	Data Encryption Standard

	The NSA has announced that the Data Encryption Standard, or
DES for short, would not be supported when it expired. Various banks
have pushed for its retention on the grounds that it's secure enough
for the time being.
	This is to advise all and sundry that in the 1979 to 1980 period
there appeared an article in the Proceedings of the Soviet Academy of
Science giving a simple way of pruning decision trees for DES ciphers
which describes equivalence classes of keys and allows greatly reduced
processing to break a DES cipher. The reduction in processing is such
that breaking a DES cipher would amount to on order 1.5 hours on a
standard IBM PC. There have been rumors that such a program is in
circulation and that a copy of it at NSA led to its withdrawal of
support for DES.
	Be advised that DES is EXTREMELY likely to be vulnerable and
that other crypto methods are probably needed to secure data.
	The Soviet article goes on to give some conditions on the
factors used for public key encryption which prevent or allow easy
breaking of those ciphers, so it is probably required reading for anyone
serious about protecting information.

