Signing Documents with Adobe Acrobat Reader

Signing Documents with Adobe Acrobat Reader

It is possible to use Adobe Acrobat Reader to “sign” documents.  There are actually several levels of both security and complexity, so depending on what you want to do you can either choose the easiest, or the most secure (well, at least more secure).   Here are the options:

  1. Add an image of your handwritten signature (easiest).
  2. Add a digital signature using a self-signed certificate (more secure)
  3. Add a digital signature using a certificate signed by a Certificate Authority (even more secure)

Option 1 is the easiest, and it’s basically a replacement for the steps of  a) printing something out, b) signing it with a pen, and then c) scanning it to send to someone else.   The idea is that you load a photo of your personal signature into Acrobat Reader (or you create a signature with the mouse — but who can do that?) and then Acrobat Reader can overlay this signature onto your document.   But this option is not the most secure, because after all, if you can add an image of a signature, so can someone else.

Option 2 adds a digital signature to the document, which is more secure.  To set this up you create a “certificate” file, which is encoded by a password.   (Adobe Reader helps you do this.)  Whenever you want to sign a document you will simply type that secret password to add the signature.  This is more secure than option 1, with not much extra work to set up at the beginning, so this is probably what you want to do.  It’s still possible for someone to spoof a signature by just creating a digital signature with your name on it, but it won’t match the digital signature you usually use, so it will be possible to spot a forgery if someone checks it carefully.  It can also show a warning if the document has been altered after you have signed it.

Option 3 adds extra authentication.  Instead of creating a “self-signed” certificate (that’s what is done in Option 2) the certificate you use to sign is itself signed by a higher-level certificate, from what’s called a Certificate Authority (CA).   This is how certificates work for secure web pages (that use https) to avoid spoofing.  This option is not currently available at SUNY New Paltz, and for everyday work documents that’s (probably) okay.

So there are really two options, and in Adobe Acrobat you choose them with two different tools:

  1. To sign digitally with a certificate, select the Tools menu and then “Certificates“.
  2. To sign with an image, select the Tools menu and then “Fill & Sign“.

Either way, there is some initial set-up you have to go through the first time you sign document, but after that the process is fairly easy either way whenever you need to sign a document.

Signing with a Certificate

Your certificate is your public key, signed by your private key (or by a Certificate Authority – but that option is currently not available).   Adobe Acrobat will do all the heavy lifting to create your certificate (and private key) – all you have to do is answer some simple questions.

  1. When you want to sign a document using a digital certificate, pull down the Tools menu from the top of the window and select “Certificates,” then click on the “Digitally Sign”  option at the top of the window.
  2. Use your mouse to drag out a rectangle where you wish to place the signature.
  3. If you have not yet created a signing certificate (a “Digital ID”) then you will need to do that (once), as follows:
    1. Select  “Configure Digital ID”
    2. Select the option to “Create a new Digital ID”
    3. Select the option to “Save to Windows Certificate Store”  to make your certificate public1
    4. Enter your Name, organization information, and e-mail address.
  4. Once you have created a certificate (a “Digital ID”) then simply select that file (it’s probably already selected) and press “Continue”.
  5. Click on “Lock document after signing” if you want that option, and then enter your password to unlock your signing certificate.

If you work from both home or office the easiest thing to do is to create two different signing certificates (Digital ID’s), but you can also export a certificate from your work computer and take it home and import it on your home computer, so that you only sign with one Digital ID.

Adding a Signature Image

A digital signature is more secure, but if you really just have  to add an image of your hand-written signature then here is how to do it:

  1. Write your signature on a blank piece of paper, take a picture of it, and move a copy of that picture to your computer as a JPEG image.  You’ll just have to add this image to Acrobat Reader the first time you sign something, and after that it will remember your signature.
  2. Open a PDF document you wish to sign, and pull down the Tools menu to “Fill and Sign”
  3. When asked what you want to do, select “Fill and Sign”
  4. Click on the “Sign” tool along the top toolbar  (the default seems to be the “Add Text” tool, and you don’t want that).
  5. If you don’t yet have a signature image loaded, select “Add Signature”, and then..
    1. at the top of the window that pops up, select “Image”
    2. Use the file chooser to select the image containing your handwritten signature
    3. Press “Apply”
  6. Once you have a signature image loaded, click on it to select it.
  7. Drag the image of your signature into position, and use the dot at the corner to resize it.
  8. Click anywhere away from the signature image to leave it in place.  Click back on the signature image to modify the position or size.  Once you save the document you will no longer be able to adjust the size or position of the signature.

Using Both!

It’s possible (though somewhat complicated) to create a digital signature which includes an image of your handwritten signature.   How cool is that?   If you are willing to go through a few hoops, here is how to do it.

The way this works is that your digital signature has the option to include an image, which is referred to by Acrobat Reader as a “logo”.   And since it is Adobe, your “logo” has to be a PDF file; it can’t be a JPEG or PNG image.   So you will need an image of your handwritten signature stored as a PDF file, however you manage to do that.    And you probably want to put this file in the folder:

C:\Users\<username>\AppData\Roaming\Adobe\Acrobat\DC\Security

where “<username>” is your own username on the computer.  This is where Adobe Acrobat stores PKI2 so putting files here will make

With this image in place, and after you have already created your digital signing certificate, follow the directions above to Sign With a Certificate.   When you get to the step where you would press “Sign,”  (and maybe enter a password), first press the “create” and select ….

(to be competed soon)

 



Notes and References

  1. This makes your certificate public, so that others can verify your digital signature, but it does not publish your private key.  The “Certificate Store” is “storage” for certificates, not a palace to buy them.
  2. Public Key Infrastructure, the technology that underlies digital signatures and public key encryption.
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