IndexError：字符串索引超出范围 - Python

Question

Im getting this error.

mac_decrypt+=decrypt_datei[i]
IndexError: string index out of range

I tried everything but no success. Can someone help me pls, where I do mistake!

Here is Code:

lauf = len(decrypt_datei) - 1
nachricht_decrypt = ''
nachricht_length = ord(decrypt_datei[lauf])
nachricht_length = len(decrypt_datei) - (nachricht_length + 1)
lauf -= 1
while nachricht_length <= lauf:
    nachricht_decrypt += decrypt_datei[nachricht_length]
    nachricht_length += 1
print('entschluesselung fertig!')
print('mac Ueberpruefung:')

while s == False:
    # Mac UeberprUefen/ Nachricht zeigen
    macpassword_try = raw_input('Geben Sie den Macpassword:')
    hash_macpassword_try = hashlib.sha512(macpassword_try).hexdigest()

    lauf = ord(decrypt_datei[0])
    mac_decrypt = ''
    i = 1
    while i <= lauf:
        mac_decrypt += decrypt_datei[i]
        i += 1

Answer 1

The problem probably lies in:

lauf = ord(decrypt_datei[0])

ord returns an integer representing the Unicode code point of the character.

If you would have ord('a') that would return 97 thus if your string decrypt_datei contains 'a' and len(decrypt_datei) is smaller than 97 it will result in string index out of range

I suspect logical error here.