Trifid cipher

In classical cryptography, the trifid cipher is a cipher invented around 1901 by Felix Delastelle, which extends the concept of the bifid cipher to a third dimension, allowing each symbol to be fractionated into 3 elements instead of two.

While the bifid uses the Polybius square to turn each symbol into coordinates on a 5 × 5 (or 6 × 6) square, the trifid turns them into coordinates on a 3 × 3 × 3 cube.

As with the bifid, this is then combined with transposition to achieve diffusion.

However a higher degree of diffusion is achieved because each output symbol depends on 3 input symbols instead of two.

Thus the trifid was the first practical trigraphic substitution.

Operation

Several variants probably exist of the Trifid cipher, and there are known Cyrillic variations of it as well.

Below is one example but most decoders work slightly differently.

All Triffid systems use TABLE,ROW,COLUMN or some variation of it.

The principle remains the same but the result will be completely different.