Monome-Dinome

History

The Monome-Dinome cipher appeared in the Sep-Oct 1996 edition of American Cryptogram Association (ACA) magazine The Cryptogram in an article written by ACA member Frank Lewis (R. MASTERTON) and which is similar to cipher systems used during the 1930s and 40s. It is a numeric cipher produced from a 3x8 grid containing a 24-letter keyed alphabet. The digits 0-9 identify the second and third rows, with the first row not assigned a number. The remaining 8 digits are placed above each column.

Description

The cipher is formed from the row and column indicators producing coordinates for each plaintext character or, for characters on the top row, a single number. The numbers can be random or created from a keyword using the alphabetic order of letters as the key numbers. To create the cipher a keyed alphabet is created from a key word, with repeated letters being omitted, followed by the unused letters of the alphabet in alphabetic order. J and Z are replaced by I and Y respectively. This is written into a 3x8 table and the columns and rows 2 and 3 are numbered using the numbers 0-9. These can be created from a 10-letter keyword using the alphabetical order of the letters or using the numbers in random order. The first two numbers of the numeric key are assigned to rows 2 and 3. For example using the key word GROUCHOMARX and appending unused alphabet letters produces the keyed alphabet:

GROUCHMAXBDEFIKLNPQSTVWY

A 10-letter keyword, JOURNALIST, is used to create the numerical key, 3607514289, from the order of its letters. This is then written into the grid to produce the following table:

0 7 5 1 4 2 8 9

G R O U C H M A

3 X B D E F I K L

6 N P Q S T V W Y

The plaintext is then converted to numbers by locating them in the table and, if the letter is in the top row, the cipher number is the single digit in the same column. Letters in the other rows are replaced by the row digit followed by the column digit.

Example

Keyword #1: GROUCHOMARX

Keyword #2: JOURNALIST (3607514289)

Plaintext: I've had a wonderful time, but this wasn't it - Groucho Marx.

07514289

GROUCHMA

3 XBDEFIKL

6 NPQSTVWY

Plaintext: i v e h a d a w o n d e r f u l t i m e b u t

Ciphertext: 32 62 31 2 9 35 9 68 5 60 35 31 7 34 1 39 64 32 8 31 37 1 64

Plaintext: t h i s w a s n t i t g r o u c h o m a r x

Ciphertext: 64 2 32 61 68 9 61 60 64 32 64 0 7 5 1 4 2 5 8 9 7 30

Ciphertext: 32623 12935 96856 03531 73413 96432 83137 16464 23261 68961 60643 26407 51425 89730

Solving

Solving method: Hill Climbing search.

If a plaintext tip is entered the score will be increased if the tip pattern is found in the resulting text.