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Bryan Maloney wrote:

> (only monalphabetic substitution
> > ciphers, actually, for those who care).  He got enough practice
>
> That's kind of like "the champ will fight all comers, who agree to be
> blindfolded, hop on one leg, and only attempt elbow strikes", isn't it?

Now, yes.  150 years ago, given that most advanced cryptography
and cryptanalytic practice was a deep military secret, not really.
The U.S. state of the art during the Civil War was a grid-based
transposition system, done *word by word* rather than letter by
letter, with a few code words and nulls.  The Confederacy never
solved this system at all.

Try this on for size (GUARD is a keyword indicating the specific
grid used):

GUARD THIS THE MILITARY SYSTEM MESSAGE ENCRYPTED USED DURING
CIVIL OUT THIS BY BY WHAT WAR I WE THE THE IS FILL CALL UNION
GRID A


--
John Cowan      http://www.ccil.org/~cowan              [log in to unmask]
        You tollerday donsk?  N.  You tolkatiff scowegian?  Nn.
        You spigotty anglease?  Nnn.  You phonio saxo?  Nnnn.
                Clear all so!  'Tis a Jute.... (Finnegans Wake 16.5)