[draft] End of Support For Kerberos 4

Cesar Garcia Cesar.Garcia at morganstanley.com
Fri Aug 20 16:44:06 EDT 2004

what are the timeframes for 1.4/1.5 (if known)?

On 08/20/04 16:19:43, Sam Hartman wrote:
> [Comments before I send this to kerberos-announce are welcome.]
> With the release of MIT Kerberos version 1.3, MIT began the process of
> ending support for version 4 of the Kerberos protocol.  IN the 1.3
> release, we default to disabling Kerberos protocol version 4 on MIT
> KDCs.
> Now we announce the continuation of our plan to end support for
> Kerberos 4.  This plan will continue in two phases.  First, MIT is
> committed to including Kerberos 4 support in release 1.4 of MIT
> Kerberos.  However we plan to remove Kerberos 4 support from some
> future version of MIT Kerberos; hopefully we will be able to remove
> Kerberos 4 support for the 1.5 release of MIT Kerberos.
> Secondly, MIT has ended development of Kerberos 4 except for two
> special projects.  The first project is to merge the Kerberos 4
> implementation used on Windows into the main Kerberos 4 implementation
> used on Unix and the Mac.  The second project is the eventual removal
> of all Kerberos 4 functionality.  MIT will continue to provide
> critical security fixes for Kerberos 4, but routine bug fixing and
> feature enhancements are at an end.
> We recommend any sites that have not already done so begin a migration
> to Kerberos 5.  Kerberos 5 provides  support for strong  encryption,
> extensibility, much better cross-vendor interoperability and ongoing
> development and enhancement.    
> Over the past year, two developments have lead to the critical need to
> end support for Kerberos 4.  The first is the NIST decision to end
> certification for the DES encryption system [1].  DES is the only
> encryption supported by Kerberos 4.  Affording the equipment necessary
> to break DES encryption is within the means of many companies and all
> major governments.  As such, DES cannot be considered secure for any
> long-term keys, especially including the ticket-granting key that is
> central to a Kerberos.  Secondly, protocol flaws were discovered in
> Kerberos 4 [2].  These flaws make cross-realm authentication an
> unacceptable security risk for Kerberos 4 and call into question the
> security of the entire Kerberos 4 protocol.
> We wish you all the best of luck in your migration to Kerberos 5 and
> hope you enjoy the flexibility and power of the new protocol.
>                               References
> [1]  http://csrc.ncsl.nist.gov/publications/nistbul/09-02itl.pdf
> [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. 
>        (http://web.mit.edu/tlyu/papers/krb4peril-ndss04.pdf)
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