这段代码有多安全？

Question

这段代码有多安全？可以在没有密码的情况下解密文本/文件吗？

from Crypto.Cipher import AES
from Crypto import Random
import hashlib
import base64
import os
import struct


BS = 16
pad = lambda s: s + (BS - len(s) % BS) * chr(BS - len(s) % BS).encode()
unpad = lambda s: s[:-ord(s[len(s)-1:])]

class AESCipher(object):
    def __init__(self, key, salt):
        self.key = hashlib.pbkdf2_hmac('sha256', key.encode(), salt.encode(), 100000)

def encrypt(self, plaintext):
    plaintext = pad(plaintext.encode())
    iv = Random.new().read(BS)
    cipher = AES.new(key=self.key, mode=AES.MODE_CBC, iv=iv)
    enc = cipher.encrypt(plaintext)
    return base64.b64encode(iv + enc).decode()

def decrypt(self, enc):
    enc = base64.b64decode(enc)
    iv = enc[:BS]
    enc = enc[BS:]
    cipher = AES.new(key=self.key, mode=AES.MODE_CBC, iv=iv)
    plaintext = cipher.decrypt(enc)
    return unpad(plaintext).decode()

def encrypt_file(self, in_file_name, out_file_name=None, chunk_size=1024 * 64):
    if not out_file_name:
        out_file_name = in_file_name + '.enc'

    iv = Random.new().read(BS)
    cipher = AES.new(key=self.key, mode=AES.MODE_CBC, iv=iv)
    file_size = os.path.getsize(in_file_name)

    with open(in_file_name, 'rb') as in_file:
        with open(out_file_name, 'wb') as out_file:
            out_file.write(struct.pack('<Q', file_size))
            out_file.write(iv)

            while True:
                chunk = in_file.read(chunk_size)
                if len(chunk) == 0:
                    break
                elif len(chunk) % 16 != 0:
                    chunk += b' ' * (16 - len(chunk) % 16)

                out_file.write(cipher.encrypt(chunk))

def decrypt_file(self, in_file_name, out_file_name=None, chunk_size=1024 * 64):
    if not out_file_name:
        out_file_name = os.path.splitext(in_file_name)[0]
        if out_file_name == in_file_name:
            out_file_name += '.decrypted'

    with open(in_file_name, 'rb') as in_file:
        with open(out_file_name, 'wb') as out_file:
            orig_size = struct.unpack('<Q', in_file.read(struct.calcsize('Q')))[0]
            iv = in_file.read(16)
            cipher = AES.new(key=self.key, mode=AES.MODE_CBC, iv=iv)

            while True:
                chunk = in_file.read(chunk_size)
                if len(chunk) == 0:
                    break

                out_file.write(cipher.decrypt(chunk))
            out_file.truncate(orig_size)

我可以使用此脚本加密我的数据吗？我使用hashlib来派生密钥，也许我应该使用pyCrypto中的密钥派生函数？