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Fail to remove signature

Dear guy
Recently, when I used Aspose. PDf component which version is 18.0 to remove the digital signature that signatured by Adobe. PPKLite standard, It raised following error, “You cannot change this document because it is certified” , and the attachment was the PDF document I tested .
Please help ,thx

1.pdf

bellow is the code by C#

string localPdfInFile = “c:\1.pdf”;
System.IO.MemoryStream mtmTmp = null;
try
{
mtm = new System.IO.MemoryStream(File.ReadAllBytes(localPdfInFile));
pfs = new Aspose.Pdf.Kit.PdfFileSignature();
pfs.BindPdf(mtm);
//first remove all digital signature

            if (pfs.IsContainSignature() && (names = pfs.GetSignNames()).Count > 0)
            {
                foreach (object name in names)
                {
                    pfs.RemoveSignature(name.ToString());
                }
                mtmTmp = new MemoryStream();
                pfs.Save(mtmTmp);
            }
            else
            {
                mtmTmp = mtm;
            }
        }
        catch (Exception ex)
        {
            
        }
        finally
        {
            pfs = null;
        }

@wengyeung

Thank you for contacting support.

Please note that the PDF document is secured with Password Security and Changes in the document are not allowed, as in the screenshot Secured.PNG. In case you are able to modify it with Adobe Acrobat then please share the steps so that we may proceed further to assist you.

Sorry for that ,It document i uploaded had set owner password , the password is “123456”

@wengyeung

Thank you for the information. Kindly share the steps and generated PDF file if you are able to achieve same requirements with Adobe Acrobat so that we may investigate further to help you out.

Dear guy ,bellow is the steps for our procedure .

  1. Convert word by Pdf995 into PDF with owner password “123456” and privilege of Printing.
  2. Upload the PDF to service at internet base on Web API for injecting the Digital Signature supported by Adobe official .
  3. We should reset the privilege allow user to copy content at PDF document and occurs the error .

@wengyeung

Thank you for the details about creation of shared PDF document.

Let us elaborate our request little more. Aspose.PDF mimics the behavior of Adobe Acrobat so please share if you are able to remove the signatures using Adobe Acrobat while mentioning those steps and generated PDF file so that we may proceed to help you out.