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r/dailyprogrammer #101 intermediate

By: a guest on Sep 28th, 2012  |  syntax: Python  |  size: 2.65 KB  |  hits: 192  |  expires: Never
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  1. #reddit.com/r/dailyprogrammer
  2. #intermediate-101
  3.  
  4. import sys, Image
  5.  
  6. #CONSTANTS
  7. TERMINATION = '11111111'
  8.  
  9. def steg(image_fn,data_fn):
  10.     #read in our image file and declare variables
  11.     img = Image.open(image_fn)
  12.     pixels = img.load()
  13.     im_width = img.size[0]
  14.     im_height = img.size[1]
  15.  
  16.     #read in our data file and declare variables
  17.     with open(data_fn, 'r') as f:
  18.         data = f.read()
  19.     b_data = ""
  20.     for char in data:
  21.         b_data += '%08d'%int(bin(ord(char))[2:])
  22.        
  23.     b_data += TERMINATION #used to find end when getting data out
  24.    
  25.     #verify image file is large enough
  26.     pix_needed = len(b_data) / 2
  27.     if im_width * im_height < pix_needed:
  28.         print 'Image file too small for data'
  29.         sys.exit()
  30.  
  31.     #add data to image file
  32.     for x in range(im_width):
  33.         for y in range(im_height):
  34.             if len(b_data) == 0:
  35.                 break
  36.                
  37.             pix = pixels[x,y]
  38.            
  39.             blueBase = bin(pix[2])[2:] #current pixels blue binary value
  40.             newBlue = blueBase[:-2] + b_data[0:2] #create new binary value
  41.            
  42.             b_data = b_data[2:] #remove used bits from b_data
  43.            
  44.             pixels[x,y] = (pix[0],pix[1],int(newBlue,2)) #put new pixel into image file
  45.         else:
  46.             continue
  47.         break
  48.  
  49.     #save new image as png
  50.     new_file = 'steg_' + image_fn[:image_fn.rfind('.')] + '.png'
  51.     img.save(new_file)
  52.     return 'image saved as ' + new_file
  53.        
  54. def desteg(image_fn):
  55.     #read in our image file and declare variables
  56.     img = Image.open(image_fn)
  57.     pixels = img.load()
  58.     im_width = img.size[0]
  59.     im_height = img.size[1]
  60.  
  61.     #get bianry data
  62.     b_data = ""
  63.     for x in range(im_width):
  64.         for y in range(im_height):
  65.             pix = pixels[x,y]
  66.             b_data += bin(pix[2])[-2:]
  67.            
  68.     #get actual data
  69.     s_data = ""
  70.     for x in range(0,len(b_data),8):
  71.         chunk = b_data[x:x+8]
  72.         if chunk == TERMINATION:
  73.             break #end of steganography data
  74.        
  75.         char = chr(int(chunk,2))
  76.         s_data += char
  77.  
  78.     return s_data
  79.    
  80.  
  81. #Process args
  82. if len(sys.argv) == 1:
  83.     print 'Usage: steganography.py {steg|desteg} {image file} {data file(steg only)}'
  84.     sys.exit()
  85.    
  86. if sys.argv[1] == 'steg' and len(sys.argv) == 4:
  87.     i_file = sys.argv[2]
  88.     d_file = sys.argv[3]
  89.     print steg(i_file,d_file)
  90. elif sys.argv[1] == 'desteg' and len(sys.argv) == 3:
  91.     i_file = sys.argv[2]
  92.     print desteg(i_file)
  93. else:
  94.     print 'Usage: steganography.py {steg|desteg} {image file} {data file(steg only)}'
  95.     sys.exit()
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