A message digest, or hash, serves roughly the same purpose our journal entries do. We give a brief description of the notarial act (oath/acknowledgement), the kind of document (POA, deed, etc.), and the names of some or all of the signers. We put similar information at the bottom of a loose certificate (plus the number of pages). If there's a question about whether a person really signed a document, these descriptions would settle the matter in some cases, but not in others. It also protects the privacy of the signer, to a degree. It doesn't delve into the details of the document.
A message digest is created by doing a calculation on all the characters in a digital file. The result gives away no information about what was in the file, but if any changes are made to the file, the hash will change. It's basically a perfected version of the descriptions we put in journals and at the bottom of loose certificates, but it only works on digital files, not paper ones. |
