Python 3.6：读取一个非空的二进制文件被Python解释为空

Question

我有以下代码，其中'password'是传递给函数的字符串。问题是，当我试图读取在前半段代码中创建的文件时，Python将其解释为空（尽管文件资源管理器和文本编辑器告诉我它包含内容）。这4个打印语句是为了协助调试（发现here）。

def encryptcredentials(username, password): 
    # Create key randomly and save to file 
    key = get_random_bytes(16) 
    keyfile = open("key.bin", "wb").write(key) 

    password = password.encode('utf-8') 

    path = "encrypted.bin" 

    # The following code generates a new AES128 key and encrypts a piece of data into a file 
    cipher = AES.new(key, AES.MODE_EAX) 
    ciphertext, tag = cipher.encrypt_and_digest(password) 

    file_out = open(path, "wb") 
    [file_out.write(x) for x in (cipher.nonce, tag, ciphertext)] 

    print("the path is {!r}".format(path)) 
    print("path exists: ", os.path.exists(path)) 
    print("it is a file: ", os.path.isfile(path)) 
    print("file size is: ", os.path.getsize(path)) 

    # At the other end, the receiver can securely load the piece of data back, if they know the key. 
    file_in = open(path, "rb") 
    nonce, tag, ciphertext = [file_in.read(x) for x in (16, 16, -1)] 

控制台输出是这样的：

the path is 'encrypted.bin' 
path exists: True 
it is a file: True 
file size is: 0 

Here's an image of how the file is displayed in File Explorer.

看来，有在[file_out.write(x) for x in (cipher.nonce, tag, ciphertext)]产生的.bin文件的内容，但我不能让Python阅读。

欢迎所有建议。我正在运行Python 3.6,32位。

Answer 1

您必须close甚至flushfile_out.write(x)之后的文件，因此您的数据是从buffer写入文件。

[file_out.write(x) for x in (cipher.nonce, tag, ciphertext)] 
file_out.close()