1. Use the Fractionated Morse cipher with key = FINAL to encrypt the plaintext:
ID: 3737846 • Letter: 1
Question
1. Use the Fractionated Morse cipher with key = FINAL to encrypt the plaintext:
Y O U M U S T P R E P A R E T O S U C C E E D
FRACTIONATED MORSE CHART
… .|- --| |.|
..- .|| -|. |-.
..| -.. -|- |--
.-. -.- -|| |-|
.-- -.| |.. ||.
.-| --. |.- ||-
.|. ---
2. Decrypt the following ciphertext, which was encrypted with the Fractionated Morse cipher using key=FINAL
n r n f z c s b c j x m w r a c q u
Explanation / Answer
The encryption consists, first of all, of encoding the plain message in Morse, with a separator |, between each letter, and between each word.
Example: DCODE MORSE is encoded in Morse -..|-.-.|---|-..|.||--|---|.-.|...|.||
The morse message is divided into trigrams (3 characters) and completed with . or - if required
Example: -.., |-., -.|, ..., ||. (A dot has been added)
Each trigram is then substituted with the following table (read in columns) to get the encoded message.
A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
. . . . . . . . . - - - - - - - - - | | | | | | | |
. . . - - - | | | . . . - - - | | | . . . - - - | |
. - | . - | . - | . - | . - | . - | . - | . - | . -
Example: -.. corresponds to J, |-. for V, -. for L, etc. The final encrypted message is JVLNVGZQODSGY
How to decrypt fractionated Morse cipher?
The decryption uses the same table as 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: Consider the message ONTGCI, it gives --|---|.-.|...|.||
The plain message is then obtained by deciphering this code in Morse (with | as the letter separator).
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