Add support for new WiFi configuration encryption

[scrool]

See https://github.com/scrool/xled-docs/issues/17 . My preliminary tests looks like cryptography library needs to be replaced because it doesn't support 48 byte (384 bit) long encryption key. arc4 seems like a good candidate.

[scrool]

A code snippet to integrate into/instead of existing encryption:

#!/usr/bin/env python3

import base64
import itertools
import struct
import sys

from arc4 import ARC4

import xled.security

if len(sys.argv) != 4:
    print("Args: <mac-address> <ssid> <wifi-password>", file=sys.stderr)
    sys.exit(1)

KEYv2 = [38, 128, 245, 135, 159, 238, 44, 117, 17, 170, 8, 21, 71, 68, 142, 4,
       153, 205, 104, 7, 110, 9, 50, 98, 93, 196, 222, 124, 56, 152, 158, 136,
       128, 238, 42, 183, 51, 103, 143, 162, 13, 204, 133, 216, 148, 205, 148,
       79]

mac = xled.security.netaddr.EUI(sys.argv[1])

secret = b''.join([struct.pack("B", (x ^ y)) for x, y in zip(KEYv2, itertools.cycle(mac.packed))])

padded_ssid = sys.argv[2].ljust(64, "\x00")
padded_pass = sys.argv[3].ljust(64, "\x00")

arc4 = ARC4(secret)
cipher = arc4.encrypt(padded_ssid)
encrypted = base64.b64encode(cipher).decode("utf-8")
print("Encrypted SSID: {}".format(encrypted))

arc4 = ARC4(secret)
cipher = arc4.encrypt(padded_pass)
encrypted = base64.b64encode(cipher).decode("utf-8")
print("Encrypted password: {}".format(encrypted))