OneNote and notebook security/integrity

[SICPADBA]

Is there any way to lock previous entries in OneNote to prevent editing or deleting? We are looking to use OneNote as an electronic lab notebook system (ELN) which has some strict requirements on preserving the integrity of its contents. 



One idea is to use a digital signature that would lock a section that is signed off. But I cannot find any information about digital signature support in OneNote. I find references that they are supported in Office2007 but not OneNote specifically. 



Another idea is to version and publish the notes to a SharePoint site or directly to a website. This would probably suffice, but explode the storage requirements. 



Any ideas?