Crypter Vigenère Python

[fred]

Bonjour voici un code fait maison sur le cryptage de Vigenère

from operator import add, sub
from string import ascii_lowercase as alphabet
from itertools import cycle

DICO_ALPHA = {letter: ord(letter)-97 for letter in alphabet}

# {'b': 1, 'c': 2, 'a': 0, 'f': 5, 'g': 6, 'd': 3, 'e': 4, 'j': 9, 'k': 10, 'h': 7, 'i': 8, 'n': 13, 'o': 14, 'l': 11, 'm': 12, 'r': 17, 's': 18, 'p': 15, 'q': 16, 'v': 21, 'w': 22, 't': 19, 'u': 20, 'z': 25, 'x': 23, 'y': 24}

DICO_NUMBER = {k:v for v, k in DICO_ALPHA.items()}

# {0: 'a', 1: 'b', 2: 'c', 3: 'd', 4: 'e', 5: 'f', 6: 'g', 7: 'h', 8: 'i', 9: 'j', 10: 'k', 11: 'l', 12: 'm', 13: 'n', 14: 'o', 15: 'p', 16: 'q', 17: 'r', 18: 's', 19: 't', 20: 'u', 21: 'v', 22: 'w', 23: 'x', 24: 'y', 25: 'z'}

def cypher(text, key, func='encrypt'):
    text = text.lower()
    res = ''
    ind = 0
    ind_max = len(text)

    if func == 'encrypt':
        op = add # add two numbers
    else:
        op = sub # subtract two numbers
    
    for letter in cycle(key):
        n = op(DICO_ALPHA[text[ind]], DICO_ALPHA[letter]) % 26
        res += DICO_NUMBER[n]
        ind += 1
        if ind == ind_max:
            break
    return res.upper() # string uppercase

print(cypher('azertyuiop', 'sdhgf')) # encrypt by default
# SCLXYQXPUU

print(cypher('SCLXYQXPUU', 'sdhgf', 'decrypt')) # decrypt
# AZERTYUIOP

à bientôt,