Python 3.6：讀取一個非空的二進制文件被Python解釋爲空

Question

我有以下代碼，其中'password'是傳遞給函數的字符串。問題是，當我試圖讀取在前半段代碼中創建的文件時，Python將其解釋爲空（儘管文件資源管理器和文本編輯器告訴我它包含內容）。這4個打印語句是爲了協助調試（發現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)] 

控制檯輸出是這樣的：

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.

看來，有在[file_out.write(x) for x in (cipher.nonce, tag, ciphertext)]產生的.bin文件的內容，但我不能讓Python閱讀。

歡迎所有建議。我正在運行Python 3.6,32位。

Answer 1

您必須close甚至flushfile_out.write(x)之後的文件，因此您的數據是從buffer寫入文件。

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