beaufort_cipher.py

"""
Author: Mohit Radadiya
"""

fromstringimportascii_uppercase

dict1= {char: ifori, charinenumerate(ascii_uppercase)}
dict2=dict(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
defgenerate_key(message: str, key: str) ->str:
"""
 >>> generate_key("THE GERMAN ATTACK","SECRET")
 'SECRETSECRETSECRE'
 """
x=len(message)
i=0
whileTrue:
ifx==i:
i=0
iflen(key) ==len(message):
break
key+=key[i]
i+=1
returnkey


# This function returns the encrypted text
# generated with the help of the key
defcipher_text(message: str, key_new: str) ->str:
"""
 >>> cipher_text("THE GERMAN ATTACK","SECRETSECRETSECRE")
 'BDC PAYUWL JPAIYI'
 """
cipher_text=""
i=0
forletterinmessage:
ifletter==" ":
cipher_text+=" "
else:
x= (dict1[letter] -dict1[key_new[i]]) %26
i+=1
cipher_text+=dict2[x]
returncipher_text


# This function decrypts the encrypted text
# and returns the original text
deforiginal_text(cipher_text: str, key_new: str) ->str:
"""
 >>> original_text("BDC PAYUWL JPAIYI","SECRETSECRETSECRE")
 'THE GERMAN ATTACK'
 """
or_txt=""
i=0
forletterincipher_text:
ifletter==" ":
or_txt+=" "
else:
x= (dict1[letter] +dict1[key_new[i]] +26) %26
i+=1
or_txt+=dict2[x]
returnor_txt


defmain() ->None:
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__":
importdoctest

doctest.testmod()
main()