find_hidden_data.py

import sys
import os
import tempfile
import binascii
from PIL import Image

if __name__ == '__main__':
    filename = sys.argv[1]
    tempdir = tempfile.mkdtemp()
    temppath = tempdir + os.path.basename(filename)
    original = Image.open(filename)
    original.load()
    data = bytearray(open(filename, 'rb').read())
    hidden_ranges = []

    for i in range(0, len(data)):
        data[i] = data[i] ^ 0xff
        with open(temppath, 'wb') as f:
            f.write(data)
        data[i] = data[i] ^ 0xff
        try:
            modified = Image.open(temppath)
            if modified.tobytes() == original.tobytes():
                if len(hidden_ranges) == 0:
                    hidden_ranges.append([i, i+1])
                else:
                    if hidden_ranges[-1][1] == i:
                        hidden_ranges[-1][1] = i+1
                    else:
                        hidden_ranges.append([i, i+1])
        except Exception:
            continue   
        sys.stdout.write('\r{:01.4}%     '.format(100.0 * i / len(data)))
        sys.stdout.flush()
    sys.stdout.write('\r')
    for h in hidden_ranges:
        print('Useless range [{}:{}]: {}'.format(h[0], h[1], binascii.hexlify(data[h[0]:h[1]])))