I was attempting to use this class however I do not see the ProtectedData class under System.Security.Cryptography. Any reason why!

This is what I have so far ...

Imports System.Security.Cryptography
Imports System.text.Encoding
Imports System

Public Class Security
Private Shared arrEntropybyte As Byte() = {1,2,3,4,5,6,7,8,9,0}

Public Shared Function Encrypt(ByVal stringToEncrypt As String) As String
Dim arrStringbyte As Byte()
Dim encryptedDBString As Byte()
Try
' Convert the string to a byte array:
arrStringbyte = Unicode.GetBytes(stringToEncrypt)
' Encrypt string
encryptedDBString = ProtectedData.Protect(stringToEncrypt, arrEntropybyte, DataProtectionScope.CurrentUser)
Catch ex As Exception
Throw ex
End Try
End Function
End Class