I am using this code to Encrypt a PDF , works fine.

But how do i Decrypt this pdf ???

Code:
Imports System.IO
Imports iTextSharp.text.pdf

Public Class Form1

    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        Using input As Stream = New FileStream("C:\NS\test.pdf", FileMode.Open, FileAccess.Read, FileShare.Read)
            Using output As Stream = New FileStream("C:\NS\test_encrypted.pdf", FileMode.Create, FileAccess.Write, FileShare.None)
                Dim reader As New PdfReader(input)
                PdfEncryptor.Encrypt(reader, output, True, "secret", "secret", PdfWriter.ALLOW_PRINTING)
            End Using
        End Using
    End Sub
End Class