krb5-1.4 is released

Tom Yu tlyu at MIT.EDU
Thu Jan 27 18:44:09 EST 2005


The MIT Kerberos Team announces the availability of MIT Kerberos 5
Release 1.4.  Please see below for a list of some major changes
included, or consult the README file in the source tree for a more
detailed list of significant changes.


You may retrieve the Kerberos 5 Release 1.4 source from the
following URL:

The homepage for the krb5-1.4 release is:

Further information about Kerberos 5 may be found at the following


In the past few years, several developments have shown the inadequacy
of the security of version 4 of the Kerberos protocol.  These
developments have led the MIT Kerberos Team to begin the process of
ending support for version 4 of the Kerberos protocol.  The plan
involves the eventual removal of Kerberos 4 support from the MIT
implementation of Kerberos.

The Data Encryption Standard (DES) has reached the end of its useful
life.  DES is the only encryption algorithm supported by Kerberos 4,
and the increasingly obvious inadequacy of DES motivates the
retirement of the Kerberos 4 protocol.  The National Institute of
Standards and Technology (NIST), which had previously certified DES as
a US government encryption standard, has officially announced[1] its
intention to withdraw the specification of DES.

NIST's action reflects the long-held opinion of the cryptographic
community that DES has too small a key space to be secure.  Breaking
DES encryption by an exhaustive search of its key space is within the
means of some individuals, many companies, and all major governments.
Consequently, DES cannot be considered secure for any long-term keys,
particularly the ticket-granting key that is central to Kerberos.

Serious protocol flaws[2] have been found in Kerberos 4.  These flaws
permit attacks which require far less effort than an exhaustive search
of the DES key space.  These flaws make Kerberos 4 cross-realm
authentication an unacceptable security risk and raise serious
questions about the security of the entire Kerberos 4 protocol.

The known insecurity of DES, combined with the recently discovered
protocol flaws, make it extremely inadvisable to rely on the security
of version 4 of the Kerberos protocol.  These factors motivate the MIT
Kerberos Team to remove support for Kerberos version 4 from the MIT
implementation of Kerberos.

The process of ending Kerberos 4 support began with release 1.3 of MIT
Kerberos 5.  In release 1.3, the KDC support for version 4 of the
Kerberos protocol is disabled by default.  Release 1.4 of MIT Kerberos
continues to include Kerberos 4 support (also disabled by default in
the KDC), but we intend to completely remove Kerberos 4 support from
some future release of MIT Kerberos, possibly as early as the 1.5
release of MIT Kerberos.

The MIT Kerberos Team has ended active development of Kerberos 4,
except for the eventual removal of all Kerberos 4 functionality.  We
will continue to provide critical security fixes for Kerberos 4, but
routine bug fixes and feature enhancements are at an end.

We recommend that any sites which have not already done so begin a
migration to Kerberos 5.  Kerberos 5 provides significant advantages
over Kerberos 4, including support for strong encryption,
extensibility, improved cross-vendor interoperability, and ongoing
development and enhancement.

If you have questions or issues regarding migration to Kerberos 5, we
recommend discussing them on the kerberos at mailing list.


[1] National Institute of Standards and Technology.  Announcing
    Proposed Withdrawal of Federal Information Processing Standard
    (FIPS) for the Data Encryption Standard (DES) and Request for
    Comments.  Federal Register 04-16894, 69 FR 44509-44510, 26 July
    2004.  DOCID:fr26jy04-31.

[2] Tom Yu, Sam Hartman, and Ken Raeburn. The Perils of
    Unauthenticated Encryption: Kerberos Version 4. In Proceedings of
    the Network and Distributed Systems Security Symposium. The
    Internet Society, February 2004.



* Fix heap buffer overflow in password history
   mechanism. [MITKRB5-SA-2004-004]

* Add implementation of the RPCSEC_GSS authentication flavor to the
  RPC library. Thanks to Kevin Coffman and the CITI group at the
  University of Michigan.

* Thread safety for krb5 libraries.

* Merged Athena telnetd changes for creating a new option for
  requiring encryption.

* The kadmind4 backwards-compatibility admin server and the v5passwdd
  backwards-compatibility password-changing server have been removed.

* Yarrow code now uses AES.

* New client commands kcpytkt and kdeltkt for Windows.

* New command mit2ms on Windows.

* Merged Athena changes to allow ftpd to require encrypted passwords.

* Incorporate gss_krb5_set_allowable_enctypes() and
  gss_krb5_export_lucid_sec_context(), which are needed for NFSv4,
  from Kevin Coffman.
Version: GnuPG v1.2.5 (SunOS)

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