HIP Working Group                                            P. Nikander
Internet-Draft                             Ericsson Research Nomadic Lab
Expires: April 18, August 21, 2005                                     J. Laganier
                                                  LIP / Sun Microsystems
                                                        October 18, 2004
                                                       February 20, 2005

    Host Identity Protocol (HIP) Domain Name System (DNS) Extensions
                         draft-ietf-hip-dns-00
                         draft-ietf-hip-dns-01

Status of this Memo

   This document is an Internet-Draft and is subject to all provisions
   of section 3 of RFC 3667.  By submitting this Internet-Draft, each
   author represents that any applicable patent or other IPR claims of
   which he or she is aware have been or will be disclosed, and any of
   which he or she become aware will be disclosed, in accordance with
   RFC 3668.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF), its areas, and its working groups.  Note that
   other groups may also distribute working documents as
   Internet-Drafts.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   The list of current Internet-Drafts can be accessed at
   http://www.ietf.org/ietf/1id-abstracts.txt.

   The list of Internet-Draft Shadow Directories can be accessed at
   http://www.ietf.org/shadow.html.

   This Internet-Draft will expire on April 18, August 21, 2005.

Copyright Notice

   Copyright (C) The Internet Society (2004). (2005).

Abstract

   This document specifies two new resource records (RRs) for the Domain
   Name System (DNS), and how to use them with the Host Identity
   Protocol (HIP).  These records RRs allow a HIP node to store in the DNS its
   Host Identity (its (HI, the public key), component of the node public-private
   key pair), Host Identity Tag (a (HIT, a truncated hash of its public
   key), and the Domain Name or IP addresses of its Rendezvous Servers
   (RVS).

Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  3
   2.  Conventions used in this document  . . . . . . . . . . . . . .  5
   3.  Use cases  . . .  Usage Scenarios  . . . . . . . . . . . . . . . . . . . . . . .  6
     3.1   Simple static singly homed end-host  . . . . . . . . . . .  7
     3.2   Mobile end-host  . . . . . . . . . . . . . . . . . . . . .  7  8
     3.3   Multi-homed Site or End-host   Mixed Scenario . . . . . . . . . . . . . . .  7 . . . . . . .  9
   4.  Overview of using the DNS with HIP . . . . . . . . . . . . . .  8 10
     4.1   Different types of HITs  . . . . . . . . . . . . . . . . .  8
       4.1.1   Host Assigning Authority (HAA) field . . . . . . . . .  8
     4.2   Storing HI and HIT in DNS  . . . . . . . . . . . . . . . .  8
     4.3   Storing HAA in DNS . . . . . . . . . . . . . . . . . . 10
       4.1.1   Different types of HITs  . .  8
     4.4   Providing multiple IP addresses . . . . . . . . . . . . .  9
       4.4.1 10
     4.2   Storing Rendezvous Servers in the DNS  . . . . . . . .  9
     4.5 . . 11
     4.3   Initiating connections based on DNS names  . . . . . . . .  9
     4.6   HI and HIT verification  . . . . . . . . . . . . . . . . .  9 11
   5.  Storage Format . . . . . . . . . . . . . . . . . . . . . . . . 10 12
     5.1   HIPHI RDATA format . . . . . . . . . . . . . . . . . . . . 10 12
       5.1.1   HIT type format  . . . . . . . . . . . . . . . . . . . 10 12
       5.1.2   HIT algorithm format . . . . . . . . . . . . . . . . . 10 12
       5.1.3   PK algorithm type format  . . . . . . . . . . . . . . . 10 . . 12
       5.1.4   HIT format . . . . . . . . . . . . . . . . . . . . . . 11 13
       5.1.5   Public key format  . . . . . . . . . . . . . . . . . . 11 13
     5.2   HIPRVS RDATA format  . . . . . . . . . . . . . . . . . . . 11 13
       5.2.1   Preference format  . . . . . . . . . . . . . . . . . . 12 14
       5.2.2   Rendezvous server type format  . . . . . . . . . . . . 12 14
       5.2.3   Rendezvous server format . . . . . . . . . . . . . . . 12 14
   6.  Transition mechanisms  . .  Presentation Format  . . . . . . . . . . . . . . . . . . 14
   7.  Security Considerations . . . 16
     6.1   HIPHI Representation . . . . . . . . . . . . . . . . 15
     7.1   Attacker tampering with an unsecure HIPHI RR . . . 16
     6.2   HIPRVS Representation  . . . . 15
     7.2   Attacker tampering with an unsecure HIPRVS RR . . . . . . 15
     7.3   Opportunistic HIP . . . . . . . . 16
     6.3   Examples . . . . . . . . . . . . 16
     7.4   Anonymous Initiator . . . . . . . . . . . . . 17
   7.  Retrieving Multiple HITs and IPs from the DNS  . . . . . . 16
     7.5   Hash and HITs Collisions . . 18
   8.  Transition mechanisms  . . . . . . . . . . . . . . . 16
   8.  IANA Considerations . . . . . 19
   9.  Security Considerations  . . . . . . . . . . . . . . . . 17
   9.  Acknowledgments . . . 20
     9.1   Attacker tampering with an unsecure HIPHI RR . . . . . . . 20
     9.2   Attacker tampering with an unsecure HIPRVS RR  . . . . . . 20
     9.3   Opportunistic HIP  . . . . . . . 18
   10.   References . . . . . . . . . . . . . 21
     9.4   Unpublished Initiator HI . . . . . . . . . . . . 19
   10.1  Normative references . . . . . 21
     9.5   Hash and HITs Collisions . . . . . . . . . . . . . . . 19
   10.2  Informative . . 21
   10.   IANA Considerations  . . . . . . . . . . . . . . . . . . . . 22
   11.   Acknowledgments  . . . . . . . . . . . . . . . . . . . . . . 23
   12.   References . . . . . . . . . . . . . . . . . . . . . . . . . 24
   12.1  Normative references . . . . . . . . . . . . . . . . . . . 20
       Authors' Addresses . 24
   12.2  Informative references . . . . . . . . . . . . . . . . . . . 25
       Authors' Addresses . . 20
   A.  Using multiple HIs with multiple IPs . . . . . . . . . . . . . 21
   B. . . . . . . . 25
   A.  Document Revision History  . . . . . . . . . . . . . . . . . . 23 26
       Intellectual Property and Copyright Statements . . . . . . . . 24 27

1.  Introduction

   This document specifies two new resource records (RRs) for the Domain
   Name System (DNS) [7], [1], and how to use them with the Host Identity
   Protocol (HIP) [9]. [10].  These records RRs allow a HIP node to store in the DNS
   its Host Identity (its (HI, the public key), component of the node
   public-private key pair), Host Identity Tag (a (HIT, a truncated hash of
   its public key), HI), and the Domain Name or IP addresses of its Rendezvous
   Servers (RVS) [12]. [13].

   The current Internet architecture defines two global namespaces: IP
   addresses and domain names.  The Domain Name System provides a two
   way lookup between these two namespaces.  The HIP architecture [10] [11]
   defines a new third namespace, called the Host Identity Namespace.
   This namespace is composed of Host Identifiers (HI) of HIP nodes.
   The Host Identity Tag (HIT) is one representation of an HI.  This
   representation is obtained by taking the output of a secure hash
   function applied to the HI, truncated to the IPv6 address size.  HITs
   are supposed to be used in the place of IP addresses in some within most ULPs
   and applications.

        +-----+                +-----+
        |     |-------I1------>|     |
        |  I  |<------R1-------|  R  |
        |     |-------I2------>|     |
        |     |<------R2-------|     |
        +-----+                +-----+

   The Host Identity Protocol [9] [10] allows two HIP nodes to establish
   together a
   pair of unidirectional IPsec Security HIP Association.  These SAs are  A HIP association is bound to the HI instead of IP addresses.  The proposed HIP
   multi-homing mechanisms [11] allow a node to dynamically change its
   set of underlying IP addresses while maintaining IPsec SA and
   transport layer session survivability.  The HIP rendezvous extensions
   [12] proposal allows a HIP node to maintain HIP reachability while
   not relying on dynamic DNS updates nodes
   HIs rather than to make its peers aware of its
   current location (the set of their IP address(es)). address(es).

   Although a HIP node can initiate HIP communication
   "opportunistically" (without
   "opportunistically", i.e., without a priori knowledge of its peer's HI),
   HI, doing so exposes both endpoints to Man-in-the-Middle attacks on
   the HIP handshake. handshake and its cryptographic protocol.  Hence, there is a
   desire to gain knowledge of peers' HI before applications and ULPs
   initiate communication.

   Currently, most of the Internet  Because many applications that need use the Domain
   Name System [1] to communicate
   with name nodes, DNSSEC [3] is a remote straightforward way to
   provision nodes with the HIP informations (i.e.  HI and possibly RVS)
   of nodes named in the DNS tree, without introducing or relying on an
   additional piece of infrastructure.

                    +-----+
           +--I1--->| RVS |---I1--+
           |        +-----+       |
           |                      v
        +-----+                +-----+
        |     |<------R1-------|     |
        |  I  |-------I2------>|  R  |
        |     |<------R2-------|     |
        +-----+                +-----+

   The proposed HIP multi-homing mechanisms [12] allow a node to
   dynamically change its set of underlying IP addresses while
   maintaining IPsec SA and transport layer session survivability.  The
   HIP rendezvous extensions [13] proposal allows a HIP node to maintain
   HIP reachability while it is changing its current location (the node
   IP address(es)).  This rendezvous service is provided by a third
   party, the node's Rendezvous Server (RVS).  An initiator (I) willing
   to establish a HIP association with a responder (R) would typically
   initiate a HIP exchange by sending an I1 towards the RVS IP address
   rather than towards the responder IP address.  Then, the RVS,
   noticing that the receiver HIT is not its own, but the HIT of a HIP
   node registered for the rendezvous Service, would relay the I1 to the
   responder.  Typically the responder would then complete the exchange
   without further assistance from the RVS by sending an R1 directly to
   the initiator IP address.

   Currently, most of the Internet applications that need to communicate
   with a remote host first translate a domain name (often obtained via
   user input) into one or more IP address(es).  This step occurs prior
   to communication with the remote host, and relies on a DNS lookup.

   With HIP, IP addresses are expected to be used mostly for on-the-wire
   communication between end hosts, while most ULPs and applications
   uses HIs or HITs instead (ICMP might be an example of an ULP not
   using them).  Consequently, we need a means to translate a domain
   name into an HI.  Using the DNS for this translation is pretty
   straightforward: We define a new HIPHI (HIP HI) resource record.
   Upon query by an application or ULP for a FQDN -> IP lookup, the
   resolver would then additionally perform an FQDN -> HI lookup, and
   use it to construct the resulting HI -> IP mapping (which is internal
   to the HIP layer).  The HIP layer uses the HI -> IP mapping to
   translate HIs and their local representations (HITs, IPv4 and
   IPv6-compatible LSIs) into IP addresses and vice versa.

   This draft introduces the following new DNS Resource Records:
      - HIPHI, for storing Host Identifiers and Host Identity Tags
      - HIPRVS, for storing rendezvous server information

2.  Conventions used in this document

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in RFC2119 [2]. [4].

3.  Use cases  Usage Scenarios

   In this section, we briefly introduce a number of use cases usage scenarios
   where the DNS is useful with the Host Identity Protocol.

   With HIP, most application and ULPs are unaware of the IP addresses
   used to carry packets on the wire.  Consequently, a HIP node could
   take advantage of having multiple IP addresses for fail-over,
   redundancy, mobility, or renumbering, in a manner which is
   transparent to most ULPs and applications (because they are bound to
   HIs, hence they are agnostic to these IP address changes).

   In these situations, a node wishing to be reachable by reference to
   its FQDN should store the following informations in the DNS:

   o  A set of IP address(es).
   o  A Host Identity (HI) and/or Host Identity Tag (HIT).
   o  An IP address or DNS name of its Rendezvous Server(s) (RVS).

   When a HIP node wants to initiate a communication with another HIP
   node, it first needs to perform a HIP base exchange to set-up a HIP
   association towards its peer.  Although such an exchange can be
   initiated opportunistically, i.e., without a priori knowledge of the
   responder's HI, by doing so both nodes knowingly risk
   man-in-the-middle attacks on the HIP exchange.  To prevent these
   attacks, it is recommended that the initiator first obtain the HI of
   the responder, and then initiate the exchange.  This can be done, for
   example, through manual configuration or DNS lookups.  Hence, a new
   HIPHI RR is introduced.

   When a HIP node is frequently changing its IP address(es), the
   dynamic DNS update latency may prevent it from publishing its new IP
   address(es) in the DNS.  For solving this problem, the HIP
   architecture introduces Rendezvous Servers (RVS).  A HIP host uses a
   Rendezvous Server as a Rendezvous point, to maintain reachability
   with possible HIP initiators.  Such a HIP node would publish in the
   DNS its RVS IP address or DNS name in a HIPRVS RR, while keeping its
   RVS up-to-date with its current set of IP addresses.

   Then, when some other node wants to initiate a HIP exchange with such
   a responder, it retrieves the RVS IP address by looking up a HIPRVS
   RR at the FQDN of the responder, and sends an I1 to this IP address.
   The I1 will then be relayed by the RVS to the responder, which will
   then complete the HIP exchange, either directly or via the RVS [12]. [13].

   Note that storing HIP RR information in the DNS at a FQDN which is
   assigned to a non-HIP node might have ill effects on its reachability
   by HIP nodes.

3.1  Simple static singly homed end-host

               [A? HIPRVS? HIPHI?]
               [www.example.com  ]          +-----+
          +-------------------------------->|     |
          |                                 | DNS |
          | +-------------------------------|     |
          | |  [A? HIPRVS? HIPHI?      ]    +-----+
          | |  [www.example.com        ]
          | |  [A IP-R                 ]
          | |  [HIPHI 10 3 2 HIT-R HI-R]
          | v
        +-----+                              +-----+
        |     |--------------I1------------->|     |
        |  I  |<-------------R1--------------|  R  |
        |     |--------------I2------------->|     |
        |     |<-------------R2--------------|     |
        +-----+                              +-----+

   A HIP node having (R) with a single static network attachment, wishing to be
   reachable by reference to its FQDN, FQDN (www.example.com), would store in
   the DNS, in addition to its IP address(es), address(es) (IP-R), its Host Identity (HI)
   (HI-R) in a HIPHI resource record.

3.2  Mobile end-host

   A mobile HIP node wishing to be reachable by reference to its FQDN
   would store in the DNS, instead of its IP address(es), its HI in a
   HIPHI RR, and the IP address(es) of its

               [A? HIPRVS? HIPHI?]
               [www.example.com  ]          +-----+
         +--------------------------------->|     |
         |                                  | DNS |
         | +--------------------------------|     |
         | |   [A? HIPRVS? HIPHI?      ]    +-----+
         | |   [www.example.com        ]
         | |   [HIPRVS 1 2 IP-RVS      ]
         | |   [HIPHI 10 3 2 HIT-R HI-R]
         | |
         | |                +-----+
         | | +------I1----->| RVS |-----I1------+
         | | |              +-----+             |
         | | |                                  |
         | | |                                  |
         | v |                                  v
        +-----+                              +-----+
        |     |<---------------R1------------|     |
        |  I  |----------------I2----------->|  R  |
        |     |<---------------R2------------|     |
        +-----+                              +-----+

   A mobile HIP node (R) wishing to be reachable by reference to its
   FQDN (www.example.com) would store in the DNS, possibly in addition
   to its IP address(es) (IP-R), its HI (HI-R) in a HIPHI RR, and the IP
   address(es) of its Rendezvous Server(s) (IP-RVS) in HIPRVS resource
   record(s).  The mobile HIP node also need to notify its Rendezvous
   Servers of any change in its set of IP address(es).

   A host wanting to reach this mobile host would then send an I1 to one
   of its RVS.  Following, the RVS will relay the I1 up to the mobile
   node, which will complete the HIP exchange.

3.3  Multi-homed Site or End-host  Mixed Scenario

               [A? HIPRVS? HIPHI?]
               [www.example.com  ]          +-----+
         +--------------------------------->|     |
         |                                  | DNS |
         | +--------------------------------|     |
         | |   [A? HIPRVS? HIPHI?      ]    +-----+
         | |   [www.example.com        ]
         | |   [A IP-R1                ]
         | |   [A IP-R2                ]
         | |   [HIPRVS 1 2 IP-RVS1     ]
         | |   [HIPRVS 1 2 IP-RVS2     ]
         | |   [HIPHI 10 3 2 HIT-R HI-R]
         | |
         | |               +------+
         | | +-----I1----->| RVS1 |------I1------+
         | | |             +------+              |
         | v |                                   v
        +-----+                               +-----+
        |     |---------------I1------------->|     |
        |     |                               |     |
        |  I  |<--------------R1--------------|  R  |
        |     |---------------I2------------->|     |
        |     |<--------------R2--------------|     |
        +-----+                               +-----+
             |                                   ^
             |             +------+              |
             +-----I1----->| RVS2 |------I1------+
                           +------+

   A HIP node might be configured with several distinct network attachments more than one IP address
   (multi-homed), or Rendezvous Server (multi-reachable).  In these
   cases, it is multi-homed. possible that the DNS returns multiples A HIP node attached to a network with multiple ISPs is in a
   multi-homed site will possibly have or AAAA RRs,
   as well as HIPRVS containing one or multiple prefixes and addresses.
   Such HIP node might also be reachable via several distinct Rendezvous Servers.  In
   addition to its set of IP address(es), address(es) (IP-R1, IP-R2), a multi-homed
   end-host would store in the DNS its HI (HI-R) in a HIPHI RR, and
   possibly the IP address(es) of its RVS(s) (IP-RVS1, IP-RVS2) in
   HIPRVS RRs.

4.  Overview of using the DNS with HIP

4.1  Storing HI and HIT in DNS

   Any conforming implementation may store Host Identifiers in a DNS
   HIPHI RDATA format.  An implementation may also store a HIT along
   with its associated HI.  If a particular form of an HI or HIT does
   not already have a specified RDATA format, a new RDATA-like format
   SHOULD be defined for the HI or HIT.

4.1.1  Different types of HITs

   There are _currently_ two types of HITs.  HITs of the first type
   consists just of the least significant bits of the hash of the public
   key.  HITs of the second type consist of a binary prefix Host
   Assigning Authority (HAA) field, and only the last bits come from a
   hash of the Host Identity.  This latter format for HIT is recommended
   for 'well known' systems.  It is possible to support a resolution
   mechanism for these names in directories like DNS.

   Note that the format how HITs are stored in the DNS may be different
   form the format actually used in protocols, the HIP base exchange [9]
   [10] included.  This is because the DNS RR explicitly contains the
   HIT type and algorithm, while some protocols may prefer to use a
   prefix to indicate the HIT type.  The implementations are expected to
   use the actual HI when comparing Host Identities.

4.1.1

4.1.1.1  Host Assigning Authority (HAA) field

   The 64 bits of HAA supports two levels of delegation.  The first is a
   registered assigning authority (RAA).  The second is a registered
   identity (RI, commonly a company).  The RAA is 24 bits with values
   assign sequentially by ICANN.  The RI is 40 bits, also assigned
   sequentially but by the RAA.

   As IPv6 "global site-local" addresses were proposed in the IPv6 WG to
   replace IPv6 site-local address, it is questionable if HIP needs a
   kind of "global site-local" HAA, which would be generated by a given
   site by setting the RAA field to 0 while the RI field is filled by
   either random or EUI-48 bits.

4.2  Storing HI and HIT in DNS

   Any conforming implementation may store Host Identifiers in a DNS
   HIPHI RDATA format.  An implementation may also store a HIT along
   with its associated HI.  If a particular form of an HI or HIT does
   not already have a specified RDATA format, a new RDATA-like format
   SHOULD be defined for the HI or HIT.

4.3

4.1.1.2  Storing HAA in DNS

   Any conforming implementation may store a site's domain name Host Assigning
   Authority (HAA) in a DNS HIPHI RDATA format.  A HAA MUST be stored
   similarly to
   like a Type 2 HIT, while the least significant bits of the HIT
   extracted from the HI hash output are set to 0. zero, the Host Identity
   Length is set zero, and the Host Identity field is omitted.  If a
   particular form of a HAA does not already have an associated HIT
   specified RDATA format, a new RDATA-like format SHOULD be defined for
   the HIT/HAA.

4.4  Providing multiple IP addresses

   With HIP, ULPs doesn't see which IP address is indeed used

4.1.1.3  HI and HIT verification

   Upon return of a HIPHI RR, a host MUST always calculate the
   HI-derivative HIT to carry
   packets on be used in the wire.  Consequently, a HIP node could take advantage
   of having multiple IP addresses for ULPs and applications fail over,
   redundancy, etc.  This can be achieved either by storing multiple
   addresses exchange, as specified in the DNS,
   HIP architecture [11], while these addresses might the HIT possibly embedded along SHOULD
   only be those of
   different IP interfaces or Rendezvous servers.

4.4.1 used as an optimization (e.g.  table lookup).

4.2  Storing Rendezvous Servers in the DNS

   The HIP Rendezvous server (HIPRVS) resource record indicates an
   address (or or a FQDN resolvable into an address) domain name of a RendezVous Server, towards which a HIP
   I1 packet might be sent to trigger the establishment of an
   association with the entity named by this resource record. record [13].

   An RVS receiving such an I1 would then forward relay it to the appropriate
   responder (the owner of the destination HIT in this I1). I1 receiver HIT).  The responder will
   then complete the exchange with the initiator,
   possibly typically without
   ongoing help from the RVS.

   Any conforming implementation may store Rendezvous Server's IP
   address(es) or DNS name in a DNS HIPRVS RDATA format.  If a
   particular form of a RVS reference does not already have a specified
   RDATA format, a new RDATA-like format SHOULD be defined for the RVS.

4.5

4.3  Initiating connections based on DNS names

   A

   On a HIP node, a Host Identity Protocol exchange SHOULD be initiated
   whenever an Upper Layer Protocol attempt to communicate with an
   entity and the DNS lookup returns HIPHI and/or HIPRVS resource
   records.  Furthermore, if the  If a DNS
   lookups also lookup returns one or more HIPRVS resource records, the addresses of these
   RVS SHOULD be put in the destination IP addresses list while
   initiating RRs and no A nor
   AAAA RRs, the afore mentioned HIP exchange. exchange SHOULD be initiated
   towards one of these RVS [10].  Since some hosts may choose not to
   have HIPHI information in DNS, hosts MAY implement support for
   opportunistic HIP.

4.6  HI and HIT verification

   Upon return of a HIPHI RR, a host MUST always calculate the
   HI-derivative HIT to be used in the HIP exchange, as specified in the
   HIP architecture [10], while the HIT possibly embedded along SHOULD
   only be used as an optimization (e.g., table lookup).

5.  Storage Format

5.1  HIPHI RDATA format

   The RDATA for a HIPHI RR consists of a HIT type, an algorithm type, a
   HIT, and a public key.

           0                   1                   2                   3
           0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
          +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
          |   HIT type    | HIT algorithm |  PK algorithm |               |
          +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+    HIT        |
          ~                                                               ~
          +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
          |                                                               /
          /                          Public Key                           /
          /                                                               /
          +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-|

5.1.1  HIT type format

   The HIT type field indicates the Host Identity Tag (HIT) type and the
   implied HIT format.

   The following values are defined:

      0         No HIT is present. present
      1         A Type 1 HIT is present. present
      2         A Type 2 HIT is present. present
      3-6       Unassigned
      7         A HAA is present. present

5.1.2  HIT algorithm format

   The HIT algorithm indicates the hash algorithm used to generate the
   Host Identity Tag (HIT) from the HI.

   The following values are defined:

      0		Reserved.         Reserved
      1         SHA1
      2-255     Unassigned

5.1.3  PK algorithm type format

   The PK algorithm type field indicates the public key cryptographic
   algorithm and the implied public key field format.  This document
   reuse the values defined for the 'algorithm type' of the IPSECKEY RR [13]
   [14] 'gateway type' field.

   The presently defined values are given only informally:

      0	No key is present.

      1 A DSA key is present, in the format defined in RFC2536 [3]. [5].
      2 A RSA key is present, in the format defined in RFC3110 [5]. [6].

5.1.4  HIT format

   There's currently two types of HITs, and a single type of HAA.  Both
   of them have a variable length and are stored in network byte order within a single self-describing
   variable length wire-encoded <character-string> holding the bits (as per Section 3.3
   of the HITs or HAA: [2]):

   o  A *Type 1* HIT: least significant bits of the hash (e.g., SHA1) of
      the public key (Host Identity), which is possibly following in the
      HIPHI RR.
   o  A *Type 2* HIT: binary prefix (HAA) concatenated with a the least
      significant bits of the hash (e.g., SHA1) of the public key (Host
      Identity), which is possibly following in the HIPHI RR.
   o  A HAA: binary prefix (HAA) concatenated with 0, up to the
      associated HIT length.

5.1.5  Public key format

   Both of the public key types defined in this document (RSA and DSA)
   reuse the public key formats defined for the IPSECKEY RR [13] [14] (which
   in turns contains the algorithm-specific portion of the KEY RR RDATA,
   all of the KEY RR DATA after the first four octets, corresponding to
   the same portion of the KEY RR that must be specified by documents
   that define a DNSSEC algorithm).

   In the future, if a new algorithm is to be used both by IPSECKEY RR
   and HIPHI RR, it would probably use the same public key encodings for
   both RRs.  Unless specified otherwise, the HIPHI public key field
   would use the same public key format as the IPSECKEY RR RDATA for the
   corresponding algorithm.

   The DSA key format is defined in RFC2536 [3]. [5].

   The RSA key format is defined in RFC3110 [5]. [6] and the RSA key size
   limit (4096 bits) is relaxed in the IPSECKEY RR [14] specification.

5.2  HIPRVS RDATA format

   The RDATA for a HIPRVS RR consists of a preference value, a
   Rendezvous server type and either one or more Rendezvous server
   address, or one Rendezvous server FQDN. domain name.

           0                   1                   2                   3
        0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
          +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
          |  preference   |     type      |                               |
          +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+      Rendezvous server        |
          ~                                                               ~
          +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

5.2.1  Preference format

   This is an unsigned 8-bit preference order for this record.  This value, used to specify the preference given
   to this RR amongst others at the same owner.  Lower values are
   preferred.  If there is a tie with within some RRs, RR subset, the server
   should return a permutation (e.g.  round robin) of the set of RRs ordered in a RRs,
   such that the requester load balancing
   manner (e.g., round robin). is fairly balanced amongst all RRs of
   the set.

5.2.2  Rendezvous server type format

   The Rendezvous server type indicates the format of the information
   stored in the Rendezvous server field.

   This document reuses the type values for the 'gateway type' field of
   the IPSECKEY RR [13]. [14].  The presently defined values are given only
   informally:

      0 Reserved.
      1

   1.  One or more 4-byte IPv4 address(es) in network byte order are
       present.
      2
   2.  One or more 16-byte IPv6 address(es) in network byte order are
       present.
      3
   3.  One or more variable length wire-encoded domain names as
       described in section 3.3 of RFC1035 [1]. [2].  The wire-encoded format
       is self-describing, so the length is implicit.  The domain names
       MUST NOT be compressed.

5.2.3  Rendezvous server format

   The Rendezvous server field indicates one or more address(es) (or one
   or more FQDN(s) resolvable into one Rendezvous
   Server(s) IP address(es), or more address(es)) towards
   which a domain name(s).  A HIP I1 packet might be send in order sent to
   any of these RVS would reach the entity named by this resource
   record.

   This document reuses the format used for the 'gateway' field of the
   IPSECKEY RR [13], [14], but allows to concatenate several IP (v4 or v6)
   addresses.  The presently defined formats for the data portion of the
   Rendezvous server field are given only informally:

   o  One or more 32-bit IPv4 address(es) in network byte order.
   o  One or more 128-bit IPv6 address(es) in network byte order.
   o  One or more variable length wire-encoded domain names as described
      in section 3.3 of RFC1035 [1]. [2].  The wire-encoded format is
      self-describing, so the length is implicit.  The domain names MUST
      NOT be compressed.

6.  Transition mechanisms

   During a transition period, instead  Presentation Format

   This section specifies the representation of storing the HI or HIT HIPHI and HIPRVS RR
   in a zone data master file.

6.1  HIPHI RR, the Representation

   The HIT MAY be stored in an AAAA RR.  If a Type, HIT is stored in
   an AAAA RR, it MUST be returned as the last item in the set of AAAA
   RRs returned to avoid algorithm, PK algorithm, and Public Key are
   REQUIRED.  The HIT field is OPTIONAL.

   The HIT Type, HIT algorithm, and PK algorithm are represented as most
   unsigned integers.

   The HIT field is represented as possible conflicts with non-HIP IPv6
   nodes.

   During a transition period, similarly to what may happen with HITs, the RVS's IP address might be stored in an A Base16 encoding [8] (a.k.a.  hex
   or AAAA RR instead hexadecimal) of a
   HIPRVS RR. the public key.  If a RVS IP address no HIT is stored in an A or AAAA RR, it to be indicated,
   then the HIT algorithm MUST be returned as zero and the last item in HIT field must be ".".

   The Public Key field is represented as the set Base64 encoding [8] of returned RRs to avoid as
   most as possible conflicts with non-HIP IPv6 nodes.

7.  Security Considerations

   Though the security considerations
   public key.

   The complete representation of the HIP DNS extensions still
   need to HPIHI record is:

   IN           HIPHI ( hit-type hit-algorithm pk-algorithm
                        base16-encoded-hit
                        base64-encoded-public-key )

6.2  HIPRVS Representation

   The Preference and RVS Type fields are REQUIRED.  At least one RVS
   field MUST be more investigated present.

   The HIT Type, HIT algorithm, and documented, this section contains a
   description PK algorithm are represented as
   unsigned integers.

   The RVS field is represented by one or more:
   o  IPv4 dotted decimal address(es)
   o  IPv6 colon hex address(es)
   o  uncompressed domain name(s)

   The complete representation of the known threats involved with the usage HPIRVS record is:

   IN           HIPRVS  ( preference rendezvous-server-type
                          rendezvous-server[1]
                                ...
                          rendezvous-server[n] )

6.3  Examples

   Example of the HIP
   DNS extensions.

   In a manner similar to the IPSECKEY RR [13], the HIP DNS Extensions
   allows to provision two HIP nodes node with the public keying material
   (HI) a HI but no HIT:

   www.example.com           IN    HIPHI ( 0 1 2
                              .
                              AB3NzaC1kc3MAAACBAOBhKnTCPOuFBzZQX/N3O9dm9P9ivUIMoId== )

   Example of their peer.  These HIs will be subsequently used in a key
   exchange between the peers.  Hence, the HIP DNS Extensions introduce
   the same kind node with a HI and a HIT:

   www.example.com           IN    HIPHI ( 1 1 2
                              120cf10ea842e0ba53320f1fe0ba5d3a3
                              AB3NzaC1kc3MAAACBAOBhKnTCPOuFBzZQX/N3O9dm9P9ivUIMoId== )

   Example of threats that IPSECKEY does, plus threats caused by
   the possibility a node with an IPv6 RVS:

   www.example.com           IN    HIPRVS ( 10 2 2001:0db8:0200:1:20c:f1ff:fe0b:a533 )

   Example of using unpublished initiator and opportunistic mode
   in HIP.

   A HIP a node SHOULD obtain both the HIPHI and with three IPv4 RVS:

   www.example.com           IN    HIPRVS RRs ( 10 1 192.0.2.2 192.0.99.2 192.0.199.2)

   Example of a node with two named RVS:

   www.example.com           IN    HIPRVS ( 10 3 rvs.uk.example.com rvs.us.example.com )

7.  Retrieving Multiple HITs and IPs from the DNS

   If a trusted
   party trough host receives multiple HITs in a secure channel insuring proper data integrity of the
   RRs.  This might be DNSSEC, or another secure channel response to another
   directory lookup service.

   In the absence of a proper secure channel, both parties are
   vulnerable DNS query, those
   HITs MUST be considered to MitM and DoS attacks, denote a single service, and unrelated parties might be
   subject to DoS attacks as well.  These threats are described in the
   following sections.

7.1  Attacker tampering
   semantically equivalent from that point of view.  When initiating a
   base exchange with an unsecure HIPHI RR

   The HIPHI RR contains public keying material in the form of denoted service, the named
   peer's public key (the HI) and its secure hash (the HIT).  Both of
   these are not sensitive host SHOULD be prepared
   to attacks where an adversary gains knowledge accept any of them.  However, an attacker that is able to mount an active attack
   on HITs as the DNS, i.e., tampers with peer's identity.  A host MAY implement
   this HIPHI RR (e.g., by using DNS
   spoofing) is able the opportunistic mode (destination HIT null in I1), or
   by sending multiple I1s, if needed.

   In particular, if a host receives multiple HITs and multiple IP
   addresses in response to mount Man-in-the-Middle attacks on a DNS query, the
   cryptographic core of host cannot know how the eventual HIP exchange (responder's HIPHI
   and HIPRVS rewritten by
   HITs are reachable at the attacker).

7.2  Attacker tampering with an unsecure HIPRVS RR listed IP addresses.  The HIPRVS RR contains a destination mapping may be
   any, i.e., all HITs may be reachable at all of the listed IP address where
   addresses, some of the named peer
   is HITs may be reachable at some of the IP
   addresses, or there may even be one-to-one mapping between the HITs
   and IP addresses.  In general, the host cannot know the mapping and
   MUST NOT expect any particular mapping.

   It is RECOMMENDED that if a host receives multiple HITs, the host
   SHOULD first try to initiate the base exchange by using the
   opportunistic mode.  If the returned HIT does not match with any of
   the expected HITs, the host SHOULD retry by sending further I1s, one
   at time, trying out all of the listed HITs.  If the host receives an I1 (HIP Rendezvous Extensions IPSECKEY RR [12] ).
   Thus, an attacker able
   R1 for any of the I1s, the host SHOULD continue to tamper use the successful
   IP address until an R1 with this RRs a listed HIT is able to redirect I1
   packets sent to received, or the named peer to a chosen host has
   tried all HITs, and try the other IP address, for DoS or
   MitM attacks.  Note that this kind addresses only after that.  A
   host MAY also send multiple I1s in parallel, but sending such I1s
   MUST be rate limited to avoid flooding (as per Section 8.4.1 of attacks are not specific
   [10]).

8.  Transition mechanisms

   During a transition period, to HIP
   and exist independently allows to whether or not store the HIP and informations
   of a node in a DNS server which does not support the HIPHI and HIPRVS RR are
   used.  Such an attacker might tamper with
   RRs, A and AAAA RRs as well.

   An attacker might obviously use these two attacks in conjunction: It
   will replace the responder's HI and RVS IP address by its owns MAY be overloaded.  A HIT would typically be
   stored in a
   spoofed DNS packet sent to the initiator HI, then redirect all
   exchanged packets through him AAAA RR and mount a MitM on HIP.  In this case
   HIP won't provide confidentiality nor initiator HI protection from
   eavesdroppers.

7.3  Opportunistic HIP RVS in either a A HIP initiator may not or AAAA RR.  If such a
   situation occurs, the overloaded RRs MUST be aware returned as the last
   items of its peer's HI, and/or its HIT
   (e.g., because the DNS does not contains HIP material, returned RRs set (A or AAAA), to avoid as most as
   possible conflicts with non-HIP IPv6 nodes.

9.  Security Considerations

   Though the security considerations of the
   resolver isn't HIP-enabled), and attempt an opportunistic HIP
   exchange towards its known IP address, filling DNS extensions still
   need to be more investigated and documented, this section contains a
   description of the responder HIT
   field known threats involved with zeros in the I1 header.  Such an initiator is vulnerable
   to a MitM attack because it can't validate usage of the HI and HIT contained
   in HIP
   DNS extensions.

   In a replied R1.  Hence, an implementation MAY choose not manner similar to use
   opportunistic mode.

7.4  Anonymous Initiator

   A the IPSECKEY RR [14], the HIP initiator may choose DNS Extensions
   allows to use an unpublished HI, which is not
   stored in provision two HIP nodes with the DNS by means public keying material
   (HI) of their peer.  These HIs will be subsequently used in a HIPHI RR.  A responder associating
   with such an initiator knowingly risks a MitM attack because it
   cannot validate key
   exchange between the initiator's HI. peers.  Hence, an implementation MAY
   choose not to use unpublished mode.

7.5  Hash and HITs Collisions

   As many cryptographic algorithm, some secure hashes (e.g.  SHA1, used
   by the HIP to generate a HIT from an HI) eventually become insecure,
   because an exploit has been found in which an attacker with a
   reasonable computation power breaks one of DNS Extensions introduce
   the security features same kind of threats that IPSECKEY does, plus threats caused by
   the hash (e.g., its supposed collision resistance).  This is why possibility given to a HIP end-node implementation SHOULD NOT authenticate its HIP peers
   based solely on node to initiate or accept a HIT retrieved from DNS, but rather use HIP
   exchange using "Opportunistic" or "Unpublished Initiator HI" modes.

   A HIP node SHOULD obtain both the HI
   and HIT.

8.  IANA Considerations

   IANA needs to allocate two new RR type code for HIPHI and HIPRVS RRs from a trusted
   party trough a secure channel insuring proper data integrity of the standard RR type space.

   IANA does not need to open
   RRs.  DNSSEC [3] provides such a new registry for secure channel.

   In the HIPHI RR type for
   public key algorithms because absence of a proper secure channel, both parties are
   vulnerable to MitM and DoS attacks, and unrelated parties might be
   subject to DoS attacks as well.  These threats are described in the
   following sections.

9.1  Attacker tampering with an unsecure HIPHI RR reuse 'algorithms types'
   defined for the IPSECKEY RR [13].

   The presently defined numbers are
   given here only informally:

      0 is reserved
      1 is RSA
      2 is DSA

   IANA needs to open a new registry for the HIPHI RR HIT type.  Defined
   types are:

      0		No HIT is present
      1		A Type 1 HIT is present
      2		A Type 2 HIT is present
      3-6	Unassigned
      7		A HAA contains public keying material in the form of the named
   peer's public key (the HI) and its secure hash (the HIT).  Both of
   these are not sensitive to attacks where an adversary gains knowledge
   of them.  However, an attacker that is present

   Adding new reservations requires IETF consensus RFC2434 [14].

   IANA needs able to open a new registry for mount an active attack
   on the DNS, i.e., tampers with this HIPHI RR HIT algorithm
   type.  Defined types are:

      0		Reserved
      1		SHA1
      2-255	Unassigned

   Adding new reservations requires IETF consensus RFC2434 [14].

   IANA does not need (e.g., using DNS
   spoofing) is able to open a new registry for mount Man-in-the-Middle attacks on the HIPRVS RR
   Rendezvous server type because
   cryptographic core of the eventual HIP exchange (responder's HIPHI RR reuse the 'gateway types'
   defined for
   and HIPRVS rewritten by the IPSECKEY attacker).

9.2  Attacker tampering with an unsecure HIPRVS RR [13].

   The presently defined numbers are
   given here only informally:

      0 is reserved
      1 is IPv4
      2 is IPv6
      3 is HIPRVS RR contains a wire-encoded uncompressed domain name

9.  Acknowledgments

   Some parts of this draft stem from [9].  This work destination IP address where the named peer
   is heavily
   influenced reachable by [13], which serves as an I1 (HIP Rendezvous Extensions IPSECKEY RR [13] ).
   Thus, an attacker able to tamper with this RRs is able to redirect I1
   packets sent to the named peer to a model chosen IP address, for DoS or
   MitM attacks.  Note that this document.

   The authors would like kind of attacks are not specific to thanks the following people, who have
   provided thoughtful and helpful discussions and/or suggestions, that
   have improved this document: Rob Austein, Hannu Flinck, Tom
   Henderson, Miika Komu, Andrew McGregor, Erik Nordmark, and Gabriel
   Montenegro.

10.  References

10.1  Normative references

   [1]   Mockapetris, P., "Domain names - implementation and
         specification", STD 13, RFC 1035, November 1987.

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

   [3]   Eastlake, D., "DSA KEYs and SIGs in the Domain Name System
         (DNS)", RFC 2536, March 1999.

   [4]   Crawford, M., "Binary Labels in the Domain Name System", RFC
         2673, August 1999.

   [5]   Eastlake, D., "RSA/SHA-1 SIGs and RSA KEYs in the Domain Name
         System (DNS)", RFC 3110, May 2001.

   [6]   Bush, R., Durand, A., Fink, B., Gudmundsson, O. and T. Hain,
         "Representing Internet Protocol version 6 (IPv6) Addresses in
         the Domain Name System (DNS)", RFC 3363, August 2002.

   [7]   Klensin, J., "Role of the Domain Name System (DNS)", RFC 3467,
         February 2003.

   [8]   Thomson, S., Huitema, C., Ksinant, V. and M. Souissi, "DNS
         Extensions to Support IP Version 6", RFC 3596, October 2003.

   [9]   Moskowitz, R., Nikander, P. and P. Jokela, "Host Identity
         Protocol", draft-ietf-hip-base-01 (work in progress), October
         2004.

   [10]  Moskowitz, R. and P. Nikander, "Host Identity Protocol
         Architecture", draft-ietf-hip-arch-00 (work in progress),
         October 2004.

   [11]  Nikander, P., "End-Host Mobility and Multi-Homing with Host
         Identity Protocol", draft-ietf-hip-mm-00 (work in progress),
         October 2004.

   [12]  Laganier, J. and L. Eggert, "Host Identity Protocol (HIP)
         Rendezvous Extensions", draft-ietf-hip-rvs-00 (work in
         progress), October 2004.

   [13]  Richardson, M., "A method for storing IPsec keying material in
         DNS", draft-ietf-ipseckey-rr-10 (work in progress), April 2004.

10.2  Informative references

   [14]  Narten, T. and H. Alvestrand, "Guidelines for Writing an IANA
         Considerations Section in RFCs", BCP 26, RFC 2434, October
         1998.

   [15]  Rescorla, E. HIP
   and B. Korver, "Guidelines for Writing RFC Text on
         Security Considerations", BCP 72, RFC 3552, July 2003.

Authors' Addresses

   Pekka Nikander
   Ericsson Research Nomadic Lab
   JORVAS  FIN-02420
   FINLAND

   Phone: +358 9 299 1
   EMail: pekka.nikander@nomadiclab.com

   Julien Laganier
   LIP (CNRS-INRIA-ENSL-UCBL) & Sun Labs (Sun Microsystems)
   180, Avenue de l'Europe
   Saint Ismier CEDEX  38334
   France

   Phone: +33 476 188 815
   EMail: ju@sun.com

Appendix A.  Using multiple HIs exist independently to whether or not HIP and the HIPRVS RR are
   used.  Such an attacker might tamper with multiple IPs

   The A and AAAA RRs defined in this document are "flat", as well.

   An attacker might obviously use these two attacks in conjunction: It
   will replace the sense that the IP
   addresses responder's HI and HIs are associated RVS IP address by its owns in a
   spoofed DNS packet sent to an FQDN the initiator HI, then redirect all
   exchanged packets through him and mount a MitM on an equality basis. HIP.  In
   the this case where
   HIP won't provide confidentiality nor initiator HI protection from
   eavesdroppers.

9.3  Opportunistic HIP

   A HIP initiator may not be aware of its peer's HI, and/or its HIT
   (e.g., because the DNS does not contains HIP material, or the
   resolver isn't HIP-enabled), and attempt an FQDN opportunistic HIP
   exchange towards its known IP address, filling the responder HIT
   field with zeros in the I1 header.  Such an initiator is resolved into multiple HIs (HIPHI RRs) vulnerable
   to a MitM attack because it can't validate the HI and
   IP addresses (A, AAAA or HIPRVS RRs), HIT contained
   in a replied R1.  Hence, an implementation MAY choose not to use
   opportunistic mode.

9.4  Unpublished Initiator HI

   A HIP initiator may choose to use an unpublished HI, which is not
   stored in the requester DNS by means of a HIPHI RR.  A responder associating
   with such an initiator knowingly risks a MitM attack because it
   cannot associate validate the initiator's HI.  Hence, an implementation MAY
   choose not to use unpublished mode.

9.5  Hash and HITs Collisions

   As many cryptographic algorithm, some secure hashes (e.g.  SHA1, used
   by HIP to generate a HIT from an IP address HI) eventually become insecure,
   because an exploit has been found in which an attacker with a specific HI, nor
   reasonable computation power breaks one of the opposite.

   Considering security features of
   the following DNS-IP load balancing model: Multiple
   initiators are querying a DNS server with A or AAAA RRs at hash (e.g., its supposed collision resistance).  This is why a given
   FQDN.  The DNS server replies with
   HIP end-node implementation SHOULD NOT authenticate its HIP peers
   based solely on a round-robin ordered set of IP
   addresses, causing each initiator to connect HIT retrieved from DNS, but SHOULD rather use
   HI-based authentication.

10.  IANA Considerations

   IANA needs to a different address
   (the first address of the set they received allocate two new RR type code for HIPHI and HIPRVS from
   the DNS).  This
   model can be extended standard RR type space.

   IANA needs to HIP by having the DNS returning open a
   round-robin ordered set of HIs and IP addresses.  But then new registry for the
   problem HIPHI RR HIT type.  Defined
   types are:

      0         No HIT is that present
      1         A Type 1 HIT is present
      2         A Type 2 HIT is present
      3-6       Unassigned
      7         A HAA is present

   Adding new reservations requires IETF consensus RFC2434 [16].

   IANA needs to open a new registry for the initiator would HIPHI RR HIT algorithm.
   Defined types are:

      0         Reserved
      1         SHA1
      2-255     Unassigned

   Adding new reservations requires IETF consensus RFC2434 [16].

   IANA does not need to map each of these HIs to open a subset of new registry for the returned set of IP addresses.  Hence, perhaps there HIPHI RR type for
   public key algorithms because the HIPHI RR reuse 'algorithms types'
   defined for the IPSECKEY RR [14].  The presently defined numbers are
   given here only informally:

      0 is reserved
      1 is a RSA
      2 is DSA

   IANA does not need for having to open a "hierarchical" model new registry for these RRs, which will
   allows to tie an HI to the HIPRVS RR
   Rendezvous server type because the HIPHI RR reuse the 'gateway types'
   defined for the IPSECKEY RR [14].  The presently defined numbers are
   given here only informally:

      0 is reserved
      1 is IPv4
      2 is IPv6
      3 is a specific subset of IP addresses, as
   illustrated wire-encoded uncompressed domain name

11.  Acknowledgments

   As usual in the figure below:

                                       FQDN
                                         |
                                     +---+---+
                                     |       |
                                     V       V
           FQDN                   HI1,HI2   HI3
            |                        |       |
    +---+---+---+---+---+          +-+-+     |
    |   |   |   |   |   |          |   |     |
    V   V   V   V   V   V          V   V     V
   IP1 IP2 IP3 HI1 HI2 HI3        IP1 IP2   IP3

   'Flat' DNS model Vs. 'Hierarchical' HI model

   However, as HIs and Type 1 HITs are not yet resolvable using IETF, this document is the DNS,
   implementing such result of a model would certainly prove to be difficult. collaboration
   between many people.  The
   use of Distributed Hash Tables (DHTs) might help authors would like to resolve HIs, but
   at this point the whole story isn't known.  In thanks the absence of HI
   resolvability, there is two solutions: index IP addresses author
   (Michael Richardson), contributors and
   HIs/HITs used by HIP with a common key (e.g., the IP address, reviewers of the
   HIT, a 8-bit int, etc.), or use a per-HI DNS name, pointed IPSECKEY RR
   [14] specification, which this document was framed after.  The
   authors would also like to by thanks the
   FQDN global following people, who have
   provided thoughtful and helpful discussions and/or suggestions, that
   have helped improving this document: Rob Austein, Hannu Flinck, Tom
   Henderson, Miika Komu, Andrew McGregor, Erik Nordmark, and Gabriel
   Montenegro.  Some parts of this draft stem from [10].

12.  References

12.1  Normative references

   [1]   Mockapetris, P., "Domain names - concepts and facilities", STD
         13, RFC 1034, November 1987.

   [2]   Mockapetris, P., "Domain names - implementation and
         specification", STD 13, RFC 1035, November 1987.

   [3]   Eastlake, D. and C. Kaufman, "Domain Name System Security
         Extensions", RFC 2065, January 1997.

   [4]   Bradner, S., "Key words for use in RFCs to the set of HIs, Indicate Requirement
         Levels", BCP 14, RFC 2119, March 1997.

   [5]   Eastlake, D., "DSA KEYs and pointing to SIGs in the HIs, Domain Name System
         (DNS)", RFC 2536, March 1999.

   [6]   Eastlake, D., "RSA/SHA-1 SIGs and IP
   addresses associated with this particular set of HIs.  to map to
   specific HIs, RSA KEYs in a manner similar to what is done with NS RRs.

   In the first solution (indexing), each HIPHI, HIPRVS, Domain Name
         System (DNS)", RFC 3110, May 2001.

   [7]   Bush, R., Durand, A., Fink, B., Gudmundsson, O. and HIPLOC (a
   new to-be-defined RR carrying T. Hain,
         "Representing Internet Protocol version 6 (IPv6) Addresses in
         the IP address of a HIP node, to be
   used by HIP instead of A Domain Name System (DNS)", RFC 3363, August 2002.

   [8]   Josefsson, S., "The Base16, Base32, and Base64 Data Encodings",
         RFC 3548, July 2003.

   [9]   Thomson, S., Huitema, C., Ksinant, V. and AAAA RRs, if present) would contain an
   additional HI index field allowing M. Souissi, "DNS
         Extensions to link an HI with a subset of Support IP
   addresses Version 6", RFC 3596, October 2003.

   [10]  Moskowitz, R., Nikander, P. and vice versa.  This solution is neither space-efficient,
   nor it is architecturally clean.

   In the second solution (parallel DNS names P. Jokela, "Host Identity
         Protocol", draft-ietf-hip-base-01 (work in progress), October
         2004.

   [11]  Moskowitz, R. and bindings), the PTR RR
   is used to alias the name of a group of node into multiple FQDNs,
   which are then bound to set of HIs P. Nikander, "Host Identity Protocol
         Architecture", draft-ietf-hip-arch-00 (work in progress),
         October 2004.

   [12]  Nikander, P., "End-Host Mobility and Multi-Homing with Host
         Identity Protocol", draft-ietf-hip-mm-00 (work in progress),
         October 2004.

   [13]  Laganier, J. and L. Eggert, "Host Identity Protocol (HIP)
         Rendezvous Extensions", draft-ietf-hip-rvs-00 (work in
         progress), October 2004.

   [14]  Richardson, M., "A method for storing IPsec keying material in
         DNS", draft-ietf-ipseckey-rr-12 (work in progress), January
         2005.

12.2  Informative references

   [15]  Jokela, P., Moskowitz, R. and IP addresses, as shown P. Nikander, "Using ESP transport
         format with HIP", draft-jokela-hip-esp-00 (work in the
   figure below.  These additional FQDNs are kind of HIP sub-FQDNs; progress),
         February 2005.

   [16]  Narten, T. and H. Alvestrand, "Guidelines for Writing an
   easy way to generate them is to suffix, or prefix the unqualified
   name with a sufficient number of bits of the HIT to prevent
   collisions local to a FQDN (e.g., foo.bar.com might haves multiple
   HIP sub-FQDNs: foo_2fa6.bar.com, foo_8cc4.bar.com, etc.).

                                       FQDN
                                         |
                                     +---+---+
                                     |       |
                                     V       V
      FQDN_1<--FQDN-->FQDN_2      HI1,HI2   HI3
        |               |            |       |
    +---+---+---+     +-+-+        +-+-+     |
    |   |   |   |     |   |        |   |     |
    V   V   V   V     V   V        V   V     V
   HI1 HI2 IP1 IP2   HI3 IP3      IP1 IP2   IP3

   The 'Hierarchical' HIP model fitting IANA
         Considerations Section in a 'Flat' DNS model

   The current plan is to use the second solution unless HIP WG members
   express desire to have the first solution implemented. RFCs", BCP 26, RFC 2434, October
         1998.

Authors' Addresses

   Pekka Nikander
   Ericsson Research Nomadic Lab
   JORVAS  FIN-02420
   FINLAND

   Phone: +358 9 299 1
   EMail: pekka.nikander@nomadiclab.com

   Julien Laganier
   LIP (CNRS-INRIA-ENSL-UCBL) & Sun Labs (Sun Microsystems)
   180, Avenue de l'Europe
   Saint Ismier CEDEX  38334
   France

   Phone: +33 476 188 815
   EMail: ju@sun.com

Appendix B. A.  Document Revision History

   +-----------+-------------------------------------------------------+
   | Revision  | Comments                                              |
   +-----------+-------------------------------------------------------+
   | 00 01        | Compared to draft-nikander-hip-dns-00: Merge draft-ietf-hip-dns-01: Removed HIP        |
   |           | multihomed site and end-host use cases. Remove HAA rendezvous registration protocol. Removed references  |
   |           | related to DNS. Added figures. Added text not required for Type 2 HIT definition.  |
   |           | Remove IPv6 LSIs definitions. Replace fixed length    |
   |           | and algorithm Type 1 and Type 2 HITs by variable      |
   |           | length, type and algorithm HITs. Remove 'Policy       |
   |           | Considerations' section. Fill-in 'Security            |
   |           | Considerations' section. Allow for several IP         |
   |           | addresses in the same HIPRVS RR. Reuse the type       |
   |           | values and IANA registries of IPSECKEY RR. Add Annex  |
   |           | discussing alternatives for storing multiple |
   |           | parallels FQDN-to-HI HITs and HI-to-IP at a single FQDN. IP.                                          |
   |           | Minor fixes to figures and their descriptive text.                                                       |
   | 00        | Update references. Initial version as a HIP WG item.                     |
   +-----------+-------------------------------------------------------+

Intellectual Property Statement

   The IETF takes no position regarding the validity or scope of any
   Intellectual Property Rights or other rights that might be claimed to
   pertain to the implementation or use of the technology described in
   this document or the extent to which any license under such rights
   might or might not be available; nor does it represent that it has
   made any independent effort to identify any such rights.  Information
   on the procedures with respect to rights in RFC documents can be
   found in BCP 78 and BCP 79.

   Copies of IPR disclosures made to the IETF Secretariat and any
   assurances of licenses to be made available, or the result of an
   attempt made to obtain a general license or permission for the use of
   such proprietary rights by implementers or users of this
   specification can be obtained from the IETF on-line IPR repository at
   http://www.ietf.org/ipr.

   The IETF invites any interested party to bring to its attention any
   copyrights, patents or patent applications, or other proprietary
   rights that may cover technology that may be required to implement
   this standard.  Please address the information to the IETF at
   ietf-ipr@ietf.org.

Disclaimer of Validity

   This document and the information contained herein are provided on an
   "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS
   OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET
   ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED,
   INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE
   INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED
   WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.

Copyright Statement

   Copyright (C) The Internet Society (2004). (2005).  This document is subject
   to the rights, licenses and restrictions contained in BCP 78, and
   except as set forth therein, the authors retain all their rights.

Acknowledgment

   Funding for the RFC Editor function is currently provided by the
   Internet Society.