Fractionated Morse Cipher

The encryption consists, first of all, of encoding the plain message in Morse (point . for short, dash - for long), with a separator |, between each letter, and between each word a double separator ||.

Example: DCODE MORSE is encoded in Morse -..|-.-.|---|-..|.||--|---|.-.|...|.||

The morse message is divided into trigrams (groups 3 characters) and completed with . or - if required (for the last one)

Example: -.., |-., -.|, ..., ||. (A dot has been added)

Each trigram is then substituted with the following table (read in columns) to get the encoded message.

Example: -.. corresponds to J, |-. for V, -. for L, etc. The final encrypted message is JVLNVGZQODSGY

It is possible to mix the order of the letters of the alphabet to complicate the decryption.

The fractionated Morse decryption requires to know the table used for the encryption (possibly generated with a disordered alphabet or a key).

Each letter of the encrypted message is re-associated with the corresponding trigram.

Example: The message ONTGCI gives --|---|.-.|...|.||

The plain message is then obtained by deciphering this code in Morse (with | as the letter separator).

Example: The decoded plain message is MORSE.

Sometimes a final letter is erroneous or appears in addition to the original message, this is due to the completion in trigrams during the encryption process.

The message is composed of letters and has a coincidence index a little lower than that of the language of the plain text.

Some bigrams or trigrams can never appear as IS, IT, ... IZ or RS, RT, ... RZ because they would introduce three separators ||| which is impossible.

Frequency analysis of trigrams and quadrigrams can give a good estimate of the position of the words THE, OF, etc. in the text.

During encryption, the first row of the table is the alphabet used, a deranged alphabet, or an alphabet generated from a key is also a possibility.