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basic stego lsb to hide a plaintext message in a png image using a null term to determine end
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| #!/usr/bin/python3 | |
| from PIL import Image | |
| NULL = 00000000 | |
| def string_bin(text): | |
| return ''.join(['{:08b}'.format(ord(c)) for c in text]) | |
| def spl_bin(binary): | |
| return [binary[i:i+8] for i in range(0, len(binary), 8)] | |
| def bin_string(binary): | |
| return ''.join(chr(eval('0b'+v)) for v in spl_bin(binary)) | |
| # In bytes | |
| def get_max_message_size(image_file): | |
| size = 0 | |
| with Image.open(image_file) as im: | |
| w, h = im.size | |
| size = w * h * 3/8 | |
| return round(size) | |
| def hide_message_lsb(image_file, message): | |
| i = 0 | |
| data = string_bin(message) + str(NULL) | |
| with Image.open(image_file) as im: | |
| w, h = im.size | |
| for x in range(0, w): | |
| for y in range(0, h): | |
| pixel = list(im.getpixel((x, y))) | |
| for n in range(0, 3): | |
| if i < len(data): | |
| pixel[n] = pixel[n] & ~1 | int(data[i]) | |
| i += 1 | |
| im.putpixel((x, y), tuple(pixel)) | |
| im.save('_{}'.format(image_file), 'PNG') | |
| def extract_message(image_file): | |
| ext = [] | |
| with Image.open(image_file) as im: | |
| w, h = im.size | |
| for x in range(0, w): | |
| for y in range(0, h): | |
| pixel = list(im.getpixel((x, y))) | |
| for n in range(0, 3): | |
| ext.append(str(pixel[n]&1)) | |
| bin_mesg = ''.join([str(x) for x in ext]) | |
| recv = [] | |
| for b in spl_bin(bin_mesg): | |
| if b == str(11111111): | |
| break | |
| recv.append(b) | |
| return ''.join(recv[:-1]) |
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