Trifid Cipher: Encrypt and Decrypt Online The Trifid cipher combines substitution with transposition and fractionation. It was invented by Felix Delastelle, a Frenchman who invented several other ciphers including the bifid cipher and the four-square ciphers. Trifid cipher is very similar to bifid cipher, except that instead of a 5 by 5 key square (in bifid) it uses a 3 by 3 by 3 key configuration. Use the above Trifid cipher decoder and encoder to encrypt/decrypt simple messages. If this tool was helpful, tweet it or share it.