This archive file contains the Zendian problem, a complex
cryptographic puzzle consisting of hundreds of different
messages enciphered in several different systems.
The Zendian problem was conceived as a training exercise, 
I believe by Lambros D. Callimahos, an associate of
William Friedman.

I've never tackled the Zendian problem, but I believe that
some of the messages are deliberate fakes, such as one might
encounter in real-world conditions.  Others have errors.
Some of the messages are said to be enciphered by machine
cryptosystems.  (I believe that the Zendian problem dates
to the 1950's.)  The messages are supposed to be intercepts
collected all at the same (fictitious) location, I think.

Jim Gillogly says:  "Keith Thompson of NASA scanned them in and
sent them to Doug Gwyn, who made some corrections and sent them to
Jim Reeds, who made some more fixes and sent them to me.  There are
still some errors, many of which are in one or the other of the
printed versions, so I'd say they're now part of the cryptanalysis
problem."

Mark Riordan   19 November 1995
