Cryptology - Unofficial St. Mary's College of California Web Site

206 CHAPTER 10. TRANSPOSITION CIPHERS
and U6. This gives the ciphertext
the increasing they go period this as fortified into some be it
and Kingston direction you up cross numbers Wiley boy Burton & If
will too in far strongly go ought surely free without your which
at ought and between on are greatly For Pontoons front you we move
as be stores You Not to delay spare should least to probably us our
preparing
Since the entire message has not yet been enciphered, we proceed by choosing
a new key and enciphering as the new key demands. In this case (since this was
an actual message) Stanton and McDowell were chosen. They each represented
the same system: 6 × 6 with nulls atop columns 1, 5, and 6 and below columns
1, 2 and 3.
fortune the time
oppose a crossing and with your
RELAY to keep open complete and
rapid communications between us so that
we can move combined on him
Let me hear from you if
possible at once No news from
speed this more
(Relay is the code word for cavalry.) The pattern is up the diagonal from bottom
right to top left, followed by D1, U6, U5, D3, U4.
Putting the final portion of the message into cipher as well gives
To Jaque Knoxville, Enemy the increasing they go period this as
fortified into some be it and Kingston direction you up cross numbers
Wiley boy Burton & if will too in far strongly go ought surely free
without your which it ought and between or are greatly for pontoons
front you we move as be stores you not to delay spare should least
to probably us our preparing Stanton from you combinedly between to
oppose fortune roanoke rapid we let possible speed if him that and
your time a communication can me at this news in so complete with
the crossing keep move hear once3e more no from us open and McDowell
julia five thousand ferry the you must drove at them prisoners
artillery men pieces wounded to Godwin relay horses in Lambs of and
yours truly quick killed Loss the our minds ten snow two deserters
Bennet Gordon answer also with across day
E.P. Alexander, the founder of the Confederate Army Signal Corps, received
this ciphertext and was asked to translate it. His account (from Gary W. Gallagher
Fighting for the Confederacy: The Personal Recollections of General
Edward Porter Alexander, pages 302-03) of this incident is quite informative:
I had never seen a cipher of this character before, but it was very clear
that is was simply a disarrangement of words, what may be called, for
short, a jumble. Each correspondent, of course, had what was practically
a list of the natural numbers, say from one up to 50, or whatever limit
was used, taken in an agreed jumble, as for instance beginning 19, 3, 41,
22 &c. Then, the first word of the cipher would be the 19th of the genuine
message, the 2nd cipher would be 3rd of message, the 3rd cipher the 41st,
&c.