Unable to verify Signatures placed on PDFs with the Signature Appliance Client v8.0 or later

Product:
DocuSign Signature Appliance (“CoSign”)

Description:
When a Digital Signature is placed on a PDF document using the Signature Appliance Client v8.0 or later, the signature cannot be verified in older applications such as OmniSign (v7.x or older).
Note: OmniSign was renamed in the Signature Appliance client v8.0 to “Prepare and Sign”.

Symptoms seen in OmniSign;
When you attempt to validate a signature in OmniSign (CoSign client v7.5 and below) that was signed using Prepare and Sign (Signature Appliance v8.0 and above) you may see the following issue;

User-added image
Note: The error message itself will vary depending on the application doing the signature verification however, a failure to verify the signature is the key symptom.

Reason:
When placing Digital Signatures using the Signature Appliance Client v8.0 or later, PDFs are signed with a different signing algorithm (i.e. ETSI.CAdES.detached instead of adbe.pkcs7.detached). Unfortunately, some older applications cannot successfully verify these signatures.

Resolution:
  • For client v8.0 -> v8.2, there is no fix for this issue except to re-sign the document with an older version of the client, or to verify the signature in a newer version of the application; 
  • The ability to choose the signing algorithm will be added to the Signature Appliance client v8.4. This means you will be able to control which signing algorithm you sign with.
Additional information: Thank you,
The Signature Appliance team at DocuSign Support


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