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(Go) PDF Sign Under Existing SignatureSee more PDF Signatures ExamplesThis example explains how sign a previously-signed PDF and place the signature appearance below the existing signature. Note: This example requires Chilkat v9.5.0.85 or greater.
// This example requires the Chilkat API to have been previously unlocked. // See Global Unlock Sample for sample code. pdf := chilkat.NewPdf() // Load a PDF to be signed. success := pdf.LoadFile("qa_data/pdf/sign_testing_4/hello_signed.pdf") if success == false { fmt.Println(pdf.LastErrorText()) pdf.DisposePdf() return } // The PDF we'll be signing already has a signature added in Adobe Acrobat DC. // It looks like this: // (Notice the Adobe background logo, which is commonly what you'll see when a signature // is created by Adobe Acrobat. Chilkat (obviously) does not create signatures using the Adobe // logo because it would be a copyright violation.) // Options for signing are specified in JSON. json := chilkat.NewJsonObject() // In most cases, the signingCertificateV2 and signingTime attributes are required. json.UpdateInt("signingCertificateV2",1) json.UpdateInt("signingTime",1) // To put our new signature underneath the existing signature, we have to specify the page // where the existing signature is found, and then we can specify "under" for the "appearance.y" json.UpdateInt("page",1) json.UpdateString("appearance.y","under") json.UpdateString("appearance.fontScale","10.0") json.UpdateString("appearance.text[0]","Reason: Agreement Accepted by John") json.UpdateString("appearance.text[1]","Date: current_dt") // Load the signing certificate. (Use your own certificate.) cert := chilkat.NewCert() success = cert.LoadPfxFile("qa_data/pfx/myPdfSigningCert.pfx","secret") if success == false { fmt.Println(cert.LastErrorText()) pdf.DisposePdf() json.DisposeJsonObject() cert.DisposeCert() return } // Tell the pdf object to use the certificate for signing. success = pdf.SetSigningCert(cert) if success == false { fmt.Println(pdf.LastErrorText()) pdf.DisposePdf() json.DisposeJsonObject() cert.DisposeCert() return } // Note: When adding an additional signature to a PDF, the existing signatures // are validated, and this includes validating the certificates previously used to // create the existing signatures. (A signature typically embeds the signing certs.) // In some cases, the certificates and/or certs in the chain of authentication for // existing signatures are not present, and are not available on the current system. // In this case, you can skip the validation by setting this keyword in UncommonOptions: pdf.SetUncommonOptions("NO_VERIFY_CERT_SIGNATURES") success = pdf.SignPdf(json,"qa_output/hello_signed.pdf") if success == false { fmt.Println(pdf.LastErrorText()) pdf.DisposePdf() json.DisposeJsonObject() cert.DisposeCert() return } fmt.Println("The PDF has been successfully cryptographically signed.") // Here's a screenshot of the 2nd signature positioned under the 1st in Adobe Acrobat: pdf.DisposePdf() json.DisposeJsonObject() cert.DisposeCert() |
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