Hash-Based Addresses (HBA)
RFC 5535

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Network Working Group                                         M. Bagnulo
Request for Comments: 5535                                          UC3M
Category: Standards Track                                      June 2009

                       Hash-Based Addresses (HBA)

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

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Abstract

   This memo describes a mechanism to provide a secure binding between
   the multiple addresses with different prefixes available to a host
   within a multihomed site.  This mechanism employs either
   Cryptographically Generated Addresses (CGAs) or a new variant of the
   same theme that uses the same format in the addresses.  The main idea
   in the new variant is that information about the multiple prefixes is
   included within the addresses themselves.  This is achieved by
   generating the interface identifiers of the addresses of a host as

Bagnulo                     Standards Track                     [Page 1]
RFC 5535                          HBA                          June 2009

   hashes of the available prefixes and a random number.  Then, the
   multiple addresses are generated by prepending the different prefixes
   to the generated interface identifiers.  The result is a set of
   addresses, called Hash-Based Addresses (HBAs), that are inherently
   bound to each other.

Table of Contents

   1. Introduction ....................................................3
   2. Terminology .....................................................4
   3. Overview ........................................................4
      3.1. Threat Model ...............................................4
      3.2. Overview ...................................................4
      3.3. Motivations for the HBA Design .............................5
   4. Cryptographic Generated Addresses (CGAs) Compatibility
      Considerations ..................................................6
   5. Multi-Prefix Extension for CGA ..................................8
   6. HBA-Set Generation ..............................................9
   7. HBA Verification ...............................................11
      7.1. Verification That a Particular HBA Address
           Corresponds to a Given CGA Parameter Data Structure .......11
      7.2. Verification That a Particular HBA Address Belongs to the
           HBA Set Associated with a Given CGA Parameter Data
           Structure .................................................11
   8. Example of HBA Application in a Multihoming Scenario ...........13
      8.1. Dynamic Address Set Support ...............................16
   9. DNS Considerations .............................................17
   10. IANA Considerations ...........................................18
   11. Security Considerations .......................................18
      11.1. Security Considerations When Using HBAs in the
            Shim6 Protocol ...........................................20
      11.2. Privacy Considerations ...................................22
      11.3. SHA-1 Dependency Considerations ..........................22
      11.4. DoS Attack Considerations ................................22
   12. Contributors ..................................................23
   13. Acknowledgments ...............................................23
   14. References ....................................................24
      14.1. Normative References .....................................24
      14.2. Informative References ...................................24