Python3 -加密和解密图像(Fernet)问题

Question

日安，

我在做密码学的作业。这是一个简单的任务，我需要拍摄任何图像，把它变成HEX，加密它，然后解密它。

由于我在Python中工作，任务中没有具体的加密方法，所以我只使用Fernet。

我有加密和解密脚本。

加密似乎是有效的，因为作为测试，我用原始HEX创建了一个txt文档，在解密之后，程序声明原来的HEX和解密的HEX是相同的，但是解密后的图像没有加载。

有人能帮个新手吗？

加密器：

import binascii
from cryptography.fernet import Fernet

img = 'panda.png'
with open(img, 'rb') as f:
    content = f.read()
hexValue = binascii.hexlify(content)
key = Fernet.generate_key()

with open('info/key.txt', mode='w+') as keyValue:
    keyValue.write(key)
    keyValue.seek(0)

f = Fernet(key)
encHexVal = f.encrypt(hexValue) 

with open('info/encryptedHex.txt', mode='w+') as hexValueFile:
    hexValueFile.write(encHexVal)
    hexValueFile.seek(0)
a = f.decrypt(encHexVal)

with open('info/realValue.txt', mode='w+') as writeHex:
    originalHex = writeHex.write(hexValue)

with open('info/realValue.txt', mode='r') as reading:
    realValue = reading.read()
if realValue == a:
    print("We're good to go!")
else:
    print("Oops something went wrong. Check the source code.")

解密器：

import binascii
from cryptography.fernet import Fernet

with open('info/key.txt', mode='rb') as keyValue:
    key = keyValue.read()
    f = Fernet(key)
with open('info/encryptedHex.txt', mode='rb') as imageHexValue:
    hexValue = imageHexValue.read()
a = f.decrypt(hexValue)
with open('info/realValue.txt', mode='r') as compare:
    realContents = compare.read()

print("Small test in safe environment...")
if realContents == a:
    print("All good!")
else:
    print("Something is wrong...")
data = a.encode()
data = data.strip()
data = data.replace(' ', '')
data = data.replace('\n', '')
with open('newImage.png', 'wb') as file:
    file.write(data)

我正在使用“功夫熊猫”网上的一张随机图片：

​

Answer 1

主要的问题是，虽然您已经加密，然后在加密器中加密，但在解密器中解密后，您不会解除加密。更常见的做法是用另一种方式加密，然后加密，这样加密的二进制文件就可以存储在常规文本文件中，或者通过http发送。

您在尝试将bytes对象写入以文本打开的文件时有几个问题。我在路上修好了。但这确实让我感到困惑，为什么一个名为'info/encryptedHex.txt‘的文件将是二进制文件。

加密器

import binascii
from cryptography.fernet import Fernet

# Generate keyfile
#
# TODO: Overwrites key file on each run, invalidating previous
# saves. You could do `if not os.path.exists('info/key.txt'):`
key = Fernet.generate_key()
with open('info/key.txt', mode='wb') as keyValue:
    keyValue.write(key)

# Encrypt image
img = 'panda.png'
with open(img, 'rb') as f:
    content = f.read()
hexValue = binascii.hexlify(content)

f = Fernet(key)
encHexVal = f.encrypt(hexValue) 

with open('info/encryptedHex.txt', mode='wb') as hexValueFile:
    hexValueFile.write(encHexVal)

# Verification checks
a = f.decrypt(encHexVal)

# hexed bytes is same encoding as 'ascii'
with open('info/realValue.txt', mode='wb') as writeHex:
    originalHex = writeHex.write(hexValue)

with open('info/realValue.txt', mode='r', encoding='ascii') as reading:
    realValue = reading.read()
if realValue == a.decode('ascii'):
    print("We're good to go!")
else:
    print("Oops something went wrong. Check the source code.")

解密器

import binascii
from cryptography.fernet import Fernet

# Generate keyfile
#
# TODO: Overwrites key file on each run, invalidating previous
# saves. You could do `if not os.path.exists('info/key.txt'):`
key = Fernet.generate_key()
with open('info/key.txt', mode='wb') as keyValue:
    keyValue.write(key)

# Encrypt image
img = 'panda.png'
with open(img, 'rb') as f:
    content = f.read()
hexValue = binascii.hexlify(content)

f = Fernet(key)
encHexVal = f.encrypt(hexValue) 

with open('info/encryptedHex.txt', mode='wb') as hexValueFile:
    hexValueFile.write(encHexVal)

# Verification checks
a = f.decrypt(encHexVal)

# hexed bytes is same encoding as 'ascii'
with open('info/realValue.txt', mode='wb') as writeHex:
    originalHex = writeHex.write(hexValue)

with open('info/realValue.txt', mode='r', encoding='ascii') as reading:
    realValue = reading.read()
if realValue == a.decode('ascii'):
    print("We're good to go!")
else:
    print("Oops something went wrong. Check the source code.")
(base) td@timpad:~/dev/SO/Encrypting and decrypting in image$ cat de.py
import binascii
from cryptography.fernet import Fernet

with open('info/key.txt', mode='rb') as keyValue:
    key = keyValue.read()
    f = Fernet(key)
with open('info/encryptedHex.txt', mode='rb') as imageHexValue:
    encHexValue = imageHexValue.read()
hexValue = f.decrypt(encHexValue)
binValue = binascii.unhexlify(hexValue)

with open('info/realValue.txt', mode='rb') as compare:
    realContents = compare.read()

print("Small test in safe environment...")
if realContents == hexValue:
    print("All good!")
else:
    print("Something is wrong...")
with open('newImage.png', 'wb') as file:
    file.write(binValue)