线程安全 RijndaelManaged、ICryptoTransform.TransformFinalBlock？

Question

假设我们有这样的代码在构造函数中运行：

    Dim initVectorBytes As Byte() = System.Text.Encoding.ASCII.GetBytes(initVector)
    Dim saltValueBytes As Byte() = System.Text.Encoding.ASCII.GetBytes(saltValue)

    Dim passPharse As String = GenerateKeyString(EncryptionKey)

    Dim password As Rfc2898DeriveBytes = New Rfc2898DeriveBytes(passPharse, saltValueBytes, passwordIterations)

    Dim keyBytes As Byte() = password.GetBytes(CInt(keySize / 8))

    mSymmetricKey = New RijndaelManaged()
    mSymmetricKey.Padding = PaddingMode.PKCS7

    mSymmetricKey.Mode = CipherMode.CBC
    mSymmetricKey.BlockSize = 128

    mSymmetricKey.Key = keyBytes
    mSymmetricKey.IV = initVectorBytes

    mDecryptor = mSymmetricKey.CreateDecryptor()
    mEncryptor = mSymmetricKey.CreateEncryptor()

然后是 2 个公共函数：

Public Function Encrypt(ByVal plainText As String) As String
    Dim plainTextBytes As Byte() = System.Text.Encoding.UTF8.GetBytes(plainText)
    Dim cipherTextBytes As Byte() = mEncryptor.TransformFinalBlock(plainTextBytes, 0, plainTextBytes.Length)

    Dim cipherText As String = Convert.ToBase64String(cipherTextBytes)

    Return cipherText
End Function
Public Function Decrypt(ByVal cipherText As String) As String
    Dim cipherTextBytes As Byte() = Convert.FromBase64String(cipherText)

    Dim plainTextBytes As Byte() = mDecryptor.TransformFinalBlock(cipherTextBytes, 0, cipherTextBytes.Length)

    Dim plainText As String = System.Text.Encoding.UTF8.GetString(plainTextBytes, 0, plainTextBytes.Length)

    Return plainText
End Function

从多个线程调用这些函数是否是线程安全的？

Answer 1

根据文档，它不是线程安全的。您将在 RijndaelManagedTransform 实例code>mDecryptor 和 mEncryptor 变量。 TransformFinalBlock 是一个实例方法，根据 MSDN 不是线程安全的：

任何公共静态（在视觉中共享
基本）该类型的成员是线程
安全的。任何实例成员都不是
保证线程安全。

如果您想保证拥有线程安全的代码，您可能需要同步对 TransformFinalBlock 方法的调用。