Public Sub EncryptExample()
      Dim zipFile As AbstractFile = New DiskFile("ZipFile.zip")

      ' If the zip file already exists
      If zipFile.Exists Then
        ' Delete it
        zipFile.Delete()
      End If

      Dim zip As New ZipArchive(zipFile)

'       The length of the password is not limited. However, to preserve compatibility
'      with other Zip compression utilities, it is recommended that you limit passwords
'      to no greater than 80 characters.
'      
'      It is also advisable to only use ASCII characters because there is no
'      accepted standard on how to encode non-ASCII characters in passwords. 
      Dim password As String = "MyPassword"

      zip.DefaultEncryptionMethod = EncryptionMethod.WinZipAes
      zip.DefaultEncryptionStrength = 256
      zip.DefaultEncryptionPassword = password

      Using batch As New AutoBatchUpdate(zip)
        Dim sourceFolder As AbstractFolder = New DiskFolder("D:\Temp\foo")

        ' Zip the contents of the source folder
        sourceFolder.CopyFilesTo(zip, True, True)
      End Using
    End Sub

    Public Sub DecryptExample()
      ' Setup a zip file
      Dim zipFile As AbstractFile = New DiskFile("ZipFile.zip")

      ' If the zip file doesn't exist
      If (Not zipFile.Exists) Then
        ' Fail
        Return
      End If

      ' Setup a destination folder
      Dim destinationFolder As AbstractFolder = New DiskFolder("D:\Temp\Unzip")

      Dim zip As New ZipArchive(zipFile)

'       The length of the password is not limited. However, to preserve compatibility
'      with other Zip compression utilities, it is recommended that you limit passwords
'      to no greater than 80 characters.
'      
'      It is also advisable to only use ASCII characters because there is no
'      accepted standard on how to encode non-ASCII characters in passwords. 

      ' Set up the list of password possible for the items in this archive
      Me.m_passwords = New String() { "MyPassword", "wrong password", "fkEI-969=6kei$[BbZ ""6Iq- =[", "}8{)zM#$k//O?t~=iG'Si{AF""S~'/8@1n" }

      ' Use our most likely password as the default
      zip.DefaultDecryptionPassword = Me.m_passwords(0)

      ' Subscribe to the events that will allow us to handle invalid passwords
      Dim events As New ZipEvents()
      AddHandler events.ItemProgression, AddressOf OnItemProgression
      AddHandler events.ItemException, AddressOf OnItemException

      ' Unzip the contents of the zip archive to the destination folder
      zip.CopyFilesTo(events, zip, destinationFolder, True, True)
    End Sub

    Private Sub OnItemProgression(ByVal sender As Object, ByVal e As ItemProgressionEventArgs)
      ' We're about to process a new item 

      ' Reset the password index
      Me.m_passwordIndex = 0
    End Sub

    Private Sub OnItemException(ByVal sender As Object, ByVal e As ItemExceptionEventArgs)
      Dim badPassword As Boolean = False

      ' Get the archive object we passed through the user data
      Dim zip As ZipArchive = CType(e.UserData, ZipArchive)

      ' We will try to ascertain if we have an invalid password 

      Dim invalidDecryptionPasswordException As InvalidDecryptionPasswordException
      Dim fileSystemIOException As FileSystemIOException

      invalidDecryptionPasswordException = TryCast(e.Exception, InvalidDecryptionPasswordException)
      fileSystemIOException = TryCast(e.Exception, FileSystemIOException)

      ' If the exception says that a bad password was supplied
      If invalidDecryptionPasswordException IsNot Nothing Then
        badPassword = True
      ' If we had an I/O error during decryption
      ElseIf fileSystemIOException IsNot Nothing Then
        Dim zippedFile As ZippedFile = TryCast(e.CurrentItem, ZippedFile)

        ' If we were reading from a zipped file encrypted in the 'compatible' method
        If zippedFile IsNot Nothing AndAlso zippedFile.Encrypted AndAlso zippedFile.EncryptionMethod.Equals(EncryptionMethod.Compatible) Then
'           It's possible the I/O error occurred because the password is invalid.
'          The was the 'compatible' encryption is designed doesn't provide for 100%
'          accurate bad password detection, unfortunately.
'            
'          Note that AES encryption has no such design flaw. 
          badPassword = True
        End If
      End If

      ' If we had a bad password
      If badPassword Then
        ' If we haven't gone through our password list
        If Me.m_passwordIndex < Me.m_passwords.Length Then
          ' Set the current password and move the index to the next password
          zip.DefaultDecryptionPassword = Me.m_passwords(Me.m_passwordIndex)
          Me.m_passwordIndex += 1

          ' Retry unzipping the file
          e.Action = ItemExceptionAction.Retry
        Else
          ' Skip the file
          e.Action = ItemExceptionAction.Ignore
        End If
      End If
    End Sub

    Private m_passwords() As String
    Private m_passwordIndex As Integer