[英]python - Steganography - UnicodeDecode Error
我正在编写一个Python脚本来隐藏图像中的数据。 它基本上隐藏了.PNG中每个像素的RGB映射中红色的最后两位中的位。 该脚本适用于小写字母,但会出现句号错误。 它产生此错误:
追溯(最近一次通话):文件“ E:\\ Python \\ Steganography \\ main.py”,行65,在打印中(取消隐藏('coded-img.png'))文件“ E:\\ Python \\ Steganography \\ main。 py”,第60行,在取消隐藏消息中= bin2str(binary)文件“ E:\\ Python \\ Steganography \\ main.py”,第16行,在bin2str中,返回n.to_bytes((n.bit_length()+ 7)// 8 ,'big')。decode()UnicodeDecodeError:'utf-8'编解码器无法解码位置6的字节0x80:无效的起始字节
这是我的代码:
from PIL import Image
def str2bin(message):
binary = bin(int.from_bytes(message.encode('utf-8'), 'big'))
return binary[2:]
def bin2str(binary):
n = int(binary, 2)
return n.to_bytes((n.bit_length() + 7) // 8, 'big').decode()
def hide(filename, message):
image = Image.open(filename)
binary = str2bin(message) + '00000000'
data = list(image.getdata())
newData = []
index = 0
for pixel in data:
if index < len(binary):
pixel = list(pixel)
pixel[0] >>= 2
pixel[0] <<= 2
pixel[0] += int('0b' + binary[index:index+2], 2)
pixel = tuple(pixel)
index += 2
newData.append(pixel)
print(binary)
image.putdata(newData)
image.save('coded-'+filename, 'PNG')
def unhide(filename):
image = Image.open(filename)
data = image.getdata()
binary = '0'
index = 0
while binary[-8:] != '00000000':
binary += bin(data[index][0])[-2:]
index += 1
binary = binary[:-1]
print(binary)
print(index*2)
message = bin2str(binary)
return message
hide('img.png', 'alpha.')
print(unhide('coded-img.png'))
请帮忙。 谢谢!
您的代码至少存在两个问题。
第一个问题是您的编码可能会错位1位,因为bin()
函数的输出中不包括前导空位:
>>> bin(int.from_bytes('a'.encode('utf-8'), 'big'))[2:]
'1100001'
# This string is of odd length and (when joined with the terminating '00000000')
# turns into a still odd-length '110000100000000' which is then handled by your
# code as if there was an extra trailing zero (so that the length is even).
# During decoding you compensate for that effect with the
#
# binary = binary[:-1]
#
# line. The latter is responsible for your stated problem when the binary
# representation of your string is in fact of even length and doesn't need
# the extra bit as in the below example:
>>> bin(int.from_bytes('.'.encode('utf-8'), 'big'))[2:]
'101110'
您最好在前面加上一个额外的空位(如果需要),将二进制字符串补充为偶数长度。
另一个问题是,在恢复隐藏消息的同时,可以通过将一个(部分恢复的)符号的前导位与另一符号的尾随级联来提前满足停止条件binary[-8:] == '00000000'
。 例如,在以下情况下可能会发生这种情况
符号@ (ASCII码= 64,即未设置6个低阶位),后跟任何ASCII码值小于64(即未设置2个高阶位)的字符;
一个空格字符(ASCII码= 32,即未设置4个低位),后跟换行符/换行符(ASCII码= 10,即未设置4个高位)。
您可以通过要求在最后8位都未设置时对一个完整字节进行解码来解决该错误:
while not (len(binary) % 8 == 0 and binary[-8:] == '00000000'):
# ...
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