public void DecryptDemo() {
  PGPLib pgp = new PGPLib();
  FileInfo encryptedFile = new FileInfo(@"C:\Test\INPUT.pgp");
  FileInfo privateKeyFile = new FileInfo(@"C:\Test\private.key");
  FileInfo outputFile = new FileInfo(@"C:\Test\decrypted.txt");
  pgp.DecryptFile(encryptedFile, privateKeyFile, "pass123", outputFile);
}

using System;
using System.IO;
using DidiSoft.Pgp;

public class DecryptDemo
{
 public void Demo()
 {
    // initialize the library
    PGPLib pgp = new PGPLib();

    FileInfo inputFile = new FileInfo(@"c:\INPUT.pgp");
    FileInfo privateKeyLocation = new FileInfo(@"c:\private_key.asc");
    string privateKeyPassword = "key password";
    FileInfo decryptedOutput = new FileInfo(@"c:\OUTPUT.txt");

    // decrypt and obtain the original file name
    string originalFileName = 
      pgp.DecryptFile(inputFileLocation,
                      privateKeyLocation,
                      privateKeyPassword,
                      decryptedOutput);        
 }
}

Imports System
Imports System.IO
Imports DidiSoft.Pgp

Public Class DecryptDemo
Public Sub Demo()
    ' create an instance of the library
    Dim pgp As New PGPLib()

    ' decrypt and obtain the original file name
    Dim originalFileName As String
    originalFileName = 
      pgp.DecryptFile(New FileInfo("c:\INPUT.pgp"), _
                      New FileInfo("c:\private_key.asc"), _
                      "key password", _
                      New FileInfo("c:\OUTPUT.txt"))
 End Sub
End Class