Signed Document - Validation Error

Hi Naresh,

Thanks for the sharing! As per the screenshot, there are two error/warning message that caught my attention:
"There have been subsequent changes to the document"

I think this is the main cause to the error, could you manually downloaded the PDF from sender UI, without any potential changes, and see if the error is consistent?

"Signer's identity is unknown because it has not been included in your list of trusted certificates and none of its parent certificates are trusted certificates"

Does this warning appear in all signed documents from this specific OneSpan Sign instance? Or this is starting on a specific date? Or only this specific package? You can try to following the knowledge based article created by our support team, which showcases you how to trust the certificate used to sign this PDF:

https://support.onespan.com/csm?sys_kb_id=99685a7bdb1e734044d9ef0848961927&id=kb_article_view&sysparm_rank=1&sysparm_tsqueryId=3ec0bff8dbce68103ea55c83f396195f

And please let me know if this makes any difference.

Duo

Hello,

Our company uses Nuance and I have viewed the file referred to that addresses Validating Signatures with Nuance but I don't have the same options available when I click on the Signature Properties and try to Verify Signature I am unable to "Verify Identity". 

Hi Danid,

As per this Q&A from nuance site, do you have any chance to right-click on the digital signature and choosing “Verify Signature” from the context menu? This option is supposed to allow the signature to be verified.

Duo

If I right click and hit "Verify Signature" it just returns the error: Signature Invalid: Signature Corrupted!  It's my own signature that I tested so it should not be corrupted in any way.

Hi Danid,

Just consulted with support team and seems we don't officially support Nuance Power PDF, however, I will still try my best to assist you. So if it's a testing package, could you supply below information to [email protected] so that I can have a closer look at your PDF?
#1. this corrupted PDF

#2. re-download another copy of signed PDF, but without opening with Nuance PDF

I think we first need to identify if it's caused by the sealed certificate or the Nuance PDF configuration.

Duo

Hi Danielle,

Thanks for your sharing! And below are some of my findings:

#1. if I opened both of your PDFs in Adobe Reader, it suggests that both signatures are valid, so I don't think the PDF or certificate itself has any corruption.

#2. I downloaded the Nuance Power PDF trial version. By default the certificate signed by OneSpan Sign wasn't trusted, but if I followed the above KB article, the signature turned valid

#3. Comparing to the screenshot you provided, the most notable difference is the additional information "Signed by:" is missing.(I guess that's the reason why "Show Certificate" and "Verify Identity" buttons are disabled)

Duo