public void SaveDocument(
    Stream stream,
    DocumentFormat format,
    EncryptionSettings encryptionSettings
)

Public Sub SaveDocument(
    stream As Stream,
    format As DocumentFormat,
    encryptionSettings As EncryptionSettings
)

// Add a reference to the DevExpress.Docs.dll assembly.
using DevExpress.Spreadsheet;
using System.IO;
// ...

Workbook workbook = new Workbook();
// ...

// Specify encryption settings.
EncryptionSettings encryptionSettings = new EncryptionSettings();
encryptionSettings.Type = DevExpress.Spreadsheet.EncryptionType.Strong;
encryptionSettings.Password = "password";

// Save the document.
using (FileStream stream = new FileStream("Document.xlsx",
    FileMode.Create, FileAccess.ReadWrite))
{
    workbook.SaveDocument(stream, DocumentFormat.Xlsx, encryptionSettings);
}

' Add a reference to the DevExpress.Docs.dll assembly.
Imports DevExpress.Spreadsheet
Imports System.IO
' ...

Dim workbook As New Workbook()
' ...

' Specify encryption settings.
Dim encryptionSettings As New EncryptionSettings()
encryptionSettings.Type = DevExpress.Spreadsheet.EncryptionType.Strong
encryptionSettings.Password = "password"

' Save the document.
Using stream As New FileStream("Document.xlsx", FileMode.Create, FileAccess.ReadWrite)
    workbook.SaveDocument(stream, DocumentFormat.Xlsx, encryptionSettings)
End Using

SpreadsheetDocumentFormat documentFormat = new SpreadsheetDocumentFormat((int)format);
    workbook.SaveDocument(resultStream, documentFormat, encryptionSettings);
}

else
        workbook.SaveDocument(resultStream, documentFormat, encryptionSettings);
}