有什么方法可以改进我在 C# 中的 AES 加密代码？

Question

我有这段用于 AES 加密的代码，有人可以验证这段代码是否正确吗？效果很好，但我更关心算法的实现。

// Plaintext value to be encrypted.

//Passphrase from which a pseudo-random password will be derived.
//The derived password will be used to generate the encryption key.

//Password can be any string. In this example we assume that this passphrase is an ASCII string.

//Salt value used along with passphrase to generate password.
//Salt can be any string. In this example we assume that salt is an ASCII string.

//HashAlgorithm used to generate password. Allowed values are: "MD5" and "SHA1".
//SHA1 hashes are a bit slower, but more secure than MD5 hashes.

//PasswordIterations used to generate password. One or two iterations should be enough.

//InitialVector (or IV). This value is required to encrypt the first block of plaintext data.
//For RijndaelManaged class IV must be exactly 16 ASCII characters long.

//KeySize. Allowed values are: 128, 192, and 256.
//Longer keys are more secure than shorter keys.

//Encrypted value formatted as a base64-encoded string.


public static string Encrypt(string PlainText, string Password, string Salt, string HashAlgorithm, int PasswordIterations, string InitialVector, int KeySize)
{
    byte[] InitialVectorBytes = Encoding.ASCII.GetBytes(InitialVector);
    byte[] SaltValueBytes = Encoding.ASCII.GetBytes(Salt);
    byte[] PlainTextBytes = Encoding.UTF8.GetBytes(PlainText);
    PasswordDeriveBytes DerivedPassword = new PasswordDeriveBytes(Password, SaltValueBytes, HashAlgorithm, PasswordIterations);
    byte[] KeyBytes = DerivedPassword.GetBytes(KeySize / 8);
    RijndaelManaged SymmetricKey = new RijndaelManaged();
    SymmetricKey.Mode = CipherMode.CBC;
    ICryptoTransform Encryptor = SymmetricKey.CreateEncryptor(KeyBytes, InitialVectorBytes);
    MemoryStream MemStream = new MemoryStream();
    CryptoStream CryptoStream = new CryptoStream(MemStream, Encryptor, CryptoStreamMode.Write);
    CryptoStream.Write(PlainTextBytes, 0, PlainTextBytes.Length);
    CryptoStream.FlushFinalBlock();
    byte[] CipherTextBytes = MemStream.ToArray();
    MemStream.Close();
    CryptoStream.Close();
    return Convert.ToBase64String(CipherTextBytes);
}

public static string Decrypt(string CipherText, string Password, string Salt, string HashAlgorithm, int PasswordIterations, string InitialVector, int KeySize)
{
    byte[] InitialVectorBytes = Encoding.ASCII.GetBytes(InitialVector);
    byte[] SaltValueBytes = Encoding.ASCII.GetBytes(Salt);
    byte[] CipherTextBytes = Convert.FromBase64String(CipherText);
    PasswordDeriveBytes DerivedPassword = new PasswordDeriveBytes(Password, SaltValueBytes, HashAlgorithm, PasswordIterations);
    byte[] KeyBytes = DerivedPassword.GetBytes(KeySize / 8);
    RijndaelManaged SymmetricKey = new RijndaelManaged();
    SymmetricKey.Mode = CipherMode.CBC;
    ICryptoTransform Decryptor = SymmetricKey.CreateDecryptor(KeyBytes, InitialVectorBytes);
    MemoryStream MemStream = new MemoryStream(CipherTextBytes);
    CryptoStream cryptoStream = new CryptoStream(MemStream, Decryptor, CryptoStreamMode.Read);
    byte[] PlainTextBytes = new byte[CipherTextBytes.Length];
    int ByteCount = cryptoStream.Read(PlainTextBytes, 0, PlainTextBytes.Length);
    MemStream.Close();
    cryptoStream.Close();
    return Encoding.UTF8.GetString(PlainTextBytes, 0, ByteCount);
}

我不是专业安全人员或专业程序员，我开始学习并且喜欢理解它

我的计划是构建一个需要最少输入但遵循标准的 AES 加密函数，以便在 PHP 和 JavaScript 等其他语言中轻松制作等效函数！

谢谢

Answer 1

一些通用的cmets。第一个是围绕IV。通常，您希望 IV 是随机的。通过将其限制为（可显示的）ASCII，您在某种程度上限制了可能的值。一般来说，您最好 a) 使用 GenerateIV() 方法，b) 将 IV 值添加到密文中，这样 c) 您不需要将其作为参数传递给任一函数。

第二条评论是，一般来说，您需要计划未来对加密需求的变化。最好在密文旁边嵌入一些版本控制或参数信息，并避免在代码中嵌入特定的加密设置。例如，如果以后您决定将密码的迭代次数加倍，您可能仍希望解密使用旧设置加密的值（或警告用户该值不再可访问）。

您还可以将大量决策推送到您的配置文件中。例如，您可以在今天映射到 RijndaelManaged 的​​ create a name for your crypto 提供程序（例如 MyAppSymmetricCrypto），但在以后可以更改为当时合适的任何内容。

Answer 2

除了@Damien_The_Unbeliever 的回答

MS 建议使用Rfc2898DeriveBytes 而不是PasswordDeriveBytes。 （然后您可以从方法参数中删除“HashAlgorithm”）。

您可以根据密码计算 IV：

var bytes = new Rfc2898DeriveBytes(password, salt, iterations);
var key = bytes.GetBytes(keySize);
var iv = bytes.GetBytes(ivSize);

您应该检查输入值是否存在无效值/范围。

将MemoryStream 和CryptoStream 类包装在using 语句中。