The Trifid Cipher is the Bifid Cipher taken to one more dimension. Instead of using a 5x5 Polybius Square, you use a 3x3x3 cube. Otherwise everything else remains the same.
As with the Bifid Cipher, the cube can be mixed to add an extra layer of protection, but for these examples we not be using a mixed alphabet cube.
Layer 1
123
1ABC
2DEF
3GHI
Layer 2
123
1JKL
2MNO
3PQR
Layer 3
123
1STU
2VWX
3YZ.
The first step is to use the cube to convert the letters into numbers. We will be writing the numbers vertically below the message in the order of Layer, Column, Row.
secret message
311213 2133111
123322 1211112
121321 2211132
The numbers are now read off horizontally and grouped into triplets.
311 213 213 311 112 332 212 111 121 213 212 211 132
The cube is used again to convert the numbers back into letters which gives us our ciphertext.
sppsdxmabpmjf
To decipher a Trifid encrypted message, you first convert each letter into its corresponding number via the cube. Now, divide the long string of numbers into three equal rows. Now, read off each column and use the cube to convert the three numbers into the plaintext letter.
PLAINTEXT
secretmessage
CIPHERTEXT
sppsdxmabpmjf
