Trifid Cipher
Encode and decode using the Trifid cipher. A 3D fractionating cipher invented by Felix Delastelle.
Used to generate the 3x3x3 cube
Group size for fractionation
Trifid Cube (3 layers)
How Trifid Works
- Each letter has 3D coordinates (layer, row, column)
- Split message into groups of period length
- Write all layers, then rows, then columns
- Read in groups of 3 to get new coordinates
What is the Trifid Cipher?
The Trifid cipher is a classical cipher invented by Felix Delastelle around 1902. It extends the Bifid cipher's concept into three dimensions, using a 3×3×3 cube instead of a 5×5 square, allowing it to encode 27 symbols (A-Z plus one extra).
How It Works
The Cube
The 27-character alphabet is arranged in a 3×3×3 cube. Each letter has three coordinates: layer (0-2), row (0-2), and column (0-2).
Encryption Process
- Divide the plaintext into groups of the period length
- Convert each letter to its three coordinates
- Write all layer values, then rows, then columns
- Read the combined digits in groups of 3 as new coordinates
- Convert back to letters
The Period
The period determines how letters are grouped for fractionation:
- Small period (3-5): More diffusion per letter
- Large period: Affects more letters at once
- Period = message length: Maximum diffusion
Trifid in Geocaching
The Trifid cipher appears in puzzles because:
- Advanced cipher: More challenging than basic substitutions
- 3D aspect: Interesting visual element
- Historical: Part of classical cryptography
- Two parameters: Both keyword and period can be puzzle clues
Breaking the Cipher
Without the keyword and period:
- Period determination: Try common periods (5, 7, etc.)
- Hill climbing: Optimize the cube arrangement
- Known plaintext: Greatly simplifies the attack
- Dictionary attack: Try common keywords