AST week's article promised for this issue the first of a series of rules and regulations governing the structure of cipher systems.
The above mentioned digest of rules is calculated to aid our readers in judging the relative merit of various ciphers. And to further this end, this weekly series will be interspersed with brief surveys of the different classes of ciphers. Here is the first proposition:
(1) A cipher should employ symbols that are easy to write, read, and pronounce; and that are transmissible by existing modes of communication.
Since existing methods of communication are in general best adapted—aside from a few punctuation marks or special signs— to the sending of letters and figures, in selecting symbols for a cipher system it would seem best to limit one's self to these latter characters.
For various reasons most ciphers employ either letters or figures only. But should it be decided to use both letters and figures in the same cipher it would seem advisable, to avoid confusion, to omit either the letters I and O, or the figures 1 and 0.
Proposition one would appear to scrap all arbitrary character ciphers, such as the stroke cipher of Charles Ⅰ explained in this article.
But are such ciphers altogether taboo?
Not at all.
It is even conceivable that in some particular case such a cipher might serve better than any other.
Further, arbitrary character ciphers possess their own peculiar virtues. Thus, signs or marks are capable of minute differences of form whereby a number of symbols, apparently identical to casual observation or even to a very close inspection, might actually have as many altogether different meanings.
But the advantages of the cipher of ordinary letters or figures in general far outweigh those of the arbitrary character cipher.
For example, letters and figures are easier to write, read, and check, in enciphering and deciphering. They can be transcribed by hand or typewriter; or printed with ordinary type in any newspaper, magazine, or other publication, without any special process of reproduction.
In common with any written communication, ciphers of letters and figures can, of course, be dispatched by the usual carrier methods; as, for example, mail, courier, carrier pigeon, messenger dog, or message-throwing devices such as the message-carrying projectiles used during the World War.
Using auxiliary alphabets, of which the International Morse Code is an example, such a cipher is also capable of acoustic transmission by guns, bells, musical instruments, raps, scratches, and so on. And the symbols being pronounceable, oral and telephonic transmission are also practicable.
Similarly, visual systems—such as signal panels, smoke signals, the heliograph, flash lights, pyrotechnics, and wigwag and semaphore flags—come in for their share of attention. Nor must we forget the most important of all, electric transmission, including the land, radio, and cable telegraphs.
The above brief survey by no means exhausts the above classes. And communication by the senses of touch—blind writing, for example—taste and smell have not even been mentioned. Enough has been said, however, to demonstrate that from the viewpoint of transmission a cipher of letters or figures is the most desirable.
Our first proposition being thus firmly established, we can now turn our attention to this week's cryptograms. Both of these are typewriter ciphers, using some symbols that are not transmissible by some established communication methods. Hence, they are somewhat beyond the pale of the above proposition.
They are not intended to be very difficult. Nevertheless, they will be found amusing and instructive, especially if the solver tries to discover the principles of the cipher alphabets, as aids to analysis. Another interesting fact about typewriter ciphers is that any one familiar with typewriter keyboards can often identify the machine upon which a given cipher has been formulated.
The answers to ciphers Nos. 3 and 4 will be published in next week's department.
Here goes. Let us know how you make out.
CIPHER No. 3 (Louis K. Bender, Los Angeles, California).
BWYGEBH LW KEJJE?RSY NRY V:T NI OWB NT EBKRLYUT
CIPHER No. 4 (Arthur Bellamy, Jamaica Plain, Boston, Massachusetts).
5603248534$ -74:8$* 7$ $3'34@# 3&$6 ;35*9%$ 9- $3:%8:_ ?80*34 ;3$$&_3$ @$ :7;3497$ 8:_3:897$ $?*3;3$ 9- $7"$5857589: @#0*@"35$ @43 43@%8#6 %3'8$3% -94 8:$5@:?3 5*3$3 17334 ?*@4@?534$ @43 178?=#6 248553: 7$8:_ 5*3 23## =:92: 597?* $6$53; @:% $*8-5 =36
Last week's No. 2, in Charles Ⅰ stroke cipher, as simple substitution ciphers go, should have been relatively easy to solve. The two symbols used alone, of course, signified A and I. The three-symbol group occurring three times was evidently THE.
Substituting these values in other short words wherever they occurred should have led to the immediate discovery of AND, AT, IN, and THERE; after which the rest of the translation, subjoined, should have followed in a few minutes: "The blow I saw given, and at the instant there was such a groan by the thousands as I desire I may never hear again."
Here is the Charles Ⅰ stroke alphabet:
Remember, you still have one more week in which to solve last week's No. 1, Mr. Davidson's free subscription cipher.
And, speaking of contests, we beg to announce one for next week in which there will be a prize for every solver!