Decrypt PDF

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

But how do i Decrypt this pdf ???

Code:

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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

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You don't really decrypt an encrypted pdf. The way you "decrypt" it is to open it and supply the password that it was encrypted with. For example:

Code:

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Dim password As String = "secret"
Dim reader as New PdfReader(pdfFilePath, PdfWriter.GetISOBytes(password))

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Ok , looks alright.

I am trying to open it , but where do i put the code ??

Want to open the file with a button

"C:\NS\test_encrypted.pdf"

If you want to open the pdf file using the default application, just start a process. Put this code in a button click event handler

Code:

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Dim pdfFile As String = "C:\NS\test_encrypted.pdf"
If IO.File.Exists(pdfFile) Then
    Process.Start(pdfFile)
End If

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The default pdf reader application (i.e. Acrobat Reader) will prompt you for the password, and then open the file.

If you want to open it programmatically (nothing shown on screen) so that you can do other stuff with it (also programmatically) then do as I posted in the previous post.

stanav ,thanks

But i can't get it to work so it opens with the programm (nothing shown on screen) .I think i do something wrong with process start ?????

The other code works great.



Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2.Click
Dim password As String = "secret"
Dim pdfTemplate As String = (My.Application.Info.DirectoryPath & "\test_encrypted.pdf")
Dim pdfReader As PdfReader = New PdfReader(pdfTemplate, PdfWriter.GetISOBytes(password))

Process.Start(My.Application.Info.DirectoryPath & "\test_encrypted.pdf")


End Sub

stanav,

I think i found something , i converted it from # to vb

But it is not working , what am i missing here ????

Imports System.IO
Imports iTextSharp.text.pdf
Public Class Form1
Dim WorkingFolder As String = ("C:\NSG\")
Dim InputFile As String = Path.Combine(WorkingFolder, "BM1.pdf")
Dim OutputFile As String = Path.Combine(WorkingFolder, "BM_dec.pdf")
'will be created automatically //You must provide owner password but not the user password.


Private Sub DecryptFile(ByVal inputFile As String, ByVal outputFile As String)

Dim password As String = "1234"
' Your Key Here
Try
Dim reader As New PdfReader(inputFile, New System.Text.ASCIIEncoding().GetBytes(password))

Using memoryStream As New MemoryStream()
Dim stamper As New PdfStamper(reader, memoryStream)
stamper.Close()
reader.Close()
File.WriteAllBytes(outputFile, memoryStream.ToArray())

End Using
Catch err As Exception
'' Console.WriteLine(err.Message)
MsgBox("")
End Try
End Sub

Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
DecryptFile(WorkingFolder, "BM1.pdf")
End Sub
End Class