Caesar and Vigenère ciphers

caesar_cipher.py

MAX_KEY_SIZE = 26


def get_mode():
    while True:
        # Você quer criptografar ou decriptografar?
        print('Wollen Sie zu verschlüsseln [v] oder zu entschlüsseln [e]?')

        mode = input().lower()

        if mode in 'verschlusseln v entschlusseln e'.split():
            return mode
        else:
            # Escreva "criptografar" ou "descriptografar".''
            print('Geben Sie "Verschlüsseln" oder "entschlüsseln".')


def get_message():
    # Entre com a mensagem.
    print('Geben Sie Ihre Nachricht: ')

    return input()


def get_key():
    key = 0

    while True:
        # Escolha um número entre 1 e 26 (MAX_KEY_SIZE).
        print('Geben Sie eine Nummer (1-%s)' % (MAX_KEY_SIZE))

        key = int(input())

        if key >= 1 and key <= MAX_KEY_SIZE:
            return key


def get_translated_msg(mode, message, key):
    if mode[0] == 'e':
        key = -key

    translated = ''

    for symbol in message:
        if symbol.isalpha():
            num = ord(symbol)

            num += key

            if symbol.isupper():
                if num > ord('Z'):
                    num -= 26
                elif num < ord('A'):
                    num += 26
            elif symbol.islower():
                if num > ord('z'):
                    num -= 26
                elif num < ord('a'):
                    num += 26

            translated += chr(num)
        else:
            translated += symbol

    return translated


mode = get_mode()
message = get_message()
key = get_key()

# Texto traduzido.
print('Übersetzt Text: ')
print(get_translated_msg(mode, message, key))

vigenere_cipher.py

LETTERS = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ'


def get_mode():
    while True:
        # Você quer criptografar ou decriptografar?
        print('Wollen Sie zu verschlüsseln [v] oder zu entschlüsseln [e]?')

        mode = input().lower()

        if mode in 'verschlusseln v entschlusseln e'.split():
            return mode
        else:
            # Escreva "criptografar" ou "descriptografar".''
            print('Geben Sie "Verschlüsseln" oder "entschlüsseln".')


def get_key(message):
    while True:
        # Informe a chave de segurança.
        print('Geben Sie den Sicherheitsschlüssel ein.')

        key = input()

        if len(key) <= len(message):
            return key


def get_translated_msg(mode, message, key):
    translated = []

    key_idx = 0
    key = key.upper()

    for symbol in message:
        num = LETTERS.find(symbol.upper())

        if num != -1:
            if mode[0] == 'v':
                num += LETTERS.find(key[key_idx])
            elif mode[0] == 'e':
                num -= LETTERS.find(key[key_idx])

            num %= len(LETTERS)

            if symbol.isupper():
                translated.append(LETTERS[num])
            elif symbol.islower():
                translated.append(LETTERS[num].lower())

            key_idx += 1

            if key_idx == len(key):
                key_idx = 0
        else:
            translated.append(symbol)

    return ''.join(translated)


def get_message():
    # Entre com a mensagem.
    print('Geben Sie Ihre Nachricht: ')

    return input()


mode = get_mode()
message = get_message()
key = get_key(message)

# Texto traduzido.
print('Übersetzt Text: ')
print(get_translated_msg(mode, message, key))