Python/ciphers/beaufort_cipher.py

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"""
Author: Mohit Radadiya
"""
from string import ascii_uppercase
dict1 = {char: i for i, char in enumerate(ascii_uppercase)}
dict2 = {i: char for i, char in enumerate(ascii_uppercase)}
# This function generates the key in
# a cyclic manner until it's length isn't
# equal to the length of original text
def generate_key(message: str, key: str) -> str:
"""
>>> generate_key("THE GERMAN ATTACK","SECRET")
'SECRETSECRETSECRE'
"""
x = len(message)
i = 0
while True:
if x == i:
i = 0
if len(key) == len(message):
break
key += key[i]
i += 1
return key
# This function returns the encrypted text
# generated with the help of the key
def cipher_text(message: str, key_new: str) -> str:
"""
>>> cipher_text("THE GERMAN ATTACK","SECRETSECRETSECRE")
'BDC PAYUWL JPAIYI'
"""
cipher_text = ""
i = 0
for letter in message:
if letter == " ":
cipher_text += " "
else:
x = (dict1[letter] - dict1[key_new[i]]) % 26
i += 1
cipher_text += dict2[x]
return cipher_text
# This function decrypts the encrypted text
# and returns the original text
def original_text(cipher_text: str, key_new: str) -> str:
"""
>>> original_text("BDC PAYUWL JPAIYI","SECRETSECRETSECRE")
'THE GERMAN ATTACK'
"""
or_txt = ""
i = 0
for letter in cipher_text:
if letter == " ":
or_txt += " "
else:
x = (dict1[letter] + dict1[key_new[i]] + 26) % 26
i += 1
or_txt += dict2[x]
return or_txt
def main():
message = "THE GERMAN ATTACK"
key = "SECRET"
key_new = generate_key(message, key)
s = cipher_text(message, key_new)
print(f"Encrypted Text = {s}")
print(f"Original Text = {original_text(s, key_new)}")
if __name__ == "__main__":
import doctest
doctest.testmod()
main()