Why a 3×3×3 cube instead of the usual square?

A classic 5×5 Polybius square holds 25 cells and must merge two letters such as I and J. A 3×3×3 cube has 27 cells, enough for all 26 letters plus one extra symbol (a period here) with no merging needed, while keeping each axis a single digit from 1 to 3.

How is a character turned into coordinates?

Each character maps to an index from 0 to 26. That index is split into a layer (Z), a row (Y), and a column (X), each from 1 to 3, by treating it as a base-3 number. The output triplet is written X then Y then Z.

Is this a secure cipher?

No. Like all classical substitution ciphers it is a fixed mapping with no key, so it is trivially broken by frequency analysis. It is a teaching and puzzle tool, useful for learning about coordinate encodings, not for protecting real secrets.

What happens to spaces and unsupported characters?

When encoding, any character not in the 27-cell set (including spaces) is simply skipped, so the output is a clean stream of triplets. When decoding, a triplet that maps to no cell, or a malformed group, shows as a question mark.

How do I separate triplets when decoding?

You can separate them with spaces, commas, or newlines, for example 111 211 321. The tool also accepts a continuous run of digits whose length is a multiple of three and splits it into triplets automatically.

3D Polybius Cube Cipher

The Polybius square is one of the oldest coordinate ciphers, turning each letter into a pair of numbers. This variant stretches the idea into three dimensions: a 3×3×3 cube with 27 cells, one for each of the 26 letters plus a period, so every character becomes an X-Y-Z triplet of single digits.

How it works

The 27 characters fill the cube in order. A character’s index n (0 to 26) is decomposed like a base-3 number into a layer, row, and column:

z (layer)  = floor(n / 9) + 1
y (row)    = floor((n mod 9) / 3) + 1
x (column) = (n mod 3) + 1
output     = "x y z"   (each 1..3)

Decoding reverses the arithmetic: index = (z-1)*9 + (y-1)*3 + (x-1), then the character at that index is looked up. Because the mapping is a simple bijection, encode and decode are exact inverses.

Tips and example

The letter A is index 0, giving coordinates 111; B is index 1, giving 211; J is index 9, the first cell of the second layer, giving 112. Encoding GERA yields four triplets. This makes a neat puzzle format because the output uses only the digits 1, 2, and 3. Remember it offers no real security — it is a fixed mapping with no key — so treat it as a learning toy for coordinate systems and classical ciphers.