Python AES加密解密报encoding without a string argument错误解决

我创建了一个无扩展名的二进制文件，用于存储经AES加密的文本内容，在读取文件尝试解密提取文本时，触发如下报错：

Exception in Tkinter callback 
Traceback (most recent call last):  
  File "C:\Users\conitc11\AppData\Local\Programs\Python\Python39\lib\tkinter\__init__.py",
line 1884, in __call__
    return self.func(*args)
  File "c:\Users\conitc11\Desktop\PY\REPORTEBIOSTAR.py", line 338, in
LecturaBinario
    encrypted_text = pad(bytes(content, 'utf-8'), 16)
TypeError: encoding without a string argument

初始业务代码 #

最初编写的加解密、文件读写逻辑如下：

def EncrypConfig(message):  
    entryMessage = pad(bytes(message, 'utf-8'), 16)
    obj = AES.new(secret_key, AES.MODE_CBC, iv)
    print('Original message is: ', entryMessage)
    encrypted_text = obj.encrypt(entryMessage)
    print('The encrypted text', encrypted_text)
    return encrypted_text
def CreacionBinario():
    f = open('cfg', 'wb')
    columnasConfig[0] = cbDepartamento.get()   
    columnasConfig[1] = '2345G564D5645'
    columnasConfig[2] = lector.get()
    EncrypConfig(columnasConfig[0])
    print('Texto a encryptar: ' + columnasConfig[0])
    f.write((bytes(str(EncrypConfig(columnasConfig[0])), 'utf-8')))
    print('Texto encryptado: ' + str(EncrypConfig(columnasConfig[0])))
    f.close()
def LecturaBinario():
    with open('cfg', 'rb') as fh:
        content = fh.read()
    print('Content:' + str(content))
    encrypted_text = pad(bytes(content, 'utf-8'), 16)
    rev_obj = AES.new(secret_key, AES.MODE_CBC, iv)    
    decrypted_text = rev_obj.decrypt(encrypted_text)
    print("Print the full content of the binary file:")
    print(content)
    print("DecriptedText: ", decrypted_text.decode('utf-8'))

调试过程 #

我参考标准AES加解密样例做调试，参考代码如下：

from email.message import Message
from os import urandom
from Crypto.Cipher import AES
from Crypto.Util.Padding import pad

# 密文生成逻辑
secret_key = urandom(16)
iv = urandom(16)
obj = AES.new(secret_key, AES.MODE_CBC, iv)

message = pad(bytes('All Users', 'utf-8'), 16)
print('Original message is: ', message)
encrypted_text = obj.encrypt(message)
print('The encrypted text', encrypted_text)

# 解密逻辑
rev_obj = AES.new(secret_key, AES.MODE_CBC, iv)
decrypted_text = rev_obj.decrypt(encrypted_text)
print('The decrypted text', decrypted_text.decode('utf-8'))

调试阶段尝试的两种修改方案均失败，对应现象如下：

• 不对读取到的content做bytes转换，直接传入pad方法，解密后未输出正确明文，仅返回<built-in method decode of bytes object at 0x0000019C7EFDFC00>的方法引用
• 同时移除pad填充处理和bytes转换，触发ValueError: Data must be padded to 16 byte boundary in CBC mode报错

修复方案 #

经过逐行调试定位根因后，共做了三点调整：

• 优化加密函数逻辑：将原entryMessage = pad(bytes(message, 'utf-8'), 16)调整为message = pad(bytes(str(text), 'utf-8'), 16)，同时将AES实例初始化语句移到填充逻辑之前，理顺代码执行顺序
• 修正二进制文件写入逻辑：将原错误的f.write((bytes(str(EncrypConfig(columnasConfig[0])), 'utf-8')))替换为f.write(EncrypConfig(listOfConfig))，直接写入加密方法返回的原始字节对象。这是最核心的修复点：加密方法返回的本身就是符合CBC模式块长度要求的密文字节流，转成字符串再重新编码会彻底破坏密文结构
• 移除读取逻辑中多余的填充和编码转换：删除原encrypted_text = pad(bytes(content, 'utf-8'), 16)语句，直接将文件读取到的原始字节内容传入解密方法即可。加密阶段已经完成了符合要求的块填充，读取解密阶段不需要二次处理

修复后可运行代码 #

secret_key = b'somebinarykey12'
iv = b'somebinaryvalue1'
def EncrypConfig(text):
    obj = AES.new(secret_key, AES.MODE_CBC, iv)  
    message = pad(bytes(str(text), 'utf-8'), 16) 
    encrypted_text = obj.encrypt(message)
    return encrypted_text
def CreacionBinario():
    f = open('cfg', 'wb')
    columnasConfig[0] = cbDepartamento.get()   
    columnasConfig[1] = txtContraseñaSave.get()
    columnasConfig[2] = lector.get()
    columnasConfig[3] = checkedLilWindow2.get()    
    listOfConfig = [columnasConfig[0], columnasConfig[1], columnasConfig[2], columnasConfig[3]]
    f.write(EncrypConfig(listOfConfig))
    print('Texto a encryptar: ', listOfConfig)   
    print('Texto encryptado: ', EncrypConfig(listOfConfig))
    f.close()
def LecturaBinario():
    with open('cfg', 'rb') as fh:
        content = fh.read()
    print('Content:', content)
    rev_obj = AES.new(secret_key, AES.MODE_CBC, iv)    
    decrypted_text = rev_obj.decrypt(content)
    print("Print the full content of the binary file:")
    print(content)
    print('The decrypted text: ', decrypted_text.decode('utf-8'))
    listFromFile = list[decrypted_text.decode('utf-8')]
    return listFromFile[1] 

内容的提问来源于stack exchange，提问作者José Timaure