moth/packages/steg/100/encode

#! /usr/bin/python

import os
import sys
import md5
import cStringIO as StringIO

plaintext = sys.stdin
inf = os.fdopen(3)

outf = sys.stdout
for i in range(3):
    outf.write(inf.readline())

# Set the low-order bits in output file
i = 0
while True:
    c = plaintext.read(1)
    if c:
        c = ord(c)
    else:
        c = 0
    img_bytes = inf.read(8)
    if not img_bytes:
        break
    if len(img_bytes) < 8:
        outf.write(img_bytes)
        break
    for j in range(8):
        bit = 7 - j
        img_byte = ord(img_bytes[j]) & 0xFE
        noise_bit = (c & (1<<bit)) >> bit
        out_byte = img_byte | noise_bit
        outf.write(chr(out_byte))