Working with Security

13 Sep 202411 minutes to read

You can encrypt a Word document with password to restrict unauthorized access. You can also control the types of changes you make to this document.

To quickly encrypt and decrypt a Word document with the .NET Word (DOCIO) Library, please check out this video:

Encrypting with password

The following code example shows how to encrypt the Word document with password.

NOTE

Refer to the appropriate tabs in the code snippets section: C# [Cross-platform] for ASP.NET Core, Blazor, Xamarin, UWP, .NET MAUI, and WinUI; C# [Windows-specific] for WinForms and WPF; VB.NET [Windows-specific] for VB.NET applications.

//Opens an existing document from stream through constructor of WordDocument class
FileStream fileStreamPath = new FileStream("Template.docx", FileMode.Open, FileAccess.Read, FileShare.ReadWrite);
WordDocument document = new WordDocument(fileStreamPath, FormatType.Automatic);
//Encrypts the Word document with a password
document.EncryptDocument("password");
//Saves the Word document to MemoryStream
MemoryStream stream = new MemoryStream();
document.Save(stream, FormatType.Docx);
//Closes the document
document.Close();
//Opens an input Word document
WordDocument document = new WordDocument("Template.docx");
//Encrypts the Word document with a password
document.EncryptDocument("password");
//Saves and closes the Word document instance
document.Save("Sample.docx", FormatType.Docx);
document.Close();
'Opens an input Word document
Dim document As New WordDocument("Template.docx")
'Encrypts the Word document with a password
document.EncryptDocument("password")
‘Saves and closes the Word document instance
document.Save("Sample.docx", FormatType.Docx)
document.Close()

You can download a complete working sample from GitHub.

Opening the encrypted Word document

The following code example shows how to open the encrypted Word document.

//Opens an existing document from stream through constructor of WordDocument class
FileStream fileStreamPath = new FileStream("Template.docx", FileMode.Open, FileAccess.Read, FileShare.ReadWrite);
//Opens an encrypted Word document
WordDocument document = new WordDocument(fileStreamPath, "password");
//Saves the Word document to MemoryStream
MemoryStream stream = new MemoryStream();
document.Save(stream, FormatType.Docx);
//Closes the document
document.Close();
//Opens an encrypted Word document
WordDocument document = new WordDocument ("Template.docx", "password");
//Saves and closes the Word document instance
document.Save("Sample.docx", FormatType.Docx);
document.Close();
'Opens an encrypted Word document
Dim document As New WordDocument("Template.docx", "password")
‘Saves and closes the Word document instance
document.Save("Sample.docx", FormatType.Docx)
document.Close()
//"App" is the class of Portable project.
Assembly assembly = typeof(App).GetTypeInfo().Assembly;
using (WordDocument document = new WordDocument())
{
    //Loads or opens an existing Word document from stream
    Stream inputStream = assembly.GetManifestResourceStream("CreateWordSample.Assets.Test.doc");
    //Loads or opens an existing Word document through Open method of WordDocument class
    document.Open(inputStream, FormatType.Automatic, "password");
    MemoryStream stream = new MemoryStream();
    //Saves the Word file to MemoryStream
    await document.SaveAsync(stream, FormatType.Doc);
    //Saves the stream as Word file in local machine
    Save(stream, "Result.doc");
    document.Close();
}
//Saves the Word document
async void Save(MemoryStream streams, string filename)
{
    streams.Position = 0;
    StorageFile stFile;
    if (!(Windows.Foundation.Metadata.ApiInformation.IsTypePresent("Windows.Phone.UI.Input.HardwareButtons")))
    {
        FileSavePicker savePicker = new FileSavePicker();
        savePicker.DefaultFileExtension = ".doc";
        savePicker.SuggestedFileName = filename;
        savePicker.FileTypeChoices.Add("Word Documents", new List<string>() {".doc"});
        stFile = await savePicker.PickSaveFileAsync();
    }
    else
    {
        StorageFolder local = Windows.Storage.ApplicationData.Current.LocalFolder;
        stFile = await local.CreateFileAsync(filename, CreationCollisionOption.ReplaceExisting);
    }
    if (stFile != null)
    {
    using (IRandomAccessStream zipStream = await stFile.OpenAsync(FileAccessMode.ReadWrite))
    {
        //Write compressed data from memory to file
        using (Stream outstream = zipStream.AsStreamForWrite())
        {
            byte[] buffer = streams.ToArray();
            outstream.Write(buffer, 0, buffer.Length);
            outstream.Flush();
        }
    }
}
//Launch the saved Word file
await Windows.System.Launcher.LaunchFileAsync(stFile);
}

You can download a complete working sample from GitHub.

Remove encryption

You can open the encrypted Word document and remove the encryption from the document. The following code example shows how to remove the encryption from encrypted Word document.

//Opens an existing document from stream through constructor of WordDocument class
FileStream fileStreamPath = new FileStream("Template.docx", FileMode.Open, FileAccess.Read, FileShare.ReadWrite);
//Opens an encrypted Word document
WordDocument document = new WordDocument(fileStreamPath, "password");
//Removes encryption in Word document
document.RemoveEncryption();
//Saves the Word document to MemoryStream
MemoryStream stream = new MemoryStream();
document.Save(stream, FormatType.Docx);
//Closes the document
document.Close();
//Opens an encrypted Word document
WordDocument document = new WordDocument("Template.docx", "password");
//Removes encryption in Word document
document.RemoveEncryption();
//Saves and closes the Word document instance
document.Save("Sample.docx", FormatType.Docx);
document.Close();
'Opens an encrypted Word document
Dim document As New WordDocument("Template.docx", "password")
'Removes encryption in Word document
document.RemoveEncryption()
‘Saves and closes the Word document instance
document.Save("Sample.docx", FormatType.Docx)
document.Close()
//"App" is the class of Portable project
Assembly assembly = typeof(App).GetTypeInfo().Assembly;
//Create new Word document instance
using (WordDocument document = new WordDocument())
{
    //Loads or opens an existing Word document from stream
    Stream inputStream = assembly.GetManifestResourceStream("Sample.Assets.Template.docx");
    //Loads or opens an existing Word document using the Open method of WordDocument class
    document.Open(inputStream, FormatType.Docx, "password");
    //Removes encryption in Word document
    document.RemoveEncryption();
    MemoryStream stream = new MemoryStream();
    //Saves the Word file to MemoryStream
    document.Save(stream, FormatType.Docx);
    //Closes the Word document instance
    document.Close();
    //Saves the stream as Word file in local machine
    Save(stream, "Sample.Docx");
}
//Refer to the following link to save Word document in UWP platform
//https://help.syncfusion.com/document-processing/word/word-library/net/create-word-document-in-uwp#save-word-document-in-uwp

You can download a complete working sample from GitHub.

Protecting Word document from editing

You can restrict a Word document from editing either by providing a password or without password.

The following are the types of protection:

  1. AllowOnlyComments: You can add/modify only the comments in the Word document.

  2. AllowOnlyFormFields: You can modify the form field values in the Word document.

  3. AllowOnlyRevisions: Allow only revisions to be made to existing content. After enabling this flag, accept and reject changes options in Microsoft Word application are disabled.

  4. AllowOnlyReading: You can only view the content in the Word document.

  5. NoProtection: You can access/edit the Word document contents as normally.

The following code example shows how to restrict editing to modify only form fields in a Word document.

FileStream fileStreamPath = new FileStream("Template.docx", FileMode.Open, FileAccess.Read, FileShare.ReadWrite);
//Opens an existing document from file system through constructor of WordDocument class
using (WordDocument document = new WordDocument(fileStreamPath, FormatType.Docx))
{
    //Sets the protection with password and it allows only to modify the form fields type
    document.Protect(ProtectionType.AllowOnlyFormFields, "password"); 
    MemoryStream stream = new MemoryStream();
    document.Save(stream, FormatType.docx);
    //Closes the Word document
    document.Close();
}
//Opens a Word document
WordDocument document = new WordDocument(@"Template.docx");
//Sets the protection with password and it allows only to modify the form fields type
document.Protect(ProtectionType.AllowOnlyFormFields, "password"); 
//Saves the Word document
document.Save("Protection.docx", FormatType.Docx);
document.Close();
'Opens a Word document
Dim document As New WordDocument("Template.docx")
'Sets the protection with password and it allows only to modify the form fields type
document.Protect(ProtectionType.AllowOnlyFormFields, "password")
'Saves the Word document
document.Save("Protection.docx", FormatType.Docx)
document.Close()

You can download a complete working sample from GitHub.

Online Demo

  • Explore how to encrypt and decrypt the Word document using the .NET Word Library (DocIO) in a live demo here.
  • See how to protect the Word document from editing using the .NET Word Library (DocIO) in a live demo here.