“ValueError：Fernet 密钥必须是 32 个 url 安全的 base64 编码字节。”将 str 转换为 fernet key 时

Question

所以我试图将原始字符串密码转换为 fernet 密钥，我已经解决了无数的问题，甚至使用 ChatGPT 因为如果有人理解我为什么做错了并且可以提供一点帮助，我非常绝望请这样做。

# Convert the string to bytes
key_bytes = self.PrintPassword.encode()

# Base64 encode the bytes
base64_encoded_key = base64.urlsafe_b64encode(key_bytes)

# Create a Fernet key using the encoded bytes
fernet_key = base64.urlsafe_b64decode(base64_encoded_key)

self. Fern = Fernet(fernet_key)

Answer 1

您的字符串长度应为 32 个字节。 为了确保这个大小，您可以对其进行哈希处理，然后将其传递给您的函数，如下所示：

from cryptography.hazmat.backends import default_backend
from cryptography.hazmat.primitives import hashes
from cryptography.hazmat.primitives.kdf.pbkdf2 import PBKDF2HMAC
from cryptography.fernet import Fernet
import os
import base64

class YourClass:
    def __init__(self, password):
        self.password = password

    def generate_fernet_key(self):
        # Convert the password to bytes if it's not already
        password_bytes = self.password.encode()

        # Generate a salt
        salt = os.urandom(16)

        # Use PBKDF2HMAC to derive a secure key from the password
        kdf = PBKDF2HMAC(
            algorithm=hashes.SHA256(),
            length=32,  # Fernet keys are 32 bytes
            salt=salt,
            iterations=100000,
            backend=default_backend()
        )
        key = base64.urlsafe_b64encode(kdf.derive(password_bytes))
        self.fern = Fernet(key)

        # Optionally, return the key and salt for storage
        return key, salt

# Example usage
your_class_instance = YourClass("your_password_here")
fernet_key, salt = your_class_instance.generate_fernet_key()

现在您可以使用 your_class_instance.fern 进行加密/解密