加密填充无效异常

Question

我正在使用 Visual Basic.net 并且有以下 System.Security.Cryptography.CryptographicException 异常：

填充无效，无法移除。

这是我的代码：

    Public Sub SaveEncryptedObjectToFile(FileName As String, Item As Object)
    Dim fs As FileStream
    Dim encryptor As CryptoStream

    Dim formatter As New BinaryFormatter

    Dim password As String = "MyPassword"
    Dim salt As String = "InitialVector123"

    Dim AES As AesManaged = New AesManaged
    AES.Padding = PaddingMode.PKCS7
    AES.Mode = CipherMode.CBC

    Dim HashAlgorithm As String = "SHA1" 'Can be SHA1 or MD5
    Dim PasswordIterations As Integer = 2
    Dim InitialVector As String = "InitialVector123" 'This should be a string of 16 ASCII characters.
    Dim KeySize As Integer = 256 'Can be 128, 192, or 256.

    Dim InitialVectorBytes As Byte() = Encoding.ASCII.GetBytes(InitialVector)
    Dim SaltValueBytes As Byte() = Encoding.ASCII.GetBytes(salt)
    Dim DerivedPassword As PasswordDeriveBytes = New PasswordDeriveBytes(password, SaltValueBytes, HashAlgorithm, PasswordIterations)
    Dim KeyBytes As Byte() = DerivedPassword.GetBytes(CInt(KeySize / 8))

    Dim encryptTransf As ICryptoTransform = AES.CreateEncryptor(KeyBytes, InitialVectorBytes)

    fs = New FileStream(FileName, FileMode.Create)
    encryptor = New CryptoStream(fs, encryptTransf, CryptoStreamMode.Write)

    Try
        formatter.Serialize(encryptor, Item)
    Catch e As SerializationException
        Console.WriteLine("Failed to serialize. Reason: " & e.Message)
        Throw
    Finally
        fs.Close()
    End Try
End Sub

Public Function OpenEncryptedObjectFromFile(FileName As String) As Object
    Dim fs As New FileStream(FileName, FileMode.Open)
    Dim decryptor As CryptoStream

    Dim ItemToReturn As New Object

    Dim password As String = "MyPassword"
    Dim salt As String = "InitialVector123"

    Dim AES As AesManaged = New AesManaged
    AES.Padding = PaddingMode.PKCS7
    AES.Mode = CipherMode.CBC

    Dim HashAlgorithm As String = "SHA1" 'Can be SHA1 or MD5
    Dim PasswordIterations As Integer = 2
    Dim InitialVector As String = "InitialVector123" 'This should be a string of 16 ASCII characters.
    Dim KeySize As Integer = 256 'Can be 128, 192, or 256.

    Dim InitialVectorBytes As Byte() = Encoding.ASCII.GetBytes(InitialVector)
    Dim SaltValueBytes As Byte() = Encoding.ASCII.GetBytes(salt)
    Dim DerivedPassword As PasswordDeriveBytes = New PasswordDeriveBytes(password, SaltValueBytes, HashAlgorithm, PasswordIterations)
    Dim KeyBytes As Byte() = DerivedPassword.GetBytes(CInt(KeySize / 8))
    'Dim KeyBytes As Byte() = Rfc2898DeriveBytes(CInt(KeySize / 8))

    Dim decryptTrans As ICryptoTransform = AES.CreateDecryptor(KeyBytes, InitialVectorBytes)

    Try
        Dim formatter As New BinaryFormatter

        decryptor = New CryptoStream(fs, decryptTrans, CryptoStreamMode.Read)
        ItemToReturn = DirectCast(formatter.Deserialize(decryptor), Object)
        Return ItemToReturn
    Catch e As SerializationException
        Console.WriteLine("Failed to deserialize. Reason: " & e.Message)
        Throw
    Finally
        fs.Close()
    End Try
End Function

异常发生在以下行：

ItemToReturn = DirectCast(formatter.Deserialize(decryptor), Object)

我不确定这是否与 CryptographicException 有任何关系，但我目前收到以下警告：

'Public Overrides Function GetBytes(cb As Integer) As Byte()' 已过时：'Rfc2898DeriveBytes 取代 PasswordDeriveBytes 以从密码中派生密钥材料，在新应用程序中是首选。'。

在这一行：

Dim KeyBytes As Byte() = DerivedPassword.GetBytes(CInt(KeySize / 8))

我在网上查了一下，找不到任何可行的解决方案来解决这个警告。

Answer 1

为了诊断问题，您需要查看正在生成的内容。更改解密端以期望没有填充。这将允许它越过异常并产生一些东西。

然后您可以检查输出以帮助诊断问题。作为第一个猜测，我会检查你的钥匙。确保加密密钥逐字节地与解密密钥相同。不匹配的键是您遇到填充错误的可能原因之一。