LSB隐写算法

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LSB循序替换隐写算法
原理
首先将需要隐写的文件用二进制流的方式读取并保存在字符串S当中，然后顺序提取BMP图片的像素点，每一个像素点包含K（R、G、B）三种颜色，每一种颜色能够嵌入1bit信息，每一个像素点就能够嵌入3bit的信息。
隐写部分：

Kr = Kr – mod(Kr,2) + int(S[i])
Kg = Kg – mod(Kg,2) + int(S[i+1])
Kb = Kb – mod(Kb,2) + int(S[i+2])

提取部分：

    S = S + mod(Kr,2)
    S = S + mod(Kg,2)
    S = S + mod(Kb,2)

隐写部分代码

# -*- coding: UTF-8 -*-
from PIL import Image

def plus(str):
    return str.zfill(8)

def get_key(strr):
    tmp = strr
    f = file(tmp,"rb")
    str = ""
    s = f.read()
    for i in range(len(s)):
        str = str+plus(bin(ord(s[i])).replace('0b',''))
    f.closed
    return str

def mod(x,y):
    return x%y;
*str1为载体图片路径，str2为隐写文件，str3为加密图片保存的路径*
def func(str1,str2,str3):   
    im = Image.open(str1)
    width = im.size[0]
    height = im.size[1]
    count = 0
    key = get_key(str2)
    keylen = len(key)
    for h in range(0,height):
        for w in range(0,width):
            pixel = im.getpixel((w,h))
            a=pixel[0]
            b=pixel[1]
            c=pixel[2]
            if count == keylen:
                break
            a= a-mod(a,2)+int(key[count])
            count+=1
            if count == keylen:
                im.putpixel((w,h),(a,b,c))
                break
            b =b-mod(b,2)+int(key[count])
            count+=1
            if count == keylen:
                im.putpixel((w,h),(a,b,c))
                break
            c= c-mod(c,2)+int(key[count])
            count+=1
            if count == keylen:
                im.putpixel((w,h),(a,b,c))
                break
            if count % 3 == 0:
                im.putpixel((w,h),(a,b,c))
   im.save(str3)

提取部分代码

```
# -*- coding:UTF-8 -*-
from PIL import Image

def mod(x,y):
    return x%y;

def toasc(strr):
    return int(strr, 2)
*le为文件的长度，str1为加密载体图片的路径，str2为提取文件的保存路径*
def func(le,str1,str2):
    a=""
    b=""
    im = Image.open(str1)
    lenth = le*8
    width = im.size[0]
    height = im.size[1]

    for h in range(0, height):
        for w in range(0, width):
            pixel = im.getpixel((w, h))
            if count%3==0:
                count+=1
                b=b+str((mod(int(pixel[0]),2)))
                if count ==lenth:
                    break
            if count%3==1:
                count+=1
                b=b+str((mod(int(pixel[1]),2)))
                if count ==lenth:
                    break
            if count%3==2:
                count+=1
                b=b+str((mod(int(pixel[2]),2)))
                if count ==lenth:
                    break
        if count == lenth:
            break
    with open(str2,"wb") as f:
        for i in range(0,len(b),8):
            stra = toasc(b[i:i+8])
            f.write(chr(stra))
            stra =""
    f.closed

“`