How to prevent my signatures from being copied from a pdf file

[AMSOS]

Hi. I have been electronically signing pdfs as needed. I use the create/scan signatures option in the markup tools in Mac OS Preview.

This has been a convenient way to insert my signatures in a pdf quickly. I had noticed that these signatures seem to be "locked in" and made a part of the pdf. Today, I realised that my signatures can actually be copied simply with the Cmd+C keys!

This means the receiver of my signed file can simply copy my signatures from the pdf and paste them in another document. I tried this in MS Word now and it works easily.

Am I missing some security option here? Or, is Preview an inherently insecure software with which to sign documents? Or, maybe there is no lock-in of your signatures possible with pdfs in general.

Thanks!

 

[usagora]

Hi. I have been electronically signing pdfs as needed. I use the create/scan signatures option in the markup tools in Mac OS Preview.

This has been a convenient way to insert my signatures in a pdf quickly. I had noticed that these signatures seem to be "locked in" and made a part of the pdf. Today, I realised that my signatures can actually be copied simply with the Cmd+C keys!

This means the receiver of my signed file can simply copy my signatures from the pdf and paste them in another document. I tried this in MS Word now and it works easily.

Am I missing some security option here? Or, is Preview an inherently insecure software with which to sign documents? Or, maybe there is no lock-in of your signatures possible with pdfs in general.

Thanks!

I mean, even if it were "locked in", anyone could easily do a screen grab of it.

But try "exporting" the PDF as another PDF and see if that locks in any annotations like that. I don't have my Mac with me now to try it myself, but I think that may work. But again, it's not really going to make anything more secure.

 

[0128672]

Maybe test with the export Permissions options to limit copying text and graphics. I tested it by setting an owner password, saved the exported PDF, then tried to copy the signature, and no copy option was available.

Still as @usagora mentioned, one can take a screen shot.

 

[Toutou]

Am I missing some security option here? Or, is Preview an inherently insecure software with which to sign documents? Or, maybe there is no lock-in of your signatures possible with pdfs in general.

You're not missing a security option, you're merely mistaking an eye-candy feature for a security feature. Your signature (more precisely an image of your handwritten signature) can add a lot of class to your letter or a work document, but while it can be legally binding under some circumstances, it should not be used for anything even remotely serious.

There is a mechanism with a similar name: a digital signature, which has nothing to do with your handwritten signature. A digital signature is a cryptographic proof of authorship (and integrity) and the process of creating and securing your digital identity can be a bit involved.

So yes, the last sentence is quite accurate. The content of a PDF file isn't secured in any way and whoever is able to read it can also rip the image of your signature out of it and use it elsewhere.

 

[AMSOS]

I mean, even if it were "locked in", anyone could easily do a screen grab of it.

But try "exporting" the PDF as another PDF and see if that locks in any annotations like that. I don't have my Mac with me now to try it myself, but I think that may work. But again, it's not really going to make anything more secure.

Well, that's also true. I'll try that soon.
I guess for best security one should only go with digital signatures.

 

[AMSOS]

Maybe test with the export Permissions options to limit copying text and graphics. I tested it by setting an owner password, saved the exported PDF, then tried to copy the signature, and no copy option was available.

Still as @usagora mentioned, one can take a screen shot.

View attachment 1830931

Great, thanks. This helps too.
I think it's best to not sign your full name and use a shorthand. Even if it's copied, it might not be a big deal.