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INTERNET-DRAFT                                    Donald E. Eastlake 3rd
                                                                     IBM
Expires April 1999                                          October 1998




             Detached Domain Name System (DNS) Information
             -------- ------ ---- ------ ----- -----------

                         Donald E. Eastlake 3rd



Status of This Document

   This draft, file name draft-ietf-dnssec-ddi-06.txt, is intended to be
   become a Proposed Standard RFC.  Distribution of this document is
   unlimited. Comments should be sent to the DNS Security Working Group
   mailing list <dns-security@tis.com> or to the author.

   This document is an Internet-Draft.  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.  Internet-Drafts may be updated, replaced, or obsoleted by
   other documents at any time.  It is not appropriate to use Internet-
   Drafts as reference material or to cite them other than as a
   ``working draft'' or ``work in progress.''

   To view the entire list of current Internet-Drafts, please check the
   "1id-abstracts.txt" listing contained in the Internet-Drafts Shadow
   Directories on ftp.is.co.za (Africa), ftp.nordu.net (Northern
   Europe), ftp.nis.garr.it (Southern Europe), munnari.oz.au (Pacific
   Rim), ftp.ietf.org (US East Coast), or ftp.isi.edu (US West Coast).

   [Changes from last draft: change date, update author info, define 64
   bit retrieval time format to avoid year 2106 problem, permit text
   data format to have more than four digits of year, add IANA
   Considerations section]













Donald E. Eastlake 3rd                                          [Page 1]

INTERNET-DRAFT          Detached DNS Information            October 1998


Abstract

   A standard format is defined for representing detached DNS
   information.  This is anticipated to be of use for storing
   information retrieved from the Domain Name System (DNS), including
   security information, in archival contexts or contexts not connected
   to the Internet.



Table of Contents

      Status of This Document....................................1

      Abstract...................................................2
      Table of Contents..........................................2

      1. Introduction............................................3
      2. General Format..........................................3
      2.1 Binary Format..........................................4
      2.2. Text Format...........................................5
      3. Usage Example...........................................5
      4. IANA Considerations.....................................5
      5. Security Considerations.................................6

      References.................................................7
      Author's Address...........................................7
      Expiration and File Name...................................7
























Donald E. Eastlake 3rd                                          [Page 2]

INTERNET-DRAFT          Detached DNS Information            October 1998


1. Introduction

   The Domain Name System (DNS) is a replicated hierarchical distributed
   database system [RFC 1034, 1035] that can provide highly available
   service.  It provides the operational basis for Internet host name to
   address translation, automatic SMTP mail routing, and other basic
   Internet functions.  The DNS has been extended as described in
   [draft-ietf-dnssec-secext2-*.txt] to permit the general storage of
   public cryptographic keys in the DNS and to enable the authentication
   of information retrieved from the DNS though digital signatures.

   The DNS was not originally designed for storage of information
   outside of the active zones and authoritative master files that are
   part of the connected DNS.  However there may be cases where this is
   useful, particularly in connection with archived security
   information.



2. General Format

   The formats used for detached Domain Name System (DNS) information
   are similar to those used for connected DNS information. The primary
   difference is that elements of the connected DNS system (unless they
   are an authoritative server for the zone containing the information)
   are required to count down the Time To Live (TTL) associated with
   each DNS Resource Record (RR) and discard them (possibly fetching a
   fresh copy) when the TTL reaches zero.  In contrast to this, detached
   information may be stored in a off-line file, where it can not be
   updated, and perhaps used to authenticate historic data or it might
   be received via non-DNS protocols long after it was retrieved from
   the DNS.   Therefore, it is not practical to count down detached DNS
   information TTL and it may be necessary to keep the data beyond the
   point where the TTL (which is defined as an unsigned field) would
   underflow.  To preserve information as to the freshness of this
   detached data, it is accompanied by its retrieval time.

   Whatever retrieves the information from the DNS must associate this
   retrieval time with it.  The retrieval time remains fixed thereafter.
   When the current time minus the retrieval time exceeds the TTL for
   any particular detached RR, it is no longer a valid copy within the
   normal connected DNS scheme.  This may make it invalid in context for
   some detached purposes as well.  If the RR is a SIG (signature) RR it
   also has an expiration time.  Regardless of the TTL, it and any RRs
   it signs can not be considered authenticated after the signature
   expiration time.






Donald E. Eastlake 3rd                                          [Page 3]

INTERNET-DRAFT          Detached DNS Information            October 1998


2.1 Binary Format

   The standard binary format for detached DNS information is as
   follows:

                        1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 3 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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                      first retrieval time                     |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |          RR count             |                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+     Resource Records (RRs)    |
   /                                                               /
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-|
   |                       next retrieval time                     |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |          RR count             |                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+     Resource Records (RRs)    |
   /                                                               /
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   /                              ...                              /
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |     hex 20    |
   +-+-+-+-+-+-+-+-+

   Retrieval time - the time that the immediately following information
      was obtained from the connected DNS system.  It is an unsigned
      number of seconds since the start of 1 January 1970, GMT, ignoring
      leap seconds, in network (big-endian) order.  Note that this time
      can not be before the initial proposal of this standard.
      Therefore, the initial byte of an actual retrieval time,
      considered as a 32 bit unsigned quantity, would always be larger
      than 20 hex.  The end of detached DNS information is indicated by
      a "retrieval time" field initial byte equal to 0x20.  Use of a
      "retrieval time" field with a leading unsigned byte of zero
      indicates a 64 bit (actually 8 leading zero bits plus a 56 bit
      quantity).  This 64 bit format will be required when retrieval
      time is larger than 0xFFFFFFFF, which is some time in the year
      2106.  The meaning of retrieval times with an initial byte between
      0x01 and 0x1F is reserved (see section 5).  Retrieval times will
      not generally be 32 bit aligned with respect to each other due to
      the variable length nature of RRs.

   RR count - an unsigned integer number (with bytes in network order)
      of following resource records retrieved at the preceding retrieval
      time.

   Resource Records - the actual data which is in the same format as if
      it were being transmitted in a DNS response.  In particular, name
      compression via pointers is permitted with the origin at the


Donald E. Eastlake 3rd                                          [Page 4]

INTERNET-DRAFT          Detached DNS Information            October 1998


      beginning of the particular detached information data section,
      just after the RR count.



2.2. Text Format

   The standard text format for detached DNS information is as
   prescribed for zone master files [RFC 1035] except that the $INCLUDE
   control entry is prohibited and the new $DATE entry is required
   (unless the information set is empty). $DATE is followed  by the date
   and time that the following information was obtained from the DNS
   system as described for retrieval time in section 2.1 above.  It is
   in the text format YYYYMMDDHHMMSS where YYYY is the year (which may
   be more than four digits to cover years after 9999), the first MM is
   the month number (01-12), DD is the day of the month (01-31), HH is
   the hour in 24 hours notation (00-23), the second MM is the minute
   (00-59), and SS is the second (00-59).  Thus a $DATE must appear
   before the first RR and at every change in retrieval time through the
   detached information.



3. Usage Example

   A document might be authenticated by a key retrieved from the DNS in
   a KEY resource record (RR).  To later prove the authenticity of this
   document, it would be desirable to preserve the KEY RR for that
   public key, the SIG RR signing that KEY RR, the KEY RR for the key
   used to authenticate that SIG, and so on through SIG and KEY RRs
   until a well known trusted key is reached, perhaps the key for the
   DNS root or some third party authentication service. (In some cases
   these KEY RRs will actually be sets of KEY RRs with the same owner
   and class because SIGs actually sign such record sets.)

   This information could be preserved as a set of detached DNS
   information blocks.



4. IANA Considerations

   Allocation of meanings to retrieval time fields with a initial byte
   of between 0x01 and 0x1F requires an IETF consensus.








Donald E. Eastlake 3rd                                          [Page 5]

INTERNET-DRAFT          Detached DNS Information            October 1998


5. Security Considerations

   The entirety of this document concerns a means to represent detached
   DNS information.  Such detached resource records may be security
   relevant and/or secured information as described in [draft-ietf-
   dnssec-secext2-*.txt].  The detached format provides no overall
   security for sets of detached information or for the association
   between retrieval time and information.  This can be provided by
   wrapping the detached information format with some other form of
   signature.  However, if the detached information is accompanied by
   SIG RRs, its validity period is indicated in those SIG RRs so the
   retrieval time might be of secondary importance.








































Donald E. Eastlake 3rd                                          [Page 6]

INTERNET-DRAFT          Detached DNS Information            October 1998


References

   [RFC 1034] - Domain Names - Concepts and Facilities, P. Mockapetris,
   November 1987.

   [RFC 1035] - Domain Names - Implementation and Specifications, P.
   Mockapetris, November 1987.

   [draft-ietf-dnssec-secext2-*.txt] - Domain Name System Security
   Extensions, Donald Eastlake 3rd.




Author's Address

   Donald E. Eastlake 3rd
   IBM
   318 Acton Street
   Carlisle, MA 01741 USA

   Telephone:   +1-978-287-4877
                +1-914-784-7913
   Fax:         +1-978-371-7148
   email:       dee3@us.ibm.com



Expiration and File Name

   This draft expires April 1999.

   Its file name is draft-ietf-dnssec-ddi-06.txt.



















Donald E. Eastlake 3rd                                          [Page 7]


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