Route Transposition

Description

One of the simplest transposition ciphers is the Route Transposition Cipher where the plaintext is written into a complete block in a given direction, or route, and extracted using a different route to produce the ciphertext.

In total there are 48 different routes possible to write into the square and 48 routes to read from it. These are:

Horizontal

Vertical

Diagonal, top right to bottom left

Diagonal, bottom left to top right

Clockwise

Clockwise, from the middle

Alternative Horizontal (Boustrophedon)

Alternative Vertical

Alternative Diagonal, top right to bottom left

Alternative Diagonal, bottom left to top right

Anticlockwise

Anticlockwise, from the middle

Each of these directions can start from any corner or go in any direction if starting from the middle.

A limitation of this cipher type is that the plaintext must fill a complete block.

Example

Encipher the George Washington quote "It is far better to be alone, than to be in bad company” using a key square width of 6.

Write this into a block of width 6 in rows starting at the top left produces the following rectangle:

I T I S F A

R B E T T E

R T O B E A

L O N E T H

A N T O B E

I N B A D C

O M P A N Y

Reading from the block in columns starting from the top left results in the following cipher:

Ciphertext: IRRLA IOTBT ONNMI EONTB PSTBE OAAFT ETBDN AEAHE CY

Solving

Solving method: Brute force search.

After selecting the Route Transposition cipher, the grid width in the range of 3 to 20 can be selected from the Setup drop down menu. Only widths producing a complete grid will appear in the menu. The default setting of 0 will result in all valid grid widths being tested.