Last Updated: 14 Mar 2024 08:59 by ADMIN
Release 2024.1.305 (2024 Q1)
Created on: 22 Feb 2024 11:19
Category: ZipLibrary
Type: Bug Report
ZipLibrary: NullReferenceException when updating a zip with a password

Steps to reproduce:

1.Create a zip archive for a txt file with password protection

2. Try updating the protected file and insert a new text line for example

The settings used for decrypting the file don't seem to be used encrypting again after the update operation. Here is a sample code snippet for reproducing the error message:

    Sub Main()
        Dim sZipFilePath As String = "..\..\"


        Dim decryptionSettings As DecryptionSettings = EncryptionSettings.CreateDecryptionSettings()
        AddHandler decryptionSettings.PasswordRequired, AddressOf DecryptionSettings_PasswordRequired
        Dim compressionSettings As CompressionSettings = Nothing
        Dim encoding As Encoding = Nothing
        Using oFS As FileStream = File.Open(sZipFilePath, FileMode.OpenOrCreate)

            Using oArchive As ZipArchive = ZipArchive.Update(oFS, encoding, compressionSettings, decryptionSettings)
                For Each entry As ZipArchiveEntry In oArchive.Entries
                    Using entryStream As Stream = entry.Open()
                        Dim reader As New StreamReader(entryStream)
                        Dim content As String = reader.ReadToEnd()

                        entryStream.Seek(0, SeekOrigin.End)
                        Dim writer As New StreamWriter(entryStream)
                        writer.WriteLine("Updated line.")
                    End Using
            End Using
        End Using
    End Sub

    Private Sub CreateArchive(sZipFilePath As String)
        Using stream As Stream = File.Open(sZipFilePath, FileMode.Create)
            Dim encryptionSettings As PasswordEncryptionSettings = encryptionSettings.CreatePkzipPasswordEncryptionSettings()
            encryptionSettings.Password = "MyPassword"
            Dim compressionSettings As CompressionSettings = Nothing
            Dim encoding As Encoding = Nothing

            Using archive As ZipArchive = ZipArchive.Create(stream, encoding, compressionSettings, encryptionSettings)

                Using entry As ZipArchiveEntry = archive.CreateEntry("text.txt")
                    Dim writer As StreamWriter = New StreamWriter(entry.Open())
                    writer.WriteLine("Hello world!")
                End Using
            End Using
        End Using
    End Sub

    Private Sub DecryptionSettings_PasswordRequired(ByVal sender As Object, ByVal e As PasswordRequiredEventArgs)
        e.Password = "MyPassword"
    End Sub