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:
I just give the hint that it is a proverb.
The following is much more ingenious, and difficult of detection.
Now suppose that I want to write England; I look among the small letters in the foregoing table for e, and find that it is in a horizontal line with B, and vertical line with B, so I write down BB; n is in line with A and E, so I put AE; continue this, and England will be represented by Bbaeacbdaaaeab. Two letters to represent one is not over-tedious: but the scheme devised by Lord Bacon is clumsy enough. He represented every letter by permutations of a and b; for instance,
and so through the alphabet. Paris would thus be transformed into abbba, aaaaa, baaaa, abaaa, baaab. Conceive the labour of composing a whole despatch like this, and the great likelihood of making blunders in writing it!
A much simpler method is the following. The sender and receiver of the communication must be agreed upon a certain book of a specified edition. The despatch begins with a number; this indicates the page to which the reader is to turn. He must then count the letters from the top of the page, and give them their value numerically according to the order in which they come; omitting those which are repeated. By these numbers he reads his despatch. As an example, let us take the beginning of this article: then, I = 1, n = 2, w = 3, h = 4, e = 5, m = 6, d = 7, l = 8, o = 9, u = 10, v = 11, omitting to count the letters which are repeated. In the middle of the communication the page may be varied, and consequently the numerical significance of each letter altered. Even this could be read with a little trouble; and the word “impossible” can hardly be said to apply to the deciphering of cryptographs.
A curious instance of this occurred at the close of the sixteenth century, when the Spaniards were endeavouring to establish relations between the scattered branches of their vast monarchy, which at that period embraced a large portion of Italy, the Low Countries, the Philippines, and enormous districts in the New World. They accordingly invented a cypher, which they varied from time to time, in order to disconcert those who might attempt to pry into the mysteries of their correspondence. The cypher, composed of fifty signs, was of great value to them through all the troubles of the “Ligue,” and the wars then desolating Europe. Some of their despatches having been intercepted, Henry IV. handed them over to a clever mathematician, Viete, with the request that he would find the clue. He did so, and was able also to follow it as it varied, and France profited for two years by his discovery. The court of Spain, disconcerted at this, accused Viete before the Roman court as a sorcerer and in league with the devil. This proceeding only gave rise to laughter and ridicule.
A still more remarkable instance is that of a German professor, Hermann, who boasted, in 1752, that he had discovered a cryptograph absolutely incapable of being deciphered, without the clue being given by him; and he defied all the savants and learned societies of Europe to discover the key. However, a French refugee, named Beguelin, managed after eight days’ study to read it. This cypher – though we have the rules upon which it is formed before us – is to us perfectly unintelligible. It is grounded on some changes of numbers and symbols; numbers vary, being at one time multiplied, at another added, and become so complicated that the letter e, which occurs nine times in the paragraph, is represented in eight different ways; n is used eight times, and has seven various signs. Indeed the same letter is scarcely ever represented by the same figure; but this is not all: the character which appears in the place of i takes that of n shortly after; another symbol for n stands also for t. How any man could have solved the mystery of this cypher is astonishing.
Now let me recommend a far simpler system, and one which is very difficult of detection. It consists of a combination of numbers and letters. Both parties must be agreed on an arrangement such as that in the second line below, for on it all depends.
Now in turning a sentence such as “The army must retire” into cypher, you count the letters which make the sentence, and find that T is the first, H the second, E the third, A the fourth, R the fifth, and so on. Then look at the table. T is the first letter; 4 answers to 1; therefore write the fourth letter in the place of T; that is A instead of T. For h the second, put the seventh, which is y; for E, take the second, h. The sentence will stand “Ayh utsr emma yhutsr.” It is all but impossible to discover this cypher.
All these cryptographs consist in the exchange of numbers or characters for the real letters; but there are other methods quite as intricate, which dispense with them.
The mysterious cards of the Count de Vergennes are an instance. De Vergennes was Minister of Foreign Affairs under Louis XVI., and he made use of cards of a peculiar nature in his relations with the diplomatic agents of France. These cards were used in letters of recommendation or passports which were given to strangers about to enter France; they were intended to furnish information without the knowledge of the bearers. This was the system. The card given to a man contained only a few words, such as:
The card told more tales than the words written on it. Its colour indicated the nation of the stranger. Yellow showed him to be English; red, Spanish; white, Portuguese; green, Dutch; red and white, Italian; red and green, Swiss; green and white, Russian; etc. The person’s age was expressed by the shape of the card. If it were circular, he was