imports System.IO
Imports System.Security.Cryptography
Imports Microsoft.VisualBasic

Namespace ITS
    Public Class OneLogin

Public Function OneLogin_Decrypt(ByVal TokenKey As String, ByVal DataString As String) As String
            Dim ms As MemoryStream = Nothing
            Dim cs As CryptoStream = Nothing
            Try
                Using AES As New RijndaelManaged()
                AES.KeySize = 128
                AES.BlockSize = 128
                Dim EncryptedData As Byte() = System.Convert.FromBase64String(DataString)
                Dim SecretKey As New Rfc2898DeriveBytes(TokenKey, New Byte() {&H5E, &H7C, &H39, &H5E, &H54, &H4F, &H23, &H56, &H2A, &H47, &H48, &H63, &H54})
                Using Decryptor As ICryptoTransform = AES.CreateDecryptor(SecretKey.GetBytes(16), SecretKey.GetBytes(16))
                    ms = New MemoryStream(EncryptedData)
                    Using ms
                        cs = New CryptoStream(ms, Decryptor, CryptoStreamMode.Read)
                        Using cs
                            Dim PlainText As Byte() = New Byte(EncryptedData.Length - 1) {}
                            Return Encoding.Unicode.GetString(PlainText, 0, cs.Read(PlainText, 0, PlainText.Length))
                        End Using
                    End Using
                End Using

            End Using
        Catch ex As Exception
            Return "Error - " & ex.Message
        Finally
            If ms IsNot Nothing Then
                ms.Close()
            End If
            If cs IsNot Nothing Then
                cs.Close()
            End If
        End Try
    End Function

End Class
End Namespace