PyCryptodome错误：MAC检查失败 [英] PyCryptodome Error: MAC Check Failed

问题描述

我正在使用Python 3中的Pycryptodome开发一个加密程序，我正在尝试加密（字节）字符串，然后将其解密并验证MAC标签。当我验证它时，会引发错误。

I am working on an encryption program with Pycryptodome in Python 3. I am trying to encrypt a (byte) string and then decrypt it and verify the MAC tag. When I get to verify it, an error is thrown.

这是代码：

from Crypto.Cipher import AES
from Crypto.Random import get_random_bytes

aes_key = get_random_bytes(24)
aes_cipher = AES.new(aes_key, AES.MODE_GCM)
encrypted, MACtag = aes_cipher.encrypt_and_digest(b"A random thirty two byte string.")

# Imagine this is happening somewhere else
new_aes_cipher = AES.new(aes_key, AES.MODE_GCM, nonce=aes_cipher.nonce)
new_aes_cipher.verify(MACtag)
decrypted = new_aes_cipher.decrypt(encrypted)

这是错误：

Traceback (most recent call last):
  File "aespractice.py", line 10, in <module>
    new_aes_cipher.verify(tag)
  File "/Library/Frameworks/Python.framework/Versions/3.6/lib/python3.6/site-
packages/Crypto/Cipher/_mode_gcm.py", line 441, in verify
    raise ValueError("MAC check failed")
ValueError: MAC check failed

我看了看文档，对我来说似乎一切都很好。您为什么认为该程序以这种方式运行？任何帮助将不胜感激。

I've looked at the documentation, and I it looks to me like everything is all right. Why do you think the program is acting this way? Any help would be appreciated.

推荐答案

如果您查看身份验证模式的状态图：

If you look at the state diagram for authenticated modes:

您会看到 verify（） decrypt（）发生之后，应在最后调用c>。
因此，您可以反转呼叫，或者将其替换为组合的 decrypt_and_verify（）。

You see that verify() should be called at the very end, after any decrypt() has taken place. So, either you invert the calls or you replace them with a combined decrypt_and_verify().

这篇关于PyCryptodome错误：MAC检查失败的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！