A COMMON objection to ciphers which provide more than one fixed symbol for the same letter is that they are very often quite cumbersome to use.
This can hardly be said of Grandpré's ten by ten word square system, however, described in the last article. For encipherment and decipherment in this system are such that they can be performed mentally, if desired, and without memorizing the individual symbols, by merely remembering the eleven words used in constructing the key and calling into play a few mental gymnastics.
For example, in deciphering mentally it is only required to count down in the "master" key word to the line indicated by the tens figure of the symbol, and then to the intended message letter in that line as indicated by the units figure.
When employing the cipher in this way it is better to use a master key word consisting of ten different letters. This, of course, is not absolutely essential. But it tends to avoid confusion between horizontal key words which begin with the same letter.
Last week's Grandpré Cipher No. 175 used the subjoined key. Note that the master key word, formed in the left-hand column by the initials of the other words, is MONARCHIES.
1 2 3 4 5 6 7 8 9 0 1 M O Z A M B I Q U E 2 O B J E C T I O N S 3 N A V I G A T I O N 4 A B J U R A T I O N 5 R E T R O G R A D E 6 C O N V E N T I O N 7 H A W K E S B U R Y 8 I N F L E X I B L E 9 E Q U A T O R I A L 0 S U P P L E M E N T (a) 207187 038355 797039 etc. (b) 20 71 87 03 83 55 79 70 39 etc. (c) S H I P F O R Y O etc.
In deciphering, first group the figures of the cryptogram (a) in pairs, as shown at (b). Then, using tens figures to indicate rows and units figures for columns in the key square, find the message letters (c) represented by these numbers.
The first number, 20, for example, stands for S, the letter found at the intersection of the second row and tenth column. In the same way 71 stands for H; and so on. The translation in full of No. 175 is as follows: "Ship for your escape will anchor at nightfall near the foot of the cliff."
If you looked for OF in solving the above cipher as we suggested, you found yourself limited to four possibilities: 25-71, 56-71, 21-83 and 24-61. Taking 21-83 as OF would give you a good start right off with the last four or five words of the message. The rest would then be only a matter of gradually developing the key and message together. This should have proved an interesting problem. Did you get it?
No doubt you noticed that last week's crypt. No. 173, by J. Lloyd Hood, used every letter in the alphabet. This was a tricky one. Here is the translation: "The quick brown foxy wolf jumped over five lazy hound dogs."
Speaking of crypts, or simple substitution ciphers, a Flint, Michigan, fan suggests that we print two in each issue instead of only one as at present. How does the proposition strike you? All in favor say "aye" or "yea" or something to that effect, and send us some.
To decipher the knight's tour transposition cipher. No. 174, by M.Walker, transcribe the cryptogram by successive horizontals, left to right, into an eight by eight square, number the letters as indicated in the subjoined key, read in numerical order, and you will get the translation: "Friends, I come not here to talk. You know too well the story of our thraldom."
This cipher is based on the knight's move in the game of chess, which is from one corner of any two by three rectangle to the diagonally opposite corner. In the knight's tour every square on the chessboard is touched once only. A large number of different tours are possible, and it is an interesting diversion to compose one. The following tour is original with our correspondent:
50 1 16 37 48 63 24 35 15 38 49 64 25 36 47 62 2 51 26 17 12 9 34 23 27 14 39 10 5 18 61 46 40 3 52 13 8 11 22 33 53 28 55 4 19 6 45 60 56 41 30 7 58 43 32 21 29 54 57 42 31 20 59 44
Taking up this week's ciphers, No. 176 is a crypt, or straight letter substitution cipher, in which one of the fans is traveling under an alias. Can you find him? In No. 177 Dr. Ferrell offers an interesting and not too difficult transposition cipher. See what you can do with it.
No. 178 employs a variation by Grandpré himself of the ten by ten word square system described above. The cryptogram here takes the form of an open letter, which can be on any subject matter whatever at the pleasure of the communicating party. Any ten by ten key can be used in writing the secret message into this letter. In the present case we have used the identical key already given for Cipher No. 175.
One objection to this cipher is that the open or external communication must be many times longer than the secret or internal message. In fact, the secret message expressed in this instance consists of only two words. Nevertheless, a cipher of this kind can be of value on occasion, and the present example is plenty long enough to solve.
Now that we have added solvers' lists, solutions are coming in much larger numbers. So watch for next week's list!
CIPHER No. 176.
VETO WARDNBEH MOECO WIBEH HIRD JEM. EDWARD POMMETH, PINWIG, TENN.
CIPHER No. 177, by Dr. G. A, Ferrell, Montgomery, Alabama.
FLNIE MNSOH HTYNS BAEHL EEHST EGPEV RLEHS AUDIS PBTZB ANESE ILNGC MSIDC RATSI EKOPT EFSIA TLL
CIPHER No. 178.
May 26, 1928. Dear John: Your last letter reached me today. Will answer immediately, as I'm leaving on the twenty-ninth for several days. Will write you again upon my return, not later than the last of next week. Nothing of any importance here to tell you about. Everything is just as usual. Can't say how much longer I'll stay here. Three or four more weeks anyway. Must stop writing now, so good-bye. PHIL.