#!/usr/bin/python
"""IOS7Crypt password encryptor/decryptor"""

import os
import sys
from getopt import getopt

XLAT = [
    0x64, 0x73, 0x66, 0x64, 0x3b, 0x6b, 0x66, 0x6f,
    0x41, 0x2c, 0x2e, 0x69, 0x79, 0x65, 0x77, 0x72,
    0x6b, 0x6c, 0x64, 0x4a, 0x4b, 0x44, 0x48, 0x53,
    0x55, 0x42, 0x73, 0x67, 0x76, 0x63, 0x61, 0x36,
    0x39, 0x38, 0x33, 0x34, 0x6e, 0x63, 0x78, 0x76,
    0x39, 0x38, 0x37, 0x33, 0x32, 0x35, 0x34, 0x6b,
    0x3b, 0x66, 0x67, 0x38, 0x37,
    ]

def encrypt(password):
    seed = ord(os.urandom(1)) % 16
    return "%02d%s" % (seed, "".join(["%02x" % (ord(password[i]) ^ XLAT[seed + i]) for i in range(len(password))]))

def decrypt(h):
    (seed, h) = (int(h[:2]), h[2:])
    cipher_bytes = [int(h[i:i + 2], 16) for i in range(0, len(h), 2)]
    return "".join([chr(cipher_bytes[i] ^ XLAT[(seed + i) % len(XLAT)]) for i in range(len(cipher_bytes))])

def test():
    pass

def usage():
    print "Usage: %s [options]" % sys.argv[0]
    print "-e --encrypt\t<password>"
    print "-d --decrypt\t<hash>"
    print "-t --test\trun unit tests"
    print "-h --help\tusage"
    sys.exit()

def main():
    encrypt_mode = "ENCRYPT"
    decrypt_mode = "DECRYPT"
    test_mode = "TEST"
    mode = encrypt_mode
    password = ""
    h = ""

    (optlist, args) = ([], [])

    try:
        (optlist, args) = getopt(sys.argv[1:], "e:d:th", ["encrypt=", "decrypt=", "test", "help"])
    except Exception:
        usage()

    if len(optlist) < 1:
        usage()

    for (option, value) in optlist:
        if option == "-h" or option == "--help":
            usage()
        elif option == "-e" or option == "--encrypt":
            mode = encrypt_mode
            password = value
        elif option == "-d" or option == "--decrypt":
            mode = decrypt_mode
            h = value
        elif option == "-t" or option == "--test":
            mode = test_mode

    if mode == encrypt_mode:
        print encrypt(password)
    elif mode == decrypt_mode:
        print decrypt(h)
    elif mode == test_mode:
        test()

if __name__ == "__main__":
    main()