What is a Digital Signature and How to Apply One to an Adobe PDF

Posted by Steve Gottwals, Technical Director of Security Solutions, Adobe Systems Federal

When people think of “ digital signatures,” most picture the electronic signing of a contract or document online. It’s fast, convenient and eliminates the pain of 1) physically signing and hand-carrying a large stack of pages 2) losing a part of an important document and 3) needing all parties in one room to sign something.

An example electronic signature is show below.


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But digital signatures are different, and acts as a type of “electronic signature” or “ e-signature.”

You can say “digital signatures” is a bit of a misnomer. It should almost be called the “cryptographic integrity checker” and “authenticity trust mechanism” instead, because it’s really that much cooler.

Here’s an example of what a digital signature can look like, as represented by Adobe Acrobat and Reader:


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While a digital signature can certainly be used as an electronic signature for approval purposes, it can also be used in other interesting ways.

The Unseen Benefits of Digital Signatures

For years, digital signatures have been known to help transform company processes and customer experiences.

Digital signatures automatically:


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Digital signatures help authenticate and maintain the integrity of your file automatically.

Sometimes we need to know that a specific document hasn’t been altered. We also want to know “who” created the document, and if we trust that person or organization. Standard examples: a business partnership contract that’s frequently emailed back and forth, or when reviewing a college transcript of a potential hire.

My personal favorite example: when sending someone a recipe for fugu. Fugu is a lethally venomous, Japanese pufferfish. People actually eat this fish, so it’s important to get all the prep and cooking details 100 percent precise (and make sure no one accidentally—or intentionally—changes the content). We also want to know who is giving the instructions. Is it a world renowned chef? Or, some anonymous, potentially sadistic prankster?

OK, this is a bit contrived, but you get the point. Some documents, you just need to know for certain who it’s from, and that no one messes with it. In the case of fugu—it’s life or death.

How to Apply a Digital Signature to Your PDF

Here’s how digital signatures work:

In order to create a digital signature, a digital ID must be created or obtained from a third party. A digital ID is like an electronic driver’s license or passport that proves your identity. You can have multiple digital IDs—for instance, one for your business and another for home.

Your digital ID lets you create your own digital signature. In Adobe Acrobat, go to the Tools panel and click on Certificates. Click Digitally Sign on the top header. If a field is available, you can click on it, or you can drag out your own signature.


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Watch a 2-minute video tutorial below. We show you:

Read Next: See what happens behind the scenes with our Digital Signatures technical overview and infographic.