LibreOffice Password Protected DOCX and XLSX Files

LibreOffice offers robust, built-in compatibility for opening, editing, and saving password-protected Microsoft Office documents, including Word (.docx) and Excel (.xlsx) formats. This article explains how LibreOffice decrypts standard Office Open XML files, handles various document security levels, preserves encryption when saving, and addresses the limitations surrounding enterprise rights management.

Document Encryption and “Password to Open”

Modern Microsoft Office files (.docx and .xlsx) use standard AES (Advanced Encryption Standard) encryption, typically AES-128 or AES-256, to protect document contents.

When you open an encrypted .docx or .xlsx file in LibreOffice: 1. LibreOffice detects the encryption wrapper. 2. A password dialog automatically appears before the document loads. 3. Once the correct password is entered, LibreOffice uses standard cryptographic libraries to decrypt and display the document in LibreOffice Writer or Calc.

The user experience is seamless and virtually identical to opening the file inside Microsoft Office.

Handling “Password to Modify” and Read-Only Restrictions

Microsoft Office allows users to set a secondary password to restrict editing while still allowing read-only access without a password.

• Read-Only Mode: LibreOffice respects the read-only flag. When a document with modify restrictions is opened, it loads in read-only mode by default.
• Editing Permissions: If you click the “Edit Document” button in LibreOffice, it may ask for the modification password. Depending on the format specification used, LibreOffice allows users to edit a local copy or bypass non-cryptographic sheet/document protection mechanisms that do not use full-file encryption.

Saving Changes to Protected Files

When modifying a password-protected Microsoft Office file in LibreOffice, you can maintain or update the protection:

1. Go to File > Save As.
2. Ensure the format is set to Word 2010–365 (.docx) or Excel 2010–365 (.xlsx).
3. Check the Save with password box.
4. Click Save to open the password configuration dialog.
5. Enter a new password or re-enter the existing password.

LibreOffice will re-encrypt the file using standard Microsoft-compatible encryption, ensuring the document remains fully accessible to users on Microsoft 365, Office for Mac, or Windows.

Limitations: Information Rights Management (IRM)

While LibreOffice fully supports standard password encryption, it cannot open documents protected by Microsoft Information Rights Management (IRM), Azure Information Protection (AIP), or Microsoft Purview. These systems rely on proprietary enterprise identity servers and cloud-based authentication rather than standard password-based AES encryption.