Python/ciphers/gronsfeld_cipher.py

46 lines
1.2 KiB
Python
Raw Permalink Normal View History

from string import ascii_uppercase
def gronsfeld(text: str, key: str) -> str:
"""
Encrypt plaintext with the Gronsfeld cipher
>>> gronsfeld('hello', '412')
'LFNPP'
>>> gronsfeld('hello', '123')
'IGOMQ'
>>> gronsfeld('', '123')
''
>>> gronsfeld('yes, ¥€$ - _!@#%?', '0')
'YES, ¥€$ - _!@#%?'
>>> gronsfeld('yes, ¥€$ - _!@#%?', '01')
'YFS, ¥€$ - _!@#%?'
>>> gronsfeld('yes, ¥€$ - _!@#%?', '012')
'YFU, ¥€$ - _!@#%?'
>>> gronsfeld('yes, ¥€$ - _!@#%?', '')
Traceback (most recent call last):
...
ZeroDivisionError: integer modulo by zero
"""
ascii_len = len(ascii_uppercase)
key_len = len(key)
encrypted_text = ""
keys = [int(char) for char in key]
upper_case_text = text.upper()
for i, char in enumerate(upper_case_text):
if char in ascii_uppercase:
new_position = (ascii_uppercase.index(char) + keys[i % key_len]) % ascii_len
shifted_letter = ascii_uppercase[new_position]
encrypted_text += shifted_letter
else:
encrypted_text += char
return encrypted_text
if __name__ == "__main__":
from doctest import testmod
testmod()