Working with Password Protected PDF files
The code below shows you how to set a password for a PDF file.
This sample requires a Tools license.
C#
    
using System;
using SolidFramework.Plumbing;
using SolidFramework.Pdf;
namespace PDFPasswords
{
    class Program
    {
        [STAThread]
        static void Main(string[] args)
        {
            // Call your Solid Documents License
            SolidFramework.License.Import(@"C:\MyFolder\license.xml");
            // Set the location of your the file you want to convert
            String pdfPath = @"C:\YourFolder\yourpdf.pdf";
            //*Setting Owner and User Passwords*//
            // Create a new PdfDocument Object called document and assign the selected PDF file to it 
            using (PdfDocument document = new PdfDocument(pdfPath))
            {
                // Open the file
                document.Open();
               // Create a new Security Handler object and Assign the Password string values
                //Note: Inorder to set passwords an Encryption Algorithm must be set 
                 PdfPasswordSecurityHandler securityHandler = new PdfPasswordSecurityHandler();
                 securityHandler.OpenPassword = "user";
                 securityHandler.OwnerPassword = "owner";
                 // Assign an encryption algorithm
                 //Note: In order to set the an encryption algorithm, passwords must be set on the document 
                 securityHandler.EncryptionAlgorithm = EncryptionAlgorithm.Aes256BitsX;
                // Write the changes back into the document
                document.SaveProtected(securityHandler, OverwriteMode.ForceOverwrite);
            }
        }
    }
}
        C++
    
#include "stdafx.h"
#include "SolidFramework.h"
using namespace std;
int main()
{
    // Call your Solid Documents License
    SolidFramework::License::Import(L"c:\\yourfolder\\license.xml");
    // Add the PDF file to convert
    wstring pdfPath(L"c:\\myfolder\\yourpdf.pdf");
    //*PDF Encryption*//
    // Create a new PdfDocument Object called document and assign the selected PDF file to it 
    SolidFramework::Pdf::PdfDocumentPtr document(new SolidFramework::Pdf::PdfDocument(pdfPath));
    // Open the file
    document->Open();
    // Create a new Security Handler object and Assign the Password string values
    //Note: Inorder to set passwords an Encryption Algorithm must be set 
    SolidFramework::Pdf::PdfPasswordSecurityHandlerPtr securityHandler(new SolidFramework::Pdf::PdfPasswordSecurityHandler());
    securityHandler->setOpenPassword(L"user");
    securityHandler->setOwnerPassword(L"owner");
    // Assign an encryption algorithm
    //Note: In order to set the an encryption algorithm, passwords must be set on the document 
    securityHandler->setEncryptionAlgorithm(SolidFramework::Pdf::EncryptionAlgorithm::Aes256Bits);
    // Write the changes back into the document
    document->SaveProtected(securityHandler, SolidFramework::Plumbing::OverwriteMode::ForceOverwrite);
    securityHandler->Dispose();
    document->Close();
    document->Dispose():
    return 0;
}
        VB.Net
    
Imports SolidFramework.Plumbing
Imports SolidFramework.Pdf
Module PDFPasswords
    Sub Main()
        ' Call your Solid Documents License
        SolidFramework.License.Import("C:\MyFolder\license.xml")
        'Define a variable for your source file
        Dim sPdfPath As String
        ' Define a PDF Document object
        Dim myDocument As SolidFramework.Pdf.PdfDocument
        ' Define a new Security Handler Object
        Dim mySecurityHandler As SolidFramework.Pdf.PdfPasswordSecurityHandler
        ' Set values to your variables 
        sPdfPath = ("C:\YourFolder\filepdf.pdf")
        myDocument = New PdfDocument(sPdfPath)
        mySecurityHandler = New PdfPasswordSecurityHandler
        ' Open the file
        myDocument.Open(sPdfPath)
        ' Note: Inorder to set passwords an Encryption Algorithm must be set 
        mySecurityHandler.OpenPassword = "user"
        mySecurityHandler.OwnerPassword = "owner"
        ' Assign an encryption algorithm
        ' Note: In order to set the an encryption algorithm, passwords must be set on the document 
        mySecurityHandler.EncryptionAlgorithm = EncryptionAlgorithm.Aes256BitsX
        ' Write the changes back into the document
        myDocument.SaveProtected(mySecurityHandler, OverwriteMode.ForceOverwrite)
        ' Clean up
        myDocument.Close()
        myDocument.Dispose()
    End Sub
End Module
        