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, said I, the order of precedence among the letters, according to the frequency of their recurrence, is this, e a o i t d h n r s u y c f g l m w b k p q x z. This, however, is their order, according to the number of words begun by each respectively, s c p a d i f b l b t, etc. The most frequent compounds are th, ng, ee, ll, mm, tt, dd, nn. Pray, Matthew, do you see any one sign repeated oftener than the others in this cryptograph?
Yes, 8; it is repeated twenty-three times, said Fletcher, after a pause.
Then you may be perfectly satisfied that it stands for e, which is used far oftener than any other letter in English. Next, look along the lines and see what letters most frequently accompany it.
2 § undoubtedly; it follows 8 in several places, and precedes it in others. In the third line we have 2 § 8 82 § § 8 8 § 8 and then 2 § 8 again.
Then we may fairly assume that 2 § 8 stands for the.
The, to be sure, burst forth Fletcher. Now the next word will be money. No! it cant be, the e will not suit; perhaps it is treasure, gold, hoard, store.
Wait a little bit, I interposed. Now look what letters are doubled.
88 and 22, said my friend Mat.
And please observe, I continued, that where I draw a line and write A you have e, then double t, then e again. Probably this is the middle of a word, and as we have already supposed 2 to stand for t, we have ette , a very likely combination. We may be sure of the t now. Near the end of the third line, there is a remarkable passage, in which the three letters we know recur continually. Let us write it out, leaving blanks for the letters we do not know, and placing the ascertained letters instead of their symbols. Then it stands eχtheχeth heχeheχ ethe . Now here I have a χ repeated four times, and from its position it must be a consonant. I will put in its place one consonant after another. You see r is the only one which turns the letters into words. erthereth here. here the surely some of these should stand out distinctly separated er there th here. here the. Look! I can see at once what letters are wanting; th between there and here must be than, and then here is, must be, where. So now I have found these letters,