c# - ProtectData 类使用哪种加密算法？

Question

我知道 ProtectedData类最终调用 Windows 的数据保护 API (DPAPI)。 documentation on the DPAPI function提供了诸如 key 存储位置、谁可以解密数据等详细信息。但是，我无法找到有关实际底层加密算法是什么的任何文档。 (我需要了解安全文档保护方法的详细信息，以便进行即将进行的审计)。这只是使用 AES 还是类似的东西？这有多安全？

Answer 1

DPAPI使用三重 DES。

• It uses proven cryptographic routines, such as the strong Triple-DES algorithm in CBC mode, the strong SHA-1 algorithm, and the PBKDF2 password-based key derivation routine.
• It uses proven cryptographic constructs to protect data. All critical data is cryptographically integrity protected, and secret data is wrapped by using standard methods.
• It uses large secret sizes to greatly reduce the possibility of brute-force attacks to compromise the secrets.
• It uses PBKDF2 with 4000 iterations to increase the work factor of an adversary trying to compromise the password.
• It sanity checks MasterKey expiration dates.
• It protects all required network communication with Domain Controllers by using mutually authenticated and privacy protected RPC channels.
• It minimizes the risk of exposing any secrets, by never writing them to disk and minimizing their exposure in swappable RAM.
• It requires Administrator privileges to make any modifications to the DPAPI parameters in the registry.
• It uses Windows File Protection to help protect all critical DLLs from online changes even by processes with Administrator privileges.

DPAPI initially generates a strong key called a MasterKey, which is protected by the user's password. DPAPI uses a standard cryptographic process called Password-Based Key Derivation, described in PKCS #5, to generate a key from the password. This password-derived key is then used with Triple-DES to encrypt the MasterKey, which is finally stored in the user's profile directory.

然而，根据Passcape , DPAPI 使用 AES256。至少在 Windows 7 上。

• DPAPI uses proven cryptographic algorithms. For example, Windows 7 by default uses the AES256 encryption in the CBC mode, SHA512 for hashing and PBKDF2 as password-based key derivation routine.