即使令牌相同，加密令牌对象也会引发异常并且无法解密

Question

代码概述：令牌是相同的，但是在加密和解密之间，加密对象存储在模块级字典中 - 仍然是加密令牌不会更改。

为什么不能工作？我想在幕后有关于加密对象的事情使它变得独一无二，但我会假设它所需要的只是解密工作的正确密钥。

这里是最小的相关代码：

import sys 
from cryptography.fernet import Fernet 
import json 
import os 

key = Fernet.generate_key() 
f = Fernet(key) 


with open("storage.json", "a+") as file: 
    if os.stat("storage.json").st_size == 0: 
     file.write("{}") 
    file.seek(0) 
    storage = json.load(file) 


def write(data): 
    with open("storage.json", "w") as file: 
     json.dump(data, file) 


def encrypt(pw): 
    token = f.encrypt(bytes(pw, "utf-8")) 
    return token 


def decrypt(token): 
    return f.decrypt(token) 

if len(sys.argv) == 1: 
    to_encrypt = input("A key to encrypt: ") 
    storage[to_encrypt] = encrypt(to_encrypt).decode("utf-8") 
    print("encrypted:", storage[to_encrypt]) 
    # print("storage:", storage) 
    try: 
     write(storage) 
    except Exception as e: 
     print("error:", e) 

elif len(sys.argv) == 2: 
    to_decrypt = input("Key to decrypt: ") 
    # print(storage[to_d]) 
    print("decrypted:", f.decrypt(bytes(storage[to_decrypt], "utf-8"))) 

要使其工作：不带参数运行程序 - 它会创建一个JSON文件，输入您的字符串，其加密到该文件，并退出。
然后，运行程序传递任何单个参数。尝试获取您之前输入的相同字符串。

应该发生这种回溯：

Traceback (most recent call last): 
    File "/Users/sjung/lib/python3.5/site-packages/cryptography/fernet.py", line 101, in decrypt 
    h.verify(data[-32:]) 
    File "/Users/sjung/lib/python3.5/site-packages/cryptography/hazmat/primitives/hmac.py", line 69, in verify 
    ctx.verify(signature) 
    File "/Users/sjung/lib/python3.5/site-packages/cryptography/hazmat/backends/openssl/hmac.py", line 73, in verify 
    raise InvalidSignature("Signature did not match digest.") 
cryptography.exceptions.InvalidSignature: Signature did not match digest. 

During handling of the above exception, another exception occurred: 

Traceback (most recent call last): 
    File "test_a.py", line 43, in <module> 
    print("decrypted:", f.decrypt(bytes(storage[to_decrypt], "utf-8"))) 
    File "/Users/sjung/lib/python3.5/site-packages/cryptography/fernet.py", line 103, in decrypt 
    raise InvalidToken 
cryptography.fernet.InvalidToken 

编辑：注释掉elif线试试，但不退出系统。 这确实能工作。

Answer 1

Fernet.generate_key()生成的密钥在解密时也必须是相同的密钥。我的示例代码每次都创建一个新的密钥。

https://github.com/pyca/cryptography/issues/3982