One document matched: draft-lha-des-die-die-die-05.xml

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE rfc SYSTEM "rfc2629.dtd" [
	  <!ENTITY rfc1964 PUBLIC '' 'http://xml.resource.org/public/rfc/bibxml/reference.RFC.1964.xml'>
	  <!ENTITY rfc1510 PUBLIC '' 'http://xml.resource.org/public/rfc/bibxml/reference.RFC.1510.xml'>
	  <!ENTITY rfc2119 PUBLIC '' 'http://xml.resource.org/public/rfc/bibxml/reference.RFC.2119.xml'>
	  <!ENTITY rfc3961 PUBLIC '' 'http://xml.resource.org/public/rfc/bibxml/reference.RFC.3961.xml'>
	  <!ENTITY rfc4120 PUBLIC '' 'http://xml.resource.org/public/rfc/bibxml/reference.RFC.4120.xml'>
	  <!ENTITY rfc4121 PUBLIC '' 'http://xml.resource.org/public/rfc/bibxml/reference.RFC.4121.xml'>
	  <!ENTITY rfc4772 PUBLIC '' 'http://xml.resource.org/public/rfc/bibxml/reference.RFC.4772.xml'>
	  ]>
<rfc category="std"
     ipr="trust200902"
     docName="draft-lha-des-die-die-die-05"
     updates="1964, 1510, 3961, 4120, 4121">

  <?xml-stylesheet type='text/xsl' href='rfc2629.xslt' ?>

  <?rfc toc="no" ?>
  <?rfc symrefs="yes" ?>
  <?rfc sortrefs="yes"?>
  <?rfc iprnotified="no" ?>
  <?rfc strict="yes" ?>

  <front>
    <title>Deprecate DES support for Kerberos</title>
    <author initials='L' surname="Hornquist Astrand" fullname='Love Hornquist Astrand'>
      <organization>Apple, Inc</organization>
      <address>
        <postal>
	  <street/>
          <city>Cupertino</city> <code/>
          <country>USA</country>
        </postal>
        <email>lha@apple.com</email>
      </address>
    </author>

    <date month="July" year="2010"/>
    <abstract>
      <t>

	A long long time ago Data Encryption Standard (DES) was
	standardized. Some 30 years later (2003) is was withdrawn as a
	standard by National Institute of Standards and Technology
	(NIST), today 6 years later, its time for DES to finally
	die. By 2008 it was possible to brute force DES keys in 6.4
	days using less than USD 10k worth of hardware. So by 2008 DES
	had passed its sell-by date. This document updates RFC1964,
	RFC4120, and RFC4121 to deprecate the use of DES in Kerberos.
	Because the version of Kerberos specified in RFC1510 only
	supports DES and has been replaced by RFC4120, RFC1510 is
	reclassified as historic.
      </t>
    </abstract>
  </front>

  <middle>
    <section title="Requirements Notation">
      <t>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 <xref target="RFC2119"/>.</t>
    </section>

    <section title="Background">
      <t>
	Kerberos 5 was defined in <xref target="RFC1510"/> and updated
	in <xref target="RFC4120"/>, the Kerberos crypto system is
	defined by <xref target="RFC3961"/> and includes support for
	DES encryption types. This document updates <xref target="RFC1964"/>,
	<xref target="RFC4120"/>, and <xref target="RFC4121"/>
	to deprecate the use of DES in Kerberos.
      </t>

      <t>
	Because the version of Kerberos specified in <xref
	target="RFC1510"/> only supports DES and has been replaced by
	<xref target="RFC4120"/>, <xref target="RFC1510"/> is
	reclassified as historic.
      </t>

      <t>
	DES was withdrawn in <xref target="DES-Transition-Plan"/> by
	National Institute of Standards and Technology (NIST). IETF
	have also published its the position in <xref
	target="RFC4772"/>, which in the recommendation summery is
	made very clear: "don't use DES".
      </t>

      <t>
	In Kerberos Generic Security Services Application Programming
	Interface (GSS-API) mechanism <xref target="RFC1964"/> and the
	updated version <xref target="RFC4121"/> the following
	checksum and encryption mechanism is defined: three SGN ALG:
	0000 - DES MAC MD5, 0100 - MD2.5 0200 - DES MAC and one SEAL
	ALG 0000 - DES. With newer encryption types for Kerberos
	defined in <xref target="RFC4121"/>, Microsofts ARCFOUR4-HMAC
	based GSS-API mech, and MITs DES3 , there is no need to
	support the old DES based SGN/SEAL types.
      </t>

    </section>


    <section title="Recommendations">
      <t>
	This document removes the RECOMMENDED types from
	<xref target="RFC4120"/>:
	<list style='empty'>
	  <t>Encryption: DES-CBC-MD5(3)</t>
	  <t>Checksums: DES-MD5 (8, RSA-MD5-DES from <xref target="RFC3961"/>).</t>
	</list>
      </t>

      <t>
	Kerberos implementation and deployments SHOULD NOT implement the
	single DES encryption types: DES-CBC-CRC(1), DES-CBC-MD4(2), DES-CBC-MD5(3).
      </t>

      <t>
	Kerberos implementation and deployments SHOULD NOT implement the
	checksum type: CRC32(1), RSA-MD4(2), RSA-MD4-DES(3), DES-MAC(4), DES-MAC-K(5),
	RSA-MD4-MAC-K(6), DES-MD5(7), RSA-MD5-DES(8).
      </t>

      <t>
	Note that RSA-MD5 might be with non-DES encryption types, for
	example, when doing a TGS-REQ with a ARCFOUR-HMAC-MD5 some
	client uses RSA-MD5 for the checksum that is stored inside the
	encrypted part of the authenticator. This use of RSA-MD5
	should probably be considered safe, so the Kerberos
	implementation should make sure this usage is not disabled
	when used with legacy system that can't handle newer checksum
	types.
      </t>

      <t>
	Kerberos GSS mechanism implementation and deployments SHOULD
	NOT implement the SGN ALG: DES MAC MD5(0000), MD2.5(0100), DES
	MAC(0200) (updates <xref target="RFC1964"/>).
      </t>

      <t>
	Kerberos GSS mechanism implementation and deployments SHOULD
	NOT implement the SEAL ALG: DES(0000) (updates <xref target="RFC1964"/>).
      </t>

      <t>
	The effect of the two last sentences is that this document
	deprecates section 1.2 in <xref target="RFC1964"/>.
      </t>

    </section>

    <section title="Acknowledgements">

      <t>
	Jeffrey Hutzelman, Simon Josefsson, Mattias Amnefelt and Leif
	Johansson have read the document and provided suggestions for
	improvements. Sam hartman proposed moving <xref target="RFC1510"/> to historic.
      </t>

    </section>

    <section title="Security Considerations">

      <t>
	Removing support for single DES improves security since DES is
	considered to be insecure.
      </t>

    </section>
    <section title="IANA Considerations">

      <t>
 	There are no IANA Considerations for this document
      </t>

    </section>
  </middle>

  <back>
    <references title="Normative References">
      &rfc1964;
      &rfc2119;
      &rfc3961;
      &rfc4120;
      &rfc4121;
    </references>
    <references title="Informative References">
      
      &rfc1510;
      &rfc4772;

      <reference anchor="DES-Transition-Plan">
	
	<front>
	  <title>DES Transition Plan - Federal Register / Vol. 70, No. 96</title>
          <author><organization>National Institute of Standards and Technology</organization></author>
	  
          <date year='2006' month='May'/>
        </front>
      </reference>


    </references>
  </back>
</rfc>