de and encrypt vigenere chiffre

vigenere.py

def caesar(klartext, schluessel):
    klartext = klartext.upper()
    geheimtext = ""
    for i in range(0, len(klartext)):
        buchstabe = klartext[i]
        ascii = ord(buchstabe)
        code = ascii + schluessel
        while (code > 90):
            code = code - 26
        geheimbuchstabe = chr(code)
        geheimtext += geheimbuchstabe
    return geheimtext


def decaesar(geheimtext, schluessel):
    return caesar(geheimtext, 26 - schluessel % 26)

def vigenere(clear, key):
    clear = clear.lower()
    key = key.lower()
    out = ""
    j = 0
    for i in range(len(clear)):
        if (j >= len(key)):
            j = 0
        caesarIn = ord(key[j]) - 97
        out += caesar(clear[i], caesarIn)
        j += 1
    return out


def devigenere(secret, key):
    secret = secret.lower()
    key = key.lower()
    out = ""
    j = 0
    for i in range(len(secret)):
        if (j >= len(key)):
            j = 0
        caesarIn = ord(key[j]) - 97
        out += decaesar(secret[i], caesarIn)
        j += 1
    return out


clear = "TRITHEMIUSUNDVIGENERE"
secret = "ZVPXPQSMBWCZJZPKMZKVL"
key = "geheim"

print("Geheimtext:", vigenere(clear, key))
print("Klartext:", devigenere(secret, key))