LSB steganography with pure Python

Question

As this is pure Python so using loop with big files make the code very slow any improvements or suggestions.

Hide Code

 # Consts
HEADER_SIZE = 54
DELIMITER = "$"
class LSBEncrypter(object):
 def __init__(self):
 self.image_byte_counter = 0
 self.new_image_data = ''
 self.original_image = ''
 self.text_to_hide = ''
 def open_image(self):
 with open(ImageFile, "rb") as f:
 self.original_image = ''.join(map(chr, f.read()))
 def read_header(self):
 for x in range(0, HEADER_SIZE):
 self.new_image_data += self.original_image[x]
 self.image_byte_counter += 1
 def hide_text_size(self):
 sz = len(self.text_to_hide)
 s_sz = str(sz)
 s_sz += DELIMITER
 self.do_steg(s_sz)
 def do_steg(self, steg_text):
 for ch in range(0, len(steg_text)):
 current_char = steg_text[ch]
 current_char_binary = '{0:08b}'.format(ord(current_char))
 for bit in range(0, len(current_char_binary)):
 new_byte_binary = ''
 current_image_binary = '{0:08b}'.format(ord(self.original_image[self.image_byte_counter]))
 new_byte_binary = current_image_binary[:7]
 new_byte_binary += current_char_binary[bit]
 new_byte = chr(int(new_byte_binary, 2))
 self.new_image_data += new_byte
 self.image_byte_counter += 1
 def copy_rest(self):
 self.new_image_data += self.original_image[self.image_byte_counter:]
 def close_file(self):
 with open(StegImageFile, "wb") as out:
 out.write(bytearray(map(ord, self.new_image_data)))
 def run(self, stega_text):
 self.text_to_hide = stega_text
 self.open_image()
 self.read_header()
 self.hide_text_size()
 self.do_steg(self.text_to_hide)
 self.copy_rest()
 self.close_file()
 def hide_(self, Texte, image, steg):
 global TextToHide, ImageFile, StegImageFile
 TextToHide = Texte
 ImageFile = image
 StegImageFile = steg
 stega_instance = LSBEncrypter()
 stega_instance.run(TextToHide)

Reveal Code

 import binascii
HEADER_SIZE = 54
DELIMITER = "$"
class LSBDecrypter:
 def __init__(self):
 self.StegImageFile = ''
 # self.fh = open(StegImageFile, 'rb')
 self.number_of_chars_in_text = 0
 self.original_text = ''
 def read_header(self):
 self.fh = open(StegImageFile, 'rb')
 for i in range(0, HEADER_SIZE):
 byte = self.fh.read(1)
 def get_char(self):
 new_byte = ''
 for bit in range(0, 8):
 byte = self.fh.read(1)
 new_byte += str(ord(byte) & 0x01)
 n = int(new_byte, 2)
 desteg_char = binascii.unhexlify('%x' % n)
 desteg_char = ''.join(map(chr, desteg_char))
 return desteg_char
 def get_text_size(self):
 curr_ch = self.get_char()
 s_sz = ''
 while curr_ch != DELIMITER:
 s_sz += curr_ch
 curr_ch = self.get_char()
 if (s_sz != ''):
 self.number_of_chars_in_text = int(s_sz)
 def read_stega_text(self):
 decoded_chars = 0;
 while decoded_chars < self.number_of_chars_in_text:
 self.original_text += self.get_char()
 decoded_chars += 1
 def close_file(self):
 self.fh.close();
 def get_text(self):
 self.read_header()
 self.get_text_size()
 self.read_stega_text()
 self.close_file()
 return self.original_text
 def reveal_(self, stego):
 global StegImageFile
 StegImageFile = stego
 destag_insta = LSBDecrypter()
 text = destag_insta.get_text()
 print (text)

Answer 1

Performance:

def get_char(self):
 new_byte = ''
 for bit in range(0, 8):
 byte = self.fh.read(1)
 new_byte += str(ord(byte) & 0x01)
 n = int(new_byte, 2)
 desteg_char = binascii.unhexlify('%x' % n)
 desteg_char = ''.join(map(chr, desteg_char))
 return desteg_char

This is not as simple as it could be. You are reading 8 bits as strings to build a single byte, converting it to an integer, then to a hex string (string format before unhexlify), then to a hexadecimal string, then mapping to a character, and then joining them together. I recommend doing more math and less string conversion and concatenation.

Style:

1. Use consistent string delimiters

• You have ' in most places, like open(StegImageFile, 'rb'), but you also have DELIMITER = "$" and open(StegImageFile, "wb"). Use ' everywhere if that's what you're using.

2. Remove unnecessary parentheses

• if (s_sz != ''): should be if s_sz != '':, or even more concise: if s_sz:.

3. Consider meaningful variable names

• s_sz isn't a helpful variable name, and I don't know what it is at a glance, other than that it's the string form of sz (also not helpful).

4. Remove the space in print (text)

• You don't use spaces after any other function names.

5. Remove weird leading spaces

• The space before # Consts

• The space before import binascii