Password protection of editing

Can I protect the file with a password, so I can open that readonly without password?
Thanks

You can do that with a section protected against modifications.

For an existing file: ctrl+A (select all) → insert → section etc.

Oh yes, it works! Unfortunatelly, not in Impress, but sufficient.

Menu/File/Propierties/Security

Here you can only lock the revision marking

With LibreOffice version 3.5.7.2 and 3.6.3.2
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Try it, it protects only the record changes