Harmonizing how applications specify DANE-like usage
draft-ogud-dane-vocabulary-00

DANE                                                      O. Gudmundsson
Internet-Draft                                             Shinkuro Inc.
Intended status: Informational                             June 10, 2013
Expires: December 12, 2013

          Harmonizing how applications specify DANE-like usage
                     draft-ogud-dane-vocabulary-00

Abstract

   This document proposes a specific word usage for specifications of
   DANE like technology by different protocols/services.  DANE is a
   method for specifying in DNS records acceptable keys/certificates for
   application servers.

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   This Internet-Draft will expire on December 12, 2013.

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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  Requirements notation . . . . . . . . . . . . . . . . . .   3
   2.  Proposed Terms  . . . . . . . . . . . . . . . . . . . . . . .   3
     2.1.  DNS Navigation Records  . . . . . . . . . . . . . . . . .   3
     2.2.  DNS Integrity . . . . . . . . . . . . . . . . . . . . . .   3
     2.3.  Service Specification Records . . . . . . . . . . . . . .   4
     2.4.  Service Address Records . . . . . . . . . . . . . . . . .   4
     2.5.  Application Authentication Records  . . . . . . . . . . .   5
   3.  Example specifcation  . . . . . . . . . . . . . . . . . . . .   5
   4.  IANA considerations . . . . . . . . . . . . . . . . . . . . .   6
   5.  Security considerations . . . . . . . . . . . . . . . . . . .   6
   6.  Internationalizaiton Considerations . . . . . . . . . . . . .   6
   7.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   6
     7.1.  Normative References  . . . . . . . . . . . . . . . . . .   6
     7.2.  Informative References  . . . . . . . . . . . . . . . . .   6
   Appendix A.  Document history . . . . . . . . . . . . . . . . . .   7
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .   7

1.  Introduction

   DANE [RFC6698] is a powerful new way to provide/amend how
   authentication/authorization/confidencialty of a connection to a
   server can be protected by leveraging DNS [RFC1034] and DNSSEC
   [RFC4033] [RFC4034] [RFC4035] for the establishment of TLS connection
   [RFC5246] [RFC6347] which in many cases uses PKIX [RFC5280].  All of
   these technologies are complicated.  People familiar with one or two
   are not necessarily familiar with all the parts that needed to apply
   DANE like mechanism to other protocols.

   The goal of this document is two fold:

   o  To provide an overview of the non protocol specific parts needed
      to specify an DANE like addition.

   o  To provide a common framework for such specifications making it
      easy to review/compare the specifications.  An important goal is
      to allow the new specifications to avoid repeating explanations
      and/or definitions.

   This version of the document aims to hide complexity and focus on
   generalities.  This is done to make it easier for the reader to
   decide if the terms here are of use and if it is worthwhile for the
   DANE WG to adopt this document.  Descriptions of complexities can be
   added in later versions if the WG decides that is needed.

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   When below the notation "foo/bar" is used that is because the editor
   is not sure if both apply or which one is more appropriate, please
   advise.

1.1.  Requirements notation

   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.  Proposed Terms

   The terms below are being proposed to avoid confusion when reading
   DANE like specifications for various application protocols.

   At this point all the terms below are proposals and better terms are
   welcome.

2.1.  DNS Navigation Records

   DNS Navigation refers to any records used to traverse the DNS tree to
   find the records requested.  This includes

   NS records:  that provide a referral to DNS servers for more specific
         part of the name being looked up.  Example: name server for
         "example." will hand out a referral to server for
         "bar.example." when asked about "foo.bar.example."

   CNAME records:  records that change the location of an record, this
         for all practical purposes a pointer that only applies to that
         specific name.

   DNAME records:  specify a rewrite rule for a name to a new name.
         Example: "bar.example."  DNAME "foo.example." means that
         "www.bar.example." is to be looked up as "www.foo.example".
         DNAME applies to names that are longer than the name it, i.e.
         "bar.example." is not rewritten but "www.bar.example." is

   DANE specification explicitly requires all of these records to be
   validated by DNSSEC.  See section Section 2.2

   While traversing the DNS tree other records like A and AAAA are used
   but these records do not change the "navigation", these records do
   not explicitly need to be protected as the data retrieved from the
   addresses is expected to be protected.

2.2.  DNS Integrity

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   DNSSEC defines a records and procedures to provide integrity and
   authentication to data stored in DNS [RFC4034].  The records used to
   provide the keying information and chain of trust are DNSKEY, DS
   records.  NSEC/NSEC3 provide information about existence/non-
   existence of the requested information.  RRSIG provides a digital
   signature for a RRset.

   DNSSEC provides both Integrity and Authenticity i.e. it says the
   records came from the right source and have not been changed.

   Any DNS record that is DNS Integrity protected, will pass DNSSEC
   validation for all DNS Navigation records leading to the name and the
   record itself also passes DNSSEC validation.

   In the case of CNAME and DNAME that go "sideways" i.e. to a different
   branch of the DNS tree, both branches MUST be validated.

2.3.  Service Specification Records

   Protocols have different ways to provide information about where
   servers are located.  Web servers are frequently specified by name
   i.e. the "www" prefix.  Email servers have a special RR type (MX),
   Jabber uses SRV records, ENUM uses NAPTR records etc. and there are
   also protocols that use a combination like S-NAPTR a schema where
   NAPTR records are used to specify where to look for SRV records.

   For a DANE like specification it has to be clear as what the service
   specification records are and that these records use requires DNS
   Integrity.

   NOTE: when NAPTR records as are used they should be the same way as
   DNS Navigation records even though strictly speaking it is the
   application that evaluates the NAPTR record.

   NOTE: When there is a CNAME at the name service is expected to be
   specified at, that can be either a DNS Navigation record or a Service
   Specification Record.  Protocol specification should provide guidance
   on interpretation.

2.4.  Service Address Records

   This is where the address records used by the servers reside,
   specifications SHOULD not make a difference between what kind of
   address records are used.

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   In some cases the Service Specification records reside at the same
   name as the Service Address records like for the original TLS RFC,
   thus both kinds of records are covered by the same DNS integrity
   rules.

2.5.  Application Authentication Records

   This term refers to the records that provide information about what
   are acceptable keys or certificates for the servers to offer.

   Application Authentication Records MUST be protected by DNS Integrity
   and each protocol specification MUST explicitly state where/how to
   look up the Authentication records.

   In some cases all the servers for a service will have the same
   authentication information, in other cases it is going to be on a
   server by server case.  In the first case it is "natural" to store
   the Authentication records "at" the Service Specification records.
   In the second case it more natural to store them "at" the Address
   Records.  In this context "at" means the authentication records are
   stored at name that is an extension of the location example:
   "_443._tcp.www.example.com" for [RFC6698].  It is possible that
   neither of these locations is the right one and in that case the
   specification MUST explicitly express rules as how to find the
   Authentication Records.

   Note: above that there is no a requirement that the Application
   Address records be covered by DNS Integrity.  This is because when
   the Application Authentication records reside "at" the address
   records, DNS Integrity is inherited.  On the other hand when when
   Application Authentication Records are stored "at" the Service
   Specification Record, DNS Integrity for the address records is
   optional, as any connection to a bogus/wrong server should fail the
   Authentication tests performed at connection time.

3.  Example specifcation

   This section is an short example for a protocol that is like SSH
   [RFC4253] we will call this protocol HISS.  This is not an actual
   full specification, just here to give an idea of how to go about
   extending DANE-like to a random protocol using the terminology from
   this document.

   Location of HISS protocol DNS records:

   Service Specifcation Records:

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         HISS uses address records as the service specification record.
         This record MUST have "DNS Integrity" as explained in RFC-to-
         be-this-document.  CNAME is treated as a DNS Navigation record.

   Service Address Records:
         see: Service Specification Records.

   Application Authentication Records:
         The protocol uses the DNS HISSFP that is stored at the same
         name as the service is specified.  The HISSFP record, if
         present, takes precedence over keys stored in client cache.

   The HISS protocol and HISSFP DNS RR do not exist

4.  IANA considerations

   None

   [RFC Editor: Please remove this section before publication ]

5.  Security considerations

   TBD

6.  Internationalizaiton Considerations

   When selecting terms to use in standards documents it is important to
   select works that do not confuse international readers.  This
   document goes out of its way in selecting English terms that are
   dissimilar to avoid confusions.

7.  References

7.1.  Normative References

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997.

   [RFC6698]  Hoffman, P. and J. Schlyter, "The DNS-Based Authentication
              of Named Entities (DANE) Transport Layer Security (TLS)
              Protocol: TLSA", RFC 6698, August 2012.

7.2.  Informative References

   [RFC1034]  Mockapetris, P., "Domain names - concepts and facilities",
              STD 13, RFC 1034, November 1987.

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   [RFC4033]  Arends, R., Austein, R., Larson, M., Massey, D., and S.
              Rose, "DNS Security Introduction and Requirements", RFC
              4033, March 2005.

   [RFC4034]  Arends, R., Austein, R., Larson, M., Massey, D., and S.
              Rose, "Resource Records for the DNS Security Extensions",
              RFC 4034, March 2005.

   [RFC4035]  Arends, R., Austein, R., Larson, M., Massey, D., and S.
              Rose, "Protocol Modifications for the DNS Security
              Extensions", RFC 4035, March 2005.

   [RFC4253]  Ylonen, T. and C. Lonvick, "The Secure Shell (SSH)
              Transport Layer Protocol", RFC 4253, January 2006.

   [RFC5246]  Dierks, T. and E. Rescorla, "The Transport Layer Security
              (TLS) Protocol Version 1.2", RFC 5246, August 2008.

   [RFC5280]  Cooper, D., Santesson, S., Farrell, S., Boeyen, S.,
              Housley, R., and W. Polk, "Internet X.509 Public Key
              Infrastructure Certificate and Certificate Revocation List
              (CRL) Profile", RFC 5280, May 2008.

   [RFC6347]  Rescorla, E. and N. Modadugu, "Datagram Transport Layer
              Security Version 1.2", RFC 6347, January 2012.

Appendix A.  Document history

   [RFC Editor: Please remove this section before publication ]

   00 Initial version

Author's Address

   Olafur Gudmundsson
   Shinkuro Inc.
   4922 Fairmont Av, Suite 250
   Bethesda, MD  20814
   USA

   Email: ogud@ogud.com

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