狐爸

下面是我在微软的Libary 中看到的关于AES类库的示例文件：

我在项目里已经加了System.Security.Cryptography 的命名空间，现在我想把它的加密过程写到项目里，我是直接COPY的，代码如下：

Public Function EncryptStringToBytes_Aes(ByVal plainText As String, ByVal Key() As Byte, ByVal IV() As Byte) As Byte()
        \' Check arguments.
        If plainText Is Nothing OrElse plainText.Length <= 0 Then
            Throw New ArgumentNullException("plainText")
        End If
        If Key Is Nothing OrElse Key.Length <= 0 Then
            Throw New ArgumentNullException("Key")
        End If
        If IV Is Nothing OrElse IV.Length <= 0 Then
            Throw New ArgumentNullException("IV")
        End If
        Dim encrypted() As Byte
        \' Create an Aes object
        \' with the specified key and IV.
        Using aesAlg As Aes = Aes.Create()

            aesAlg.Key = Key
            aesAlg.IV = IV

            \' Create a decrytor to perform the stream transform.
            Dim encryptor As ICryptoTransform = aesAlg.CreateEncryptor(aesAlg.Key, aesAlg.IV)
            \' Create the streams used for encryption.
            Using msEncrypt As New MemoryStream()
                Using csEncrypt As New CryptoStream(msEncrypt, encryptor, CryptoStreamMode.Write)
                    Using swEncrypt As New StreamWriter(csEncrypt)

                        \'Write all data to the stream.
                        swEncrypt.Write(plainText)
                    End Using
                    encrypted = msEncrypt.ToArray()
                End Using
            End Using
        End Using

        \' Return the encrypted bytes from the memory stream.
        Return encrypted

    End Function \'EncryptStringToBytes_Aes
但是会提示出错，说没有定义AES的类？这种情况要怎么处理？