In 1680, when M. de Louvois was French Minister of War, he summoned before
him one day a gentleman named Chamilly, and gave him the following
instructions:
“Start this evening for Basle, in Switzerland; you will reach it in three
days; on the fourth, punctually at two o’clock, station yourself on the
bridge over the Rhine, with a portfolio, ink, and a pen. Watch all that
takes place, and make a memorandum of every particular. Continue doing so
for two hours; have a carriage and post-horses awaiting you;, and at four
precisely mount, and travel night and day till you reach Paris. On the
instant of your arrival, hasten to me with your notes.”
De Chamilly obeyed; he reached Basle, and on the day and at the hour
appointed, stationed himself, pen in hand, on the bridge. Presently a
market-cart drives by; then an old woman with a basket of fruit passes;
anon, a little urchin trundles his hoop by; next an old gentleman in blue
top-coat jogs past on his gray mare. Three o’clock chimes from the
cathedral tower. Just at the last stroke, a tall fellow in yellow
waistcoat and breeches saunters up, goes to the middle of the bridge,
lounges over, and looks at the water; then he takes a step back and
strikes three hearty blows on the footway with his staff. Down goes every
detail in De Chamilly’s book. At last the hour of release sounds, and he
jumps into his carriage. Shortly before midnight, after two days of
ceaseless travelling, De Chamilly presented himself before the minister,
feeling rather ashamed at having such trifles to record. M. de Louvois
took the portfolio with eagerness, and glanced over the notes. As his eye
caught the mention of the yellow-breeched man, a gleam of joy flashed
across his countenance. He rushed to the king, roused him from sleep,
spoke in private with him for a few moments, and then four couriers who
had been held in readiness since five on the preceding evening were
despatched with haste. Eight days after, the town of Strasbourg was
entirely surrounded by French troops, and summoned to surrender: it
capitulated and threw open its gates on the 30th of September 1681.
Evidently the three strokes of the stick given by the fellow in yellow
costume, at an appointed hour, were the signal of the success of an
intrigue concerted between M. de Louvois and the magistrates of
Strasbourg, and the man who executed this mission was as ignorant of the
motive as was M. de Chamilly of the motive of his.
Now this is a specimen of the safest of all secret communications, but it
can only be resorted to on certain rare occasions. When a lengthy despatch
is required to be forwarded, and when such means as those given above are
out of the question, some other method must be employed. Herodotus gives
us a story to the point: it is found also, with variations, in Aulus
Gellius.
“Histiæus, when he was anxious to give Aristagoras orders to revolt, could
find but one safe way, as the roads were guarded, of making his wishes
known: which was by taking the trustiest of his slaves, shaving all the
hair from off his head, and then pricking letters upon the skin, and
waiting till the hair grew again. This accordingly he did; and as soon as
ever the hair was grown, he despatched the man to Miletus, giving him no
other message than this: ‘When thou art come to Miletus, bid Aristagoras
shave thy head, and look thereon.’ Now the marks on the head were a
command to revolt.”--Bk. v. 35.
In this case no cypher was employed; we shall come, now, to the use of
cyphers.
When a despatch or communication runs great risk of falling into the hands
of an enemy, it is necessary that its contents should be so veiled, that
the possession of the document may afford him no information whatever.
Julius Cæsar and Augustus used cyphers, but they were of the utmost
simplicity, as they consisted merely in placing D in the place of A; E in
that of B, and so on; or else in writing B for A, C for B, etc.
Secret characters were used at the Council of Nicæa; and Rabanus Maurus,
Abbot of Fulda and Archbishop of Mayence in the ninth century, has left us
an example of two cyphers, the key to which was discovered by the
Benedictines. It is only a wonder that any one could have failed to
unravel them at the first glance. This is a specimen of the first:
.Nc.p.t v:rs:·:s B::n.f:c.. :rch. gl::r.::s.q:.:: m:rt.r.s
The secret of this is that the vowels have been suppressed and their
places filled by dots,--one for i, two for a, three for e, four for o, and
five for u. In the second example, the same sentence would run--Knckpkt
vfrsxs Bpnkfbckk, etc., the vowel-places being filled by the
consonants--b, f, k, p, x. By changing every letter in the alphabet, we
make a vast improvement on this last; thus, for instance, supplying the
place of a with z, b with x, c with v, and so on. This is the system
employed by an advertiser in a provincial paper which I took up the other
day in the waiting-room of a station, where it had been left by a farmer.
As I had some minutes to spare, before the train was due, I spent them in
deciphering the following:
Jp Sjddjzb rza rzdd ci sijmr, Bziw rzdd xr ndzt:
and in ten minutes I read: “If William can call or write, Mary will be
glad.”
A correspondence was carried on in the _Times_ during May 1862 in cypher.
I give it along with the explanation.
Wws.--Zy Efpdolj T dpye l wpeepc ez mjcyp qzc jzf--xlj T daply qfwwj
zy lww xleepcd le esp tyepcgtph? Te xlj oz rzzo. Ecfde ez xj wzgp--T
lx xtdpclmwp. Hspy xlj T rz ez Nlyepcmfcj tq zywj ez wzzv le jzf.--May
8.
This means--“On Tuesday I sent a letter to Byrne for you. May I speak
fully on all matters at the interview? It may do good. Trust to my love. I
am miserable. When may I go to Canterbury if only to look at you?”
A couple of days later Byrne advertises, slightly varying the cypher:
Wws.--Sxhrdktg hdbtewxcv “Tmwxqxixdc axzt” udg pcdewtg psktgexhtbtce
... QNGCT. “Discover something _Exhibition-like_ for another
advertisement. Byrne.”
This gentleman is rather mysterious: I must leave my readers to conjecture
what he means by “Exhibition-like.” On Wednesday came two advertisements,
one from the lady--one from the lover. WWS. herself seems rather
sensible--
Tydeplo zq rztyr ez nlyepcmfcj, T estyv jzf slo xfns mpeepc delj le
szxp lyo xtyo jzfc mfdtypdd.--WWS., May 10.
“Instead of going to Canterbury, I think you had much better stay at home
and mind your business.”
Excellent advice; but how far likely to be taken by the eager wooer, who
advertises thus?--
Wws.--Fyetw jzfc qlespc lydhpcd T hzye ldv jzf ez aczgp jzf wzgp xp.
Efpdol ytrse le zyp znwznv slgp I dectyr qczx esp htyozh qzc wpeepcd.
Tq jzt lcp yze lmwp le zyp T htww hlte. Rzo nzxqzce jzf xj olcwtyr
htqp.
“Until your father answers I won’t ask you to prove you love me. Tuesday
night at one o’clock have a string from the window for letters. If you are
not able at one I will wait. God comfort you, my darling wife.”
Only a very simple Romeo and Juliet could expect to secure secrecy by so
slight a displacement of the alphabet.
When the Chevalier de Rohan was in the Bastille, his friends wanted to
convey to him the intelligence that his accomplice was dead without having
confessed. They did so by passing the following words into his dungeon,
written on a shirt: “Mg dulhxcclgu ghj yxuj; lm ct ulgc alj.” In vain did
he puzzle over the cypher, to which he had not the clue. It was too short:
for the shorter a cypher letter, the more difficult it is to make out. The
light faded, and he tossed on his hard bed, sleeplessly revolving the
mystic letters in his brain, but he could make nothing out of them. Day
dawned, and, with its first gleam, he was poring over them: still in vain.
He pleaded guilty, for he could not decipher “Le prisonnier est mort; il
_n’a rien dit_.”
Another method of veiling a communication is that of employing numbers or
arbitrary signs in the place of letters, and this admits of many
refinements. Here is an example to test the reader’s sagacity:
§ †431 45 2+9 +§51 4= 8732+ 287 45 2+9 †¶=+