Python byDreamy postedJul 17, 2019

Image 기반 Steganography 예제

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https://www.geeksforgeeks.org/image-based-steganography-using-python/



[Python 3]


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# Python program implementing Image Steganography
 
# PIL module is used to extract
# pixels of image and modify it
from PIL import Image
 
# Convert encoding data into 8-bit binary
# form using ASCII value of characters
def genData(data):
         
        # list of binary codes
        # of given data
        newd = []
         
        for i in data:
            newd.append(format(ord(i), '08b'))
        return newd
         
# Pixels are modified according to the
# 8-bit binary data and finally returned
def modPix(pix, data):
     
    datalist = genData(data)
    lendata = len(datalist)
    imdata = iter(pix)
 
    for i in range(lendata):
         
        # Extracting 3 pixels at a time
        pix = [value for value in imdata.__next__()[:3] +
                                imdata.__next__()[:3] +
                                imdata.__next__()[:3]]
                                     
        # Pixel value should be made
        # odd for 1 and even for 0
        for j in range(0, 8):
            if (datalist[i][j]=='0') and (pix[j]% 2 != 0):
                 
                if (pix[j]% 2 != 0):
                    pix[j] -= 1
                     
            elif (datalist[i][j] == '1') and (pix[j] % 2 == 0):
                pix[j] -= 1
                 
        # Eigh^th pixel of every set tells
        # whether to stop ot read further.
        # 0 means keep reading; 1 means the
        # message is over.
        if (i == lendata - 1):
            if (pix[-1] % 2 == 0):
                pix[-1] -= 1
        else:
            if (pix[-1] % 2 != 0):
                pix[-1] -= 1
 
        pix = tuple(pix)
        yield pix[0:3]
        yield pix[3:6]
        yield pix[6:9]
 
def encode_enc(newimg, data):
    w = newimg.size[0]
    (x, y) = (0, 0)
     
    for pixel in modPix(newimg.getdata(), data):
         
        # Putting modified pixels in the new image
        newimg.putpixel((x, y), pixel)
        if (x == w - 1):
            x = 0
            y += 1
        else:
            x += 1
             
# Encode data into image
def encode():
    img = input("Enter image name(with extension): ")
    image = Image.open(img, 'r')
     
    data = input("Enter data to be encoded : ")
    if (len(data) == 0):
        raise ValueError('Data is empty')
         
    newimg = image.copy()
    encode_enc(newimg, data)
     
    new_img_name = input("Enter the name of new image(with extension): ")
    newimg.save(new_img_name, str(new_img_name.split(".")[1].upper()))
 
# Decode the data in the image
def decode():
    img = input("Enter image name(with extension) :")
    image = Image.open(img, 'r')
     
    data = ''
    imgdata = iter(image.getdata())
     
    while (True):
        pixels = [value for value in imgdata.__next__()[:3] +
                                imgdata.__next__()[:3] +
                                imgdata.__next__()[:3]]
        # string of binary data
        binstr = ''
         
        for i in pixels[:8]:
            if (i % 2 == 0):
                binstr += '0'
            else:
                binstr += '1'
                 
        data += chr(int(binstr, 2))
        if (pixels[-1] % 2 != 0):
            return data
             
# Main Function     
def main():
    a = int(input(":: Welcome to Steganography ::\n"
                        "1. Encode\n 2. Decode\n"))
    if (a == 1):
        encode()
         
    elif (a == 2):
        print("Decoded word- " + decode())
    else:
        raise Exception("Enter correct input")
         
# Driver Code
if __name__ == '__main__' :
     
    # Calling main function
    main()



[Python 2]


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# Python program implementing Image Steganography
 
# PIL module is used to extract
# pixels of image and modify it
from PIL import Image
import sys, os
 
# Convert encoding data into 8-bit binary
# form using ASCII value of characters
def genData(data):
    # list of binary codes
    # of given data
    newd = []
 
    for i in data:
        newd.append(format(ord(i), '08b'))
    return newd
 
 
# Pixels are modified according to the
# 8-bit binary data and finally returned
def modPix(pix, data):
    datalist = genData(data)
    lendata = len(datalist)
    imdata = iter(pix)
 
    for i in range(lendata):
 
        # Extracting 3 pixels at a time
        pix = [value for value in imdata.next()[:3] +
               imdata.next()[:3] +
               imdata.next()[:3]]
 
        # Pixel value should be made
        # odd for 1 and even for 0
        for j in range(0, 8):
            if (datalist[i][j] == '0') and (pix[j] % 2 != 0):
 
                if (pix[j] % 2 != 0):
                    pix[j] -= 1
 
            elif (datalist[i][j] == '1') and (pix[j] % 2 == 0):
                pix[j] -= 1
 
        # Eigh^th pixel of every set tells
        # whether to stop ot read further.
        # 0 means keep reading; 1 means the
        # message is over.
        if (i == lendata - 1):
            if (pix[-1] % 2 == 0):
                pix[-1] -= 1
        else:
            if (pix[-1] % 2 != 0):
                pix[-1] -= 1
 
        pix = tuple(pix)
        yield pix[0:3]
        yield pix[3:6]
        yield pix[6:9]
 
 
def encode_enc(newimg, data):
    w = newimg.size[0]
    (x, y) = (0, 0)
 
    for pixel in modPix(newimg.getdata(), data):
 
        # Putting modified pixels in the new image
        newimg.putpixel((x, y), pixel)
        if (x == w - 1):
            x = 0
            y += 1
        else:
            x += 1
 
 
# Encode data into image
def encode(orgfilename, msg, outfilename):
    img = orgfilename
    image = Image.open(img, 'r')
 
    data = msg
    if (len(data) == 0):
        raise ValueError('Data is empty')
 
    newimg = image.copy()
    encode_enc(newimg, data)
 
    new_img_name = outfilename
    newimg.save(new_img_name, str(new_img_name.split(".")[1].upper()))
 
 
# Decode the data in the image
def decode(filename):
    img = filename
    image = Image.open(img, 'r')
 
    data = ''
    imgdata = iter(image.getdata())
 
    while (True):
        pixels = [value for value in imgdata.next()[:3] +
                  imgdata.next()[:3] +
                  imgdata.next()[:3]]
        # string of binary data
        binstr = ''
 
        for i in pixels[:8]:
            if (i % 2 == 0):
                binstr += '0'
            else:
                binstr += '1'
 
        data += chr(int(binstr, 2))
        if (pixels[-1] % 2 != 0):
            print data
            return data
 
        # Main Function
 
def printUsage():
    print " This program Encode / Decode hidden message into image."
    print " <Usage>"
    print "   Encode: steg_test.py -a [input_filename] [message] [out_filename]"
    print "   Decode: steg_test.py -b [out_filename]"
 
if __name__ == '__main__':
    if len(sys.argv) < 3:
        printUsage()
        exit(0)
 
    if sys.argv[1] == '-a':
        if len(sys.argv) == 5:
            encode(sys.argv[2], sys.argv[3], sys.argv[4])
        else:
            printUsage()
    elif sys.argv[1] == '-b':
        if len(sys.argv) == 3:
            decode(sys.argv[2])
        else:
            printUsage()
    else:
        printUsage()


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