish the SA.




4.6.2.11 ID_DER_ASN1_GN



   The ID_DER_ASN1_GN type specifies the binary DER encoding of an ASN.1

   X.500 GeneralName [X.509] of the principal whose certificates are

   being exchanged to establish the SA.




4.6.2.12 ID_KEY_ID



   The ID_KEY_ID type specifies an opaque byte stream which may be used

   to pass vendor-specific information necessary to identify which pre-

   shared key should be used to authenticate Aggressive mode

   negotiations.




4.6.3 IPSEC Notify Message Types



   ISAKMP defines two blocks of Notify Message codes, one for errors and

   one for status messages.  ISAKMP also allocates a portion of each

   block for private use within a DOI.  The IPSEC DOI defines the

   following private message types for its own use.



       Notify Messages - Error Types       Value

       -----------------------------       -----

       RESERVED                            8192



       Notify Messages - Status Types      Value

       ------------------------------      -----

       RESPONDER-LIFETIME                  24576

       REPLAY-STATUS                       24577

       INITIAL-CONTACT                     24578



   Notification Status Messages MUST be sent under the protection of an

   ISAKMP SA: either as a payload in the last Main Mode exchange; in a

   separate Informational Exchange after Main Mode or Aggressive Mode

   processing is complete; or as a payload in any Quick Mode exchange.

   These messages MUST NOT be sent in Aggressive Mode exchange, since

   Aggressive Mode does not provide the necessary protection to bind the

   Notify Status Message to the exchange.



   Nota Bene: a Notify payload is fully protected only in Quick Mode,

   where the entire payload is included in the HASH(n) digest.  In Main

   Mode, while the notify payload is encrypted, it is not currently

   included in the HASH(n) digests.  As a result, an active substitution

   attack on the Main Mode ciphertext could cause the notify status

   message type to be corrupted.  (This is true, in general, for the

   last message of any Main Mode exchange.)  While the risk is small, a

   corrupt notify message might cause the receiver to abort the entire

   negotiation thinking that the sender encountered a fatal error.


   Implementation Note: the ISAKMP protocol does not guarantee delivery

   of Notification Status messages when sent in an ISAKMP Informational

   Exchange.  To ensure receipt of any particular message, the sender

   SHOULD include a Notification Payload in a defined Main Mode or Quick

   Mode exchange which is protected by a retransmission timer.




4.6.3.1 RESPONDER-LIFETIME



   The RESPONDER-LIFETIME status message may be used to communicate the

   IPSEC SA lifetime chosen by the responder.



   When present, the Notification Payload MUST have the following

   format:



     o  Payload Length - set to length of payload + size of data (var)

     o  DOI - set to IPSEC DOI (1)

     o  Protocol ID - set to selected Protocol ID from chosen SA

     o  SPI Size - set to either sixteen (16) (two eight-octet ISAKMP

        cookies) or four (4) (one IPSEC SPI)

     o  Notify Message Type - set to RESPONDER-LIFETIME (Section 4.6.3)

     o  SPI - set to the two ISAKMP cookies or to the sender's inbound

        IPSEC SPI

     o  Notification Data - contains an ISAKMP attribute list with the

        responder's actual SA lifetime(s)



   Implementation Note: saying that the Notification Data field contains

   an attribute list is equivalent to saying that the Notification Data

   field has zero length and the Notification Payload has an associated

   attribute list.




4.6.3.2 REPLAY-STATUS



   The REPLAY-STATUS status message may be used for positive

   confirmation of the responder's election on whether or not he is to

   perform anti-replay detection.



   When present, the Notification Payload MUST have the following

   format:



     o  Payload Length - set to length of payload + size of data (4)

     o  DOI - set to IPSEC DOI (1)

     o  Protocol ID - set to selected Protocol ID from chosen SA

     o  SPI Size - set to either sixteen (16) (two eight-octet ISAKMP

        cookies) or four (4) (one IPSEC SPI)

     o  Notify Message Type - set to REPLAY-STATUS

     o  SPI - set to the two ISAKMP cookies or to the sender's inbound

        IPSEC SPI

     o  Notification Data - a 4 octet value:



          0 = replay detection disabled

          1 = replay detection enabled




4.6.3.3 INITIAL-CONTACT



   The INITIAL-CONTACT status message may be used when one side wishes

   to inform the other that this is the first SA being established with

   the remote system.  The receiver of this Notification Message might

   then elect to delete any existing SA's it has for the sending system

   under the assumption that the sending system has rebooted and no

   longer has access to the original SA's and their associated keying

   material.  When used, the content of the Notification Data field

   SHOULD be null (i.e. the Payload Length should be set to the fixed

   length of Notification Payload).



   When present, the Notification Payload MUST have the following

   format:



     o  Payload Length - set to length of payload + size of data (0)

     o  DOI - set to IPSEC DOI (1)

     o  Protocol ID - set to selected Protocol ID from chosen SA

     o  SPI Size - set to sixteen (16) (two eight-octet ISAKMP cookies)

     o  Notify Message Type - set to INITIAL-CONTACT

     o  SPI - set to the two ISAKMP cookies

     o  Notification Data - <not included>




4.7 IPSEC Key Exchange Requirements



   The IPSEC DOI introduces no additional Key Exchange types.




5. Security Considerations



   This entire memo pertains to the Internet Key Exchange protocol

   ([IKE]), which combines ISAKMP ([ISAKMP]) and Oakley ([OAKLEY]) to

   provide for the derivation of cryptographic keying material 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 and in the cipher references.




6. IANA Considerations



   This document contains many "magic" numbers to be maintained by the

   IANA.  This section explains the criteria to be used by the IANA to

   assign additional numbers in each of these lists.  All values not

   explicitly defined in previous sections are reserved to IANA.




6.1 IPSEC Situation Definition



   The Situation Definition is a 32-bit bitmask which represents the

   environment under which the IPSEC SA proposal and negotiation is

   carried out.  Requests for assignments of new situations must be

   accompanied by an RFC which describes the interpretation for the

   associated bit.



   If the RFC is not on the standards-track (i.e., it is an

   informational or experimental RFC), it must be explicitly reviewed

   and approved by the IESG before the RFC is published and the

   transform identifier is assigned.



   The upper two bits are reserved for private use amongst cooperating

   systems.




6.2 IPSEC Security Protocol Identifiers



   The Security Protocol Identifier is an 8-bit value which identifies a

   security protocol suite being negotiated.  Requests for assignments

   of new security protocol identifiers must be accompanied by an RFC

   which describes the requested security protocol.  [AH] and [ESP] are

   examples of security protocol documents.



   If the RFC is not on the standards-track (i.e., it is an

   informational or experimental RFC), it must be explicitly reviewed

   and approved by the IESG before the RFC is published and the

   transform identifier is assigned.



   The values 249-255 are reserved for private use amongst cooperating

   systems.




6.3 IPSEC ISAKMP Transform Identifiers



   The IPSEC ISAKMP Transform Identifier is an 8-bit value which

   identifies a key exchange protocol to be used for the negotiation.

   Requests for assignments of new ISAKMP transform identifiers must be

   accompanied by an RFC which describes the requested key exchange

   protocol.  [IKE] is an example of one such document.



   If the RFC is not on the standards-track (i.e., it is an

   informational or experimental RFC), it must be explicitly reviewed

   and approved by the IESG before the RFC is published and the

   transform identifier is assigned.



   The values 249-255 are reserved for private use amongst cooperating

   systems.




6.4 IPSEC AH Transform Identifiers



   The IPSEC AH Transform Identifier is an 8-bit value which identifies

   a particular algorithm to be used to provide integrity protection for

   AH.  Requests for assignments of new AH transform identifiers must be

   accompanied by an RFC which describes how to use the algorithm within

   the AH framework ([AH]).



   If the RFC is not on the standards-track (i.e., it is an

   informational or experimental RFC), it must be explicitly reviewed

   and approved by the IESG before the RFC is published and the

   transform identifier is assigned.



   The values 249-255 are reserved for private use amongst cooperating

   systems.




6.5 IPSEC ESP Transform Identifiers



   The IPSEC ESP Transform Identifier is an 8-bit value which identifies

   a particular algorithm to be used to provide secrecy protection for

   ESP.  Requests for assignments of new ESP transform identifiers must

   be accompanied by an RFC which describes how to use the algorithm

   within the ESP framework ([ESP]).



   If the RFC is not on the standards-track (i.e., it is an

   informational or experimental RFC), it must be explicitly reviewed

   and approved by the IESG before the RFC is published and the

   transform identifier is assigned.



   The values 249-255 are reserved for private use amongst cooperating

   systems.




6.6 IPSEC IPCOMP Transform Identifiers



   The IPSEC IPCOMP Transform Identifier is an 8-bit value which

   identifier a particular algorithm to be used to provide IP-level

   compression before ESP.  Requests for assignments of new IPCOMP

   transform identifiers must be accompanied by an RFC which describes

   how to use the algorithm within the IPCOMP framework ([IPCOMP]).  In

   addition, the requested algorithm must be published and in the public

   domain.



   If the RFC is not on the standards-track (i.e., it is an

   informational or experimental RFC), it must be explicitly reviewed

   and approved by the IESG before the RFC is published and the

   transform identifier is assigned.



   The values 1-47 are reserved for algorithms for which an RFC has been

   approved for publication.  The values 48-63 are reserved for private

   use amongst cooperating systems.  The values 64-255 are reserved for

   future expansion.




6.7 IPSEC Security Association Attributes



   The IPSEC Security Association Attribute consists of a 16-bit type

   and its associated value.  IPSEC SA attributes are used to pass

   miscellaneous values between ISAKMP peers.  Requests for assignments

   of new IPSEC SA attributes must be accompanied by an Internet Draft

   which describes the attribute encoding (Basic/Variable-Length) and

   its legal values.  Section 4.5 of this document provides an example

   of such a description.



   The values 32001-32767 are reserved for private use amongst

   cooperating systems.




6.8 IPSEC Labeled Domain Identifiers



   The IPSEC Labeled Domain Identifier is a 32-bit value which

   identifies a namespace in which the Secrecy and Integrity levels and

   categories values are said to exist.  Requests for assignments of new

   IPSEC Labeled Domain Identifiers should be granted on demand.  No

   accompanying documentation is required, though Internet Drafts are

   encouraged when appropriate.



   The values 0x80000000-0xffffffff are reserved for private use amongst

   cooperating systems.




6.9 IPSEC Identification Type



   The IPSEC Identification Type is an 8-bit value which is used as a

   discriminant for interpretation of the variable-length Identification

   Payload.  Requests for assignments of new IPSEC Identification Types

   must be accompanied by an RFC which describes how to use the

   identification type within IPSEC.



   If the RFC is not on the standards-track (i.e., it is an

   informational or experimental RFC), it must be explicitly reviewed

   and approved by the IESG before the RFC is published and the

   transform identifier is assigned.



   The values 249-255 are reserved for private use amongst cooperating

   systems.




6.10 IPSEC Notify Message Types



   The IPSEC Notify Message Type is a 16-bit value taken from the range

   of values reserved by ISAKMP for each DOI.  There is one range for

   error messages (8192-16383) and a different range for status messages

   (24576-32767).  Requests for assignments of new Notify Message Types

   must be accompanied by an Internet Draft which describes how to use

   the identification type within IPSEC.



   The values 16001-16383 and the values 32001-32767 are reserved for

   private use amongst cooperating systems.




7. Change Log




7.1 Changes from V9



     o  add explicit reference to [IPCOMP], [DEFLATE], and [LZS]

     o  allow RESPONDER-LIFETIME and REPLAY-STATUS to be directed

        at an IPSEC SPI in addition to the ISAKMP "SPI"

     o  added padding exclusion to Secrecy and Integrity Length text

     o  added forward reference to Section 4.5 in Section 4.4.4

     o  update document references




7.2 Changes from V8



     o  update IPCOMP identifier range to better reflect IPCOMP draft

     o  update IANA considerations per Jeff/Ted's suggested text

     o  eliminate references to DES-MAC ID ([DESMAC])

     o  correct bug in Notify section; ISAKMP Notify values are 16-bits




7.3 Changes from V7



     o  corrected name of IPCOMP (IP Payload Compression)

     o  corrected references to [ESPCBC]

     o  added missing Secrecy Level and Integrity Level to Figure 1

     o  removed ID references to PF_KEY and ARCFOUR

     o  updated Basic/Variable text to align with [IKE]

     o  updated document references and add intro pointer to [ARCH]

     o  updated Notification requirements; remove aggressive reference

     o  added clarification about protection for Notify payloads

     o  restored RESERVED to ESP transform ID namespace; moved ESP_NULL

     o  added requirement for ESP_NULL support and [ESPNULL] reference

     o  added clarification on Auth Alg use with AH/ESP

     o  added restriction against using conflicting AH/Auth combinations




7.4 Changes from V6



   The following changes were made relative to the IPSEC DOI V6:



     o  added IANA Considerations section

     o  moved most IANA numbers to IANA Considerations section

     o  added prohibition on sending (V) encoding for (B) attributes

     o  added prohibition on sending Key Length attribute for fixed

        length ciphers (e.g. DES)

     o  replaced references to ISAKMP/Oakley with IKE

     o  renamed ESP_ARCFOUR to ESP_RC4

     o  updated Security Considerations section

     o  updated document references




7.5 Changes from V5



   The following changes were made relative to the IPSEC DOI V5:



     o  changed SPI size in Lifetime Notification text

     o  changed REPLAY-ENABLED to REPLAY-STATUS

     o  moved RESPONDER-LIFETIME payload definition from Section 4.5.4

        to Section 4.6.3.1

     o  added explicit payload layout for 4.6.3.3

     o  added Implementation Note to Section 4.6.3 introduction

     o  changed AH_SHA text to require SHA-1 in addition to MD5

     o  updated document references




7.6 Changes from V4



   The following changes were made relative to the IPSEC DOI V4:



     o  moved compatibility AH KPDK authentication method from AH

        transform ID to Authentication Algorithm identifier

     o  added REPLAY-ENABLED notification message type per Architecture

     o  added INITIAL-CONTACT notification message type per list

     o  added text to ensure protection for Notify Status messages

     o  added Lifetime qualification to attribute parsing section

     o  added clarification that Lifetime notification is optional

     o  removed private Group Description list (now points at [IKE])

     o  replaced Terminology with pointer to RFC-2119

     o  updated HMAC MD5 and SHA-1 ID references

     o  updated Section 1 (Abstract)

     o  updated Section 4.4 (IPSEC Assigned Numbers)

     o  added restriction for ID port/protocol values for Phase I




7.7 Changes from V3 to V4



   The following changes were made relative to the IPSEC DOI V3, that

   was posted to the IPSEC mailing list prior to the Munich IETF:



     o  added ESP transform identifiers for NULL and ARCFOUR

     o  renamed HMAC Algorithm to Auth Algorithm to accommodate

        DES-MAC and optional authentication/integrity for ESP

     o  added AH and ESP DES-MAC algorithm identifiers

     o  removed KEY_MANUAL and KEY_KDC identifier definitions

     o  added lifetime duration MUST follow lifetype attribute to

        SA Life Type and SA Life Duration attribute definition

     o  added lifetime notification and IPSEC DOI message type table

     o  added optional authentication and confidentiality

        restrictions to MAC Algorithm attribute definition

     o  corrected attribute parsing example (used obsolete attribute)

     o  corrected several Internet Draft document references

     o  added ID_KEY_ID per ipsec list discussion (18-Mar-97)

     o  removed Group Description default for PFS QM ([IKE] MUST)




Acknowledgments



   This document is derived, in part, from previous works by Douglas

   Maughan, Mark Schertler, Mark Schneider, Jeff Turner, Dan Harkins,

   and Dave Carrel.  Matt Thomas, Roy Pereira, Greg Carter, and Ran

   Atkinson also contributed suggestions and, in many cases, text.




References



   [AH]      Kent, S., and R. Atkinson, "IP Authentication Header", RFC

             2402, November 1998.



   [ARCH]    Kent, S., and R. Atkinson, "Security Architecture for the

             Internet Protocol", RFC 2401, November 1998.



   [DEFLATE] Pereira, R., "IP Payload Compression Using DEFLATE", RFC

             2394, August 1998.



   [ESP]     Kent, S., and R. Atkinson, "IP Encapsulating Security

             Payload (ESP)", RFC 2406, November 1998.



   [ESPCBC]  Pereira, R., and R. Adams, "The ESP CBC-Mode Cipher

             Algorithms", RFC 2451, November 1998.



   [ESPNULL] Glenn, R., and S. Kent, "The NULL Encryption Algorithm and

             Its Use With IPsec", RFC 2410, November 1998.



   [DES]     Madson, C., and N. Doraswamy, "The ESP DES-CBC Cipher

             Algorithm With Explicit IV", RFC 2405, November 1998.



   [HMACMD5] Madson, C., and R. Glenn, "The Use of HMAC-MD5 within ESP

             and AH", RFC 2403, November 1998.



   [HMACSHA] Madson, C., and R. Glenn, "The Use of HMAC-SHA-1-96 within

             ESP and AH", RFC 2404, November 1998.



   [IKE]     Harkins, D., and D. Carrel, D., "The Internet Key Exchange

             (IKE)", RFC 2409, November 1998.



   [IPCOMP]  Shacham, A., Monsour, R., Pereira, R., and M. Thomas, "IP

             Payload Compression Protocol (IPComp)", RFC 2393, August

             1998.



   [ISAKMP]  Maughan, D., Schertler, M., Schneider, M., and J. Turner,

             "Internet Security Association and Key Management Protocol

             (ISAKMP)", RFC 2408, November 1998.



   [LZS]     Friend, R., and R. Monsour, "IP Payload Compression Using

             LZS", RFC 2395, August 1998.



   [OAKLEY]  Orman, H., "The OAKLEY Key Determination Protocol", RFC

             2412, November 1998.



   [X.501]   ISO/IEC 9594-2, "Information Technology - Open Systems

             Interconnection - The Directory:  Models", CCITT/ITU

             Recommendation X.501, 1993.



   [X.509]   ISO/IEC 9594-8, "Information Technology - Open Systems

             Interconnection - The Directory:  Authentication

             Framework", CCITT/ITU Recommendation X.509, 1993.




Author's Address



   Derrell Piper

   Network Alchemy

   1521.5 Pacific Ave

   Santa Cruz, California, 95060

   United States of America



   Phone: +1 408 460-3822

   EMail: ddp@network-alchemy.com




Full Copyright Statement



   Copyright (C) The Internet Society (1998).  All Rights Reserved.



   This document and translations of it may be copied and furnished to

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