如何使用密码术从用户输入的 python 中解密消息？

Question

我能够解密运行脚本的消息，但当我使用用户输入法获取加密消息时无法解密。我有这个简单的脚本：from cryptography.hazmat.primitives.ciphers import Cipher, algorithms, modesfrom cryptography.hazmat.backends import default_backendfrom cryptography.hazmat.primitives import paddingpadder = padding.PKCS7(128).padder()backend = default_backend()def operation_getmessage():    messagesinput = input("Please, insert messages to decrypt: ")    messagesinput = bytes(messagesinput, "utf-8")    message = padder.update(messagesinput)    message += padder.finalize()    return messagekeyinput = input("Please insert the key used for encrypt : ")print(keyinput)key = bytes(str(keyinput), 'ascii')print("key value is :", key)message = operation_getmessage()cipher = Cipher(algorithms.TripleDES(key), modes.ECB(), backend=backend)encryptor = cipher.encryptor()message_encrypt = encryptor.update(message) + encryptor.finalize()print("Value of message_encrypted:", message_encrypt)test = operation_getmessage()print("Value of test: ", test)decryptor = cipher.decryptor()message_decrypt = decryptor.update(test) + decryptor.finalize()print("Value of message_decrypted is: ", message_decrypt)unpadder = padding.PKCS7(128).unpadder()data = unpadder.update(message_decrypt)print("Value of message is: ", data + unpadder.finalize())

Answer 1

我使用了@Ralf 和@Kevin_Fontaine 的建议来修复您的代码，使其正常工作。这是更正后的脚本，更改了几行并标有注释：

import base64   # new line here

from cryptography.hazmat.primitives.ciphers import Cipher, algorithms, modes

from cryptography.hazmat.backends import default_backend

from cryptography.hazmat.primitives import padding

backend = default_backend()

def operation_getmessage():

    padder = padding.PKCS7(128).padder()  # new line here

    messagesinput = input("Please, insert messages to decrypt: ")

    messagesinput = bytes(messagesinput, "utf-8")

    message = padder.update(messagesinput)

    message += padder.finalize()

    return message

keyinput = input("Please insert the key used for encrypt : ")

print(keyinput)

key = bytes(str(keyinput), 'ascii')

print("key value is :", key)

message = operation_getmessage()

cipher = Cipher(algorithms.TripleDES(key), modes.ECB(), backend=backend)

encryptor = cipher.encryptor()

message_encrypt = encryptor.update(message) + encryptor.finalize()

print("Value of message_encrypted:", base64.b64encode(message_encrypt))  # new line here

test = operation_getmessage()

test = base64.b64decode(test)  # new line here

print("Value of test: ", test)

decryptor = cipher.decryptor()

message_decrypt = decryptor.update(test) + decryptor.finalize()

print("Value of message_decrypted is: ", message_decrypt)

unpadder = padding.PKCS7(128).unpadder()

data = unpadder.update(message_decrypt)

print("Value of message is: ", data + unpadder.finalize())

Answer 2

查看文档：

之后finalize()被称为该对象可以不再被使用; update()并且finalize()将引发一个AlreadyFinalized例外。

尝试初始化padder函数内部operation_getmessage()，以便每次调用函数时它都是一个新的填充器。

def operation_getmessage():
    padder = padding.PKCS7(128).padder()
    ...
    return message