import os
import sys

KEY_SIZE = 10


def expand_key(key, length):
    return int(length / len(key)) * key + key[0:(length % len(key))]


def xor(s1, s2):
    assert len(s1) == len(s2)
    return bytes([(a ^ b) for a, b in zip(s1, s2)])


def main():
    if len(sys.argv) <= 2:
        key = os.urandom(KEY_SIZE)

        filename = sys.argv[1]

        f = open(filename,'rb')
        data = f.read()
        f.close()

        expanded_key = expand_key(key, len(data))
        data_encrypted = xor(expanded_key, data)

        print(data_encrypted)

        f = open(filename + ".enc", "wb")
        f.write(data_encrypted)
        f.close()

        print("File %s encrypted with key: %s" % (filename, key.hex()))
    else:
        print("Usage: %s <filename>" % (sys.argv[0]))

if __name__ == "__main__":
    main()