Signing a PDF

Michael DyerSenior Enterprise Support Engineer
Edited by: Andrew Leniart
This article discusses some different options for signing a PDF.
A common question from many users is, how do I sign a PDF?  Well, this is actually a complex question. There are multiple ways to sign a PDF so you need to clarify what the user is really looking for. Are they looking to do a handwritten signature, as in placing their signature on a document as if they printed it out, signed it, and scanned it back? Or, are they looking to do a digital signature?  

A digital signature is a type of e-signature that provides the assurance of a signer’s identity and also identifies if the document has been altered since it was signed. Digital signatures can also be generated using a cloud-based document signing system such as Nitro Sign or  DocuSign.

If the user is looking to add a written signature to a PDF, there are a couple of ways they can do this. In your PDF editing programs such as Adobe Acrobat or Nitro Pro, you can create a stamp of your signature. The simplest way to do this is to sign your name on a piece of paper, then scan that piece of paper into your document as a JPEG and crop the image so that it only includes the signature; then import that as a stamp into your PDF editor.

You can also create a signature in the PDF editing program. For example, in Adobe Acrobat you would select “place signature” and then you have three options to create a signature. You can type text and select a script font to create a pseudo-signature. You can draw a signature with your mouse and save that, or you can import an image just like you would with a stamp and save that as a signature. This is the simplest way to put your name on a form as if you had signed by hand.

A digital signature, on the other hand, is in e-signature that is used to authenticate the signer of a document and also to verify if the document has been altered since it was signed. This is a more secure form of signing a document.

To digitally sign a PDF, you first have to have a digital ID configured on your workstation. Digital IDs can be locally generated and stored in the Windows Certificate Store, or they can be created from a PKCS#12 digital ID file. If you create the digital ID from a file, it is more flexible because you can use the same ID on multiple computers. For example, if you had an office workstation and a notebook with the same certificate installed, you could open the same secured PDF file on both computers. Digital IDs created in the Windows Certificate Store are locked to that specific workstation.

Once you have a digital ID configured on your workstation you can then sign the PDF. In Adobe Acrobat you would select “sign with certificate” and you will then be prompted to draw a rectangle where you wish to place the signature and to select a digital ID. You will then be prompted to fill out additional details to go with the signature and when you click finish, a digital signature is applied to the document. If the document is altered in any way after the digital signature is applied, the signature will be flagged as invalid and a note will come up that the document had been altered since the signature was applied.

You can also use a cloud-based document signature application such as Nitro Sign or  DocuSign. This type of application allows you to send a document to an individual for signing and they can then send the signed document back to you through the app. This is a very secure way of sending documents and having them signed and returned.

So, in conclusion, when a user asks you how to sign a PDF, your first question should be, “Tell me more about what you want to do?”  There are many signing options in PDFs and you need to make sure you’re addressing the correct question.

Michael DyerSenior Enterprise Support Engineer

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