5 Replies Latest reply on Mar 30, 2015 12:38 PM by Avalon80

    Can't clear signature box (Acrobat X Pro)




      I have read some into this and have tried some different fixes with no luck. I had to re-image a person's PC who uses PKI certs. on a CAC to sign PDFs. Acrobat X Pro was re-installed and updated. The digital ID on the CAC is the same before the re-image and it validates. I went to ECA.ORC.com to update the HW4/5/signing certs. and had them jacked into Outlook (just in case it calls on that for some reason). The edit function under tools is grayed out and there is no "security" on the PDF. The customer claims he could right click the signature box and the option to clear would be there; it is not there now. What am I missing here? Thanks.

        • 1. Re: Can't clear signature box (Acrobat X Pro)
          Steven.Madwin Adobe Employee

          Hi Mike,


          In the grand scheme of things; in order to clear a signature you need to be the person that created the signature. What this really means is Acrobat has to have access to the private key of the digital ID that was used to create the signature (Acrobat doesn't really know if you're the person that signed the file as it is not yet sentience, maybe we'll get that into the next version ). So the real question is, is the digital ID that was used to created the digital signature on the CAC that has been loaded in the Windows Certificate Store?. If the signer (the person whose machine you rebuilt) has procured a new CAC with updated digital IDs, and that's the CAC you plugged in, then they need to dig out the CAC with the certificate (digital ID) they used to sign with and plug that into the card reader. Even if the certs are expired Acrobat will make the match and allow them to clear the signature.


          I hope this helps,


          • 2. Re: Can't clear signature box (Acrobat X Pro)
            Avalon80 Level 1



            Thanks for the reply. The CAC with the digital ID is the same. Nothing has changed or has been updated. The customer has been researching this issue also and said he found some sort of registry modification that may solve the issue. I will investigate to see.

            • 3. Re: Can't clear signature box (Acrobat X Pro)
              Avalon80 Level 1

              Below is what my customer saw but its for v.11 and he has 10 Pro. The Key mentioned is not even there in 10.


              Digital Signatures



              Data type  boolean: DWORD value > REG_DWORD 
              Version #11.0+
              HKLM PathHKLM\SOFTWARE\Policies\Adobe\(product name)\(version)\FeatureLockdown\cSecurity\cDigSig
              SummarySpecifies whether to disable and lock the ability for a signer to clear their own signature.
              DetailsPossible values include: 
              • 0: Disable signature clearing.
              • 1: Enable signature clearing.
              GUI mappingThe Clear Signature menu item which appears when a user right clicks on a signature.
              • 4. Re: Can't clear signature box (Acrobat X Pro)
                Steven.Madwin Adobe Employee

                Hi Mike,


                The reason your customer is not seeing that particular registry entry is because it would be set by an enterprise's customized installer. Adobe has a tool that allows an enterprise that needs to deploy Acrobat across a lot of seats to customize the installation, and one of those possible customization is to set feature lock-down parameters that a normal user (i.e. someone without admin rights) could not modify.


                That said, if your customer truly has the access to the private key used to create the signature that they would like to clear, then the next thing to look at is if the document has been locked at signing. If you are signing the last remaining signature field you have the option of locking the document. When your customer signed, if they were not the final signer it is possible that whomever added the final signature that the selected the Lock Document After Signing option on the Sign Document dialog, thus preventing your client from clearing their signature. Have them right mouse click on the signature they want to clear and then choose Show Signature Properties from the pop-up menu.


                On the Signature Properties look for the string I've circled in the screen shot below.

                Cert Prop.jpg



                • 5. Re: Can't clear signature box (Acrobat X Pro)
                  Avalon80 Level 1



                  It looks like the customer found a workaround in this thread; How do I delete all existing digital signatures in Adobe Acrobat? You, Steven, are in this too. My customer is OK with this method but it is different than the way it was. New PDF's are not an issue.