Sign multiple signatures in existing document - document has been altered

[Daniel Kraut]

Hi,

I created a document with 2 or more signature fields and then fill those fields with certificates with Syncfusion. Opening the signed document in Adobe Reader or using the new feature ValidateSignatures(..), only the last signed signature field is valid, and others produce error:

The document has been altered or corrupted since the signature was applied

Is it possible to sign document with multiple signatures without invalidating previous signatures? I tried to set the DocumentPermissions property on PdfSignature object to AllowComments or AllowFormFill and none of them solved my problem. I attached a simple project to this post to reproduce my problem.

Attachment: InvalidSignature_b8fd9898.zip

[Gowthamraj Kumar]

Hi Daniel, 

  

Thank you for using Syncfusion product. 

  

Yes. We can add multiple signature in PDF document without invalidating previous signatures. For this, we have use the licensed packages for creation to resolve this invalidate signature issue.  

Note: Please make ensure whether you have using licensed assemblies. If you are using trial version, it will invalidate the older signature because of adding watermark to PDF.   

  

Please let us know if you need any further assistance on this. 

  

Regards, 

Gowthamraj K 

[Joao Paulo Lima Braga]

Hi there,

I followed all the instructions here and in this reply, but no success. I am also getting the first signature invalidated after I apply the second signature. Any help on this problem? Thanks in advance.

Joao Paulo

[Sowmiya Loganathan]

Hi Joao,  

We have analyzed the reported issue (first signature invalidated after apply the second one) and suspect that the issue may occurs due to using of trial assemblies (because of adding watermark). So please use the licensed assemblies to add the multiple signature in PDF document. 

Please find the below sample which illustrate the same from below,  

Sample: https://www.syncfusion.com/downloads/support/forum/150660/ze/DigitalSignatureSample-67646444  

Output document: https://www.syncfusion.com/downloads/support/forum/150660/pd/Sample-143531831  

Output document screenshot:  

 

Please try the above sample in your end and let us know the result.  

Regards, 

Sowmiya Loganathan 

[Itay]

Hi,

I am not using trial assemblies (and no watermarks) yet get same result when signing 1 PDF with 2 signatures

Please check attached image and doc

Thanks

Attachment: 2Signatures_c6032196.zip

[Sowmiya Loganathan]

Hi Itay,   

We have created the sample to add multiple signature in the given PDF document (two signature in single PDF page) by adding two signature fields in it. Please find the download link for the same from below,   

Sample: https://www.syncfusion.com/downloads/support/forum/150660/ze/DigitalSignatureSample-1550448773   

Output document: https://www.syncfusion.com/downloads/support/forum/150660/pd/Sample-1257674360   

Please try the above sample in your end and let us know if you have any concerns on this.   

Regards,  

Sowmiya Loganathan