Fraud concern with human signed signature on PDF

Report · Jul 26, 2019

When a customer signs on tablet computer that is then printed as a PDF, will the signature automatically convert to an image (jpeg, PNG, BMP) or will it just render like the text? If I right-click a signature on a PDF and get the blue box and a "Save as" with image extension , does this mean someone added the image of the signature? I ask this because I signed on a tablet and see that the other party duplicated my signature somehow and put it into another part of the document that I did not see on the tablet or agree to. I realize this is probably fraud but I need to know if it proves my sig was added because I can right-click it and it gets the blue box and the Save As shows it is an image that can be saved on its own separate from document.

Report · Jul 27, 2019

Human signed signatures ("scribbles"/"wet signatures") on a PDF have no legal value and can be faked in moments. If it's in one PDF it can be put in another like any other computer file. You cannot tell how a signature got into a file, and whether it was an original or a copy, they are the same thing.

This is why "digital signatures" were invented. Not a thing on screen at all, but based on certificates. If done carefully and properly, this has legal value and cannot be faked.

Report · Jul 27, 2019

First, I thank you so much for taking your time to respond. I did and do agree with everything you said. However, I am the customer not the Seller so I have no choice as to how they gather signatures or whether they use live signatures or digital signatures so your advice would help them but unfortunately does not help me.

of course any signature on a PDF or photocopy can be duplicated and placed elsewhere. However, my state law recognizes live signatures signed electronic devices such as UPS uses. I have hundreds of dollars on the line in the current situation that I need to get back and my attorney says that to prove fraud and what equates to forgery in this state, I need to be able to present the answer to the questions I asked here.

To recap the most important question, if what is signed on an electronic device is then printed to a PDF, would clicking on the signature produce a “Save As” filename.bmp? If this was not added as an image, wouldn’t the signature NOT be clickable to “Save As” an Element separate from the document?

i am open to one or more answers from anyone who can offer me a correct technical answer.

thanks so very much!

Report · Jul 27, 2019

We can't give a definite answer because it depends on how the application you used works and what exact tool you've used to sign it.

I would say it's probably not an image per se, but an annotation. However, that can also be very easily "lifted" and copied to other documents or other places in the same file.

Again, any way you "sign" on a digital device that isn't backed by a certificate with a public and a private key is basically meaningless and can be easily faked, with no real way of proving it, since it's an exact duplicate.

If the burden of proof is on you to prove that you haven't signed it, you can't really do it, because you've given them an exemplar of your signature in a non-secure way. If it's on them, unless they have video of you doing it, and they have access to a "wet" signature of yours, they can't prove they didn't do it.

Report · Jul 27, 2019

A simple answer: sometimes you will get a Save As prompt for a picture (e.g. a signature in a PDF). This may be the original (first generation copy) or a duplicate. They will be the same thing in every way, so there is no way to tell. Printing to PDF may change things or it may not; again, you can't tell. That is the essence of digital files. The file and everything in them can be duplicated and copied exactly, with no change or deterioration. This is a correct technical answer, though I realise it is not one you are looking for. You are free to keep asking in the hope of a different one.

A professional (paid) digital forensic specialist might find something. We are not here to offer legal advice, including technical advice that is used to support legal advice. Adobe do not allow it, that's not what the forums are for. Also, you should realise that in a court of law the free advice of an anonymous person on a forum is worth less than zero.

Report · Jul 27, 2019

Not to worry. Looking for tech answer (might help others too) not legal advice. I have my lawyer for that. But neither he nor I are technical.Experts. So I am doing technical research not legal research.

When a photo is added to a web page, for instance, you can right-click it and save it separate from the text and html. Same with my signatures on the PDF which led me to pursue this question.

I hand scribbled on a PDF I created and printed then created a new PDF and the scribble does not give me a save as when I right click. I also pulled up a tax return that is a PDF and right-clicked mu CPA’s signature and it also Is not clickable and does not give me a Save As or image extension (.bmp, .jpg, etc.).

So, my question is technical not legal however I may use my newfound knowledge.

Again, I do appreciate the generosity here of those taking the time to help enlighten me!

Report · Jul 27, 2019

A PDF is just a container for many different kinds of graphics. A signature might be done as a series of shapes or lines, or an image. Or many images. Or something else. You cannot generalise, because there is nothing special about signatures on the page, so you are really asking about the many different ways graphics might be in a PDF.

Report · Jul 27, 2019

Well, sort of. I am not asking how different sorts of graphics can be embedded or created on a PDF. I am asking how to identify if a signature image was added since an original signature is not an image.

Report · Mar 31, 2025

@tommip32246962 did you eventually get the answer you were looking for (somewhere else)? I'm looking into the same thing; checking if there are ways to see if a signature in a pdf-doc has been put there as an image. The specific signature I'm looking into can be moved and Adobe even tells me it's an image. Can this only be true for images placed in a file, or can a wet/real signature also be rendered into an image (accidently) when scanning the original doc? Hope you or someone else can help me out.

Report · Mar 31, 2025

Any type of image in a PDF file can be easily copied. Use a digital signature field for something that can't be. You can have it display your "wet" signature as its appearance, but the important bit is the validation process of that field, which can only happen using the public key you can share with others.

Report · Jul 27, 2019

Extracting images from a PDF file is not as straightforward as it is from a

web-page, but it is possible nonetheless and the result is an identical

digital copy of the original image.

On Sat, Jul 27, 2019, 12:55 Test Screen Name <forums_noreply@adobe.com>

Report · Jul 27, 2019

In many cases a signature is an image by the time it gets into a PDF. It may be drawn with a pen or pointer but that doesn't mean it stays as shapes. Or that it doesn't.