Spiral Cipher

Spiral writing is a way of writing text not from left to right, but in a spiral (usually following a rectangular grid) with a predefined direction of rotation. This writing can be similar to a cipher by transposition, since the text is read differently, such as from left to right.

To encrypt a message by spiral writing, imagine a quadrangular spiral (written in a square). Then write the message by turning like a spiral/snail.

The final encrypted message is generally constituted by a reading in rows or columns of the grid obtained.

Decryption is writing the message in rows or in columns and reading the text in a spiral. It is necessary to know the mode of writing (inward or outward, trigonometric direction or clockwise, etc.)

a spiral reading gives the plain message ROTATIONS.

Since spiral encryption is a transposition cipher, the coincidence index of the text is the same of the original plain message language.

Sometimes a word or text is formed on one or all of the lines created, the word can be written backwards.

Ideally the encrypted message has a number of square characters (whose square root is an integer: 9, 16, 25, 36 etc.)

Any reference to a vortex, cyclone, spiral, or anything rotating is a clue.

The variants of the spiral writing reside in the text writing (internal or external spiral) and direction (clockwise or counterclockwise spiral), but also in reading the text (line, column or even starting from the end)

It also possible to use another pattern than a spiral, see route cipher.