Deprecate DES, "export strength" RC4, and other weak cryptographic algorithms in Kerberos
draft-ietf-krb-wg-des-die-die-die-03

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Last updated 2012-02-16 (latest revision 2012-02-10)
Replaces draft-lha-des-die-die-die
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Network Working Group                               L. Hornquist Astrand
Internet-Draft                                                Apple, Inc
Updates: 1510, 1964, 4120, 4121, 4757                              T. Yu
(if approved)                                    MIT Kerberos Consortium
Intended status: BCP                                   February 16, 2012
Expires: August 19, 2012

   Deprecate DES, "export strength" RC4, and other weak cryptographic
                         algorithms in Kerberos
                  draft-ietf-krb-wg-des-die-die-die-03

Abstract

   The Kerberos 5 network authentication protocol, originally specified
   in RFC1510, can use the Data Encryption Standard (DES) for
   encryption.  Almost 30 years after first publishing DES, the National
   Institute of Standards and Technology (NIST) finally withdrew the
   standard in 2005, reflecting a long-established consensus that DES is
   insufficiently secure.  By 2008, commercial hardware costing less
   than USD 15,000 could break DES keys in less than a day on average.
   DES is long past its sell-by date.  Accordingly, this document
   updates RFC1964, RFC4120, RFC4121, and RFC4757 to deprecate the use
   of DES, "export strength" RC4, and other weak cryptographic
   algorithms in Kerberos.  Because RFC1510 (obsoleted by RFC4120)
   supports only DES, this document reclassifies RFC1510 as Historic.

Status of this Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
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   Internet-Drafts are draft documents valid for a maximum of six months
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   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on August 19, 2012.

Copyright Notice

   Copyright (c) 2012 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

Hornquist Astrand & Yu   Expires August 19, 2012                [Page 1]
Internet-Draft          Deprecate DES in Kerberos          February 2012

   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.

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.  Introduction

   The original specification of the Kerberos 5 network authentication
   protocol [RFC1510] supports only the Data Encryption Standard (DES)
   for encryption.  For many years, the cryptographic community has
   regarded DES as providing inadequate security, mostly because of its
   small key size.  Accordingly, this document reclassifies [RFC1510]
   (obsoleted by [RFC4120]) as Historic, and updates current Kerberos-
   related specifications [RFC1964], [RFC4120], and [RFC4121] to
   deprecate the use of DES and other weak cryptographic algorithms in
   Kerberos, including some unkeyed checksums and hashes, along with the
   weak "export strength" RC4 enctype of [RFC4757].

3.  Affected specifications

   The original IETF specification of Kerberos 5 [RFC1510] only supports
   DES for encryption.  [RFC4120] obsoletes [RFC1510] and updates the
   Kerberos specification to include additional cryptographic
   algorithms, but still permits the use of DES.  [RFC3961] describes
   the Kerberos cryptographic system and includes support for DES
   encryption types, but it does not specify requirement levels for
   them.

   The specification of the Kerberos Generic Security Services
   Application Programming Interface (GSS-API) mechanism [RFC1964] and
   its updated version [RFC4121] define checksum and encryption
   mechanisms based on DES.  With the existence of newer encryption
   types for Kerberos GSS-API defined in [RFC4121], Microsoft's RC4-HMAC
   based GSS-API mechanism, and MIT's DES3 (which is not published as an

Hornquist Astrand & Yu   Expires August 19, 2012                [Page 2]
Internet-Draft          Deprecate DES in Kerberos          February 2012

   RFC), there is no need to support the old DES based integrity (SGN)
   and confidentiality (SEAL) types.
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