If you are experiencing an issue with validating our E-signature and receiving a message stating that one or more signatures are invalid, please note that this message does not indicate that the signature is indeed invalid. It simply means that the certificate used to sign the document must be first trusted by the PDF software that is being used to verify the signature.

To resolve this issue, the PDF software must trust the certificate. The following steps may be used to do so. 

1. Click on the signature

2. Click on "Signature Properties"

3. Click on "Show Signer's Certificate"

4. Click on the "Trust" tab and select "Add to Trusted Certificates"

Please note that the foregoing method must be applied only to trusted certificates.  

Please note that while the above procedure might be applicable when using other PDF software, we only acknowledge validating signatures using Adobe Acrobat, as stated in our documentation: https://community.onespan.com/documentation/onespan-sign/guides/quick-start-guides/user/minimum-software-requirements#Minimum

Alternatively, the above may be achieved by updating the Automatic Adobe Approved Trust List (AATL).

1. Select the Adobe account icon and click on "Preferences"

2. Navigate to "Trust Manager" and select "Update Now"

OneSpan Sign is a part of the Adobe Approved Trust List, via our certificate issuer "Global Sign". Updating the list can resolve the "Invalid signature issue"

When clicking on "Show Signer's Certificate", the "Summary" tab will show the certificate issued by GlobalSign, as follows: 

"GlobalSign" is listed on the Adobe site, mentioned first as leading certificate authority with regards to trusted service providers: https://helpx.adobe.com/sign/kb/digital-certificate-providers.html