Forensic Notes allows you to validate the authenticity of notes and attachments by physical file or by providing a SHA-512 Hash. To determine the SHA-512 Hash of your physical file, we suggest you download the following tool. Although it looks a bit ‘dated’, it is one of the easier to use applications for this purpose.
HashMyFiles by NirSoft
http://www.nirsoft.net/utils/hash_my_files.html
Download links can be found near the bottom of the page.