Digital Signature utility

[agibsonsw]

Hello. Office 2010.

I was just reading through this page about adding a Digital Signature to a document. Is this feature really any use? Does it provide any authenticity without requiring a (perhaps paid for) add-in?

[stuck]

Don't know anything about signing an Office doc, we never let Word docs out of the building but you might want to read here:
https://www.globalsign.co.uk/microsoft- ... t-signing/

All our stuff goes out as an Adobe Certified Document Services PDF. It costs money to get the signature in the first place but there is no cost to the end user. They do have to use Adobe Reader though to see that the signature is valid.

Ken

[agibsonsw]

Thank you @stuck. Yes, I was kinda assuming that the Digital Signature is of limited use without a third-party to maintain, and authenticate, the signatures.

Andy.

[HansV]

For serious use, you'd need to get a digital certificate from one of the official certificate authorities, such as VeriSign.

When you send a digitally signed document to others for the first time, the recipients will see a dialog when they open the document, asking whether they trust the signature. If they do, the signature will be stored on their computer, and next time you send a document, it will be trusted automatically - the signature proves that it really comes from you.

This isn't necessary for ordinary documents, of course, but it can be useful for confidential documents.

[agibsonsw]

Thank you @Hans.

I suppose one could insert a hidden paragraph containing an encrypted key/hash, and contact the recipient to advise them of the key to unlock :) - but this probably wouldn't be acceptable from a legal-standpoint.

Andy

[StuartR]

...
This isn't necessary for ordinary documents, of course, but it can be useful for confidential documents.

A digital signature does not help increase confidentiality. You need to use encryption for that.

A digital signature helps to ensure the integrity of a document. If the document has been altered in any way then the signature will no longer be valid. The signature also helps to ensure non-repudiation. After you have signed the document you can't deny that it was you that signed it.