gronsfeld_cipher.py

fromstringimportascii_uppercase


defgronsfeld(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) forcharinkey]
upper_case_text=text.upper()

fori, charinenumerate(upper_case_text):
ifcharinascii_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

returnencrypted_text


if__name__=="__main__":
fromdoctestimporttestmod

testmod()