alphabetencode.py

# EncryptTools (ENGLISH CHARACTER ONLY!!!)
# This version of the format supports numbers and capital letters and is case-sensitive

import random
from collections import namedtuple
EncryptedNamedTuple = namedtuple('Encrypted', 'text, key')
char = ['a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z', 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z']
excp = ["'", '!', '@', '#', '$', '%', '^', '&', '*', '(', ')', '_', '-', '=', '+', '"', '<', '>', '/', '[', ']', '{', '}', '.', ',', ' ', '1', '2', '3', '4', '5', '6', '7', '8', '9', '0', '?']

def encrypt(message):
    """
    Encrypts a message with a random key. Returns a Encrypted object.
    """
    err = True
    while err is True:
        try:
            count = 0
            enckey = _pdigitrand(len(message))
            split = list(message)
            enckey2 = list(str(enckey))
            enc = []
            for i in split:
                if not i in char and i not in excp:
                    raise ValueError("Characters must be in English only.")
                if i in excp:
                    enc.append(i)
                else:
                    l = char.index(i)
                    q = l + int(enckey2[count])
                    enc.append(char[q])
                count = count + 1
        except IndexError:
            err = True
        else:
            err = False
        if err == False:
            return Encrypted(''.join(enc), enckey)
        
def decrypt(encrypted):
    """
    Decrypts a Encrypted object returned by encrypt()
    """
    if not isinstance(encrypted, Encrypted):
        raise TypeError("'encrypted' must be an Encrypted object")
    enckey = encrypted.key
    count = 0
    split = list(encrypted.message)
    enckey2 = list(str(enckey))
    enc = []
    for i in split:
        if i in excp:
            enc.append(i)
        else:
            l = char.index(i)
            q = l - int(enckey2[count])
            enc.append(char[q])
        count = count + 1
    return ''.join(enc)

def decryptwithkey(message, key):
    """
    Decrypts with raw message and key.
    """
    if len(str(key)) != len(message):
        raise ValueError("Key is invalid. Key length should be equal to message length.")
    return decrypt(Encrypted(message, key))

def encryptastuple(message):
    """
    Encrypts a message with a random key. Returns a namedtuple.
    """
    tmp = encrypt(message)
    return EncryptedNamedTuple(tmp.message, tmp.key)

def _pdigitrand(n):
    range_start = 10**(n-1)
    range_end = (10**n)-1
    return random.randint(range_start, range_end)

class Encrypted(object):
    def __init__(self, encrypted, key):
        self.message = encrypted
        self.key = key
    def __str__(self):
        return self.message