Host Identity Protocol Version 2 (HIPv2)
RFC 7401

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Internet Engineering Task Force (IETF)                 R. Moskowitz, Ed.
Request for Comments: 7401                                HTT Consulting
Obsoletes: 5201                                                  T. Heer
Category: Standards Track              Hirschmann Automation and Control
ISSN: 2070-1721                                                P. Jokela
                                            Ericsson Research NomadicLab
                                                            T. Henderson
                                                University of Washington
                                                              April 2015

                Host Identity Protocol Version 2 (HIPv2)

Abstract

   This document specifies the details of the Host Identity Protocol
   (HIP).  HIP allows consenting hosts to securely establish and
   maintain shared IP-layer state, allowing separation of the identifier
   and locator roles of IP addresses, thereby enabling continuity of
   communications across IP address changes.  HIP is based on a Diffie-
   Hellman key exchange, using public key identifiers from a new Host
   Identity namespace for mutual peer authentication.  The protocol is
   designed to be resistant to denial-of-service (DoS) and man-in-the-
   middle (MitM) attacks.  When used together with another suitable
   security protocol, such as the Encapsulating Security Payload (ESP),
   it provides integrity protection and optional encryption for upper-
   layer protocols, such as TCP and UDP.

   This document obsoletes RFC 5201 and addresses the concerns raised by
   the IESG, particularly that of crypto agility.  It also incorporates
   lessons learned from the implementations of RFC 5201.

Status of This Memo

   This is an Internet Standards Track document.

   This document is a product of the Internet Engineering Task Force
   (IETF).  It represents the consensus of the IETF community.  It has
   received public review and has been approved for publication by the
   Internet Engineering Steering Group (IESG).  Further information on
   Internet Standards is available in Section 2 of RFC 5741.

   Information about the current status of this document, any errata,
   and how to provide feedback on it may be obtained at
   http://www.rfc-editor.org/info/rfc7401.

Moskowitz, et al.            Standards Track                    [Page 1]
RFC 7401                          HIPv2                       April 2015

Copyright Notice

   Copyright (c) 2015 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (http://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1. Introduction ....................................................5
      1.1. A New Namespace and Identifiers ............................6
      1.2. The HIP Base Exchange (BEX) ................................6
      1.3. Memo Structure .............................................7
   2. Terms and Definitions ...........................................7
      2.1. Requirements Terminology ...................................7
      2.2. Notation ...................................................8
      2.3. Definitions ................................................8
   3. Host Identity (HI) and Its Structure ............................9
      3.1. Host Identity Tag (HIT) ...................................10
      3.2. Generating a HIT from an HI ...............................11
   4. Protocol Overview ..............................................12
      4.1. Creating a HIP Association ................................12
           4.1.1. HIP Puzzle Mechanism ...............................14
           4.1.2. Puzzle Exchange ....................................15
           4.1.3. Authenticated Diffie-Hellman Protocol with
                  DH Group Negotiation ...............................17
           4.1.4. HIP Replay Protection ..............................18
           4.1.5. Refusing a HIP Base Exchange .......................19
           4.1.6. Aborting a HIP Base Exchange .......................20
           4.1.7. HIP Downgrade Protection ...........................20
           4.1.8. HIP Opportunistic Mode .............................21
      4.2. Updating a HIP Association ................................24
      4.3. Error Processing ..........................................24
      4.4. HIP State Machine .........................................25