ciphers.trifid_cipher

The trifid cipher uses a table to fractionate each plaintext letter into a trigram, mixes the constituents of the trigrams, and then applies the table in reverse to turn these mixed trigrams into ciphertext letters.

https://en.wikipedia.org/wiki/Trifid_cipher

Attributes

TEST_CHARACTER_TO_NUMBER

TEST_NUMBER_TO_CHARACTER

msg

Functions

__decrypt_part(→ tuple[str, str, str])

Convert each letter of the input string into their respective trigram values, join

__encrypt_part(→ str)

Arrange the triagram value of each letter of message_part vertically and join

__prepare(→ tuple[str, str, dict[str, str], dict[str, ...)

A helper function that generates the triagrams and assigns each letter of the

decrypt_message(→ str)

decrypt_message

encrypt_message(→ str)

encrypt_message

Module Contents

ciphers.trifid_cipher.__decrypt_part(message_part: str, character_to_number: dict[str, str]) → tuple[str, str, str]

Convert each letter of the input string into their respective trigram values, join them and split them into three equal groups of strings which are returned.

>>> __decrypt_part('ABCDE', TEST_CHARACTER_TO_NUMBER)
('11111', '21131', '21122')
ciphers.trifid_cipher.__encrypt_part(message_part: str, character_to_number: dict[str, str]) → str

Arrange the triagram value of each letter of message_part vertically and join them horizontally.

>>> __encrypt_part('ASK', TEST_CHARACTER_TO_NUMBER)
'132111112'
ciphers.trifid_cipher.__prepare(message: str, alphabet: str) → tuple[str, str, dict[str, str], dict[str, str]]

A helper function that generates the triagrams and assigns each letter of the alphabet to its corresponding triagram and stores this in a dictionary (character_to_number and number_to_character) after confirming if the alphabet’s length is 27.

>>> test = __prepare('I aM a BOy','abCdeFghijkLmnopqrStuVwxYZ+')
>>> expected = ('IAMABOY','ABCDEFGHIJKLMNOPQRSTUVWXYZ+',
... TEST_CHARACTER_TO_NUMBER, TEST_NUMBER_TO_CHARACTER)
>>> test == expected
True

Testing with incomplete alphabet

>>> __prepare('I aM a BOy','abCdeFghijkLmnopqrStuVw')
Traceback (most recent call last):
    ...
KeyError: 'Length of alphabet has to be 27.'

Testing with extra long alphabets

>>> __prepare('I aM a BOy','abCdeFghijkLmnopqrStuVwxyzzwwtyyujjgfd')
Traceback (most recent call last):
    ...
KeyError: 'Length of alphabet has to be 27.'

Testing with punctuations that are not in the given alphabet

>>> __prepare('am i a boy?','abCdeFghijkLmnopqrStuVwxYZ+')
Traceback (most recent call last):
    ...
ValueError: Each message character has to be included in alphabet!

Testing with numbers

>>> __prepare(500,'abCdeFghijkLmnopqrStuVwxYZ+')
Traceback (most recent call last):
    ...
AttributeError: 'int' object has no attribute 'replace'
ciphers.trifid_cipher.decrypt_message(message: str, alphabet: str = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ.', period: int = 5) → str

decrypt_message

Decrypts a trifid_cipher encrypted message.

PARAMETERS

  • message: The message you want to decrypt.

  • alphabet (optional): The characters used for the cipher.

  • period (optional): The number of characters used in grouping when it was encrypted.

>>> decrypt_message('BCDGBQY')
'IAMABOY'

Decrypting with your own alphabet and period

>>> decrypt_message('FMJFVOISSUFTFPUFEQQC','FELIXMARDSTBCGHJKNOPQUVWYZ+',5)
'AIDETOILECIELTAIDERA'
ciphers.trifid_cipher.encrypt_message(message: str, alphabet: str = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ.', period: int = 5) → str

encrypt_message

Encrypts a message using the trifid_cipher. Any punctuatuions that would be used should be added to the alphabet.

PARAMETERS

  • message: The message you want to encrypt.

  • alphabet (optional): The characters to be used for the cipher .

  • period (optional): The number of characters you want in a group whilst encrypting.

>>> encrypt_message('I am a boy')
'BCDGBQY'

>>> encrypt_message(' ')
''

>>> encrypt_message('   aide toi le c  iel      ta id  era    ',
... 'FELIXMARDSTBCGHJKNOPQUVWYZ+',5)
'FMJFVOISSUFTFPUFEQQC'
ciphers.trifid_cipher.TEST_CHARACTER_TO_NUMBER
ciphers.trifid_cipher.TEST_NUMBER_TO_CHARACTER
ciphers.trifid_cipher.msg = 'DEFEND THE EAST WALL OF THE CASTLE.'